Interscan Navigation Systems Pty. Ltd
Training Handbook
LDB-102 DISTANCE DISTANCE MEASURING EQUIPMENT TRAINING TRAINING HANDBOOK
HA72500-TH
TRAINING HANDBOOK for DISTANCE MEASURING EQUIPMENT (DME) LDB-102 Type series A72500
This handbook consists of a selection of material from the standard equipment handbook, specially chosen for use a student training notes and is intended to be used only for this purpose; it does not contain information on, and is not intended to be used as a basis for, equipment maintenance maint enance and alignment. The material consists of the following standard handbook sections: TABLE OF CONTENTS SECTION 1
BRIEF SPECIFICAT SPECIFICAT ION and SPECIFICATION
SECTION 2
TECHNICAL DESCRIPTION
SECTION 4
MAINTENANCE PROCEDURES
APPENDIX APPENDIX A
OPERATI OPERATING NG INSTRUCT INSTRUCTION IONS S
HA72500-TH TABLE of CONTENTS Section 1
Brief Specification
Section 2
Technical Description
Section 4
Maintenance Procedures
Appendix Appendix A
Operating Operating Instruction Instructions s Circuit and Wiring Diagrams
HA72500-TH
LIST OF DRAWINGS DRAWING NUMBER
DRAWING TITLE 1A69737 1A69758 2A69758 1A69873 1-3A7250 0 1A72505
Attenuator Power Supply System, Single AC Power Supply System, Dual AC 250W RF Amplifier LDB-102 DME 1kW System Rack Assembly, Single 1kW DME
CIRCUIT INTERWIRING INTERWIRING CIRCUIT BLOCK DIAGRAM INTERWIR ING (3 sheets)
69737-3-24 69758-3-23 69758-3-28 69873-3-09 69873-3-09 72500-2-26 72505-2-06
2A72505 1A72510 1A72511 1A72512 1A72514
Transponder Wiring Rack Assembly, Dual 1kW DME Monitor Module Main PWB Assembly, Monitor Module Peak Power Monitor Test Interrogator
INTERWIRING INTERWIR ING (3 sheets) INTERWIRING CIRCUIT CIRCUI T (14 sheets) CIRCUIT INTERWIRING
72505-2-37 72505-2-17 72510-3-06 72511-1-01 72512-3-01 72514-3-04
1A72515 1A72516 1A72517
Main PWB Assembly, Test Interrogator RF Generator RF Filter
CIRCUIT CIRCUI T (5 sheets) CIRCUIT CIRCUIT
72515-1-01 72516-2-01 72517-4-02
1A72518 1A72519 1A72520 1A72521
Modulator and Detector Reply Detector Receiver Video Main PWB Assembly, Receiver Video
CIRCUIT CIRCUIT INTERWIRING CIRCUIT CIRCUI T (5 sheets)
72518-2-01 72519-3-01 72520-3-04 72521-1-01
1A72522 1A72523
RF Source IF Amplifier
CIRCUIT CIRCUIT CIRCUI T (2 sheets)
72522-3-01 72523-1-01
1A72524
RF Amplifi er
CIRCUIT
72524-3-01
EMERGENCY CARDIOPULMONARY RESUSCITATION FOR UNCONSCIOUS PATIENT. STAY WITH VICTIM – CALL FOR HELP AND COMMENCE RESUSCITATION.
AIRWAY: Clear the airway. Quickly turn victim on side and remove foreign material from mouth. Place neck and jaw in correct positions.
BREATHING: If not breathing, quickly turn the victim on his back and commence expired air resuscitation. mouth or mouth to nose, using jaw lift method to open airway. Give 5 full ventilations
Check breathing and listen to breath, watch for chest movement. If breathing, leave victim on side and keep the airway clear.
Check circulation, carotid pulse. If present, continue expired air resuscitation at a rate of 15 per minute. Check the circulation after 1 minute and then every 2 minutes. If breathing returns, place the victim
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SECTION 1
SECTION 1
BRIEF DESCRIPTION AND SPECIFICATION
HA72500
SECTION 1 TABLE of CONTENTS
1.
BRIEF DESCRIPTION AND SPECIFICATION........................................... 1-1 1.1 FUNCTIONAL DESCRIPTION 1-1 1.1.1 Introduction................................................................................................ 1-1 1.1.2 Application ................................................................................................. 1-1 1.2 SYSTEM OPERATION 1-1 1.2.1 Introduction................................................................................................ 1-1 1.2.2 Distance Measuring Function..................................................................... 1-1 1.2.3 DME Pulse Generation .............................................................................. 1-2 1.2.4 System Squitter.......................................................................................... 1-2 1.2.5 Maximum Reply Rate................................................................................. 1-2 1.2.6 Identification Message ............................................................................... 1-3 1.2.7 Range and Echo ........................................................................................ 1-3 1.2.8 Remote Control and Monitoring System..................................................... 1-3 1.3 PERFORMANCE SPECIFICATION 1-3 1.4 DOCUMENTATION 1-10
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LIST of FIGURES Figure 1-1
DME Principle .......................................................................................1-2
LIST of TABLES
Table 1-1 Table 1-2
Performance Characteristics Summary.....................................................1-4 Controls and Indicators .............................................................................1-7
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SECTION 1
1. BRIEF DESCRIPTION AND SPECIFICATION 1.1
FUNCTIONAL DESCRIPTION
1.1.1
Introduction
This document describes the Distance Measuring Equipment (DME) series LDB-102 type A72500. It contains information which includes equipment description, alignment procedures, installation and operation instructions, component parts lists, and circuit diagrams. The LDB-102 is designed and manufactured to meet the requirements laid down by the International Civil Aviation Organisation (ICAO) authority for this type of equipment. The LDB-102 is fully solid state, and uses digital techniques to minimise the number of adjustable controls.
1.1.2
Application
The DME system is a navigational system which provides slant-range distance information between aircraft and a ground station. The system consists of a transmitter/receiver (interrogator) in the aircraft, and a receiver/transmitter (transponder) ground station. The interrogator transmits interrogation pulses to the transponder, which on receipt of the interrogation pulses is triggered to transmit a sequence of reply pulses which have a predetermined time delay. The time difference between interrogation and reply is measured in the interrogator and translated into a distance measurement which is presented on a digital display in the
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interrogator receives replies to its interrogations, the interrogator 'locks' onto the reply pulses and reduces its transmitted repetition rate to approximately 30 pp/s (this is called 'tracking' mode). Figure 1-1
DME Principle
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causes the receiver automatic gain control to limit the gain of the receiver until the weaker, more distant, aircraft are excluded from the transponder, thus lowering the transponder loading. Should the system reply rate still exceed the 2800 pp/s limit, video output pulses are randomly suppressed to limit the m aximum reply rate to 2800 pp/s.
1.2.6
Identification Message
Each operational DME is identified by a 2-character or 3-character Morse code message which is transmitted every 40 seconds. Each identification code (ident) is unique and identifies a specific DME site. The identification message code is programmed by preset controls within the equipment, and can be readily altered if the ident is required to be changed. Frequently, DME is collocated with ILS or VOR equipment and for this reason the DME may operate either as a master or as a slave for the generation and transmission of the station identification message. When the DME is operating as a slave unit, any failure of the external ident generator will cause the DME to internally generate and transmit the ident in place of the failed unit.
1.2.7
Range and Echo
The normal slant range for a DME system operating in the ultra high frequency band is approximately 200 nautical miles (370 km) for good conditions at maximum transponder sensitivity. This maximum range may be seriously degraded, however, by the terrain surrounding the installation and by the maximum demands of interrogating aircraft. A major contributing factor to distance accuracy degradation is the effect of echoes on the interrogation pulses arriving at the transponder. The shortest path is the direct line
HA72500
Table 1-1 CHARACTERISTIC Power Supply Requirements
Environmental Condition Limits
SECTION 1
Performance Characteristics Summary PARAMETER
VALUE/LIMITS
Voltage Current drain (normal operation, 27.0 volts DC) Single 1 kW, Single Monitor at 945 Hz (squitter rate) at 2800 Hz (maximum traffic) Dual 1 kW, Dual Monitor at 945 Hz (squitter rate) at 2800 Hz (maximum traffic)
21 to 28 volts
Temperature (indoor equipment) Relative humidity (indoor equipment)
-10 to 60 degrees C 95% (to 45 degrees C) 50% (45 to 60 degrees C) -40 to 70 degrees C (100% RH)
Antenna Frequency and Pulse Characteristics
Transmitter
Operating frequency (set by installed crystals) Pulse spacing (microseconds) Transmit X channels Y channels Decode X channels Y channels Transmitter power (measured at rack connector)
6 amperes 12 amperes 7 amperes 13 amperes
Can be set to any of 252 channels in the 962-1213 MHz band 12.0±0.1 30.0±0.1 12.0±1.0 36.0±1.0
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CHARACTERISTIC Receiver
SECTION 1
PARAMETER
VALUE/LIMITS
Receiver triggering level
-91 dBm at cabinet connector
Adjacent channel rejection
80 dB
Spurious rejection
80 dB
IF rejection
80 dB
Frequency stability
+0.002% kHz
System time delay
Test Interrogator and Monitor
X channel
35 to 50 microseconds
Y channel
50 to 56 microseconds
Accuracy
For interrogation signal levels between -81 dBm and -10 dBm at cabinet connector and throughout the range of service conditions the bias error shall not exceed +0.5 microseconds
These modules continuously interrogate the transponder and monitor its reply and initiate an alarm for the following fault conditions: REPLY DELAY Alarm limits can be set in 0.1 microseconds steps up to +1.0 microseconds SPACING Alarm limits can be set in 0.1 microseconds steps up to +1.0 microseconds EFFICIENCY Alarms when efficiency drops to 60% REPLY RATE Alarms when reply rate fails below 833 pulse-pairs per second or exceeds 3000 pulse-pairs per second PULSE WIDTH Alarms if not in range 3.0 to 4.0 microseconds PULSE RISE TIME Alarms if greater than 3.0 microseconds
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CHARACTERISTIC AC Mains Power Supply
SECTION 1
PARAMETER Output voltage range
Normal operation Test operation
21-28 volts, adjustable
18-33 volts. adjustable 30 amperes maximum 200,210,220,230,240,250,260 volts +10% Input frequency 48 to 65 Hz Line regulation 1 % for +15% variation Load regulation 0.45V over range 0 to 30 amperes Noise and ripple 200 mV peak to peak Variation of output voltage with temperature Within 0.2V over temperature range Transient response 0-20 amperes Less than 2 volts; 50 milliseconds recovery 20-0 amperes Less than 2 volts; 200 milliseconds recovery Efficiency 70% at 27 volts, 10 amperes Overcurrent protection Current limits can be set over the range 20 amperes to 30 amperes Reverse voltage protection Fuse Ambient temperature range -10 to +60 degrees C Voltage 24 volts nominal Capacity (discharged at 10-hour rates to 105 AH (for specified operating 1.85 volts per cell - AS1981) time) Operating time At maximum 6.5 hours - dual DME transponder reply 7.0 hours - single DME rate Output current rating input voltage
Battery Supply
VALUE/LIMITS
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Table 1-2 UNIT/MODULE Control Panel
SECTION 1
Controls and Indicators CONTROLTYPE Pushbutton with LED indicators
Rotary switch 10 positions 1…10 LED indicators
FUNCTION SELECT MAIN (3 buttons)
SETTINGS or INDICATION OFF/RESET (Alarms) Yellow NO1 Green NO2 Green MONITOR ALARM INHIBIT Red (toggle action) (NORMAL) MAINTENANCE (mode) ON Red (toggle action) (OFF) SOURCE (of control) LOCAL Yellow (2 buttons) REMOTE Green RECYCLE (after shutdown) ON Green (toggle action) (OFF) ALARM DELAY Delay in seconds from fault appearing until the CTU takes action. STATUS
ALARM REGISTER (indicates alarm status at last TRANSFER/ SHUTDOWN action by the equipment)
NO 1 ON NO 2 ON NORMAL TRANSFER SHUTDOWN MAINTENANCE DELAY SPACING EFFICIENCY TX RATE RF POWER
Green Green Green Yellow Red Red Red Red Red Red Red
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UNIT/MODULE Test Facility
SECTION 1
CONTROLTYPE Pushbuttons
FUNCTION SETTINGS or INDICATION Five pushbuttons, the functions of which are definable by the bottom line of the TEST FACILITY display. Through a menu of options, the following information can be selected by the se pushbuttons to be displayed on the top line of the TEST FACILITY display. Parameters Spacing Transmitter pulse spacing Delay PwrOut Effncy
Signal Levels
D. Rate Tx. Rate Width Rise Fall Vcal Rcal Tcal RV.Osc RV.RF
Reply delay RF power out Reply efficiency, when maintenance mode is OFF. When maintenance mode is ON, a sub-menu under this choice gives access to (Reply) Efficiency (normal levels) (Reply) Efficiency (high level) (Reply) Efficiency (low level) Decoded pulse rate Transmitted pulse rate Transmitted pulse width Transmitted pulse rise time Transmitted pulse fall time Voltage measurement calibration Rate measurement calibration Time measurement calibration Receiver video local oscillator Receiver video transmitter RF drive
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UNIT/MODULE CONTROLTYPE Test Facility Pushbuttons (continued) (continued)
Pushbutton Pushbutton
FUNCTION SETTINGS or INDICATION Miscellaneous (only Reset Restart count set to zero available if Alarm1 Modifies alarm register display MAINTENANCE mode so that only those alarms due not selected) to Transponder 1 are displayed Alarm2 Modifies alarm register display so that only those alarms due to Transponder 2 are displayed LEDTst Turns on all LEDs on the CTU front panel Version CTU software version identity Ident Source (for speaker) Mon1 Monitor module 1 Mon2 Monitor module 2 2440 Hz 2240 Hz tone OFF Off Source Selection Ch1 Selects the test (only available if interrogator/monitor module to Ch2 MAINTENANCE mode use for parameter, level and is selected) power supply voltage measurements Fault Limits Delay Delay upper and lower limits (only available if Spacing Spacing upper and lower limits MAINTENANCE mode Effncy Efficiency lower limit is selected) Tx.Rate Transmitted pulse rate upper and lower limits Ant.Pwr Antenna power lower limit ESC(APE) Returns to topmost menu TI RATE Sets interrogation rate of test interrogator.
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1.4
SECTION 1
DOCUMENTATION
Equipment Serial Numbers All equipment assemblies have individual serial numbers allocated. These are used to record the history of the equipment. Modification Records The modification status of all equipment is controlled with a modification register, and a modification record is attached to each item of equipment. Navaid users are not normally notified of any change of modification status as equipments with differing modification status are functionally interchangeable. Modification Bulletins During the production life of equipment, design changes may be made to alter or improve particular performance characteristics. These changes are documented on a Technical Service Bulletin (TSB) which will be f orwarded to users as appropriate. Type Numbering System All manufactured equipments; and subassemblies are identified by a 7-digit type number. For navaid equipments the type number has the form YAXXXXX, in which: •
'XXXXX is a 5-figure number which is unique to the particular assembly.
•
‘Y’ is a prefix digit which identifies a particular variant of assembly type 'XXXXX’.
•
‘A’ signifies that the equipment is avionics equipment.
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SECTION 2
SECTION 2
TECHNICAL DESCRIPTION
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SECTION 2 TABLE of CONTENTS
2.
TECHNICAL DESCRIPTION ...................................................................... 2-1 2.1 SYSTEM DESCRIPTION 2-1 2.1.1 Principles of Operation............................................................................... 2-1 2.1.2 Signal Flow ................................................................................................ 2-1 2.1.3 Mechanical Description .............................................................................. 2-5 2.1.4 Rack Wiring................................................................................................ 2-7 2.2 SUBSYSTEM DESCRIPTIONS 2-7 2.2.1 Introduction................................................................................................ 2-7 2.2.2 Transponder Subsystem ............................................................................ 2-7 2.2.3 Control and Test Subsystem ...................................................................... 2-8 2.2.4 Power Supply Subsystem .......................................................................... 2-9 2.3 MODULE DESCRIPTIONS 2-12 2.3.1 Introduction.............................................................................................. 2-12 2.3.2 RF Panel Single DME 1A72545 and RF Panel Dual DME 2A72545 ........ 2-12 2.3.3 Receiver Video 1A72520.......................................................................... 2-15 2.3.4 Transmitter Driver 1A72530 ..................................................................... 2-30 2.3.5 Transponder Power Supply 1A72525....................................................... 2-39 2.3.6 2.3.6 1kW RF Power Amplifier Assembly 1A72535.................................. 2-41 2.3.7 1kW PA Power Supply 1A72540 .............................................................. 2-44 2.3.8 Test Interrogator 1A72514 ....................................................................... 2-47 2.3.9 Monitor Module 1A72510 ......................................................................... 2-60 2.3.10 Control and Test Unit 1A72550 ................................................................ 2-86 2.3.11 Power Distribution Panel Single DME 1A72549 and Power Distribution Panel
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LIST of FIGURES Figure 2-1 Figure 2-2 Figure 2-3 Figure 2-4 Figure 2-5 Figure 2-6 Figure 2-7 Figure 2-8 Figure 2-9 Figure 2-10 Figure 2-11 Figure 2-12 Figure 2-13 Figure 2-14 Figure 2-15 Figure 2-16 Figure 2-17 Figure 2-18 Figure 2-19 Figure 2-20 Figure 2-21 Figure 2-22
Block Diagram Single 1kW DME ...........................................................2-3 Block Diagram Dual 1kW DME..............................................................2-4 Layout of DME LDB-102 Single 1kW Rack............................................2-5 Layout of DME LDB-102 Dual 1kW Rack ..............................................2-6 Transponder Subsystem Diagram.........................................................2-8 Control and Test Subsystem Diagram...................................................2-9 Single 1kW DME Power Distribution ...................................................2-10 Dual 1kW DME Power Distribution......................................................2-11 Directional Coupler 1A69755...............................................................2-13 Directional Coupler 2A69755...............................................................2-14 Waveforms for Interrogation Pulse Processing....................................2-18 Ident Keyer Waveforms.......................................................................2-22 Transmitter Driver Block Diagram .......................................................2-30 Shaped Pulse Generation Waveforms ................................................2-33 1kW RF Power Amplifier Block Diagram .............................................2-42 CTU Bus Timing - Read ......................................................................2-49 CTU Bus Timing - W rite ......................................................................2-49 Modulator and Detector Waveforms....................................................2-56 Delay Monitor......................................................................................2-62 Delay Monitor Waveforms ...................................................................2-62 Spacing Monitor ..................................................................................2-64 Spacing Monitor Waveforms ........2-64
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Table 2-4 Pulse Shaper Board Test Points .............................................................2-35 Table 2-5 Summary of Front Panel Controls and Indicators : Transmitter Driver..... 2-37 Table 2-6 Summary of Internal Controls : Transmitter Driver ..................................2-38 Table 2-7 Summary of Front Panel Controls and Indicators : Transponder Power Supply 2-40 Table 2-8 Summary of Internal Controls : Transponder Power Supply....................2-41 Table 2-9 Summary of Front Panel Controls and Indicators : PA Power Supply..... .2-46 Table 2-10 Summary of Internal Controls : PA Power Supply ...............................2-46 Table 2-11 Summary of Front Panel Controls and Indicators : Test I nterrogator Module 2-58 Table 2-12 Summary of Internal Controls: Test Interrogator Module .....................2-59 Table 2-13 Summary of Front Panel Controls and Indicators : Monitor Module.....2-83 Table 2-14 Summary of Internal Controls : Monitor Module...................................2-84 Table 2-15 Ident PLD Outputs: MA_IDENT_IN_1,2, MA_IDENT_OUT, IDENT_TONE_TRANSFORMER, DET_IDENT_KEY.........................................2-90 Table 2-16 Ident PLD Output: IDENT+ CPU_TONE..............................................2-90 Table 2-17 Ident PLD Output: IDENT_ON.............................................................2-91 Table 2-18 CTU Processor Board LED Indicators .................................................2-91 Table 2-19 CTU Processor Board Links................................................................2-92 Table 2-20 CTU Processor Board D19 and D24 Inputs.........................................2-92 Table 2-21 CTU Processor Board D18 and D23 Outputs......................................2-93 Table 2-22 CTU Front Panel Address Map ...........................................................2-95 Table 2-23 CTU Front Panel Switch Scanner and Coder Output...........................2-96 Table 2-24 RCMS Interface Address Map.............................................................2-97
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2. TECHNICAL DESCRIPTION 2.1
SYSTEM DESCRIPTION
2.1.1
Principles of Operation
The LDB-102 series DME equipment is available in several standard configurations, depending on RF power, duplication and primary power requirements. It is available as either a single equipment or dual equipment configuration; each of these may be fitted with either low power or high power RF amplifiers. The basic transponder provides modulation and RF drive to a power amplifier assembly which raises the power output to either 200 watts or 1kW Single Transponder - Single Monitor The basic transponder assembly consist of five modules, a control panel, an RF distribution panel (mounted behind the control panel), and a DC distribution panel. Low power and high power amplifier assemblies fed by a driver amplifier boosts the peak power to more than 200 watts for the low power version and more than 1kW for the high power version. Aircraft interrogation signals from the antenna pass through the RF panel to the receiver and video circuits which process the signals. If the signals are valid interrogations, then a reply is initiated through the RF power amplifiers and RF panel back to the antenna for transmission. A test interrogator, in conjunction with a monitor, continuously interrogates the
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prevents the transmitter output from coupling directly into t he receiver. The preselector, comprising three coupled resonant cavities tuned to the receive frequency, reject the IF image frequency, rejects unwanted spurious frequencies and gives further attenuation to the transmitter output frequency. The interrogation signals then pass t o the receiver video module. The receiver video module detects and decodes on-channel interrogations and encodes the synchronous reply trigger pulse pair. Random reply pulse pairs are added, if necessary, to the synchronous replies to maintain a minimum reply rate of 915 Hz. The maximum reply rate is limited to a nominal 2800 Hz by reducing receiver sensitivity. The keyed identification signal (ident) occurs every 40 seconds, the 'mark' of the ident replacing normal reply pulses with a 1350 Hz pulse train. Receiver output reply pulse pairs trigger the modulation generator in the transmitter driver module, producing RF pulses which are connected to the 1kW RF power amplifier module. The excitation frequency for the transmitter driver is provided by the local oscillator in the receiver video module. The output from the power amplifier is connected back to the RF panel, where it passes through the circulator and directional coupler to the antenna for the reply transmission to the aircraft. In a dual system, the RF panel includes a coaxial transfer relay to connect either of the transponders to the antenna, the other being terminated in a dummy load. The equipment also has a test interrogator and a monitor. These units are used together to check the performance of the DME. The test interrogator continuously interrogates the DME in a similar manner to an aircraft. This invokes the transponder to generate reply pulses; these are detected and processed by the monitor to verity that the signal parameters of the replies being generated by the transponder are within acceptable
HA72500 Figure 2-1
SECTION 2 Block Diagram Single 1kW DME
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Figure 2-2
SECTION 2
Block Diagram Dual 1kW DME
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2.1.3
SECTION 2
Mechanical Description
The LDB-102 DME is designed to be mounted in a standard 483 mm (19-inch) rack. The dimensions of the rack for both single and dual DME racks are 1800 mm high by 560 mm wide by 560 mm deep. The bulk of the electronics is contained within five modules each of 6 rack units height (267 mm) which plug into the transponder subrack and are secured by holding screws to the rack frame. Figure 2-3
Layout of DME LDB-102 Single 1kW Rack
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Figure 2-4
SECTION 2
Layout of DME LDB-102 Dual 1kW Rack
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SECTION 2
mounted in the bottom part of the main equipment rack. In a dual transponder, two of these supplies are mounted in a separate rack as Dual AC Power Supply 2A/3A69758. If standby batteries are used, these are housed in a separate, ventilated enclosure which may be either inside or outside the main equipment shelter. The physical layout of the 1kW dual transponder, dual monitor, AC supply version is shown in Figure 2-4.
2.1.4
Rack Wiring
REFER Rack Interwiring (Single 1kW DME) 72505-2-06 Rack Interwiring (Dual 1kW DME) 72505-2-17 Rack interwiring is shown in these drawings, which each consist of three sheets: •
Sheet 1 shows RF cable interwiring.
•
Sheet 2 shows signal interwiring.
•
Sheet 3 shows power interwiring.
2.2
SUBSYSTEM DESCRIPTIONS
2.2.1
Introduction
To enable easier understanding of the LDB-102 DM E system the description is split into three subsections - Transponder Subsystem, Control and Test Subsystem and the Power Supply Subsystem. For further information on nay individua modules, refer to Section 2.3 of this handbook.
HA72500 Figure 2-5
SECTION 2 Transponder Subsystem Diagram
The test interrogator operates as an independent unit simulating aircraft interrogation pulses. The transponder treats these pulses as normal interrogations and responds accordingly, allowing the test interrogator to extract operational parameters from the
HA72500 Figure 2-6
SECTION 2 Control and Test Subsystem Diagram
2.2.4
Power Supply Subsystem
2.2.4.1
Single DME Power Distribution
The single DME is supplied with nominal 240 volts 50 Hz mains AC which powers a battery charger (Power Supply 3A71130) mounted at the bottom of the transponder rack. This supplies a regulated +27 volts to the rack's battery terminals, to which batteries may be connected and charged. The battery t erminals are also connected to the distribution panel (through a diode to protect against battery reversal) which distributes the supply through circuit breakers to the rest of the DME circuitry. The CTU and the transponder are powered through a 5A circuit breaker. The CTU power (+24V_AUX) is routed via the external I/O board. The transponder power
HA72500 Figure 2-7
2.2.4.2
SECTION 2 Single 1kW DME Power Distribution
Dual DME Power Distribution
The dual DME is supplied by a Dual AC Power Supply 2A69758. This consists of two AC Power Supplies 3A71130 mounted in a rack adjacent to the transponder rack. The two separate +27 volts DC outputs of these supplies are connected to the rack's battery terminals, to which batteries may be connected and charged. The battery terminals are also connected to the distribution panel (through diodes to protect against battery reversal) which distributes the supply through circuit breakers to
HA72500 Figure 2-8
SECTION 2 Dual 1kW DME Power Distribution
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2.3
MODULE DESCRIPTIONS
2.3.1
Introduction
Section 2.3 contains functional and circuit descriptions for the modules and other assemblies comprising the DME. The material is arranged in hierarchical fashion, with each description at module level being immediately followed by sub-sections describing the elements of that module.
2.3.2 2A72545
RF Panel Single DME 1A72545 and RF Panel Dual DME
REFER Circuit Diagram 72545-3-04 (Single DME) Circuit Diagram 72545-3-05 (Dual DME) The RF panel is physically mounted behind the CTU at the back of the rack. Unrestricted access to the panel can be gained by opening the back door of the rack. The RF panel mounts all the antenna feed and coupling components permitting short feeder lengths from the output RF amplifier to maintain low RF loss and leakage. All fixed coaxial wiring is accomplished in semirigid or flexible semirigid cable which also assists in low RF leakage and low loss. In the case of a single transponder DME (see drawing 72545-3-04), the RF panel has mounted upon it a directional coupler (W3), a circulator (W1), and a receiver preselector filter (Z1). For a dual transponder system an extra preselector filter. circulator, directional coupler and transfer relay are added to enable independent operation of transponders with antenna and dummy load changeover facilities (see drawing 72545-3-05). Switch
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quarter-wave cavity sections of high Q and having an insertion loss of typically 1.5 dB at the receive frequency. As well as rejecting image and intermediate frequency signals, the filter also rejects any reflections from the transmitter which may occur due to antenna system mismatches. Within the pass-band, the filter presents a 50 ohms load to the circulator, and at t he transmit frequency the attenuation is at least 70 dB. It is tunable over the frequency band 950 to 1220 MHz.
2.3.2.2
Directional Coupler 1A69755
REFER Circuit Diagram 72545-3-04 This four coupled port directional coupler is used for monitoring and test signal injection into the antenna feeder of a single DME beacon. It is also used in a dual beacon to interrogate and monitor the off-line transponder for test purposes. It is mounted on the RF panel. The 50 ohms stripline design involves the through-line, one forward and reverse unterminated coupled line and two forward only coupled lines internally resistively terminated. Each coupler is designed for a 30 dB nominal coupling with at least 15 dB directivity over the DME frequency band. Figure 2-9
Directional Coupler 1A69755
HA72500 Figure 2-10
2.3.2.4
SECTION 2 Directional Coupler 2A69755
50 Ohm Termination 1A69757
This is a component of the RF Panel Dual DME 2A72545 and is fitted to provide a termination for the RF output of the second transponder when the second transponder is in maintenance. Physically, it is a 50 ohms 150 watts (average) resistor fixed to a base plate and which terminates a short length of semirigid cable; the loose end of the cable has a SMA connector fitted. A protection cover is fitted over the unit and the base plate is bolted to the RF panel, which acts as a heat dissipator.
2.3.2.5
RF Panel PWB Assembly Single DME 1A72547
REFER Circuit Diagram 72547-1-01
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Transponder 2 terminated, and if this input is low (0 volts) then Transponder 2 is connected to the antenna as in with Transponder 1 terminated. Table 2-1
Summary of Controls and Indicators: RF Panel (Dual) CONTROL/INDICATION FUNCTION DETAILS
TYPE Toggle switch, centre off
2.3.3
LEGEND
FUNCTION/SETTING/INDICATION
TPNDR2
The output of Transponder 2 is fed directly to the antenna. The output of Transponder 1 is terminated in the 50 ohms load.
TPNDR1
The output of Transponder 1 is fed directly to the antenna. The output of Transponder 2 is terminated in the 50 ohms load.
NORMAL
The CTU controls which transponder output is fed to the antenna.
Receiver Video 1A72520
REFER Interwiring Diagram 72520-3-04 The Receiver Video module provides the main receiver functions and contains the Main PWB Assembly Receiver Video 1A72521, RF Source 1A72522, RF Filter 1A72517, IF Amplifier 1A72523 and RF Amplifier 1A72524. The received signal is passed from the antenna into the RF panel and preselector filter on to the receiver. A circulator in the RF panel is used to isolate the receiver from the transmitter while allowing the use of a common antenna. The cavity-tuned preselector rejects the image signal and provides initial selectivity for the receiver.
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SECTION 2
as an on-channel gating pulse and to develop the AGC voltages to control the dual-gate FET amplifier stage. Both the logarithmic output pulse and the on-channel pulse are fed into the receiver video main PWB assembly for decoding and processing. In the main PWB assembly the signals from the IF amplifier detectors are detected and processed. Pulses arriving at the logarithmic pulse input without corresponding onchannel pulses are ignored as spurious or adjacent channel noise. The remaining onchannel logarithmic pulses are passed on to a half-amplitude finder circuit for accurate time referencing. The pulses are then decoded for correct pulse spacing. On receiving and detecting a valid pulse-pair the transponder then enters a programmable wait period before generating an appropriate pulse-pair for transmission as reply pulses. Transponder delay time is referenced to the 50% amplitude point on the leading edge of the first interrogation pulse. As a result of reflection, genuine interrogation pulses which appear to be valid may be received, having been delayed due to a longer transmission path. These signals could trigger a misleading reply; to prevent this happening a dead time is introduced, following a successful interrogation, to block out any such signals. All pulses for transmission are generated in the receiver video. All critical pulse durations and time delays are produced by programmable counters and shift registers for which the clocking frequency is derived from a crystal oscillator. Site-dependent programming is set by switches. The ident message is stored on four 8-way DIL switches on the main board. Depending on the appropriate external connections the ident may act as either master or slave.
HA72500
SECTION 2
pass through to the follower-amplifier N7b. In the process, the arriving log video pulse is added on to a DC pedestal voltage of approximately 0.5 volts; N7a clamps the baseline of the log input signal to +1.5 volts ( at the junction of R49 and R36) which is 0.5 volts above the reference input to D50. If the log video input pulse is a result of noise or adjacent channel signals, there will be no accompanying on-channel pulse and D50 will ignore the log video input. This method recognises valid input pulses and maintains the logarithmic shape of these pulses as they are passed to the half-height and timing detectors.
2.3.3.1.2
Half-height and Timing Detection
An adjustable (R45, 6 dB OFFSET) constant current source V15 feeds into the output of N7b. This current flowing through R44 produces an input t o N6:5 which is DC offset with respect to the waveform applied to N5:4 input. Amplifier N6:7 and delay line D38 provide a unity-gain time-delayed signal to the other input of N5:5. Thus the signal at XT6 has been offset by a DC voltage equivalent to 6 dB pulse amplitude, as well as being delayed by a period equal to half the duration of the standard input pulse. Due to the offset in amplitude and the delay applied to the pulse at XT6 the half-height point of the delayed pulse corresponds to the maximum point of the original pulse at XT13. This will always occur for all logarithmic-shaped pulses of standard duration regardless of amplitude and thus the comparator output N5:12 will always identify t he half-height point by going low at this time. As N5:12 goes low, the D-type flip-flop D26:3 is clocked with the D input pin 5 high due to the on-channel pulse still being present. D26:1 generates a pulse of 2.5 microseconds duration which is determined by the 14-stage shift register D25, clocked at 5.5296 MHz.
HA72500
SECTION 2 Figure 2-11
Waveforms for Interrogation Pulse Processing
At the time when a valid first pulse of a pulse-pair is emerging from the shift register, the second pulse will have operated D26:1 and enabled D20:3 via the gate D41:4 thus
HA72500
SECTION 2
SDES pulse trailing edge occurs approximately 10 microseconds down the shift register. After a further delay of approximately 1.8 microseconds in the half-amplitude finder, a pulse is generated with the correct separation to form a decodable pair. For Y channels, the pulse trailing edge occurs approximately 34 microseconds down the shift register. The fast-attack slow-release time constant provided by V20, R55 and C79 disables the 2.5 microsecond pulse at D26:1 for approximately 1.5 microseconds after each pulse terminates. This prevents the generation of SDES pulses with zero gap between them, which situation could cause inhibiting decoding if the trailing edge of one SDES pulse was about to generate the artificial second pulse only to be inhibited by a following SDES pulse.
2.3.3.1.5
Long Distance Echo Suppression
In a similar fashion to SDES, the long distance echo suppression (LDES) function will eliminate echo pulses with long delays. LDES is only initiated after receiving a valid pulse-pair and with the LDES switch S9 set ON, Counter D39 will be set by the pulse from D20:6 and will count the LDES PERIOD set on switch S6. D39 derives its clock, 43.2 kHz, from the divider D49 and the 5.5296 MHz crystal oscillator. The function of LDES is to inhibit decoding of an interrogation pulse-pair which is produced by a distant reflector such that it arrives after the dead time has expired. It operates by increasing the dead time by (if set to be longer than the normal dead time) an adjustable period (determined by switch S6) for those interrogations which exceed a preset level set by R46, LDES LEVEL and compared in N5:10. This provides a better compromise in traffic handling capability than would be achieved by simply increasing the dead time for all interrogation signal levels. Switch S6 sets the LDES period in multiples of the 43.2 kHz clock; that is, 23.15
HA72500
SECTION 2
Address 01 selects squitter pulses, 00 selects interrogation pulses, and 11 selects ident pulses. When a double pulse decode occurs, D11 is asynchronously loaded to a count of 12. D11 counts down to 0 at a clock rate of approximately 173 kHz, and clamps at a count of 0 by feedback from pin 12 to pin 4. The interrogation select pulse applied to D12:10 is approximately 70 microseconds in duration and drives D12 to accept the output pulse, D31:10, from the beacon delay timer. Reply pulses have a lower priority than ident pulses, but a higher priority than squitter. Thus, provided that there is no ident mark transmission in progress and D11 is counting, the multiplexer D12 will have address 00 selected, which will allow the delay timer pulse from D31:10 to enable D3:13 and the delay shift registers D32, D33 and D34. These shift registers generate the reply pulse separation time. The pulse generated by D3:10 is used as the first pulse of the pulse-pair and passes via V1 and D4:12 as the trigger pulse to the transmitter driver. The same pulse from D3:10 is delayed by the shift registers D32, D33 and D34 to create the second pulse in D35:10 at the failing edge of the clock. The time delay created by the shift registers may be varied by the switches S3 and S4. The REPLY PULSE SEPARATION switch S3 allows the delay to be altered in steps of approximately 180 nanoseconds, whereas the SELECT ENCODER MODE switch S4 provides for the selection of a 12-microsecond delay for X channel operation or a 30-microsecond delay for Y channel operation.
2.3.3.1.8
Identification Message (Ident)
The ident message is a 2-character or 3-character Morse code signal with a 1350 Hz tone and having a 'dot' period of 0.125 seconds. The tone frequency is derived from the 5.5296 MHz clock, thus assuring accuracy of the tone frequency. The ident message is set by four 8-bit SPST switches (S13, S14, S15, S16).
HA72500
SECTION 2
S15/S16 to the dot or dash line to g ive the first desired code element. With a dot selected, a high level will be produced at the code output for one full clock cycles when D51:2 goes high. When D51:2 is clocked low on the next clock pulse the generation of a 'dot-length' space is automatically inserted after the f irst element. The next clock pulse from D44:5 clocks D36 to its next state for the generation of the next code element, and the sequence is repeated. With a dash selected by closure of S1 6 to the dash position, the dash bus will be high, which will preload the dash timer D43 with a decimal 3 causing the output to remain high for three dot periods.
HA72500 Figure 2-12
SECTION 2 Ident Keyer Waveforms
HA72500
SECTION 2
The line labelled COUNTER D36 STATE in Figure 2-12 traces the counter zero 15,14, etc, states and the progression of the high along the demultiplexer output. At the end of the character generation sequence D37:13 is activated and an inhibit signal is applied to D43:4, stopping the operation of the keyer until the next start pulse is received. Where a VOR and a DME beacon are collocated they may be operated in either 'independent' mode or 'associated' mode. D30 is a divide-by-4 counter controlling the switching of D19 such that three consecutive ident code sequences from D52:3 are switched to MASTER IDENT OUT and the fourth ident code sequence is switched to D48:9 for INTERNAL IDENT.
2.3.3.1.9
Squitter
Squitter is generated as a pseudo-random set of pulses at an average rate of 945 Hz and is transmitted at the lowest priority, being preceded by t he ident message and reply pulses. As the interrogation pulse rates increase to 945 Hz, the squitter becomes totally inhibited. Squitter is generated by the action of D15 and D16 operating at different clock rates (from D49:12 and D49:1 respectively) and the arranged 'disorder` of the parallel load lines into D15. D16 is a 5-stage Johnson counter clocked at 1.35 kHz. The10 outputs go high, in turn, for one clock period. D15, an 8-bit, parallel-in, serial-out shift register, is clocked at 10.8 kHz and is loaded at a rate of 1350 Hz with the end bit always being zero, and with the other inputs loaded no bit (3/10 of t he time) with 1 bit (7/10 of the time), in the disordered pattern, from D16. This produces the required pseudo-random pulse rate.
HA72500
SECTION 2
When this over-interrogation condition exists the output pulses from D18:7 provide two output signals; one, via buffer D4:9 and XN1:9a, to the test interrogator to switch to high signal level interrogation for monitoring, and another via XN2:7 to t he W amplifier to desensitise the receiver, thus discriminating against weaker interrogations from distant aircraft. Once the receiver gain reduction has achieved control of the interrogation rate the video inhibiting via D3a, as described above, ceases. If XT22 and XT21 are bridged the receiver gain reduction is prevented and maximum response rate control is provided by the video inhibit method. This latter method treats all aircraft equally, giving each the maximum possible response rate for the interrogating conditions.
2.3.3.1.12
Output Inhibit
The TX MODULATOR TRIGS output at XN1:13c is suppressed at power switch-on, during transfer relay operate time, and (if the non-active transponder) during warm standby. Suppression is provided by a 5 volts logic level applied to XN1:29b which tristates the output, inhibiting the trigger pulses to t he modulator and stopping transmitter output pulses. The primary fault signals REPLY-DEL_FLT_1/2 and PULSE_SPAC_FLT_1/2, when low, indicate that there is a fault in the primary parameters. If both REPLY_DEL_FLT_1 and REPLY_DEL_FLT_2 or both PULSE_SPAC_FLT_1 and PULSE_SPAC_FLT_2 are low, then the counter D8 begins counting the clock pulses produced by the RC oscillator of D8:9, 10, 11. When output 9, D8:15, goes high (after about 70 seconds) the oscillator of D8 is disabled, causing D8 counter to hold its count. The high input on D4:15 inhibits TX_MODULATION_TRIGS. The action of the inhibit will be disabled when the input signal INHIBIT_DISABLE is low.
HA72500
SECTION 2
The signal generation is accomplished by the use of a crystal oscillator operating in the frequency range of 80 to 101.5 MHz, one-twelfth of the required signal frequency. The crystal oscillator output is buffered and then multiplied in three stages to produce the operating signal frequency. The oscillator stage V1 incorporates a fifth-overtone crystal G1 in series resonance in the feedback path. Feedback from V1 emitter is passed through the series resonant crystal to create selfexcitation to the transistor via a damped base tank circuit comprising of L1, C2 and C11. The tuned circuit L1, C2 and C111, as well as correcting phase shifts around the feedback loop, also ensures that the f ifth-overtone crystal operates without any tendency to change mode. An inductor, L6, is connected across the crystal and is selected to resonate with the crystal holder and crystal stray capacitances to f orm a parallel tuned circuit at the operating frequency. This prevents the stray capacitance acting as a separate feedback path which could cause parasitic oscillation and instability. Base bias for the oscillator stage V1 is derived by the resistor chain R2, R23 and R3 and L1. The transistor is operated at a low level of drive to enhance overall stability. The output from the oscillator is taken from the collector of V1 via C6 to the emitter of the grounded-base buffer-amplifier stage V2 which isolates the loading effects of the following multiplier stage from affecting the operation of the crystal oscillator. Capacitor C8 is adjusted for maximum drive into V3. The first stage of multiplication is a self-biased multiply-by-three circuit using a heavily driven transistor V3 with its collector tuned by C12 to three times the oscillator
HA72500
SECTION 2
functions normally over this range of gain reduction provided the pulse signal level is sufficiently above the CW level. Following the input amplifier stage the signal is amplified and successively detected in a cascaded set of logarithmic (log) intermediate frequency amplifiers. The eight amplifiers are divided into two groups of three, coupled via a single parallel resonant circuit which serves to increase the overall signal-to-noise ratio by restricting the bandwidth and a group of two (N1, N2) in parallel. To match the amplifier chain to the dynamic range of the input signal (-90 dBm to -10 dBm), N1 has its input attenuated so that it provides its required contribution to the log detection law at high signal levels without increasing the overall gain at low signal levels. Amplifier N1 provides amplifier N3 with the required bias potential from its pin 7 connection; N6 supplies the bias potential for t he second group of amplifiers; each amplifier is DC coupled. The detected log output from the amplifiers is then amplified in the transistor stage V5 and then delayed 1.6 microseconds in the delay line D1 before reaching the video output of the IF amplifier. The value of the delay compensates for the additional delay to the on-channel pulses in passing through the narrowband filter L3 and L6. The 63 MHz output from the log amplifier chain at N8:3 is mixed in the dual-gate FET mixer circuit of V1 with a 53.75 MHz signal generated by the third-overtone crystal oscillator circuit of V4. The output of the mixer circuit is a 9.25 MHz signal which is filtered by a narrowband filter comprising L3 and L6. L6 includes an inbuilt amplitude detector, and the video output pulses are applied to the input of a voltage comparator N10a. The reference input to this stage is a voltage set by the ON CHANNEL THRESHOLD preset R50. R50 is set to slice the signal just above the noise level, and 15 volts logic pulses are produced at the ON CHANNEL OUT terminal.
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SECTION 2
impedance is matched to the load impedance presented by the mixer by a series length of micro-stripline. Capacitor C5 AC-couples the double-balanced mixer load to V1. The signal from the RF source, which is input via connector XC3, is used as a local oscillator injection signal for the mixer as well as the low power signal for exciting the transmitter stages. The RF source input from XC3 is fed through a 50 ohms microstrip track. A level detector provides a signal for monitoring purposes. A tee-impedance transformer matches the base input impedance of V4. Bias is applied to V4 in the same manner as for V1, via a quarter-wave choke. The collector circuit incorporates a parallel micro-strip inductor pre-tuned by the bypass chip capacitor C11 and the impedances are transformed by a series capacitor into the 50 ohms wireline hybrid 3 dB coupler, W1. W1 splits the RF power between the outputs XC4 (RF output to the transmitter) and the micro-stripline feed to the mixer U1. Both output levels are approximately +11 dBm, and are sensed by the level detector circuit V8 to provide a signal for monitoring purposes. The double-balanced mixer U1 is supplied as a module and is not field repairable. The input RF signal from V1 and the RF signal from the RF source are mixed in U1 to produce the 63 MHz IF signal which is fed out via XC2 into the IF amplifier at a nominal 50 ohms impedance.
2.3.3.5
RF Filter 1A72517
REFER Circuit Diagram 72517-4-02 The RF filter is a lumped element filter used to reduce spurious frequency outputs from the RF source, before the signal is used as local oscillator for the receiver and source for the transmitter; it is tunable from 950 to 1220 MHz.
HA72500
Table 2-2 Module TYPE Yellow LED
Red LED Green LED 16-position switches
SECTION 2
Summary of Front Panel Controls and Indicators : Receiver Video CONTROL/INDICATION FUNCTION DETAILS LEGEND FUNCTION/SETTING/INDICATION REPLIES INHIBITED Flashes on and off when the receiver video is being overinterrogated. On continuously when replies are inhibited. TEST Indicates that the IDENT switch is not in the NORMAL position. DC POWER ON BEACON DELAY
16-position REPLY PULSE switch SEPARATION Toggle switch, IDENT centre off
Indicates that DC power is applied to the module. COARSE Sets the Delay parameter of the receiver video. FINE Sets the Spacing parameter of the receiver video. NORMAL OFF
Normal mode of operation. No ident is generated.
CONTINUOUS Ident is generated continuously. All interrogations are inhibited.
Toggle switch, INHIBIT spring loaded to INTERROGATIONS centre off TEST REPLY RATE Transponder replies are inhibited and squitter reduced to 810 Hz. MONITOR Test jack SDES PULSE Buffered output from the double pulse decoder, which gives the short distance echo suppression pulse to the on-channel g ating logic (15 volts, 2.5 microseconds wide. one pulse per correctly decoded pulse pair). Test jack LDES PULSE Buffered output from the dead time suppressor showing the period of
HA72500
Table 2-3 SUBASSY 1A72521 Main PWB Assembly, Receiver Video
SECTION 2
Summary of Internal Controls : Receiver Video Module TYPE
REF
CONTROL FUNCTIONS LEGEND FUNCTION/SETTING/INDICATION
Preset resistor Preset resistor Preset resistor
R37
CODE SPEED
R39
CODE REPTN
R45
ADJUST 6 dB OFFSET
Preset resistor Slide switch
R46
LONG DISTANCE ECHO SUPP LEVEL SELECT ENCODER MODE
Slide switch
S4 S5
MODE SELECT DECODER
Varies the ident code speed, which is set to 8 Hz. Varies the ident repetition rate, which is set to 1.5 Hz. Set to 0.24 volts during factory test, but may need to be varied at module test level (see Sections 3.3.8, 3.4.17). Varies the LDES DC level. X
Selects X mode operation for the encoder.
Y X Y
Selects Y mode operation for the encoder. Selects X mode operation for the decoder. Selects Y mode operation for the decoder.
16-way rotary S6 switch 16-way rotary S7 switch
SET LDES PERIOD
Slide switch
S8
SDES
Slide switch
S9
LDES
ON OFF ON
CODE ELEMENT
OFF Disables LOES operation. Set the ident Morse code characters.
8-way switch
S13
SET DEAD TIME
Sets the LDES period in multiples of 12.15 microseconds. Sets the dead time period in multiples of 11.57 microseconds Enables SDES operation. Disables SDES operation. Enables LDES operation.
HA72500
2.3.4
SECTION 2
Transmitter Driver 1A72530
REFER Interwiring Diagram 72530-3-03 The transmitter driver mounts the pulse shaper and RF amplifier stages. When used as a driver for the 1kW RF power amplifier it produces rectangular reply pulses generated in response to trigger pulses from the receiver video module. Front-panel test jacks are available for measurement of selected pulse shaper parameters and indicators are provided for TEST and DC POWER ON status. The interconnections of the subassemblies within the module are shown in Drawing 72530-3-03. The subassemblies, each with its own circuit diagram, are described individually in the following sections. Within the transmitter driver there are four subunits; these are the exciter, the medium power amplifier, the power modulation amplifier, and the pulse shaper. The three amplifiers form an amplifier chain; the RF output from the RF amplifier in the receiver video module is input to the exciter section of this amplifier chain at a level of 10 mW. This signal is successively amplified and modulated by the amplifier chain to produce the required pulse shape and timing characteristics. The final output f rom the power modulation amplifier consists of RF pulses, produced in response to trigger pulses from the receiver video module, at a level of 50 watts. Figure 2-13
Transmitter Driver Block Diagram
HA72500
2.3.4.1
SECTION 2
2.3.4.1 Pulse Shaper PWB Assembly 1A72531
REFER Circuit Diagram 72531-1-01 The pulse shaper controls the modulation characteristics of the t ransmitter amplifiers. It does this by producing modulation pulses that are accurately controlled in shape, duration, and time. Pulse production and timing are both controlled by the receiver video, which produces modulation trigger pulses to initiate pulse generation and a 5.5296 MHz signal which is used as the pulse shaper clock signal. The second major function of the pulse shaper is to provide control and adjustment of high tension and bias supplies to the three amplifier assemblies. The inputs to the pulse shaper are: a. Modulation trigger signal from the receiver video (XN1:8c). b. 5.5296 MHz clock signal from the receiver video (XN1:8a, XN1:8b). c. Provision for input from an external temperature sensor, which could be used to determine the DC pedestal level of the high level modulation pulse outputs (XN1:26c, XN1:27a). The external temperature sensor would be a forward biased diode thermally joined to the power transistor heat sink and connected in parallel with V13. (This external sensor is not used in this equipment; adequate temperature compensation is achieved by the on-board sensor V13 responding to ambient temperature changes only.) d. Provision for a detected RF input to be switch-selected to be the source from which the automatic level control of the high level modulation pulses is derived
HA72500
SECTION 2
configurations which do not use the 1kW amplifier, this latter arrangement provides for the high-level modulation in the system. d. To the power modulation amplifier: 1. High tension supply +HT (XN2:20). 2. Adjustable DC voltage POWER MOD AMP DC which supplies the collector voltage for V1 (XN2:18). e. In system configurations having 1kW outputs, high-level shaped pulse signal supplied to the modulating stages in the associated 1kW RF amplifiers (XN1:25a, XN1:25b). f.
Reference voltage TO_TX_LVL (XN1:28b) which is fed to the monitor module and CTU for measurement and comparison purposes.
The leading edge of the shaped modulation pulse is generated by a six-segment adjustable-slope integrator. The durations of the segments are timed by a 5.5296 MHz clock derived from the receiver video. The trailing edge is symmetrically generated by discharging the integrator in reverse order. Because the same generator is used for both pulses of a pair, reply separation of the RF pulses is equal to that determined by the receiver video. Further, the timing of segments by the transponder clock ensures the stability of the beacon reply. Automatic peak pulse level control is applied as a slow acting feedback loop derived either from the detected RF envelope of the 1kW output pulses of the t ransmitter or direct from the high-level output of the pulse shaper. In the quiescent state, awaiting the arrival of a modulator trigger pulse, the output of the
HA72500 Figure 2-14
SECTION 2 Shaped Pulse Generation Waveforms
HA72500
SECTION 2
Following the integrator, the pulse is injected into a two-stage filter network. The pulse amplitude is variable by the MOD PULSE AMPLITUDE adjustment R58. Because the RF amplifiers require a threshold voltage before modulation occurs, a pedestal voltage is added which is variable by the PEDESTAL VOLTAGE adjustment R53. Provision is made for the pedestal level to be determined by an input from an external temperature sensor (XN1:26c, XN1:27a) consisting of a forward biased diode thermally joined to the power transistor heat sink in parallel with V13; this is not employed in this equipment and the reference voltage for N4:3 is derived from the voltage divider R63, R65, V13 which is on-board mounted and compensates for ambient temperature variations only. The pulse and the pedestal voltage are added together in V16. The pulse and pedestal voltage is then amplified in the modulation amplifier comprising V10, V11, V5. The modulation pulse output is accessible at test point XA3 and can be applied either to the associated 1kW RF amplifier (in high-power systems) via XN1:25a, XN1:25b, or to the medium power driver (in low-power systems) via XN2:12. The modulation input to the medium power driver is controlled by the MED COLL switch S4, and can be either the modulation pulse or a variable DC voltage as set by the MED POWER DRIVER DC adjustment R115. The circuitry comprising N2 and associated components forms a video detector and automatic level control circuit. The level is adjustable using ALC LEVEL R62. The ALC source selection switch S3 allows the level control voltage to be derived either from the modulator pulse output at N3:1, or from an external pulse detection circuit. T he level control voltage is accessible at test point XT3. The loop can be disabled by the ALC LOOP switch S2; in the OPEN position this applies a +10 volts to the integrator, N1, input via R40. The two monostables D8 turn off the bilateral switch D4:3, 4 to induce a reduction in the
HA72500
SECTION 2
Table 2-4 LOCATION
On Pulse Shaper Board
Pulse Shaper Board Test Points REF
LEGEND
SIGNAL
XT1, 2
(EARTH)
Earth
XT3
(ALC)
Loop control voltage
XT4
SQUARE MODULATION
Pulse to exciter via XN2:10
XT5
(PWR MOD AMP DC)
DC control voltage to power modulation amplifier via XN2:18
XT6, 8
(EARTH)
Earth
XT7
(EXCITER DC)
Supply voltage to exciter via XN2:8
XT9
(MED PWR DRV DC)
DC control voltage for medium power driver
XT10
(VC1)
Collector voltage to exciter, first stage, via XN2:6
XT11
(TD_TX_LVL)
Detected RF output level from the transmitter driver
XT12
(TD_MOD_LVL)
Detected modulation pulse level
XA1
SQUARE MODULATION
Modulation pulse to exciter
FUNCTION GENERATOR
Output to the pulse-shaping integrator
SHAPED MODULATION
Shape modulation pulse
+15 VOLTS
Supply input to board
DRIVER LEVEL
Detected RF output from transmitter driver
XA2 Board edge (front panel XA3 jacks on XA4 Transmitter XA5 Driver) XA6 XA7
EARTH EARTH
The DRIVER DC POWER switch S1 is mounted as a front-panel control, in the NORMAL position it connects the +8 volts supply to V29 to generate the bias and
HA72500
SECTION 2
The input power level to the class A stage V1 is 10 mW and it delivers to W1 typically 100 mW. The ferrite beads on L1 and L2 keep the Q of the decoupling circuits low over a broad band of frequencies. The transistors of the next two stages each operate between pairs of 90 degree couplers. Operated in this way, both the input and output impedances of these stages approximate to 50 ohms. The transistors V3 and V4 of the second stage operate in class AB condition, their biases being supplied via the RF chokes L5 and L7. The collectors of V3 and V4 are supplied with a rectangular pulse from a common pulse source of adjustable amplitude located on the pulse shaper. This pulse amplitude may be adjusted from 8 volts to 18 volts. The pulsing of the collectors results in the second stage delivering RF pulses of approximately 1 watt peak power to the input of the 90 degree hybrid coupler W2. The third stage operates in class C condition, the bases of transistors V5 and V6 being returned to ground through L9 and L11. In this third stage microstrip circuits are again used to match the transistors V5 and V6 to their 90 degree hybrid couplers. The output impedance of the 90 degree coupler W3 appears as a 50 ohms source to the third stage, and the input impedance of the 90 degree hybrid W4 appears as a 50 ohms load. The common DC collector supply voltage to the transistors V5 and V6 is adjustable on the pulse shaper board from 15 volts to 30 volts. The third stage being driven by pulsed RF at its input delivers corresponding pulses at its output. As used in the transmitter chain of stages, the peak pulse power output from the exciter is typically 4 watts at X C2. Wire loops labelled CURRENT TEST POINT on the circuit diagram allow the magnitude and shape of the current pulses to be measured or observed on an oscilloscope using a current probe. Adjustable trimmer capacitors are provided for the input circuits of all
HA72500
SECTION 2
The capacitors C15, C16 and the resistors R6, R7, R8 act to f itter the current pulses from the HT supply. The peak pulse power of the input pulse is approximately 4 watts, and the pulse power at the output XC2 is t ypically 20 watts.
2.3.4.4
Power Modulation Amplifier 1A72534
REFER Circuit Diagram 72534-3-01 The RF pulse input to the power modulation amplifier at XC1 from the medium power driver is via a short length of semirigid transmission line which operates as a balun converting the unbalanced input coaxial circuits at the module connector to a balanced circuit at the entry points on the microstrip circuit. The amplifier uses a balanced transistor. Microstrip circuits together with some fixed and variable capacitors match the input and output impedances of the transistor to the 50 ohms balanced impedances presented by the baluns. A modulator detected signal, derived from a coupling and detector circuit (V2) is output via XN1:A to the pulse shaper, where it is used to derive a driver pulse level reference voltage. The transistor V3 in the modulation circuit is a source follower. The transistors V4 and V5 buffer the circuits on the pulse shaper against the input capacitance of V3 when used in the pulse modulated role. The inductors L2 and L3 function as RF chokes. When used as a modulator its output power is set by adjustment of the input rectangular pulse power and the amplitude of the video modulation pulse, applied to its collector. Table 2-5 Driver
Summary of Front Panel Controls and Indicators : Transmitter
HA72500
SECTION 2
Table 2-6
Summary of Internal Controls : Transmitter Driver
SUBASSY TYPE 1A72531 Preset Pulse resistors Shaper PWB Assembly
REF
R3. 5, 7, PULSE SHAPE 9, 11, 13
These vary the slope of the segments of the function generator output from base (R3) to apex (R13).
R17
INTEGRATOR BALANCE
Adjusts the balance of the function generator integrator.
R36
BACK PORCH
R52
PEDESTAL VOLTAGE
Adjusts the DC level of the shaped modulation pulse.
R54
2ND PULSE EOUALISING
Adjusts the height of the second pulse of the pulse pair to equalise it with the height of the first pulse.
R58
MOD PULSE AMPLITUDE
Adjusts the amplitude of the shaped modulation pulse.
R62
ALC LEVEL
R69
Toggle switch
CONTROL FUNCTIONS LEGEND FUNCTION/SETTING/INDICATION
POWER MOD AMP DC
Adjusts the spacing between the modulation pulses.
With S2 (ALC LOOP) in its closed position, adjusts the shaped modulation pulse amplitude. Adjusts the power modulation amplifier DC level.
R85
1W PULSE
Adjusts the pulse modulation amplitude.
R97
EXCITER DC
Adjusts the exciter DC level.
R115
MED POWER DRIVER DC
Adjusts the medium power driver DC level.
S1
DRIVER DC POWER
OFF
Power supply to exciter is off.
NORMAL
Power supply to the exciter is under
HA72500
2.3.5
SECTION 2
Transponder Power Supply 1A72525
This assembly comprises the Main PWB Assembly Transponder Power Supply 1A72526 mounted on a supporting frame; the board functions are described in the following section.
2.3.5.1
Main PWB Assembly Transponder Power Supply 1A72526
REFER Circuit Diagram 72526-1-01 This power supply is used to generate the voltage supplies required by the T ransmitter Driver 1A72530. These voltages are +15 volts, +18 volts, and HT (42-50 volts). The front panel TRANSPONDER DC POWER switch enables the transponder (transmitter driver and receiver video) to be turned ON, OFF, or to NORMAL; in this latter condition the transponder is controlled by the CTU via XN1:30b. Commands to turn the power supply on, either from the control panel or the front panel switch, will result in the relay K1 being operated by the action of V11 being turned on. With K1 operated, contacts K1a and K1b will close, supplying the transponder with +24 volts and supplying +24 volts to the internal regulators and inverter. The ON position on the front panel TRANSPONDER DC POWER switch is provided so that power may be applied to a failed system for maintenance. Normally, if a primary fault has occurred and the power has remained on, circuitry in the monitor module(s) will (after a time delay) inhibit pulse-pairs from leaving the receiver video module. However, the ON position of TRANSPONDER DC POWER activates INHIBIT DISABLE line at XN1:9c to enable the faulty system to be operated for fault diagnosis.
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The HT supply is developed by a switched mode inverter which steps up the voltage from the switched +24 volts supply. A power MOSFET V22 is used as a pulse-widthmodulated switch operating into a transformer whose output is rectified, f iltered and controlled at a constant voltage. A constant switching frequency is generated by N1, the frequency (40 kHz) being determined by R34 and C24. A sample of the output voltage presented at pin 1 of N1 is compared with the reference sample at pin 2. The circuit automatically adjusts the width of the on-pulse at pins 11, 14 so that the energy delivered from the secondary of the transformer is just sufficient to maintain a consistent DC out voltage. The HT voltage is set using the HT VOLTAGE adjustment R26. Input current overload protection is provided as follows. An override control on the pulse width generated in N1 is available through pin 9. When pin 9 is open circuit, control of the pulse width is through pin 1 only. As the resistance to ground at pin 9 is lowered, the maximum length of the pulse is progressively shortened, until it drops below 1 microsecond. As the input current increases from the supply, so does the magnitude of the current pulses through V22. The resistor R40 is chosen so that at a predetermined overload current, the peaks of the voltage pulses across R40 just turn off V26. As V26 turns off, V25 turns on to provide a current path from pin 9 to ground, bringing the current limiting action of the circuit into play. The transistors V20 and V1 8 charge and discharge respectively the input capacitance of V22, while the turn-off spike at its drain is controlled at a safe level by V12, V19 in combination, by V13, C16 and R28 in combination, and by C15 and R25 in combination. Table 2-7 Power Supply
Summary of Front Panel Controls and Indicators : Transponder
HA72500
Table 2-8 SUBASSY
SECTION 2
Summary of Internal Controls : Transponder Power Supply CONTROL FUNCTIONS TYPE
1A72526 Preset Main PWB resistor Assembly, Transponder Power Supply
2.3.6
REF R26
LEGEND HT VOLTAGE
FUNCTION/SETTING/INDICATION Sets the HT output voltage to the transmitter driver.
2.3.6 1kW RF Power Amplifier Assembly 1A72535
REFER Circuit Diagram 72535-1-07 The 1kW RF power amplifier assembly is located at the rear of t he rack behind the 1kW PA power supply which provides the power amplifier's HT supply. The elemental electrical operations of the 1kW power amplifier are: •
•
•
•
Formation of the initial shaped pulse by the power modulation amplifier. The first power amplification of the shaped pulses by the broadband amplifier pair A1, A2. Eight-way power division of the output of the A1, A2 pair by the power divider. A second broadband amplification of each eighth-part of power by the amplifiers A3, A4 .... A10, which form the output amplifier.
HA72500 Figure 2-15
SECTION 2 1kW RF Power Amplifier Block Diagram
HA72500
SECTION 2
division by eight is completed using the 90-degree hybrid circuits labelled W2, W 3, W4 and W5 on the power divider. The resistors R1, R2 and R3 provide isolation between the output ports of the Wilkinson circuits; the resistors R5, R6, R7 and R8 on the 90-degree hybrids absorb reflected power from the transistor circuits. A coupling and detector circuit creates a driver detected signal output at XC11. The second broadband amplification of each eighth-part of power is obtained by pairs of amplifiers A3, A4; A5, A6; A7, A8, A9 and A10 which operate between 90 degree 'hybrids in the same way as just described for the amplifier pair A1, A2, t hough at a higher power level.
2.3.6.2
Power Combiner 1A72537
REFER Circuit Diagram 72535-1-07 The recombining of the powers is accomplished in the power combiner circuit, through processes which are the reverse of those described for the power divider. A coupling circuit and detector creates an output detected signal output at XC12. The combined power is passed to the output through the circulator W1. The resistive load R1 connected to the circulator provides a 50 ohms resistive load for the 1kW amplifier in the event of a fault effectively removing its load - f or example, disconnection of the DME antenna. A group of 20 capacitors form the capacitor bank which provides a reservoir from which the current pulse requirements of the amplifier are supplied, thus largely confining the current pulse paths to the amplifier ground plane.
2.3.6.3
250W RF Amplifier 1A69873
HA72500 2.3.7
SECTION 2 1kW PA Power Supply 1A72540
REFER Interwiring Diagram 72540-1-03 This unit consists of the DC-DC Converter Assembly 1A72542 and attached Regulator Assembly 1A72543, the Control and Status PWB Assembly 1A72541, relay K1 and filter components. A front panel switch AMPLIFIER DC POWER mounted from the control and status board allows the 1kW RF power amplifier to be powered ON or OFF t hrough the relay K1 for test purposes.
2.3.7.1
DC-DC Converter PWB Assembly 1A72542
REFER Circuit Diagram 72542-1-01 The DC-DC converter changes the 24 volts DC supply to the DME beacon to a regulated 50 volts supply to power the 1kW RF power amplifier. The converter is protected against output short circuits and includes circuitry to prevent over-voltage supply to the 1kW power amplifier. The converter circuit consists of a power switching section and a switching signal generating section. The power switching section comprises four power FET switches, V1 through V4, associated with the ferrite-cored transformer T6. This is followed by a bridge rectifier and smoothing circuit built around L2. A second filter associated with L3 reduces the level of switching hash present on the output voltage from the supply. The switching signal generation section of the converter, located on t he Regulator PWB Assembly 1A72543, is shown in Drawing 72542-1-01 within a dotted surround. The heart of this circuit is the CA1524 (V101) which generates pulses of controlled width at a
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Snubber circuits and zener diodes limit the positive voltage turn-off spike at the FET drains to typically 80 volts. Zener diodes limit the gate voltages of the FETs to 18.4 volts. The variable resistor R16 is set for 1 mV between XP:4 and XP:3 per ampere of primary current. The pulse transformers T2, T3, T4 and T5 produce 0.1 volts per ampere of FET source pulse current; these allow the performance of the individual FETs of either pair to be measured or compared.
2.3.7.2
Control and Status PWIB Assembly 1A72541
REFER Circuit Diagram 72541-1-01 A sample of the converter voltage, taken at XP:5a on that unit goes to the control and status board where it causes the front panel green POWER ON indicator H3 to light if the voltage is between 48.5 volts and 51.9 volts. This result is achieved as follows; the variable resistor R45 is adjusted so that the two voltages at the imaginary centre of R46 is equal to the zener reference voltage (5.6 volts) of V12. A window comparator formed by two comparators of N7 monitors the voltage sample against upper and lower limits allowing H3 to light when between these two limits. A 15 volts supply is derived from the 24 volts supply via a linear voltage regulator N9 and provides the IC supply on the board. The AMPLIFIER DC POWER test switch S1, when in the NORMAL position, allows the relay K1 coil to be energised by a 5 volts signal on XN1:8. If the switch is in the ON or OFF positions then the front panel red TEST indicator H2 is lit, t he test line XN1:2 is at 0 volts and this condition is signalled to the CTU. The power amplifier signals, output, driver and modulator are buffered and then level
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Table 2-9 Supply
Summary of Front Panel Controls and Indicators : PA Power CONTROL/INDICATION FUNCTION DETAILS
TYPE
LEGEND
FUNCTION/SETTING/INDICATION
Green LED
POWER ON
Indicates that DC power is supplied to the module.
Red LED
TEST
Indicates that the AMPLIFIER POWER switch is not in the NORMAL position.
Green LED
HT ON
Indicates that the HT supply is available, and within limits.
Toggle switch, centre off
AMPLIFIER DC ON POWER OFF
HT output voltage is supplied to the 1kW RF power amplifier regardless of the power control signal state. This is required only during testing and maintenance. There is no power output from the 1kW PA power supply.
NORMAL There is HT output from the module while the power control signal from the CTU is active (high); if it is inactive (low) the HT output is set to 0 volts. Test jack
POWER AMP MODULATOR OUT
Buffered output signal from the modulation stage of the 1kW RF power amplifier.
Test jack
POWER AMP OUTPUT OUT
Buffered output signal from the output stage of the 1kW RF power amplifier.
Test jack
POWER AMP DRIVER OUT
Buffered output signal from the driver stage of the 1kW RF power amplifier.
Test jack
+15V
Internally generated +15V supply (15 volts).
Test jack
SUPPLY CURRENT -
Test jack
SUPPLY
These jacks are connected to either side of a resistor in series with the +24V IN supply. The + jack is buffered to the higher voltage side of the resistor, and the - jack to the lower voltage side (1 mV/ampere).
HA72500
2.3.8
SECTION 2
Test Interrogator 1A72514
REFER Interwiring Diagram 72514-3-04 The test interrogator module contains the Test Interrogator Main PWB Assembly (1A72515), RF Generator (1A72516), Modulator and Detector (1A72518), Reply Detector (1A72519) and Attenuator (1A69737), plus fixed 30 dB and 20 dB attenuators The interconnection of these subassemblies is shown in Drawing 72514-3-04. The front panel has a number of test jack connectors and test switches by which various operating parameters of the module can be set and checked. The test interrogator operates as an independent unit simulating aircraft interrogation pulses. The DME transponder treats these pulses as normal interrogations and responds accordingly, allowing the test interrogator to measure and display the critical transponder parameters such as transponder delay, pulse separation and efficiency. Interrogation pulses are alternately generated at two predetermined power levels, to allow different parameters to be measured. The lower level of interrogation into the transponder receiver is at -85 dBm and permits a measurement of transponder efficiency to be made. The level into the transponder receiver is then switched to -70 dBm to allow transponder delay to be measured. To enable these changes in signal level out of the test interrogator into the DME receiver, a switched PIN diode Attenuator (type 1A69737) is used. The actual levels from the test interrogator are nominally 30.5 dB higher than the levels stated above, because of the attenuation provided by the directional coupler in the RF panel, and the attenuation in the rack cabling.
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RF pulses from the RF generator are passed to a 20 dB 50 ohms attenuator pad; the output of the pad is connected directly to the input of the PIN diode stripline attenuator. The stripline attenuator is arranged such that when the PIN diode is off the attenuator loss approaches zero, and when the diode is switched on the attenuator loss increases by 15 dB. The output of the stripline attenuator is fed through a 30 dB' 50 ohms attenuator pad to the directional coupler in the RF panel. With 1 dB residual loss in the module interconnections, pulse-pairs leaving the RF generator are alternatively attenuated by 51 and 66 dB by switching the diode attenuator between each pulse-pair; these signals are further attenuated by 30 dB in the directional coupler. Transponder output pulses, extracted by the directional coupler in the antenna transmission line, are demodulated and processed, in the reply detector, to provide logic-level trigger pulses timed at the 50% amplitude points on the leading edge of each pulse. These trigger pulses are used as timing points for measuring the transponder critical time-dependent parameters. The reply detector uses a half-height pulse detector-processor identical to the one used in the modulator and detector so that the inherent delays in each detector will be equal and not affect the measurement of transponder delay. A front-panel pushbutton switch connects both the reply detector and t he modulator detector circuits to the RF generator so that the detector pulses may be checked for coincidence. As the test interrogator relies heavily on time period and rate measurements, a stable 10 MHz crystal oscillator is used as a master clock. All pulse generation and timing waveforms are derived from this stable source.
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Figure 2-16
CTU Bus Timing - Read
Figure 2-17
CTU Bus Timing - Write
HA72500 2.3.8.1.3
SECTION 2 Normal Mode Operation
Normal mode is the situation when the test interrogator interrogates the transponder and extracts parameter information from the received reply pulses. In this mode the counter/timer functions may be used to measure the parameters for display on the CTU. The 10 MHz crystal oscillator is formed with D51, G1 and associated components. This 10 MHz is divided down to 1 MHz in D39 and is fed to the divider chain D43, D44, D45 and D46. From the divider chain the four test interrogation pulse repetition frequencies frequencies (TIPRF) are derived. The TIPRFs (10 kHz, 1 kHz, 100 Hz and 50 Hz) are fed to D28 where one of the TIPRFs is selected. The selected TIPRF initiates an interrogation of the transponder as shown below.
HA72500
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The Delay parameter (DELAY_DUR_PULSE) D2:10 is set by the signal FROM_SIG_GEN_DETECTOR and is reset by the first pulse of the signal WIDTH_PULSE coincident coincident with REPLY_ACCEPT_GATES D2:7. If t here is no WIDTH_PULSE coincident coincident with the t he reply gate pulses then the monostable D2:10 times out (after approximately 180 microseconds). microseconds). The Spacing parameter (SPAC_DUR_PULSE) (SPAC_DUR_PULSE) D5:6 is set by the first W IDTH_PULSE coincident with the REPLY_ACCEPT_GATES from D2:7 and reset by a second WIDTH_PULSE coincident coincident with the REPLY_ACCEPT_GATES REPLY_ACCEPT_GATES from D5:9. If there is no second WIDTH_PULSE coincident coincident with the REPLY_ACCEPT_GATES REPLY_ACCEPT_GATES the monostable D5:6 will time out (after approximately 60 microseconds). If a reply pulse pair is correctly decoded decoded (that is, a WIDTH_PULSE W IDTH_PULSE is coincident coincident with
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SECTION 2
taking place. Signals AC0, AC1 (under control f rom the CTU), when high, cause EFF_MON_ENABLE and DEL_SPAC_MON_ENABLE to stay low.
2.3.8.1.4
Counter/Timer
The counter/timer section of the test interrogator counts and times parameters by use of the type 82C54 counter/timer chip D35. This device is controlled by the CTU via the CTU bus. For information on the programming of the 82C54, refer to manufacturer data sheets. The counter section uses two of the three counters in D35. Counter 2 is loaded with a number from the CTU bus and when COUNT_EN is set high by the CTU, a single pulse
HA72500
2.3.8.1.5
SECTION 2
Monitor Fault Limit Test Mode
Monitor Fault Limit Test (MFLT) mode is a mode in which the test interrogator is used to test the Monitor Module (1A72510). In this mode, the test interrogator creates the parameters normally derived derived from the output of the transponder and feeds these to the t he monitor module. The value of the parameter is varied by control from the CTU to determine the point at which the monitor indicates a fault. To simulate the reply the type 82C54 counter/timer D34 is used. Each of the counters is loaded with a number which gives the required TIPRF (Counter 0), Delay (Counter 1) and Spacing (Counter 2) _ see figure below. When the signal M_FLT_EN is set high, the test interrogator no longer interrogates the transponder and ignores any WIDTH_PULSEs produced produced by the t he reply detector. D28:13 is switched so the selected TIPRF is M_FLT_TIPRF (from D34:10). The signal M_FLT_REPLY produced at D29:7 (see figure below) and selected by D6 is processed
HA72500 2.3.8.2
SECTION 2 RF Generator 1A72516
REFER Circuit Diagram 72516-2-01 The RF generator signal source consists of a crystal oscillator operating at a nominal frequency of one-twelfth of the transponder receiver frequency. Any one of five crystals crystals G1-G5 may be selected selected to provide the output frequency frequency of the test interrogator. One crystal corresponds to the transponder receive receive frequency while the other four correspond to frequencies either side of the nominal receive frequency at ±160 kHz and ±900 kHz. The crystals may be selected by operating the dual-in-line switch S1 mounted on the printed board. Access to the switch is made by withdrawing the module from the rack and then operating the switch through the access hole in the cover of the RF generator diecast box. An extra switch position is included to provide a CW TEST condition for receiver AGC tests. This adds a CW signal 10 dB below the interrogation interrogation pulses. The selected fifth-overtone crystal is connected in series resonance in an in-phase feedback path between the emitter and base circuit of V1. Inductor L7 is used to resonate with the stray crystal, socket and switch capacitances creating a high series impedance and thus avoiding feedback via the stray capacitive coupling which could cause parasitic oscillation or instability. Inductor L1 is tuned to optimise the operation of the oscillator. Test point XT1 provides a DC level which indicates oscillator output when monitored with a high impedance voltmeter. Transistor V2 is configured as a grounded-base grounded-base buffer amplifier and isolates the effects of the non-linear and abrupt loading changes of the following multiplier stage from the oscillator, as well as providing sufficient gain t o drive the multiplier stages.
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The output of the switched attenuator at XFA is then passed through a 30 dB, 50 ohms fixed attenuator to the 30 dB directional coupler in the transponder antenna feed.
2.3.8.4
Modulator and Detector 1A72518
REFER Circuit Diagram 72518-2-01 The modulator and detector operates in conjunction with the RF generator to produce trapezoidal interrogation pulses of the correct duration and amplitude. Each pulse is initiated by a modulation pulse coming from the test interrogator main board. In the quiescent state, the output at N6:7 is high; the analogue multiplexer multiplexer D2 is enabled with a zero address input; N6:12 output is low and N4A is configured as a follower, having an output voltage equal to the pulse pedestal voltage set by R37. On arrival of a square wave pulse at XS7, the address presented to D2 changes from 00 to 11 by the direct connection of the pulse to D2:9 (A in Figure 2-18) and 2-18) and the action of D1d and D1c operating on D2:10 (B in Figure 2-18). 2-18). D2 now reconfigures N4A as an integrator with C11 coupling the negative voltage step at D2:13 to drive the integrator output up at a rate controlled by R19, R20 and C17. Simultaneously the XS8 signal, which follows the integrator N4A output, causes the RF generator to produce an RF pulse which increases in amplitude as the integrator output goes up. N6A changes state as the integration voltage exceeds exceeds the offset voltage across R36 so that the N6A output goes high. A video amplitude-demodul amplitude-demodulated ated pulse from the RF RF generator, at XS1, follows follows the shape of the RF pulse and operates as feedback into the modulator and detector to provide automatic level control. When the RF pulse amplitude reaches the level preset by the PULSE AMPLITUDE control R13, the video pulse amplitude will cause the comparator
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SECTION 2
To enable RF alignment of the RF generator a TEST position on switch SA is provided to allow the square-wave modulation pulses direct from the test interrogator main board to modulate the RF generator via V10 and with the ALC loop inoperative.
Figure 2-18
Modulator and Detector Waveforms
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detector bias from the RF Generator 1A72516; these signals enter the reply detector via XS7 and XS8 respectively. A signal from a pushbutton switch TEST DETECTOR COINCIDENCE on the front panel of the test interrogator module is used by the multiplexer to switch between the detected replies and detector bias of either the reply detector or the RF generator. The TEST DETECTOR COINCIDENCE check is used to ensure that the half-height detector in the reply detector has the same timing delay as the half-height detector in the RF generator. Any difference in timing delay will introduce inaccuracies in the transponder delay time measurements. The half-height signal in the reply detector appears on connector XS4 as signal WIDTH; an alternative designation for this signal is REPLY TIMING. The detected signal at the output of N1a is fed into N1b where it is buffered to create the signal REPLIES, before being passed to the peak rider circuit and the rise, fall and width time detectors. The peak rider consists of N5a and V3, and produces a DC voltage level representing the peak of the detected video pulses. The peak level is buffered by N2b and amplified by N3b and appears on connector XS3 as signal REPLY_LVL. The buffered peak level output from N2b is fed into a resistor divider chain consisting of R11, R12, R13 and R14. These resistors are used to create reference levels of 90% of peak level, 50% of peak level and 10% of peak level which are fed into comparators N4a, N4b and N5b respectively. The other input to the comparators is the buffered video pulse signal REPLIES. Comparator N4a produces a pulse that is low when any part of the video pulse is greater than 90% of the peak of the pulse. Comparator N4b produces a pulse that is low when
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Table 2-11 Summary of Front Panel Controls and Indicators : Test Interrogator Module CONTROL/INDICATION FUNCTION DETAILS TYPE
LEGEND
FUNCTION/SETTING/INDICATION
Red LED
TEST
Indicates that the MONITOR AND INTERROGATOR DC POWER switch is not in the NORMAL position.
Green LED
DC POWER ON
Indicates that DC power is applied to the monitor and test interrogator.
Pushbutton switch
CHECK DETECTOR COINCIDENCE
Connects the output of the RF generator into the reply detector, bypassing the transponder. Is used to check that the detector stages in the transponder have the same delay. The signals at the INTERROGATIONS TIMING and REPLY TIMING test jacks should match each other when this switch is p ressed. This switch will interfere with the normal operation of the monitor module connected to the test interrogator under test.
Toggle Switch, centre off
TEST TRANSPONDER DECODING
REJECT
Toggle switch, centre off 16-way rotary switch
Alters the interrogating pulse spacing outside acceptable limits to test the transponder p ulse decoder rejection.
ACCEPT +1us
Alters the interrogating pulse spacing within acceptable limits to test the transponder p ulse decoder acceptance
-1us REPLY GATE DELAY
16-way rotary switch Toggle
+2us -2us
MONITOR AND
Sets accept gate timing; variable between 0 and 60 microseconds. COARSE 16 microseconds increments. FINE
1 microsecond increments.
ON
The
supply output is connected to the test
HA72500
Table 2-12 SUBASSY 1A72515 Main PWB Assembly, Test Interrogator
SECTION 2
Summary of Internal Controls: Test Interrogator Module CONTROL/INDICATION FUNCTION DETAILS TYPE
REF
LEGEND
FUNCTION/SETTING/INDICATION
Slide switch
S4
mode
X
Sets pulse spacing for X channel operation.
Y
Sets pulse spacing for Y channel operation.
Preset resistor
R7
1A72516 Variable RF Generator capacitors
TPNDR OP LVL Used to calibrate the t ransmitted pulse peak power. CAL
C 10, 10, 14, 18, 22
Inductor
L1
6-way DIL switch
S1
1A72517 RF Filter
Variable capacitors
C1, C2
1A72518 Modulator
Preset resistors
R13
Used to align the RF generator to the operating interrogator frequencies (see Section 3.4.12).
SW1
Selects interrogations at the nominal interrogation frequency.
SW2
Selects interrogations at 160 kHz above the nominal interrogation frequency.
SW3
Selects interrogations at 160 kHz below the nominal interrogation frequency.
SW4
Selects interrogations at 900 kHz above the nominal interrogation frequency.
SW5
Selects interrogations at 900 kHz below the nominal interrogation frequency.
SW6
Adds a CW signal to the interrogation pulse at -10 dB. Used to align the RF filter (see Section 3.4.13).
Pulse amplitude
Used to align the pulse shape of the interrogations
HA72500
2.3.9
SECTION 2
Monitor Module 1A72510
REFER Interwiring Diagram 72510-3-06 The monitor module receives input signals from the associated test interrogator module and from the antenna pickup. These signals represent operational parameters, and the monitor applies a pass/fail check on each one. A pass/fail result is able to be read by t he control and test unit (CTU) which indicates an alarm or control action as required. A number of voltage levels from other modules in the transponder are also input to the monitor module where they are measured and eventually read by the CTU. The eight monitored parameters are divided into primary and secondary categories, with primary parameters being defined as those which could, if at fault, give rise to false guidance information. The parameters are: PRIMARY PARAMETERS
Transponder delay Transponder pulse spacing Transponder efficiency Transponder reply rate
SECONDARY PARAMETERS
Transponder power output effective radiated power (ERP) Transponder ident Transponder antenna integrity Transponder pulse shape
The individual monitor circuits are designed to be failsafe. As an added safeguard, the CTU regularly initiates a test routine to check that the primary parameter monitors are
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The transponder output pulses sensed by the antenna pickup probe are detected and their peak value obtained; this peak value is then compared with a DC level preset to the required fault level. The value of this fault level setting can be checked under the control of the CTU. A check of antenna integrity is made by the antenna integrity monitor. This check involves two fault parameters. "Antenna integrity 1 " fault indicates two or more open circuit antenna elements, an antenna short circuit or an antenna not connected. "Antenna integrity 2" fault indicates a single open circuit antenna element. These signals are read by the CTU to take action as appropriate. Voltage levels representing monitored parameters from various other stages in the transponder are input to the monitor. These levels are converted by an analogue-todigital converter into digital numbers that are read and processed by the CTU. The following circuit features ensure failsafe monitoring: •
•
•
•
The choice of primary fault line outputs as zero volts. The inclusion of timeout monostables to ensure that a failure in any stage of a parameter monitor will signal a fault in that parameter. Delay, spacing, efficiency, rate, ident and pulse shape monitors involve counters that are continually checked for operation. Failure to count results in a fault output. Inputs from other boards are buffered and level shifted where appropriate. Input pull-down resistors ensure that floating inputs will be driven to a state that will produce a fault. An automatic test routine is applied to the delay and spacing monitors to check
HA72500 2.3.9.1.1 Figure 2-19
SECTION 2 Delay Monitor Delay Monitor
The transponder delay is continuously being represented in the test interrogator by a positive going pulse with a duration equal to the delay time. This pulse appears as
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For an X channel the transponder delay can be between 35 and 50 microseconds and for a Y channel between 50 and 56 microseconds. The description which follows assumes a nominal transponder delay of 50 microseconds When the counter D30 has been loaded with the preset values held on switch S12 it waits for the arrival of DLY_DUR_PULSE. The rising edge of this pulse initiates the first down count that will continue while DLY_DUR_PULSE is present. It takes one clock cycle (100 nanoseconds) to initiate the First down count. If the counter reaches zero and DLY_DUR_PULSE is still present the preset value on switch S9 is loaded into the counter D30 and a second down count is initiated after 1 clock cycle. If the failing edge of the DLY_DUR_PULSE occurs before the first count has reached zero no delay_OK flag is set and the second count is not started. The signal DLY_COUNT at test point XT5 gives an indication of the lengths of the first and second down counts. If and only if the failing edge of DLY_DUR_PULSE occurs after the end of the first count and before the end of the second count will a delay_OK flag be set. The delay_OK flag is set on the failing edge of DLY_DUR_PULSE and a non-zero second count and is reset when the second count goes to zero. If the second down count reaches zero and DLY_DUR_PULSE is still asserted then no delay_OK flag is set. The existence of the delay_OK flag indicates that t he DLY_DUR_PULSE is within the window of acceptable delay limits. The primary error counter D37 is made up of two 3-bit up/down counters D37a and D37b. In a non-fault state the delay_OK flag and PRF pulses are fed into D37a. Within D37 the PRF rate is reduced to 33% of the original PRF rate. The PRF/3 rate is used to count the 3-bit counter toward zero. The delay_OK flags are used to count the 3-bit counter towards 7. If the delay_OK flag rate exceeds PRF/3 rate then the primary error counter will count to 7 and give no fault indications. If the delay_OK rate is exceeded by
HA72500 2.3.9.1.2 Figure 2-21
SECTION 2 Spacing Monitor Spacing Monitor
A test of the transponder spacing time is initiated by the PRF pulse (XT9) loading presettable counter D31 with the binary values held on S13. During the course of a test a second window count is loaded from switch S10.
HA72500
SECTION 2
For an X channel the nominal window of acceptable transponder spacing is between 11.5 microseconds and 12.5 microseconds. For a Y channel the nominal accept window is between 29.5 microseconds and 30.5 microseconds. A measurement of spacing duration is initiated by the rising edge of a TIPFIF pulse input to spacing counter D31. This edge causes the counter to reset to zero regardless of the state of the counter before the edge. Within D31 the TI PRF pulse is delayed by 1 clock cycle (100 nanoseconds) and then used to load the counter with the preset value held on switch S13. By clearing the counter before loading the preset values the initial count value can be guaranteed. When the counter D31 has been loaded with the preset values held on switch S13 it waits for the arrival of SPAC_DUR_PULSE. The rising edge of this pulse initiates the first down count that will continue while SPAC_DUR_PULSE is present. It takes one clock cycle (100 nanoseconds) to initiate the f irst down count. If the counter reaches zero and SPAC_DUR_PULSE is still present the preset value on switch S10 is loaded into the counter D31 and a second down count is initiated after 1 clock cycle. If the failing edge of the SPAC_DUR_PULSE occurs before the first count has reached zero no spacing_OK flag is set and the second count is not started. The signal SPAC_COUNT at test point XT14 gives an indication of the lengths of the first and second down counts. If and only if the failing edge of SPAC_DUR_PULSE occurs after the end of the first count and before the end of the second count will a spacing_OK flag be set. The spacing_OK flag is set on the failing edge of SPAC_DUR_PULSE and a non-zero second count and is reset when the second count goes to zero. If the second down count reaches zero and SPAC_DUR_PULSE is still asserted then no spacing_OK flag is set. The existence of the spacing_OK flag indicates that the SPAC_DUR_PULSE is within the window of acceptable spacing limits.
HA72500
SECTION 2
counts (3.2 microseconds) which is sufficient to cause both delay and spacing monitors to fail. The CTU reads faults from both monitors indicating each parameter has failed and terminates the test, thereby restoring normal operation. The test is repeated every 16 seconds, and at monitoring PRF takes approximately 0.1 seconds to complete.
2.3.9.1.4 Figure 2-23
Efficiency Monitor Efficiency Monitor
The efficiency monitor maintains a running count of each decoded reply and the PRF,
HA72500
SECTION 2
inhibit driver device D51:8 and fed into counter D49:10 as an EFF_INHIBIT signal. When this signal is asserted the counter D49 is frozen so that counting is only permitted during the time when the RF signal is low. During the transmission of an ident mark an ident_inhibit signal is fed into D51:5. This signal will also cause EFF_INHIBIT to be asserted and prevent D49 counting. By using the EFF_INHIBIT signal from D51, efficiency faults will only be registered when this signal is not asserted so that false fault indications will not be given during delay testing and ident mark.
2.3.9.1.5
Reply Rate Monitor
This section of the monitor detects if the transponder reply rate fails below a preset limit of 833 Hz or rises above a preset limit of 3 kHz. The reply rate monitor consists of two parts. The first part checks the minimum reply rate and the second checks the maximum reply rate. The buffered signal representing all replies called XDETD_TX_PULSES is used as input to both parts. The counter D45 consist of parts D45a and D45b. Each part functions identically. Figure 2-24
Rate Monitor
HA72500 2.3.9.1.5.2
SECTION 2 Maximum Reply Rate Monitor
The clock signal 1kHz_CLK is input to rate multiplier D39, configured to pass 60% of its input pulses to its output. This output used by counter D45b as a down count pulse of frequency 600 Hz. The signal XDETD_Tx_PULSES is input to a rate multiplier D43, configured to pass 10% of its input pulses to its output. The up count pulse rate used by counter D45b is calculated as: (reply rate) x 2 x 0.1 = up count pulse rate. Example: for reply rate = 3 kHz, the up count pulse rate = 600 Hz.
Provided the reply rate is less than 3 kHz, the down count pulse rate from D39 of 600 Hz will be greater than the up count pulse rate. This will cause D45b to count down to and be held at zero. If the reply rate rises above 3 kHz the up count rate will be greater than the down count rate and D45b will count up and be held at a maximum value of 15. At this point a rate_error flag will be asserted.
2.3.9.1.5.3
Fault Processing
After a rate_error flag has been raised it will be reset by the rate returning to a non-fault condition. This means that if the rate_error flag was raised by the reply rate failing below 833 Hz the rate must increase to above 833 Hz to reset the flag. If the rate_error flag was raised by the reply rate exceeding 3 kHz it must f all below 3 kHz to reset the f lag. In either case a return to a non-fault state will cause D45a or D45b to count down from the maximum count of 15. When D45a or D45b has a count value of 0 the rate_error flag is reset.
HA72500 2.3.9.1.6 Figure 2-25
SECTION 2 Ident Monitor Ident Monitor
HA72500
SECTION 2
All ident message information is extracted from the buffered signal XDETD_Tx_PULSES. When the rising edge of the f irst pulse of an XDETD_TX_PULSES pulse pair is encountered on input D33:2 a pulse of 1 clock cycle duration is created and output from D33:10. This pulse is called IDENT_DECIDE. The clock input to D33 for ident message extraction is 1 MHz. The pulse IDENT_DECIDE is input to monostable D38a:4 which produces a pulse, IDENT_GATE, of 40 microseconds duration to be f ed back into D33:14. This gating pulse is used to gate out the second pulse in the XDETD_Tx_PULSE pulse pair. If this pulse is not gated out another IDENT_DECIDE pulse will be created on the rising edge of the second pulse. If this occurs, erroneous information about the pulse pair spacing will be output from D33 as IDENT_PULSE. The pulse IDENT_DECIDE generates the signals IDENT_LOAD and IDENT_PULSE within D33. IDENT_PULSE, at D33:18, is a 3 microseconds negative-going pulse, with a pulse spacing equal to the spacing between the pulses XDETD_TX_PULSE. It is used by D40 to determine if the spacing between transmitter output pulse pairs fails within the ident window. The IDENT_DECIDE pulse is used by D40 to determine if IDENT_PULSE from the previous measurement is still high during the ident window generated within D40. If this is the case then the XDETD_Tx_PULSES pulse pair spacing is at the ident rate of 1350 Hz and output D40:18 is held high. D40:18 is called IDENT_KEYING and represents the envelope of the ident message pulse pairs. IDENT_DECIDE is also used to create the pulse IDENT_CLEAR in D33. This pulse, output from D33:22, is of 1 clock cycle duration and is used by D40 to reset its internal counter to zero after the previous ident spacing measurement.
HA72500
SECTION 2
initiates a count of 10 seconds. If this count reaches 10 the ident message has extended beyond the specified limit of 10 seconds and an IDENT_ERROR flag is raised. The inverse of IDENT_CODE is output from D38:9 and input to D33:11. This signal, IDENT_MESSAGE_SPACING, represents the spacing between ident messages. Preloading of the binary value held on switch S8 is initiated by a count of zero in D33 (the power on condition) or the rising edge of IDENT_MESSGE SPACING. After preloading the counter in D33 a down count is immediately started. The value held on S8 represents the maximum spacing between ident messages in seconds. If the count reaches zero a valid ident message has not been received within the maximum time and an IDENT_SPACING_ERROR flag is raised in D33:21. This flag is input to D47. Switch S8 can be set for a maximum ident message spacing of 2 to 128 seconds (although it would normally be set in the range 45 to 75 seconds). To ensure fail safe operation the signal IDENT_LOAD is used to retrigger a timeout monostable D42a. If D33 should fail or XDETD_Tx_PULSES not be present this monostable will timeout and will assert an ident fault signal from D42a:7. In the event of the IDENT_ERROR flag being asserted from counter D47:18, the monostable D42a is reset and a positive going IDENT FAULT is output from D42a:7. The IDENT FAULT from D42a is then fed into the fault line driver circuitry D13.
2.3.9.1.7 Figure 2-26
Effective Radiated Power Monitor Effective Radiated Power Monitor
HA72500
SECTION 2
is set at commissioning by R87. The input that appears on N9:11 is a voltage that represents the fault alarm level. The power level at N9:10 and the fault alarm level at N9:11 are compared. While the power level is greater than the fault alarm level no POWER FAULT is indicated. Should the power level fall below the fault alarm level a POWER FAULT will be indicated and the output sent to the fault line driver D13. During ERP monitor fault limit test operation the control lines PWR_TEST0 … 2 from the CTU are used to control D5. The software on the CTU will cycle through the inputs to D5. These inputs represent the following monitor fault levels: •
The power level set by R87. This is the 0 dB level.
•
Voltages representing -0.5 dB to -6.5 dB levels in -1 dB steps.
The monitor fault level output of D5:3 is fed into D1. T he control signal from the CTU PWR_TESTEN selects the monitor fault level input to D1 to be output to N9, instead of the power level. By cycling through the monitor fault levels and comparing these to the fault alarm level, the CTU can determine the fault alarm level set on the ERP monitor. The CTU will continue to cycle through the inputs to D5 until a POWER FAULT is indicated. When the POWER FAULT is indicated the input monitor fault level to D5 that forced the POWER FAULT is read by the CTU and returned as the ERP monitor fault limit.
2.3.9.1.8 Figure 2-27
Antenna Integrity Monitor Antenna Integrity Monitor
HA72500
SECTION 2
The antenna can be represented by 10 parallel 10 kilohm loads, one load for each element. This represents an equivalent load seen by the antenna integrity monitor of 1 kilohm. As each element in the antenna fails the effective load increases. A constant current source made from transistors V6 and V4 and associated components ensures that a current of less than 4 mA is fed into this effective load. An identical current produced by V2 is fed into an external 1 kilohm reference resistor. This produces a set of reference voltages that are input to the comparator network formed by quad comparator N2. The external reference resistor of 1 kilohm is located on the RF Panel PWB Assembly 1A/2A72547. a reference resistor of 1 kilohm is fed by the same current source as feeds the effective antenna load. The voltage produced across the reference resistor is buffered and multiplied by 1.18 in amplifier N1. The output from this amplifier is fed into the comparator network formed by N2. The reference input to comparator N2a:7 represents a voltage 1. 18 times the voltage produced by the effective antenna load of a fully functioning antenna. Should a multiple element failure occur then the effective antenna load, connected to N2a:6, will increase and the current source will produce a voltage across this load greater than the reference voltage. This will cause an ANTENNA_INTEGRITY_1 FAULT. The reference input to comparator N2b:5 represents a voltage 1.06 times the voltage produced by the effective antenna load of a fully functioning antenna. Should a single element failure occur, the effective antenna load, connected to N2b:4, will increase and the current source will produce a voltage across this load greater than the reference voltage. This will cause an ANTENNA_INTEGRITY_2 FAULT. The reference input to comparator N2c:8 represents a voltage 0.2 times the voltage
HA72500
SECTION 2
A test of the transponder pulse width is initiated by the PRF pulse (XT9) loading presettable counter D9 with the binary values held on S1. During the course of a test a second window count is loaded from switch S4. The values held on switches S1 and S4 are indicative of the reject limits on the transponder width. Each count on the switches represents 0.1 microseconds actual time. Figure 2-28
Width Monitor Waveforms
The signal WIDTH_COUNT appears on test point XT7 and the signal WIDTH_PULSE appears on XT11. These two test points can be monitored with an oscilloscope to check the accuracy of the switch settings. Figure 2-28 illustrates this check. When the counter D9 has been loaded with the preset values held on switch S1 it waits for the arrival of WIDTH_PULSE. The rising edge of this pulse initiates the first down
HA72500 Figure 2-29
SECTION 2 Pulse Shape Monitor
HA72500
SECTION 2
must be raised. If a f ault is to be raised the signal width_fault_indication from D23a is asserted. This signal is input to the timeout monostable D18b. Timeout monostable D18b is used to ensure t hat the counter device D9 is operating. The signal WIDTH_COUNT (XT7) is used to continually retrigger D18b. In the event of a width_fault_indication being asserted from counter D23a the monostable D18a is reset and a positive going WIDTH FAULT is output from D18b:9. This timeout monostable also has the effect that if the WIDTH_PULSE is not encountered then the retriggering signal WIDTH_COUNT will not be produced and so the monostable will timeout and the WIDTH FAULT signal from D18b:9 will be asserted. The WIDTH FAULT signal from D18b is then fed into the fault line driver circuitry D13. A test of the transponder pulse rise time is initiated by the PRF pulse (XT9) loading presettable counter D10 with the binary values held on S3. The value held on switch S3 is indicative of the maximum rise time of the transponder pulse. Each count on the switches represents 0.1 microseconds actual time. Figure 2-30
Rise Time Monitor Waveforms
HA72500
SECTION 2
must be raised. If a f ault is to be raised the signal rise_fault_indication from D23b is asserted. This signal is input to the timeout monostableD42b. Timeout monostable D42b is used to ensure that the counter device D10 is operating. The signal RISE_COUNT is used to continually retrigger D42b. In the event of a rise_fault_indication being asserted from counter D23b the monostable D42b is reset and a positive going RISE FAULT is output from D42b:9. This timeout monostable also has the effect that if the RISE_PULSE is not encountered then the retriggering signal RISE_COUNT will not be produced and so the monostable will timeout and the RISE FAULT signal from D42b:9 will be asserted. The RISE FAULT signal from D42b is then fed into t he fault line driver circuitry D13. Monitoring of rise pulses and fall pulses is accomplished using identical circuitry. A test of the transponder pulse fall time is initiated by the PRF pulse (XT9) loading presettable counter D11 with the binary values held on S2. Figure 2-31
Fall Time Monitor Waveforms
HA72500
SECTION 2
The fall_OK rate will be exceeded by PRF/3 if the FALL_PULSEs are continually greater than the maximum fall time limit or no valid FALL_PULSEs are returned from the test interrogator due to low beacon efficiency. In either case a PULSE SHAPE fault must be raised. If a fault is to be raised the signal fall_fault_indication from D17a is asserted. This signal is input to the timeout monostable D18a. A timeout monostable D18a is used to ensure that the counter device D11 is operating. The signal FALL_COUNT is used to continually retrigger D18a. In the event of a fall_fault_indication being asserted from counter D17a the monostable D18a is reset and a positive going FALL FAULT is output from D18a:7. This timeout monostable also has the effect that if the FALL_PULSE is not encountered then the retriggering signal FALL_COUNT will not be produced and so the monostable will timeout and the FALL FAULT signal from D18a:7 will be asserted. The FALL FAULT signal from D18a is then fed into the fault line driver circuitry D13.
2.3.9.1.10 Figure 2-32
Level Monitor Level Monitor
HA72500
SECTION 2
The following signal levels are read: SOURCE MODULE
SIGNAL NAME
Receiver Video
RV_LOCAL_OSC_LVL RV_Tx_LVL
Transmitter Driver
TD_MOD_LVL TD_Tx_LVL_
Power Amplifier
SOURCE MODULE Test Interrogator Transponder Power Supply
SIGNAL NAME TI_INT_RF_LVL TPNDR_OP_LVL PS_15V_LVL PS_18V_LVL
PA_DRV_LVL
PS_HT_LVL
PA_MOD_LVL
MON_24V_LVL
PA_OP_LVL PA_HT_LVL
Monitor
CALIBRATE GND
The two monitor signals CALIBRATE and GND are used by the CTU to calibrate the other level measurements. D22 and D27 are 8:1 multiplexers which are used to choose the level signal to be monitored and also provide a degree of buffering. The CTU controlled signal lines AMUX0:3 are used by D22 and D27 to choose the level to be monitored. The chosen level is buffered by N1 and fed to analogue-to-digital converter D28. The output of D28 is read under CTU control.
2.3.9.1.11 Figure 2-33
Fault Line Driver Fault Line Driver
HA72500
SECTION 2
The faults are combined in device D13 according to the following table. From this device the combined faults are directed to the CTU bus and to LED drivers. D8 and D4 are used to buffer the fault lines and drive the LEDs on the front panel. A pair of signal lines representing a DELAY fault and a SPACING fault are directed to the receiver video to inhibit beacon operation, following a primary Fault, if the CTU fails to shut the beacon down. The faults are combined as follows: FAULT TYPE PRIMARY
FAULT
FAULT GROUP
DELAYFAULT SPACING FAULT
SECONDARY
EFFICIENCYFAULT RATE FAULT IDENTFAULT POWER FAULT WIDTH FAULT RISE FAULT FALL FAULT ANTENNA INTEGRITY 1 FAULT ANTENNA INTEGRITY 2 FAULT
PULSE SHAPE FAULT ANTENNA FAULT
Each of the faults shown in italics above are able to be read by the CTU, which then takes the appropriate course of action for the indicated fault. The following front panel indicators are used to give a real-time indication of the fault status of each of the monitored parameters. With the exception of the PRIMARY and
HA72500 2.3.9.1.12
SECTION 2 Miscellaneous Circuitry
A buffered 10 MHz crystal oscillator is fed into clock device D24. This device produces clocks of 1 MHz and 1 kHz. The 1 kHz signal is fed into clock device D19 and this device produces a clock of 1 Hz. These four clock fr equencies are used for timing circuits throughout the monitor main board. D48 is used to buffer all of the clock signals before distribution around the board. Two power supplies are required on the monitor main board. These are +15 volts for buffering analogue signals from other transponder modules and +5 volts for all of the digital logic. The +5 volts supply is created by taking the +24 volts from t he test interrogator and first regulating this to +15 volts via ballast resistor R1 and 3-terminal regulator N4. This +15 volts is then further regulated to +5 volts using ballast resistor R89 and 3-terminal regulator N8. The +15 volts supply is created by directly regulating the +24 volts from the test interrogator using the adjustable three terminal regulator N6. A power supply monitor is used to provide an indication to the CTU that the two power supplies used on the monitor main board are operating. The circuit consists of a pair of window comparators that indicate if the voltages on the +5 volts supply and the +15 volts supply fall with hardwired limits. These limits are set to be 4.75 volts to 5.25 volts and 14.5 volts and 15.5 volts respectively. Should the power supplies fall outside these limits then a signal line to the CTU called MON_PS_FLT will fall to zero volts indicating that the monitor power supplies have failed. The CTU will then take an appropriate action. From the +15 volts supply two precision +5 volts references N3 and N6 are used to provide accurate +5.00 volts levels for use in ERP monitor and level monitor. The MONITOR OUPUTS switch S16 is used to determine the operational mode of the monitor module. When S16 is in NORMAL mode all parameter monitors are operational.
HA72500
SECTION 2
The received RF power is demodulated by an envelope detector V1 and the resultant video pulses are amplified and buffered by N1a and N1b respectively. Resistors R3 and R4 are used to provide a small DC bias to the detector diode V1; this enables the detector to recover signals at very low levels. The output of N1a at N1:1 is buffered by N3a, producing the signal DET_REPLIES. The output of N1b at N1:7 is fed into a peak rider circuit consisting of N4a and V3. The peak amplitude of the pulse envelope is buffered by N2b and amplified by N3b, producing the signal REPLY_LVL. The peak power monitor is capable of producing a DC level of greater than 2.5 volts for input RF power levels of +10 dBm to +20 dBm. This DC level is used by the monitor main board to determine RF power fault levels.
HA72500
Table 2-13
SECTION 2
Summary of Front Panel Controls and Indicators : Monitor Module CONTROL/INDICATION FUNCTION DETAILS
TYPE Toggle switch
LEGEND MONITOR OUTPUTS
FUNCTION/SETTING/INDICATION FAILED
All monitor outputs are set to their fault condition (high) which invokes a FAILED condition for all front panel indicators and all fault lines read by the CTU. The TEST indicator is turned on.
NORMAL
Monitor module operates normally and TEST indicator is off.
Green LED
DELAY
Green LED
SPACING
Green LED
EFFICIENCY
Green LED
RATE
Green LED
POWER
Green LED
IDENT
Green LED
ANTENNA
Green LED
SHAPE
Yellow LED
SELF TEST
Indicates that the CTU is performing a Monitor Self Test, during which the CTU will look for the two primary parameters in the fault state.
Red LED
PRIMARY
Indicates that one or both of the primary parameters (Delay, Spacing) are outside preset limits.
Yellow LED
SECONDARY
Indicates that one or more of the six secondary parameters (Efficiency, Rate, RF Power, Ident, Antenna, Shape) are outside preset limits.
Red LED
TEST
Indicates that the MONITOR OUTPUTS switch is not in the NORMAL position.
When on, indicates that the named parameter is within preset limits.
HA72500
Table 2-14 SUBASSY
SECTION 2
Summary of Internal Controls : Monitor Module CONTROL FUNCTIONS TYPE
REF
1A72511 Main Preset R87 PWB Assembly, resistor Monitor Module 8-way DIL S1 switch The Monitor Fault Limit switches S1-4 and S7-10, S12 and S13 are binary coded, with switch 1 of the DIL switches the least significant and switch 8 (or 10) the most significant. They use inverted logic, with the OFF position of the switch being active.
LEGEND
FUNCTIONISETTING/INDICATION Sets the ERP monitor fault alarm reference level to 0 dB at commissioning.
PULSE WIDTH LOWER REJECT LIMIT
1
2
3
4
5
6
7
8 ON OFF
Multiply the required lower reject limit (in microseconds) by 10 and subtract 1. Encode the switches for this value. For a lower reject limit of 2.9 microseconds the switches are encoded for a number of 28, as shown above. 8-way DIL S2 switch
FALL TIME UPPER REJECT LIMIT
1
2
3
4
5
6
7
8 ON OFF
Multiply the required upper reject limit (in microseconds) by 10 and subtract 2. Encode the switches for this value. For an upper reject limit of 3.6 microseconds the switches are encoded for a number of 34, as shown above. 8-way DIL S3 switch
RISE TIME UPPER REJECT LIMIT
1
2
3
4
5
6
7
8 ON
HA72500
SUBASSY
SECTION 2
CONTROL FUNCTIONS TYPE
REF
1A72511 Main PWB Assembly, 8-way DIL S8 Monitor Module switch
LEGEND IDENT GAP UPPER REJECT LIMIT
FUNCTIONISETTING/INDICATION 1
2
3
4
5
6
7
8 ON OFF
Subtract 2 from the required upper reject limit (in seconds). Encode the switches for this value. For an upper reject limit of 62 seconds the switches are encoded for a number of 60, as shown above. 8-way DIL S9 switch
DELAY REJECT WINDOW
1
2
3
4
5
6
7
8 ON OFF
Multiply the difference between the required upper and lower reject limits (in microseconds) by 10 and subtract 1. Encode the switches for this value. For an upper reject limit of 50.5 microseconds the difference between the limits is 1. 0 microsecond and the switches are encoded for a number of 9, as shown above. 8-way DIL S10 switch
SPACING REJECT WINDOW
1
2
3
4
5
6
7
8 ON OFF
Multiply the difference between the required upper
HA72500
SECTION 2
2.3.10
Control and Test Unit 1A72550
2.3.10.1
General
The Control and Test Unit (CTU) monitors, controls and tests various f unctions within the LDB-102 DME. The CTU contains a comprehensive test facility to allow rapid assessment of performance. By keypad selection, each of the main DME parameters, including signal levels and status conditions, can be measured and displayed. The CTU is used in conjunction with the test interrogator module(s) to perform the measurements and tests. The CTU controls the operation of a single or dual transponder configuration LDB-102 DME, both locally and remotely. It also performs data acquisition and control functions for the Remote Control and Monitoring System (RCMS). A detailed description of the controls and indicators of the CTU is given in Appendix A.3.
2.3.10.2
Mechanical
The CTU comprises three boards, namely the CTU Processor PWB Assembly (1A72552), the CTU Front Panel PWB Assembly (1A72553) and the RCMS Interface PWB Assembly (1A72555). The boards are mounted on an aluminium frame and connected using ribbon cables. A DC/DC converter is also mounted on the aluminium frame and connects to the CTU processor board. The CTU is installed in the CTU subrack. A block diagram of the CTU is shown in Figure 2-34. Details of the individual boards are given in following sections.
HA72500 2.3.10.3
SECTION 2 CTU Processor PWB Assembly 1A72552
REFER Circuit Diagram 72552-1-02
2.3.10.3.1
General
The CTU processor board provides the microprocessor and memory for t he CTU. It provides interfaces with the CTU front panel board, the RCMS interface board, and Transponders 1 and 2. The CTU also has a serial port, and controls the sourcing of the ident signals. A block diagram of the CTU processor board is shown in Figure 2-35.
2.3.10.3.2
Microprocessor
The microprocessor, D9, is a CMOS 80C186 which operates at 10 MHz. The processor provides a clock generator, an interrupt controller, three 16-bit timers, memory and peripheral chip select logic, and a wait state generator. The microprocessor supervisory chip, N2, acts as a watchdog for the processor and as a 24 volts monitor. If the watchdog input (WDI), pin 11, is not toggled within 1.6 seconds, RESET, pin 15, pulses low causing the processor to be reset. N2 monitors the 24 volts line via the power fail comparator input (PFI), pin 9. If the 24 volts line voltage drops below a preset value then the voltage at PFI drops below its threshold. This in turn causes PFO, pin 10, to go low, which activates the LOW_TPNDR_BAT alarm. The preset value may be adjusted by R32 to be anywhere in the range 18 to 23 volts. The wait state generator and address decoder, D13, is implemented using an EP610 programmable logic device (PLD). D13 generates external CTU bus signals for the
HA72500 Figure 2-35
SECTION 2 CTU Processor Board Block Diagram
HA72500 2.3.10.3.4
SECTION 2 Serial Port
The RS-422 serial port comprises two differential bus transceivers, N4 and N5, as well as a universal asynchronous receiver/transmitter (UART), D6. This arrangement allows the serial port to operate in full-duplex mode. The serial port is used to communicate with a remote maintenance monitoring system.
2.3.10.3.5
RCMS and Front Panel Interface
The interface to the RCMS interface board and the front panel board is implemented using D29, D30 and D31. D29 is an octal bus transceiver used to transfer data between the CTU processor board and the other two boards. DT/R from the processor controls the direction of data flow through the transceiver. Resistor networks RN20 and RN21 reduce noise susceptibility on input data to D29. D30 is the address buffer, and its outputs are enabled when PCS0 is low. A0 from the processor is not buffered since it is used as an enable signal rather than an address signal by the processor (analogous to BHE for the low data byte). Hence ADDR0 to the front panel and RCMS interface boards connects to A1, ADDR1 connects to A2, and so on up to ADDR6. D31 is the control byte buffer. Its outputs are always enabled. The interrupt input (XINT) from the front panel and RCMS interface enters the CTU board on XN3:34. It is ANDed with the RDY/BSY signal from the EEPROM. This has the effect of disabling XINT while the EEPROM is being written to.
HA72500 c.
SECTION 2 Select inputs:
1.
ASSOC_IDENT_SEL_1;
2.
ASSOC_IDENT_SEL_2;
3.
REC_IDENT_SEL_1; and
4.
REC_IDENT_SEL_2.
d.
Ident signal outputs: 1.
IDENT_ON;
2.
MA_IDENT_IN_1;
3.
MA_IDENT_IN_2;
4.
MA_IDENT_OUTPUT;
5.
DET_IDENT_KEY;
6.
IDENT_TONE_TRANSFORMER; and
7.
IDENT and CPU TONE.
The relationship between these is shown in Table 2-15 to Table 2-17. Table 2-15 Ident PLD Outputs: MA_IDENT_IN_1,2, MA_IDENT_OUT, IDENT_TONE_TRANSFORMER, DET_IDENT_KEY INPUTS
OUTPUTS
ASSOC_IDENT_SEL 2
1
MA_IDENT_IN 2
1
MA_IDENT_OUT
IDENT_TONE_ TRANSFORMER
DET_IDENT_KEY
HA72500
Table 2-17
SECTION 2
Ident PLD Output: IDENT_ON INPUTS
ASSOC_IDENT_SEL
OUTPUTS
REC_IDENT_SEL
2
1
2
1
x
x
1
1
0
0
0
x
x
0
0
1
0
x
x
0
1
x
0
x
x
0
2240 Hz
IDENT_ON
x
0
↑
REC_IDENT_KEYING_1
↑
REC_IDENT_KEYING_2
↑
q
x = Don't care
↑ = Low-to-high transition q = State of IDENT_ON at previous low-to-high transition of 2440 Hz
The MA_IDENT_OUTPUT signal is produced by N1 which is an optically coupled MOSFETV relay. This signal appears as either an open circuit or as a contact closure. The DET_IDENT_KEY output appears as either +24 volts or ground. The other f ive IDENT outputs are TTL level signals. The recovered ident signal at D2:9 activates buzzer B1 for monitoring purposes. The level of the signal may be adjusted using the variable resistor R33.
HA72500 Table 2-19
SECTION 2 CTU Processor Board Links LED
FUNCTION
XN5 XN6
Ground one leg of MA_IDENT_OUTPUT Watchdog disable
XN7 XN8 XN9
Select signature analysis Ident Test Watchdog Test
XN10
Pullup ASSOC_IDENTIN input to +24 volts
NOTE: The function is enabled when the link is fitted
2.3.10.3.11 Miscellaneous Inputs and Outputs There are 13 bits read by D19 and D24. Their source and signal type are summarised in Table 2-20. Table 2-20 BIT
CTU Processor Board D19 and D24 Inputs NAME
15 14
LOW_TPNDR_BATT Spare
13 12 11 10 9
SOURCE
DESCRIPTION
N2:10
High if battery voltage < preset
Spare ANT_REL_TEST TI_MON_TEST_2
External I/O Board RCMS (Transponder 2)
Ground or open circuit Ground or open circuit
TI_MON_TEST_1 TPNDR_TEST_2
Transponder 1 RCMS (Transponder 2)
Ground or open circuit Ground or open circuit
HA72500
SECTION 2
There are 16 bits output via D18 and D23. Their destination and signal type are summarised in Table 2-21. Table 2-21 BIT
CTU Processor Board D18 and D23 Outputs NAME
DESTINATION
DESCRIPTION
15
ASSOC_IDENT_SEL_2
D2:19
+24 volts or ground
14
ASSOC_IDENT_SEL_1
D2:23
+24 volts or ground
13
ANT_RELAY_CONTROL
External I/O Board
+24 volts or ground
12
RV_IDENT_INH_2
RCMS (Transponder 2)
+5 volts or ground
11
RV_TX_INH_2
RCMS (Transponder 2)
+5 volts or ground
10
RV_RF_ON_2
RCMS (Transponder 2)
+5 volts or ground
9
TPDR_PWR_ON_2
RCMS (Transponder 2)
+5 volts or ground
8
PA_PWR_ON_2
RCMS (Transponder 2)
+5 volts or ground
7
REC_IDENT_SEL_2
D2:10
+24 volts or ground
6
REC_IDENT_SEL_1
D2:14
+24 volts or ground
5
MAINT_FNS_EN
RCMS (Transponder 2) and Transponder 1
+24 volts or ground
4
RV_IDENT_INH_1
Transponder 1
+5 volts or ground
3
RV_TX_INH_1
Transponder 1
+5 volts or ground
2
RV_RF_ON_1
Transponder 1
+5 volts or ground
1
TPDR_PWR_ON_1
Transponder 1
+5 volts or ground
0
PA_PWR_ON_1
Transponder 1
+5 volts or ground
2.3.10.3.12 Counter
HA72500 2.3.10.4
SECTION 2 CTU Front Panel PWB Assembly 1A72553
REFER Circuit Diagram 72553-1-02
2.3.10.4.1
General
The front panel board provides the CTU user interface. It has switches, LEDs and a 2-line by 40-character LCD which allow the user to: a.
display operational parameters and test results; and
b.
exercise local control and monitoring of the DME.
The LCD displays a menu of functions available to the user on the function keys, while other keys have dedicated functions. A block diagram of the front panel board is shown in Figure 2-36. Figure 2-36
CTU Front Panel Board Block Diagram
HA72500
SECTION 2
Table 2-22
CTU Front Panel Address Map
A6
A5
A4
A3
A2
A1
0 0 0 0 0 0 0 0 0 0 0 0
x x 0 0 0 0 0 0 0 0 0 0
x x 0 0 0 0 0 0 0 0 0 1
x x 0 0 0 0 0 1 1 1 1 0
x x 0 0 0 1 1 0 0 1 1 0
x x 0 1 1 0 1 0 1 0 1 0
2.3.10.4.3
PCS0 XWR 0 0 0 0 0 0 0 0 0 0 0 0
0 1 0 0 1 1 1 0 0 0 0 0
XRD 1 0 1 1 0 0 0 1 1 1 1 1
SELECTS Data transceiver D7 (Write) Data transceiver D7 (Read) LCD control/address (Write) LCD data (Write) LCD data (Read) Switch scanner and coder D5 (Read) Alarm inhibit/delay D3 (Read) Alarm register 1 D11 (Write) Alarm register 2 D10 (Write) Control status 1 D12 (Write) Control status 2 D12 (Write) Miscellaneous status D8 (Write)
Liquid Crystal Display
The liquid crystal display (LCD) is 40-character by 2-line display. The view angle of the LCD may be adjusted by varying R1, which changes the feedback of the drive voltage to the LCD display provided by N1. V1 and V2 in the operational amplifier circuit provide temperature compensation. The forward voltage drop across diodes V1 and V2 varies with temperature, resulting in the positive input to the amplifier also varying with temperature; this helps to maintain good LCD contrast.
HA72500
SECTION 2
closure is recognised by D5, R10, C8 and D4 debounce switch closures and openings from the switch matrix. No switches are fitted in the S8 and S9 locations. Table 2-23
2.3.10.4.6
CTU Front Panel Switch Scanner and Coder Output I013
I014
I015
I016
SWITCH RECOGNISED
0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1
0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1
0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1
0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1
S20 S19 S18 S17 S16 S15 S14 S13 S1 S2 S3 S4 S5 S10 S9 S8
Rotary Switches
HA72500 Figure 2-37
2.3.10.5.2
SECTION 2 RCMS Interface Board Block Diagram
Interface with CTU Processor MB Assembly
The interface with the CTU processor board comprises D1, D2 and RN1-9. Resistor
HA72500 2.3.10.5.5
SECTION 2 Heartbeat Indicator
The heartbeat LED, H1, is used as a diagnostic aid to make sure that the CTU processor software is writing to the RCMS interface board. During normal operation the LED will flash about once a second.
2.3.10.5.6
Opto-isolator Inputs
The RCMS interface board is fitted with six opto-isolator inputs. Each input comprises an opto-isolator, a diode, a 3.9 volts zener diode, a 1 uF capacitor and a 4.75 kilohms resistor. The resistor limits current to the opto-isolator; the capacitor filters the applied voltage; the zener ensures that low voltage inputs do not activate the opto-isolator; and the diode protects the opto-isolator against reverse polarity voltages. The inputs are read via buffer D7. The inputs to the buffer are normally pulled high by RN11 and go low when the opto-isolator is switched on.
2.3.10.5.7
Ident Tone Transformer
The ident tone transformer, T1, is a 600 ohms balanced transformer used to send ident to a remote location via XN1:32a,c. The ident input is sourced from the CTU processor board via XN3:46. The variable resistor R1 may be used to adjust the level of the ident signal.
2.3.10.5.8
External 5 Volts Circuit
The external 5 volts circuit comprises V13, R10, R15-16, C18, C23, and N7. This circuit provides a 5 volts supply for Transponder 2 which is independent of the CTU 5 volts supply. This ensures that any problem which brings down the transponder 5 volts supply will not adversely affect CTU 5 volts.
HA72500
SECTION 2
DME is a type 1A72549; a block diagram for this is shown in Figure 2-38. For a dual DME the Power Distribution Panel is a type 2A72549; a block diagram for this is shown in Figure 2-39. The circuit breakers used have a second set of contacts which are electrically isolated from the trip contacts. These secondary contacts are connected in series and t ied to ground at one end. The other end is connected to the CTU as the TRNS_CB_OFF line. If all circuit breakers are on, the TRNS_CB_OFF signal to the CTU will be ground. If one or more of the circuit breakers are off, the TRANS_CB_OFF signal will appear as an open circuit at the CTU. Figure 2-38
Single Power Distribution Panel Block Diagram
Figure 2-39
Dual Power Distribution Panel Block Diagram
HA72500 2.3.13
SECTION 2 Power Supply System Dual AC 2A/3A69758
REFER Circuit Diagram 69758-3-28 The Dual AC Power Supply Systems 2A69758 and 3A69758 each consist of two AC Power Supplies 3A71130 mounted in an equipment rack. The two types are electrically and functionally identical but they are mounted in different rack sizes; the type supplied depends on the installation requirements. The layout of a type 2A69758 is shown in Figure 2-40, as an example. Each AC power supply positive and negative output is connected independently to the DME racks +ve and -ve battery terminals. The AC power supplies' status outputs (AC Power Normal 1 and 2, Bty Charger Normal 1 and 2 and Mains OK) are connected to terminal blocks for ease of connection. It should be noted that 'Mains OK' is from AC power supply 1 only. For detail on AC Power Supply 3A71130, refer to the handbook detail in Appendix J. Figure 2-40
Power Supply System Dual AC 2A69758 Layout
HA72500 2.3.14
SECTION 2 Transponder Subrack 1A72513
REFER Circuit Diagram 72556-2-01 The transponder subrack consists of a st andard Eurocard 6 unit by 280 mm deep card frame which accepts the five transponder plug-in modules. The card frame is fitted with a Transponder Subrack Motherboard (1A72556) in the upper three units, and an RF connector mounting panel in the lower three units to make the coaxial connections when the modules are plugged in. The chassis of the plug-in modules are grounded to the subrack through securing screws fitted to the front panels of t he modules.
2.3.15
CTU Subrack 1A72506
REFER Interwiring Diagrams 72550-1-03, 72505-2-06, 72505-2-17 The CTU subrack consists of a standard Eurocard 6 unit by 220 mm deep card frame which accepts the Control and Test Unit (1A72550) and the Power Distribution Panel (1A/2A72549); a number of spare monitors are available for expansion (for remote maintenance monitoring, for example). All modules are of the plug-in type. The CTU plugs into DIN type IDC connectors in the card frame. The power distribution panel plugs into a 15-way DIN connector in the card frame, which is connected directly to the main power loom. The chassis of the plug-in modules are grounded to the subrack through securing screws fitted to the front panels of t he modules.
HA72500
SECTION 2
Voltage regulator N1 provides a remote supply for the modem connector XN3 (for use by a remote maintenance monitoring system).
2.3.17
1kW PA Power Supply Frame 1A72503
This is designed to carry the 1kW PA Power Supply (1A72540). The frame occupies 6 units of rack space, and has a front panel which hinges forward and down to provide access to the 1kW PA power supply, which is fitted to this panel. The front panel has two straps to stop it approximately horizontally when open. It is fitted with two captive screws to secure it in t he closed position. When fitted to the rack the 1kW RF Power Amplifier (1A72535) is located directly behind the 1kW PA power supply frame.
HA72500
SECTION 4
SECTION 4
MAINTENANCE PROCEDURES
HA72500
SECTION 4 TABLE of CONTENTS
4.
MAINTENANCE PROCEDURES ............................................................... 4-1 4.1 LINE-REPLACEABLE UNITS (LRU) 4-1 4.1.1 Removal/Replacement Instructions............................................................ 4-1 4.1.2 Fault Location ............................................................................................ 4-2 4.1.3 LRU Post-Replacement Tests.................................................................... 4-9 4.2 WAVEFORMS 4-15 4.3 SPECIAL MAINTENANCE PROCEDURES 4-38 4.3.1 Stripline Printed Wiring Boards................................................................. 4-38 4.3.2 Conformal Coating ................................................................................... 4-43 4.3.3 RF Transistor Replacement ..................................................................... 4-44
HA72500
SECTION 4
LIST of FIGURES Figure 4-1 Figure 4-2 Figure 4-3 Figure 4-4 Figure 4-5 Figure 4-6 Figure 4-7 Figure 4-8 Figure 4-9 Figure 4-10 Figure 4-11
Signal Flow Block Diagram ...................................................................4-4 Lateral Positioning of Chip Capacitors.................................................4-38 Longitudinal Positioning of Chip Capacitors ........................................4-38 Chip Capacitor Soldering Requirements .............................................4-39 Soldering of Through Board Mounted Chip Capacitors........................ 4-39 Part Placement ...................................................................................4-40 Maximum/Minimum Solder Conditions ................................................4-41 Lead Placement Conditions ................................................................4-41 Lead Soldering Conditions ..................................................................4-42 Minimum Clearance of Sealed Components .......................................4-42 Multiple Lead Termination Requirements ............................................4-43
LIST of TABLES
Table 4-1
LRU Post-Replacement Tests...................................................................4-9
HA72500
SECTION 4
4. MAINTENANCE PROCEDURES 4.1
LINE-REPLACEABLE UNITS (LRU)
4.1.1
Removal/Replacement Instructions
The DME LDB-102 contains a number of line replaceable units (LRUs) which can be replaced during field servicing. A list of LRUs can be found in Section 3.4. The following sections describe the procedure for removing units. Units may be refitted by following the reverse procedure.
4.1.1.1
SMA Connectors
Most RF LRUs are connected using SMA coaxial connectors. These may be disconnected using the 8 mm open-ended spanner provided in the DME Test Accessory Kit. When reconnecting SMA connectors, ensure that the connectors are properly aligned and not cross-threaded. The connector nut should be tightened to a torque of 0.5 newton-metres (4.5 inch-pounds), which is equivalent to a light hand pressure on the spanner provided.
4.1.1.2
PWB Assemblies (General)
a.
Disconnect all external connectors.
b.
Remove the printed wiring board (PWB) fixing screws, and withdraw the PWB.
HA72500
SECTION 4
b. Remove the fixing screws and withdraw the unit.
CAUTION
When disconnecting the ‘flexible’ semirigid coaxial cables, do not strain the cables more than is necessary to permit removal of the unit being serviced. If straining of these cables is necessary, do so evenly along the length of each cable, and avoid straining the cable close to the connectors, as fatigue failure may result.
4.1.1.6
Switched Attenuator 1A69737
a. Disconnect all external connectors. b. Remove the two fixing screws, and withdraw the unit.
4.1.1.7
CTU Front Panel PWB Assembly 1A72553
a. Disconnect all external connectors. b. Remove the CTU Processor PWB Assembly 1A72552, and the RMS Interface PWB Assembly 1A72555, following the procedure described in Section 4.1.1.2. c. Remove the six fixing screws for the front panel. The CTU front panel and CTU front panel PWB assembly can then be lifted away separately from the CTU module chassis.
4.1.1.8
DC-DC Converter PWB Assembly 1A72542
a. Hinge open the front panel of the 1kW Power Supply Frame 1A72503. b. Disconnect all external connectors to the DC-DC converter.
HA72500
SECTION 4
The following guidance information is given to assist technical personnel locate a defective LRU after a DME beacon has shut down or registered a fault. The facilities discussed below may be used either individually or in combination to isolate the defective unit. a. System Block Diagrams Two levels of block diagram are included in the DME handbook to show the signal flow through the equipment. These are: 1. System Block Diagrams: Single Dual Test Facility
see Figure 2-1. see Figure 2-2. see Figure K-2.
2. Signal Flow Block Diagram; see Figure 4-1. This last drawing indicates the divisions between modules and subassemblies, and the signal flow between then. It eases the task of tracing a signal through a particular subsystem for fault location purposes. b. Test Facility The test facility, which is part of the CTU, allows rapid measurement of the main beacon parameters and internal signal levels. During troubleshooting, the parameter values and signal voltage levels may be compared with the values recorded at station commissioning. In many cases, this will isolate a fault t o a specific module. Refer to Appendix A, Section A.3, for operating instructions of the Test Facility.
HA72500 Figure 4-1
SECTION 4 Signal Flow Block Diagram
HA72500
SECTION 4
These procedures trace the signal firstly through the interrogation and receiver chain, and then through the transmitter chain. The test interrogator is used as a source of test signals for the transponder, and it is essential to obtain interrogations at the correct level from the test interrogator in order to check operation of the receiver and video signal processing. Test jacks are provided on the module front panels to f acilitate troubleshooting. The typical waveforms measured on these test points are given in Section 4.2. Reference is made to these waveforms during the signal tracing procedures.
4.1.2.2.1
Conditions for Tests
1. Operate the equipment in the MAINTENANCE mode, as described in Appendix A.1 for a single DME, and A.2 for a dual DME. 2. For a dual DME, the defective transponder will be operated as the standby. On the RF panel at the rear of the rack, connect the test interrogator of the standby transponder to the second directional coupler, so that it can be used to interrogate the standby transponder. This is described in Appendix A.2.5.1. 3. On the standby monitor of a dual DME, switch the MONITOR OUTPUTS switch to the FAILED position (this takes the monitor 'off-line'). 4. On the CTU, select MONITOR ALARM to INHIBIT. For a single DME, press the SELECT MAIN, NO 1 switch. For a dual DME, press the SELECT MAIN, NO 1 or NO 2 switch for the transponder that will be operating normally (for example, if transponder 2 is under investigation, then select NO 1 as the operating transponder so that transponder 2 becomes the standby).
HA72500
SECTION 4 If the waveforms are significantly different, malfunction of the receiver video is indicated. Either the entire module, or separate LRU, should be replaced with appropriate assemblies tuned to the correct frequency.
4.
If, after replacement of the module or circuit board assemblies, the correct waveform is still not obtained, consult Figure 4-1 to identify the block circuitry in the failed signal path.
5.
Set the oscilloscope to 0.5 volts/division and 5 microseconds/division. On the CTU, select Effncy measurement, to cause the interrogations to switch between high and low level. With only one oscilloscope channel displayed, observe the waveform on the DETECTED LOG VIDEO test jack and compare it with that in Waveform 37. If the displayed waveform does not show the two discrete pulse amplitude levels, malfunction of the level switching in t he test interrogator is indicated. Replace either the complete test interrogator, or the main board assembly and switched attenuator LRUs.
6.
Display the waveforms at the DETECTED LOG VIDEO and ON CHANNEL VIDEO test jacks. Compare the displayed waveform with those shown in Waveform 36.
7.
Similarly, display the waveform at the DOUBLE PULSE DECODER OUT test jack and compare with that in Waveform 33.
8.
Reset the oscilloscope to 10 microseconds/division and check that the waveform at the TRIGS TO MODULATOR test jack is similar to that in Waveform 35.
HA72500
SECTION 4 If this voltage is more than 3 volts out of range, then replace the DC-DC converter in the 1kW PA power supply.
2.
Trigger the oscilloscope from the TRIGS TO MODULATOR test jack on the receiver video. Display the waveform at the SHAPED MODULATION test jack on the transmitter driver, and compare the displayed waveform with that shown in Waveform 51. Check that the pulse amplitude is within the normal amplitude range stated against Waveform 51; the 1kW PA power supply must be within limits for this pulse to be correct. If the amplitude exceeds this range, and there is low (or zero) output from the transmitter, then it is probably due to the automatic level control (ALC) trying to correct the low output condition. If this pulse is absent, or significantly below the stated range, then it indicates a fault on the pulse shaper board, which should be replaced.
3.
Display the waveform at the DRIVER LEVEL test jack on the transmitter driver. If the drive waveform amplitude is within the limits stated against Waveform 52, then it indicates that the transmitter driver is satisfactory and is providing drive to the RF power amplifier. Proceed to step 9 to continue the signal tracing. If the waveform amplitude is below the limits stated, then check the performance of the transmitter driver units, as detailed in steps4 to 8.
4.
Extend the transmitter driver using the transponder extender frame. Switch on power to the transponder, switch DRIVER DC POWER to NORMAL, and check that the following supply voltages are within the limits stated:
HA72500
SECTION 4 If the waveform is low in amplitude, then it indicates either insufficient drive, from the exciter, or a fault in the medium power driver itself. Replace each subassembly in turn to determine the defective unit.
7.
Remove the cover from the power modulation amplifier and clip the current probe around the wire supplying collector current to the RF amplifier subassembly. Check that the collector current waveform is within the limits stated against Waveform 56. If the waveform is low in amplitude, then it indicates either insufficient drive from the medium power driver, or a fault in the power modulation amplifier itself. Replace each subassembly in turn to determine the defective unit.
8.
If any units have been replaced or adjusted, repeat the check described in Step 3 above. If the waveform amplitude is now within the stated limits, then replace the covers on the units in the transmitter driver, then replace the module in the rack.
9.
On the 1kW RF amplifier, display the waveform from the POWER AMP MODULATOR test jack and check that it is within the limits stated against Waveform 60. If the waveform is low in amplitude, and if it has been previously determined that the RF drive and the modulation to the 1kW RF amplifier are correct, then a fault in the 1kW power modulation amplifier is indicated. Remove the cover from the 1kW RF amplifier and replace the power modulation amplifier.
10.
On the 1kW RF amplifier, display the waveform from the POWER AMP DRIVER test jack and check that it is within the limits stated against
HA72500 4.1.3
SECTION 4 LRU Post-Replacement Tests
This section details the tests and/or adjustments required to be made to an operational beacon following the replacement of any module or subassembly. The information is presented in tabular form, and: a. contains a brief statement of the parameter or performance function required to be checked, or adjustments required to be made, as applicable, in sequence user order; and also b. cites the relevant section of this handbook in which the detailed procedure for the required check, measurement, or adjustment may be found. If any module or subassembly is replaced during servicing, then the procedure listed for that unit MUST be performed to restore the beacon to operational status. It is implicit that all other units in the beacon are in normal working order. Table 4-1
LRU Post-Replacement Tests
MODULE OR SUBASSEMBLY 1A69737 Attenuator
PARAMETER TO BE CHECKED or ADJUSTMENT TO BE MADE
REFER to SECTION
High and low switching of interrogations
3.2.4.13.2
1A69755 2A69755 Directional Coupler
1 2 3
Final receiver checks Calibrate Final check
3.2.4.13.2 3.2.4.10.5 3.2.4.18
1A69873 250W RF Amplifier
1
Check Transmitter Pulse Parameters
2
(if pulse parameters out of tolerance, then perform output
3.2.4.10.1 to 3.2.4.10.4 (3.2.4.9)
HA72500
SECTION 4
MODULE OR SUBASSEMBLY 1A72515 Test Interrogator Main PWB
PARAMETER TO BE CHECKED or ADJUSTMENT TO BE MADE 1 2
REFER to SECTION
3 4 5
Set preset switch S4 for X or Y channel Set front panel switches REPLY GATE delay to setting recorded for the station Check RF Generator output pulse amplitude and shape Check signal timing parameters Set REPLY ACCEPT GATES
6 7
Check high and low level switching of interrogations Final check
3.2.4.4.1~2 3.2.4.4.6 3.2.4.11.2 steps 2 to 5 3.2.4.13.2 3.2.4.18
1A72516 RF Generator
1 2 3 4 5 6
Install crystals for interrogate frequencies Align RF Generator Check RF Generator crystal frequencies Check RF Generator output pulse amplitude and shape Check test frequencies Final check
3.2.4.1.2 3.2.5 3.2.4.4.5 3.2.4.4.1~2 3.2.4.4.3 3.2.4.18
1A72517 RF Filter
1
Align RF Filter
2
Check receiver video module RF levels
3.2.6 steps11~13 3.2.4.5 steps 4~5
1A72518 Modulator and Detector
1
3.2.4.4.1~2
2 3
Check and adjust RF Generator output pulse amplitude and shape Check signal timing parameters Final check
1A72519 Reply Detector
1
Check detector coincidence
2 3
Calibrate peak power display Check Reply Delay measurement. (This should be within
3.2.4.4.6 step 3 3.2.4.10.5 3.2.4.13.1
3.2.4.4.6 3.2.4.18
HA72500
SECTION 4
MODULE OR SUBASSEMBLY 1A72521 Receiver Video Main PWB
PARAMETER TO BE CHECKED or ADJUSTMENT TO BE MADE
REFER to SECTION 3.2.4.2.4 3.2.4.2.4
6 7
Set internal switches S4 and S5 for X or Y channel Set code switches for station ident code Select SDES and LDES OFF or ON as required for the station Set internal DEAD TIME and LDES PERIOD switches to standard setting of 6, or to setting recorded for the station Set front panel BEACON DELAY and SPACING (SEPARATION) switches to settings recorded for the station Adjust 6 dB offset Check receiver sensitivity
8 9 10 11 12 13 14 15
Check decoding window Check reply rate Set dead time Set LDES THRESHOLD (if LDES is used) Check SDES (if used) Check station ident code Set Reply Delay Final check
1 2 3 4 5
Install crystal for reply frequency Align RF Source for operation at the station frequency (if not pre-aligned) Check RF source crystal frequency and check RF level Check receiver sensitivity Final check
1 2
Set AGC link XN2 to AGC position Align IF amplifier (if not pre-aligned)
1 2 3 4 5
1A72522 RF Source
1A72523 IF Amplifier
3.2.4.7 3.2.4.11 steps 2~3 3.2.4.11.6 3.2.4.11.8 3.2.4.11.9 3.2.4.12.1 3.2.4.12.2 3.2.4.14.1 3.2.4.13.1 3.2.4.18 3.2.4.1.2 3.2.6 3.2.4.5 3.2.4.11.3 3.2.4.18 3.2.9
HA72500
SECTION 4
MODULE OR SUBASSEMBLY 1A72530 Transmitter Driver
PARAMETER TO BE CHECKED or ADJUSTMENT TO BE MADE
REFER to SECTION 3.2.4.2.5 3.2.7
4 5 6
Set internal switches to alignment p ositions Align Transmitter Driver for operation at the station frequency (if not pre-aligned) Adjust Transmitter Driver for correct drive to RF Power Amplifier Align Transmitter output pulse Adjust ALC for correct power out Check Transmitter output pulse amplitude and shape
7
Final check
1 2
3.2.4.2.5 3.2.8
5 6 7 8
Set PWB switches to alignment positions Align function generator for nominal pulse shape (if not prealigned) Adjust Transmitter Driver for correct drive to RF Power Amplifier. Note: This is necessary only if PWB has ne ver been aligned. Adjust Transmitter Driver for correct drive to RF Power Amplifier Align Transmitter output pulse Adjust ALC for correct power out Check Transmitter output pulse amplitude and shape Final check
1
Set Pulse Shaper Board switches to a lignment positions
2
Set Exciter supply voltages to initial values
3.2.7.1 step 3 3.2.7.1
1 2 3
1A72531 Pulse Shaper PWB Assembly
3
4
1A72532 Exciter
3.2.4.8 3.2.4.9.1 3.2.4.9.2 3.2.4.10 steps 1~4 3.2.4.18
3.2.7 3.2.4.8 3.2.4.9.1 3.2.4.9.2 3.2.4.10 steps 1~4 3.2.4.18
HA72500
SECTION 4
MODULE OR SUBASSEMBLY
PARAMETER TO BE CHECKED or ADJUSTMENT TO BE MADE B
2 3 4
FOR POWER MODULATION AMPLIFIER IN 1kW POWER AMPLIFIER. Adjust Transmitter Driver for correct drive to 1kW Power Amplifier. Align transmitter output pulse. Adjust ALC for correct power out. Check Transmitter output pulse amplitude and shape.
5
Final check.
1 2 3 4
Adjust Transmitter Driver for correct drive to 1 kW PA. Align 1 kW Power Amplifier. Adjust ALC for correct power out. Check transmitter output pulse amplitude and shape.
5
Final check.
1
Prepare Transmitter Driver for 1 kW PA alignment.
2 3
Adjust ALC for correct power out. Check transmitter output pulse amplitude and shape.
4
Final check.
1A72537 Power Combiner
1
Perform all checks listed for Power Divider, 1A72536.
1A72540 1 kW PA Power Supply
1
Check power switching to 1kW Power Amplifier.
2 3
Check LED indicators. Check voltage at HT test jack and adjust if necessary.
1
1A72535 1kW Power Amplifier
1A72536 Power Divider
REFER to SECTION
3.2.4.8 3.2.4.9.1 3.2.4.9.2| 3.2.4.10 steps 1 to 4 3.2.4.18 3.2.4.8.1 3.2.4.9.1 3.2.4.9.2 3.2.4.10 steps 1 to 4 3.2.4.8.1 steps 1 to 9 3.2.4.9.2 3.2.4.10 steps 1 to 4 3.2.4.18
4.9.1 steps 4, 5 3.2.4.9.1
HA72500
SECTION 4
MODULE OR SUBASSEMBLY 1A72550 Control and Test Unit
PARAMETER TO BE CHECKED or ADJUSTMENT TO BE MADE
REFER to SECTION
1 2 3 4
Set configuration and offset switches S1 and S2 Perform rack powering sequence Adjust low voltage shutdown level Set power-on inhibit delay S11
5
Adjust ident volume and set external ident level (if applicable)
3.2.4.2.3 3.2.4.3 3.2.4.16.7 Appendix A.5.1.6 Appendix A.3.2.14
SINGLE DME 6
Check control system action for: a. Normal operation b. Primary Fault c. Secondary Fault d. Recycle DUAL DME
7
8
Check control system action for: a. Normal operation, No. 1 Main b. Primary fault c. Secondary fault d. Normal operation, No. 2 Main e. Primary fault f. Secondary fault g. Recycle Check Test Unit operation
9
Confirm correct operation of remote control and status
3.2.4.16, Part 1 3.2.4.16.1 3.2.4.16.2 3.2.4.16.3 3.2.4.16.4 3.2.4.16 Part 2 3.2.4.16.1 3.2.4.16.2 3.2.4.16.3 3.2.4.16.4 3.2.4.16.5 3.2.4.16.6 3.2.4.16.7 Appendix A 3.1.2 3.2.4.18
HA72500
4.2
SECTION 4
WAVEFORMS
WAVEFORM 1
S E T T I N G S
Monitor
Trigger from:
Test Interrogator TRIGGER jack
Timebase:
5 microseconds/division Channel 2
Mode:
DC
Sensitivity:
2 volts/division
Connect to:
Monitor ERP PULSE jack
Typical value:
3.5 to 10 volts
Included reference waveforms:
None
Conditions:
Beacon in normal operation
WAVEFORM 2
Monitor
S E T T I N G S
Trigger from:
Test Interrogator TRIGGER jack
Timebase:
1 microsecond/division Channel 1 (lower trace)
Mode:
DC
Sensitivity:
2 volts/division
ERP PULSE XA1
RISE PULSE XT3
HA72500
WAVEFORM 4
S E T T I N G S
SECTION 4
Monitor
Trigger from:
Test Interrogator TRIGGER jack
Timebase:
1 microsecond/division Channel 1
Mode:
DC
Sensitivity:
2 volts/division Channel 1
Connect to:
Channel 1 DELAY COUNT test point XT5 (upper) Channel 2 DELAY PULSE test point XT6 (lower)
Typical value:
A correctly aligned delay monitor will have the failing edge of trace 2 occurring during second pulse of trace 1.
Included reference waveforms:
None
Conditions:
Beacon in normal operation
WAVEFORM 5
Monitor
S E
Trigger from:
Test Interrogator TRIGGER jack
Timebase:
2 microseconds/division
Mode:
DC
DELAY COUNT XT5 DELAY PULSE XT6
WIDTH COUNT XT7 WIDTH PULSE XT11
HA72500
WAVEFORM 7
S E T T I N G S
SECTION 4
Monitor
Trigger from:
Test Interrogator TRIGGER jack Channel 2
Timebase:
0.5 microseconds/division
Mode:
DC
Sensitivity:
2 volts/division
Connect to:
Monitor TIPRF test point XT9
Typical value:
5 volts logic level
Included reference waveforms:
Test Interrogator TRIGGER jack
Conditions:
Beacon in normal operation
WAVEFORM 8
Monitor
S E T T I N G S
Trigger from:
Test Interrogator TRIGGER jack
Timebase:
1 microsecond/division Channel 2
Mode:
DC
Sensitivity:
2 volts/division
Connect to:
Monitor FALL PULSE test point XT10
Typical value:
5 volts logic levels
TIPRF XT9
FALL PULSE XT10
HA72500
WAVEFORM 10
S E T T I N G S
SECTION 4
Monitor
Trigger from:
Test Interrogator TRIGGER jack
Timebase:
2 microseconds/division
Mode:
DC
Sensitivity:
2 volts/division
Connect to:
Monitor RISE COUNT test point XT15 Channel 1 (upper trace) Monitor RISE PULSE test point XT3 Channel 2 (lower trace)
Typical value:
5 volts logic levels
Included reference waveforms:
None
Conditions:
Beacon in normal operation
WAVEFORM 11
Monitor
S E T T I N G
Trigger from:
Test Interrogator TRIGGER jack
Timebase:
2 microseconds/division
Mode:
DC
Sensitivity:
2 volts/division
Connect to:
Monitor FALL COUNT test point
RISE PULSE XT3 RISE COUNT XT15
FALL PULSE XT10 FALL COUNT XT16
HA72500
WAVEFORM 13 S E T T I N G S
SECTION 4
Test Interrogator
Trigger from:
Test Interrogator TRIGGER jack
Timebase:
20 microseconds/division
Mode:
DC
Sensitivity:
5 volts/division
Connect to:
Receiver Video LDES PULSE jack
Typical value:
15 volts logic levels
Included reference waveforms:
Test Interrogator INTERROGATIONS TIMING jack Channel 2
Conditions:
1. LDES switch ON 2. Beacon in normal operation
WAVEFORM 14
Test Interrogator
S E T T I N G S
Trigger from:
Test Interrogator TRIGGER jack
Timebase:
5 microseconds/division Channel 1
Mode:
DC
Sensitivity:
5 volts/division
Connect to:
Test Interrogator REPLY ACCEPT GATES jack
LDES PULSE XA2
REPLY ACCEPT GATES XA3
HA72500
WAVEFORM 16 S E T T I N G S
SECTION 4
Test Interrogator
Trigger from:
Test Interrogator TRIGGER jack
Timebase:
5 microseconds/division Channel 1
Mode:
DC
Sensitivity:
5 volts/division
Connect to:
DETECTED REPLIES jack
Typical value:
3.5 to 10 volts
Included reference waveforms:
GND Channel 2
Conditions:
Beacon in normal operation
WAVEFORM 17
Test Interrogator
S E T T I N G S
Trigger from:
Test Interrogator TRIGGER jack
Timebase:
2 microseconds/division Channel 1
Mode:
DC
Sensitivity:
2 volts/division
Connect to:
Test Interrogator DETECTED INTERROGATIONS jack
Typical value:
3.8 to 6.9 volts
DETECTED REPLIES XA7
DETECTED INTERROGATIONS XA8
HA72500
WAVEFORM 19
S E T T I N G S
SECTION 4
Test Interrogator
Trigger from:
Test Interrogator TRIGGER jack
Timebase:
5 microseconds/division Channel 2
Mode:
DC
Sensitivity:
5 volts/division
Connect to:
Test Interrogator DETECTED REPLIES jack
Typical value:
15 volts logic levels
Included reference waveforms:
Test Interrogator DETECTED REPLIES jack
Conditions:
Beacon in normal operation
WAVEFORM 20
Test Interrogator
S E T T I N G S
Trigger from:
Test Interrogator TRIGGER jack
Timebase:
10 microseconds/division Channel 1 (lower trace)
Mode:
DC
Sensitivity:
5 volts/division
Connect to:
Test Interrogator INTERROGATIONS
REPLY TIMING XA12
REPLY TIMING XA1 INTERROGATIONS TIMING XA13
HA72500
WAVEFORM 22 S E T T I N G S
SECTION 4
Test Interrogator
Trigger from:
Test Interrogator TRIGGER jack
Timebase:
10 microseconds/division
Mode:
DC
Sensitivity:
2 volts/division
Connect to:
COUNTER test point XT2 Channel 1
Typical value:
5 volts logic levels
Included reference waveforms:
None
Conditions:
1. Beacon in Maintenance Mode 2. Select Channel 1 3. Select PARAM 4. Select TX RATE
WAVEFORM 23
Test Interrogator
S E T T I N G S
Trigger from:
Test Interrogator TRIGGER jack
Timebase:
20 microseconds/division
Mode:
DC
Sensitivity:
2 volts/division
Connect to:
Test Interrogator test point XT3
COUNTER XT2
M FLT SPACING XT3
HA72500
WAVEFORM 25 S E T T I N G S
SECTION 4
Test Interrogator
Trigger from:
Test Interrogator TRIGGER jack
Timebase:
5 microseconds/division Channel 1
Mode:
DC
Sensitivity:
0.5 volts/division
Connect to:
Test Interrogator test point XT6
MICROSECOND MARKERS XT6
Typical value: Included reference waveforms:
None
Conditions:
Beacon in normal operation
WAVEFORM 26
Test Interrogator
S E T T I N G S
Trigger from:
Test Interrogator TRIGGER jack
Timebase:
10 microseconds/division
Mode:
DC
Sensitivity:
2 volts/division
Connect to:
Test Interrogator TIMER test point XT7
Typical value:
5 volts logic levels
TIMER XT7
HA72500
WAVEFORM 28 S E T T I N G S
SECTION 4
Test Interrogator
Trigger from:
Test Interrogator TRIGGER jack
Timebase:
0.1 microseconds/division
Mode:
DC
Sensitivity:
5 volts/division
Connect to:
Test Interrogator test point XT9
Typical value:
5 volts logic levels
Included reference waveforms:
None
Conditions:
1. Maintenance Mode 2. Select Channel 1 3. Select FLT LIMIT Select DELAY
WAVEFORM 29
Test Interrogator
S E T T I N G S
Trigger from:
Channel 1 to XT10
Timebase:
20 microseconds/division
Mode:
DC
Sensitivity:
2 volts/division
Connect to:
Test Interrogator test point XT10
Typical value:
5 volt logic levels
M FLT DELAY XT9
ATTENUATOR XT10
HA72500
WAVEFORM 31 S E T T I N G S
SECTION 4
Test Interrogator
Trigger from:
Test Interrogator TRIGGER jack
Timebase:
0.1 microseconds/division
Mode:
DC
Sensitivity:
5 volts/division
Connect to:
Test Interrogator test point XT12
Typical value:
15 volts logic levels
Included reference waveforms:
None
Conditions:
Beacon in normal operation
WAVEFORM 32
Receiver Video
S E T T I N G S
Trigger from:
Test Interrogator TRIGGER jack
Timebase:
2 microseconds/division Channel 2 (lower trace)
Mode:
DC
Sensitivity:
5 volts/division
Connect to:
Receiver Video SDES jack
Typical value:
15 volts logic levels
10 MHz 15V XT12
SDES PULSE XA1
HA72500
WAVEFORM 34 S E T T I N G S
SECTION 4
Receiver Video
Trigger from:
Test Interrogator TRIGGER jack
Timebase:
20 microseconds/division Channel 1
Mode:
DC
Sensitivity:
5 volts/division
Connect to:
Receiver Video DEAD TIME jack
Typical value:
15 volts logic levels
Included reference waveforms:
Test Interrogator INTERROGATION TIMING jack Channel 2
Conditions:
Beacon in normal operation
WAVEFORM 35
Receiver Video
S E T T I N G S
Trigger from:
Test Interrogator TRIGGER jack
Timebase:
10 microseconds/division Channel 1
Mode:
DC
Sensitivity:
5 volts/division
Connect to:
Receiver Video TRIGS TO MODULATOR jack
DEAD TIME XA4
TRIGS TO MODULATOR XA5
HA72500
WAVEFORM 37
S E T T I N G S
SECTION 4
Receiver Video
Trigger from:
Test Interrogator TRIGGER jack
Timebase:
5 microseconds/division
Mode:
DC
Sensitivity:
0.5 volts/division
Connect to:
Receiver Video DETECTED LOG VIDEO jack
DETECTED LOG VIDEO XA13
Typical value: Included reference waveforms:
None
Conditions:
Beacon in normal operation
WAVEFORM 38
Receiver Video
S E T T I N G S
Trigger from:
Receiver Video DOUBLE PULSE DECODER jack
Timebase:
10 microseconds/division
Mode:
DC
Sensitivity:
5 volts/division
Connect to:
Channel 1 to XT1 Channel 2 to XA3
SELECT INTERROGATION XT1
HA72500
WAVEFORM 40
S E T T I N G S
SECTION 4
Receiver Video
Trigger from:
Channel 1
Timebase:
2 microseconds/division Channel 1
Mode:
DC
Sensitivity:
5 volts/division
Connect to:
Channel 1 to Receiver Video board test point XT3
Typical value:
15 volts logic levels
Included reference waveforms:
None
Conditions:
Beacon in normal operation
WAVEFORM 41
Receiver Video
S E T T I N G S
Trigger from:
Test Interrogator TRIGGER jack
Timebase:
10 microseconds/division
Mode:
DC
Sensitivity:
5 volts/division
Connect to:
Channel 1 to Receiver Video board test point XT5 BEACON DELAY O/P
Typical value:
15 volt logic levels
XT3
BEACON DELAY O/P XT5
HA72500
WAVEFORM 43
S E T T I N G S
SECTION 4
Receiver Video
Trigger from:
Receiver Video DOUBLE PULSE DECODER OUT jack
Timebase:
0.5 microseconds/division
Mode:
DC
Sensitivity:
5 volts/division
Connect to:
Channel 1 to Receiver Video board test point XT8
Typical value: Included reference waveforms:
15 volts logic levels Channel 2 to Receiver Video DOUBLE PULSE DECODER OUT jack
Conditions:
Beacon in normal operation
WAVEFORM 44
Receiver Video
S E T T I N G
XT8
Trigger from:
Test Interrogator TRIGGER jack
Timebase:
5 microseconds/division
Mode:
DC
Sensitivity:
Channel 1 - 1 volt/division Channel 2 - 5 volts/division
XT11
HA72500
WAVEFORM 46
S E T T I N G S
SECTION 4
Receiver Video
Trigger from:
Test Interrogator TRIGGER jack
Timebase:
5 microseconds/division microseconds/division
Mode:
DC
Sensitivity:
1 volt/division
Connect to:
Channel 1 to Receiver Video board test point XT6
XT13
Typical value: Included reference waveforms:
Channel 2 connected to Receiver Video board test point XT13
Conditions:
Beacon in normal operation
WAVEFORM 47
Receiver Video
S E T T I N G S
Trigger from:
Test Interrogator TRIGGER jack
Timebase:
5 microseconds/division microseconds/division
Mode:
DC
Sensitivity:
1 volt/division
Connect to:
Channel 1 to Receiver Video board test point XT6
XT14
HA72500
WAVEFORM 49
S E T T I N G S
SECTION 4
Transmitter Transmit ter Driver
Trigger from:
Test Interrogator TRIGGER jack
Timebase:
10 microseconds/division microseconds/division Channel 1
Mode:
DC
Sensitivity:
5 volts/division
Connect to:
Transmitter Driver SQUARE MODULATION jack
Typical value:
15 volts logic levels
Included reference waveforms:
Test Interrogator PRF PULSE jack
Conditions:
Beacon in normal operation
WAVEFORM 50
Transmitter Transmit ter Driver
S E T T I N G S
Trigger from:
Test Interrogator TRIGGER jack
Timebase:
5 microseconds/division microseconds/division Channel 1
Mode:
DC
Sensitivity:
1 volt/division
Connect to:
Transmitter Driver FUNCTION GENERATOR jack
Typical value:
N/A
SQUARE MODULATION XA1
FUNCTION GENERATOR XA2
HA72500
WAVEFORM 52
S E T T I N G S
SECTION 4
Transmitter Driver
Trigger from:
Receiver Video TRIGS TO MODULATOR
Timebase:
2 microseconds/division microseconds/division
Mode:
DC
Sensitivity:
1 volt/division
Connect to:
DRIVER LEVEL jack
Typical value:
2 to 5 volts peak
Included reference waveforms:
SQUARE MODULATION
Conditions:
Beacon in normal operation
WAVEFORM 53
Pulse Shaper
S E T T I N G S
Trigger from:
Test Interrogator TRIGGER jack
Timebase:
10 microseconds/division microseconds/division
Mode:
DC
Sensitivity:
5 volts/division
Connect to:
Pulse Shaper Board test point XT4
Typical value:
DRIVER LEVEL XA5
SQUARE MODULATION MODULATION XT4
HA72500
WAVEFORM 55
S E T T I N G S
SECTION 4
Medium Power Driver
Trigger from:
Receiver Video TRIGS TO MODULATOR test jack
Timebase:
2 microseconds/division microseconds/division
Mode:
Both channels DC
Sensitivity:
Channel 1. 10 volts/division Channel 2: 1 ampere/division
Connect to:
Channel 1: Collector supply lead of RF transistor in medium power driver Channel 2: Collector supply lead of RF transistor in medium power driver, with current probe
Typical value:
COLLECTOR CURRENT
Channel 1: 16 to 28 volts peak Channel 2: 2.0 to 2.4 amperes
Included reference waveforms: Conditions:
Beacon in normal operation
WAVEFORM 56
Power Modulation Modulatio n Amplifier Amplifie r
S E
Trigger from:
Receiver Video TRIGS TO MODULATOR test jack
Timebase:
2 microseconds/division microseconds/division
COLLECTOR CURRENT
HA72500
WAVEFORM WAVEFORM 58
S E T T I N G S
SECTION 4
Transponder Power Supply
Trigger from:
Test Interrogator TRIGGER jack
Timebase:
10 microseconds/division microseconds/division
Mode:
DC
Sensitivity:
0.2 volts/division
Connect to:
Transponder Power Supply test point XT8
Typical value:
N/A
Included reference waveforms:
None
Conditions:
Beacon in normal operation
WAVEFORM WAVEFORM 59
Transponder Power Supply
S E T T I N G S
Trigger from:
Test Interrogator TRIGGER jack
Timebase:
5 microseconds/division microseconds/division
Mode:
DC
Sensitivity:
1 volt/division
Connect to:
Transponder Power Supply test point XT9
Typical value:
XT8
XT9
HA72500
WAVEFORM 61
S E T T I N G S
SECTION 4
1kW RF Amplifier Amplifie r
Trigger from:
Receiver Video TRIGS TO MODULATOR test jack
Timebase:
5 microseconds/division microseconds/division
Mode:
DC
Sensitivity:
1 volt/division
Connect to:
POWER AMP OUTPUT jack
Typical value:
4.0 to 7.5 volts peak
Included reference waveforms:
None
Conditions:
Beacon in normal operation
WAVEFORM 62
1kW RF Amplifier Amplifie r
S E T T I N G S
Trigger from:
Receiver Video TRIGS TO MODULATOR test jack
Timebase:
5 microseconds/division microseconds/division
Mode:
DC
Sensitivity:
1 volt/division
Connect to:
POWER AMP DRIVERJACK
POWER AMP Output XA2
POWER AMP DRIVER XA3
HA72500
WAVEFORM 64
S E T T I N G S
SECTION 4
1kW RF Amplifier : 250W Output Amplifiers
Trigger from:
Receiver Video TRIGS TO MODULATOR test jack
Timebase:
5 microseconds/division
Mode:
DC
Sensitivity:
2 amperes/division
Connect to:
Collector supply lead to 250W amplifiers A3-A10, with current probe
Typical value:
10 to 15 amperes peak
Included reference waveforms:
None
Conditions:
Beacon in normal operation
WAVEFORM 65
1kW RF Amplifier : Power Mod Amp
S E T T I N G S
Trigger from:
Receiver Video TRIGS TO MODULATOR test jack
Timebase:
5 microseconds/division
Mode:
DC
Sensitivity:
2 amperes/division
Connect to:
Collector supply lead to V1 of power
COLLECTOR CURRENT
COLLECTOR CURRENT
HA72500
WAVEFORM 67
S E T T I N G S
SECTION 4
Test Interrogator
Trigger from:
Receiver Video TRIGS TO MODULATOR test jack
Timebase:
1 microseconds/division Channel 1
Mode:
DC
Sensitivity:
2 volts/division
Connect to:
Test Interrogator DETECTED REPLIES jack
Typical value:
7 to 10 volts peak
Included reference waveforms:
None
Conditions:
Beacon in normal operation
DETECTED REPLIES XA7
HA72500
SECTION 4
4.3
SPECIAL MAINTENANCE PROCEDURES
4.3.1
Stripline Printed Wiring Boards
Component replacement on the flexible stripline printed wiring boards used in the LDB-102 requires that special requirements relating to positioning of components, soldering and cleaning be observed.
4.3.1.1
Positioning of Ceramic Chip Capacitors
a. Lateral Positioning. Ceramic chips must be positioned within the tr ack or pad boundaries or, when the pad is the same width as the chip, within 0.25 mm of true position (that is, 0.25 mm deviation each side of centre line); refer to Figure 4-2 Figure 4-2
Lateral Positioning of Chip Capacitors
HA72500
SECTION 4
be used; a suitable type is 'Multicore' Sn62. All fluxes must be of t he QQ-S-571E Type R or AS1834 type 2.
4.3.1.2.2
Soldering Surface Mounted Chip Capacitors
The soldering of surface mounted chip capacitors shall be such that the end result displays good wetting (solderability) indicating good joint integrity and reliability. Solder joints are to be smooth, bright and feathered to a thin edge, indicating proper wetting action. Lead material is not to be exposed within the solder connection, and no sharp protrusions or contamination (embedded foreign material) is to be evident. The contour of the component lead must be visible. The height of the solder fillet should extend at least one-third of the chip height and not higher than the end of the chip. The soldered joint surfaces should exhibit good wettability (that is, low contact angles of the solder in contact with the joined surfaces). Figure 4-4shows these requirements, together with examples of typical soldering faults. Figure 4-4
Chip Capacitor Soldering Requirements
HA72500 4.3.1.2.5
SECTION 4 Placement and Soldering of Standard Components to Stripline
Standard components (such as resistors, capacitors, diodes) when used in conjunction with stripline board must have the shortest possible leads to reduce inadvertent inductance. The following are essential requirements: a. Components must have the shortest possible leads and be as close as possible to the surface of the board. b. Stress relief bends are not required. c. For surface mounted ribbon leads, the soldered area between lead and land of ribbon wire leads is to be greater than the square of the lead width. After soldering, the distance from the top of the lead to the t op of the land is to be less that three times the lead thickness, and the lead outlines are to be visible. Maximum and minimum lead overhang conditions are shown in Figure 4-6, and maximum and minimum solder conditions are shown in Figure 4-7. Figure 4-6
Part Placement
HA72500 Figure 4-7
SECTION 4 Maximum/Minimum Solder Conditions
d. Surface mounted round, flat or coined leads are not to have any side overhang. The contact length of the lead is to be twice the width of the flattened leads, and
HA72500 Figure 4-9
SECTION 4 Lead Soldering Conditions
e. Coated or sealed components (such as capacitors) must display a minimum clearance of 0.25 mm between the solder fillet and the coating; refer Figure 4-10. Figure 4-10
Minimum Clearance of Sealed Components
HA72500 Figure 4-11
4.3.1.3
SECTION 4 Multiple Lead Termination Requirements
Cleaning
On completion of soldering, printed board assemblies should be cleaned by brush application of Freon TE35, Freon TP35 or ethyl alcohol. It should be noted that the following components and materials are adversely affected by cleaning solvents such as Freon (trichlorotriflurorethane): a. All aluminium electrolytic capacitors where ends are not sealed with epoxy resins. b. Variable and/or adjustable capacitors and resistors. c. Metal oxide resistors (such as Welwyn F series). d. Wire wound resistors (such as IRC ASW series).
HA72500
SECTION 4
c. Clean the area affected by desoldering; use Freon TP35, or equivalent. Do NOT flood or wet the conformal coating, as this may dissolve it. d. Solder in the new component with a resin flux-cored solder wire. e. Remove the flux residue and clean the surrounding conformal coating. Use a cotton-tipped applicator (cotton bud) moistened with Freon TP35, or equivalent, as soon as possible after soldering. Do NOT flood or wet the conformal coating, as this may dissolve it. f.
4.3.3
To restore the conformal coating recoat the soldered joint(s), the component leads on both sides of the board, and any bare board surfaces by brush application of Dow Corning Conformal Coating 1-2577. This material will be supplied thinned for brushing.
RF Transistor Replacement
This section describes the preferred method for removal of RF low power and high power transistors from printed wiring boards (PWB), especially microstrip circuitry on Teflon substrate: it is assumed that the device to be removed is t o be discarded as faulty, most emphasis being placed on avoiding damage to the PWB which is being reused. Care must be taken in component removal from any PWB to avoid the use of excessive heat, as this will reduce the adhesion of the copper track to the base material: this is especially critical in the microstrip-on-TefIon case, where the initial adhesion is lower than with fibreglass boards and the tracks rely on surface adhesion alone, having no plated-through holes which provide mechanical anchoring as well as thermal shunting.
HA72500
SECTION 4
b. Miscellaneous chip components can be readily removed using the two-iron method - apply the iron with the larger bit to the end of the component connected to ground plane and the smaller bit to the other end; as soon as the solder has melted both ends, lift the component between the bits and quickly remove it from the heat before it loses its end cap plating. c. If the transistor is soldered to large track areas (such as ground planes) these joints should be unsoldered first; using the larger soldering iron bit and a little fresh solder, melt the local solder and, using the solder sucker or wick, reduce the molten solder as fast and thoroughly as possible. Whilst the solder is still molten, use the sharp blade to part all transistor tabs, except one, from the copper areas: it may be necessary to complete this later. Using t he smaller soldering iron bit, reduce the solder and, again using the blade, lift the tabs of the transistor connected to the microstrip tracks, then f inally lift the remaining large tab. d. Lift the device, using pliers to hold the body and the soldering iron to finally part any joints still connected. e. Clean up all track areas by carefully using the soldering iron to reflow the solder.
HA72500
APPENDIX A
APPENDIX A
OPERATING INSTRUCTIONS
HA72500
APPENDIX A TABLE of CONTENTS
A.
OPERATING INSTRUCTIONS...................................................................A-1
A.1 OPERATING INSTRUCTIONS - SINGLE DME A-1 A.1.1 Introduction................................................................................................A-1 A.1.2 Application of Power .................................................................................. A-2 A.1.3 Local Operation..........................................................................................A-3 A.1.4 Remote Operation...................................................................................... A-3 A.1.5 Maintenance Operation..............................................................................A-4 A.1.6 Recycle Operation......................................................................................A-4 A.1.7 Typical Test Results...................................................................................A-6 A.1.8 Operating Notes......................................................................................... A-6 A.2 OPERATING INSTRUCTIONS - DUAL DME A-8 A.2.1 Introduction................................................................................................A-8 A.2.2 Application of Power .................................................................................. A-8 A.2.3 Local Operation..........................................................................................A-9 A.2.4 Remote Operation.................................................................................... A-10 A.2.5 Maintenance Operation............................................................................A-11 A.2.6 Recycle Operation....................................................................................A-14 A.2.7 Operating Notes.......................................................................................A-14 A.2.8 Typical Test Results................................................................................. A-15 A.3 CTU FACILITIES AND OPERATING PROCEDURE A-16 A.3.1 CTU Front Panel Controls........................................................................ A-16 A.3.2 CTU Front Panel Indicators...................................................................... A-32 A.4 OPERATOR CONTROLS AND INDICATORS A-34
HA72500
APPENDIX A
LIST of FIGURES Figure A-1 Figure A-2 Figure A-3 Figure A-4 Figure A-5 Figure A-6
CTU Front Panel ................................................................................ A-17 Menu Structure in Operational Modes ................................................ A-22 Menu Structure in Maintenance Mode................................................ A-23 CTU Processor Board - Control and Indicator Locations .................... A-43 CTU Front Panel Board - Control and Indicator Locations.................. A-44 CTU RMS Interface Board - Control and Indicator Locations.............. A-45
LIST of TABLES
Table A-1 Table A-2 Table A-3 Table A-4 Table A-5 Table A-6 Table A-7 Table A-8 Table A-9 Table A-10
Switch Setting Checklist - Single System ................................................. A-1 Switch Setting Checklist - Dual System.................................................... A-8 Transponder Front Panel Controls and Indicators .................................. A-34 CTU Processor Board Option Switch Settings........................................ A-40 CTU Processor Board Test Jumpers...................................................... A-41 Internal Controls : Monitor Module 1A72510 .......................................... A-46 Internal Controls : Test Interrogator 1A72514 ........................................ A-48 Internal Controls : Receiver Video 1A72520........................................... A-49 Internal Controls : Transponder Power Supply 1A72525........................ A-50 Internal Controls : Transmitter Driver 1A72530 A-51
HA72500
APPENDIX A
A. OPERATING INSTRUCTIONS A.1
OPERATING INSTRUCTIONS - SINGLE DME
A.1.1
Introduction
The procedures in this section detail the steps required to place a DME beacon (single configuration) into operation. Each mode of operation is described separately and some guidance is given concerning action required when abnormal performance occurs. For in-depth explanation of the various controls, indicators, and facilities, refer to the following sections: •
CTU Facilities and Operating Procedure: Section A.3;
•
Operator Controls and Indicators: Section A.4;
•
Module Preset Controls, Switches, Links and Indicators: Section A.5.
The checklist in Table A-1 gives the required switch settings of the front panel switches prior to placing the beacon into operation. These settings are independent of the final mode of operation of the beacon. Table A-1
Switch Setting Checklist - Single System
MODULE/UNIT AC Power Supply Power Distribution Panel
CONTROL/INDICATOR
SETTING/INDICATION
POWER
OFF
1kW POWER AMP
Off
HA72500
A.1.2
APPENDIX A
Application of Power
a. On the AC power supply, set the POWER switch to ON. Check that the front panel voltmeter indicates a voltage of 27.0 ±0.5 volts. b. On the power distribution panel, set both circuit breakers on. After a short delay (about 10 seconds), check that the following CTU front panel indicators are on: AC PWR NORM BATT CH1 LOCAL
(press LOCAL pushbutton if the indicator is off)
SELECT MAIN, OFF/RESET
(press OFF/RESET pushbutton if the indicator is off)
Check that the following CTU front panel indicators are off: TEST section: MODULES ANT RELAY POWER section: BATT CH2 BATT LOW
HA72500
APPENDIX A
A.1.3
Local Operation
A.1.3.1
Switch-on Procedure
a. Set the front panel controls initially as in Section A.1.1. b. Apply power to the beacon as in Section A.1.2. c. On the CTU, press the LOCAL control source pushbutton. This selects normal operation in the 'local' mode and the LOCAL indicator should be on. d. On the CTU, press the SELECT MAIN, NO1 pushbutton. This activates the rack in its normal operating mode. The following indications should result: 1. SELECT MAIN, NO1 indicator on. 2. NO1 ON status indicator on (this is an internal CTU preset control, adjustable from 2 to 20 seconds for a cold standby and fixed at 2 seconds for a warm standby; see A.5.1.6 for details). 3. NORMAL status indicator on, after the selected POWER ON inhibit time. This indicates that the monitor is powered, and no faults are detected. 4. All the ALARM REGISTER indicators off immediately, and stay off unless a fault is present. e. Check that no unit or module has a red indicator on. A red indicator on indicates that a test switch is not in the NORMAL position, or a fault is present.
NOTE
A monitor module self test occurs every 15 seconds (±2 seconds), and will produce a momentary PRIMARY fault display on the monitor module. This is
HA72500 A.1.4.2.1
APPENDIX A Switch-on Procedure
At the remote control panel, select DME NO1 ON. Correct operation will be indicated by the DME NORMAL indicator and RACK ON indicator (if used) turning on. At t he DME site, indications should be as in Section A.1.3.1d, except that REMOTE should be on.
A.1.4.2.2
Switch-off Procedure
At the remote control panel, select DME OFF/RESET. The DME NORMAL indicator and the DME NO1 ON indicator (if used) should turn off.
A.1.4.2.3
Reset Procedure
If a beacon shutdown occurs due to an alarm, the DME NORMAL indicator should turn off, and the SHUTDOWN indicator should turn on. To reset the beacon, select DME OFF/RESET, and then select DME NO1 ON again.
A.1.5
Maintenance Operation
The 'maintenance' mode would normally be used during servicing or alignment of the DME rack. In a single beacon installation, the 'maintenance' mode is essentially the same as the 'normal' mode, except that more extensive tests are available from the CTU, and the high test interrogation rate switches are enabled.
A.1.5.1
Switch-on Procedure
a. Set the front panel switches initially as in Section A.1.1. b. Apply power to the beacon as in Section A.1.2.
HA72500
APPENDIX A
a. The RECYCLE facility is 'enabled' when the RECYCLE indicator is on. On the CTU, press the RECYCLE pushbutton to toggle between the 'enable' and 'disable' of this facility. b. The number of restarts is recorded on the restart counter. The restart counter is displayed on the CTU's test display when the Misc softkey is pressed, from the top level of the operational mode menu.
HA72500
A.1.7
APPENDIX A
Typical Test Results
The table below shows the normal readings which would be indicated on the Test Facility of the CTU, in an operating rack. For operation of the test facility of the CTU refer to Section A.3.1.2. PARAMETER
LOWER LIMIT
UPPER LIMIT
X
49.8 µs
50.2 µs
Y
55.8 µs
56.2 µs
X
11.9 µS
12.1 µs
Y
29.9 µs
30.1 µs
POWER OUT
1.1 kW
1.3 kW
EFFICIENCY
70%
100%
95 pps
2850 pps
Varies with interrogation rate.
940 pps
2850 pps
Varies with interrogation rate.
Pulse Width
3.2 µs
3.8 µs
Pulse Rise Time
1.9 µs
2.5 µs
Pulse Fall Time
1.9 µs
2.5 µs
RV Local Oscillator
1.0 volts
3.0 volts
RV RF Drive
1.5 volts
4.5 volts
TD Drive
1.5 volts
2.5 volts
TD Modulation
1.5 volts
3.5 volts
PA Modulation
1.0 volts
3.5 volts
DELAY
SPACING
Decoded Pulse Rate Tx Pulse Rate
NOTES
Typical reply efficiency is 90%unless interrogation rate is high.
HA72500
APPENDIX A
circuit breaker to off and then on again. If t he CTU fault indicator is still on, or flashing, then the CTU module should be replaced. d. If any of the ALARM REGISTER, PRIMARY or SECONDARY indicators turn on following switch-on, then one of the transponder operating parameters is out of tolerance; if this parameter is a primary fault, the transponder should be shut down after the ALARM DELAY period. The indicators in the ALARM REGISTER can be used as a guide to locating the cause of the fault condition, after the transponder has shutdown. (See also Section 4.1.2 for LRU fault location).
HA72500
APPENDIX A
A.2
OPERATING INSTRUCTIONS - DUAL DME
A.2.1
Introduction
The procedures in this section detail the steps required to place a DME beacon (dual configuration) into operation. Each mode of operation is described separately and some guidance is given concerning action required when abnormal performance occurs. For in-depth explanation of the various controls, indicators, and facilities, refer to the following sections: •
CTU Facilities and Operating Procedures: Section A.3. Section A.3.
•
Operator Controls and Indicators: Section A.4. Section A.4.
•
Module Preset Controls, Switches, Links and Indicators: Section A.5. Section A.5.
The checklist in Table A-2 gives the required switch settings of the front panel switches prior to placing the beacon into operation. These settings are independent of the final mode of operation of the t he beacon. Table A-2
Switch Setting Checklist - Dual System
MODULE/UNIT AC Power Supplies
CONTROL/INDICATOR CONTROL/INDIC ATOR
SETTINGs1NDICATION SETTINGs1 NDICATION
POWER
OFF
Power Distribution Panel
All circuit breakers
Off
RF Panel
Antenna Relay Control Switch
NORMAL
Monitors
MONITOR OUTPUTS
NORMAL
HA72500
APPENDIX A
Check that the following CTU front panel indicators are off: TEST section: TEST section: MODULES ANT RELAY POWER section: POWER section: BATT LOW DME CONTROL section: RECYCLE
(press RECYCLE pushbutton RECYCLE pushbutton if the RECYCLE indicator RECYCLE indicator is on)
REMOTE
(press LOCAL pushbutton LOCAL pushbutton if the REMOTE indicator REMOTE indicator is on)
MAINTENANCE
(press MAINTENANCE pushbutton MAINTENANCE pushbutton if the indicator is on)
MONITOR ALARM
(press MONITOR ALARM INHIBIT pushbutton INHIBIT pushbutton if the indicator is on)
SELECT MAIN NO1 (press OFF/RESET pushbutton OFF/RESET pushbutton if the indicator is on) SELECT MAIN NO2 (press OFF/RESET push OFF/RESET push button if the indicator is on) STATUS section: STATUS section: NO1 ON NO2 ON NORMAL
HA72500
APPENDIX A
e. Check that no unit or module has a red indicator on. A red indicator on indicates that a test switch is not in the NORMAL position, NORMAL position, or a fault is present.
NOTE
A.2.3.2
A monitor module self test occurs every 15 seconds (±2 seconds), and will produce a momentary PRIMARY fault PRIMARY fault display on the monitor module. This is normal operation.
Switch-off Procedure
On the CTU, press the SELECT MAIN, OFF/RESET pushbutton. OFF/RESET pushbutton. The indicators in the STATUS section STATUS section should go off, after a short delay. The OFF/RESET indicator OFF/RESET indicator should be on, and the SELECT MAIN, NO1 NO1 and and NO2 indicators NO2 indicators should both be off.
A.2.3.3
Transfer Indication
If the main transponder has been switched off due to an alarm, the NORMAL and NORMAL and SHUTDOWN status SHUTDOWN status indicators will be off, and if the standby transponder is currently operating, the TRANSFER indicator TRANSFER indicator will be on. The faults that were present at the time of the transfer action are displayed on the ALARM REGISTER indicators. REGISTER indicators.
A.2.3.4
Shutdown Indication
If the main transponder and the standby transponder have both been switched off due to an alarm, the NORMAL and NORMAL and TRANSFER status TRANSFER status indicators will be off and the SHUTDOWN indicator SHUTDOWN indicator will be on. The faults that were present at the time of the shutdown action are displayed on the ALARM REGISTER indicators. REGISTER indicators.
A.2.3.5
Reset Procedure
HA72500 A.2.4.2.3
APPENDIX A Transfer Indication
If the main transponder has switched off due to an alarm, the DME NORMAL and NORMAL and DME SHUTDOWN status indicators will be off, and if the standby transponder is currently operating, the DME TRANSFER indicator TRANSFER indicator will be on.
A.2.4.2.4
Shutdown Indication
If the main transponder and the standby transponder have switched off due to an alarm, the DME NORMAL and NORMAL and DME TRANSFER status TRANSFER status indicators will be off, and the t he DME SHUTDOWN indicator SHUTDOWN indicator will be on.
A.2.4.2.5
Reset Procedure
To reset the beacon, select DME OFF/RESET, OFF/RESET, and then select DME NO1 ON or ON or DME NO2 ON again.
A.2.5
Maintenance Operation
The 'maintenance' mode would normally be used during servicing or alignment of the DME rack. In a dud,] beacon installation, the 'maintenance' mode allows one of the transponders to be operated separately as a single transponder while the other transponder is used for maintenance tasks. Operating in this mode, if the MONITOR ALARM is selected to be NORMAL, NORMAL, only primary faults f aults will be recognised, and shutdown is the only action that will be performed. More extensive tests are also available on the CTU, and the TI RATE 1 kHz and kHz and 10 kHz switches kHz switches are enabled.
NOTE
Only the monitor/test interrogator installed in the operating operating transponder will be used to monitor that transponder. In other words, only single monitoring is used
HA72500
APPENDIX A
7. Connect a coaxial cable from connector ERP IN on IN on the rear of the lower transponder subrack to the 10 dB attenuator on connector FWD-A on FWD-A on the upper directional coupler. c. The following following table lists the settings of of the front panel panel switches, switches, of Transponder Transponder 2, prior to placing the beacon in maintenance operation. These settings are independent independent of the final mode of operation of the beacon. UNIT AC Power Supplies
SWITCH
SETTING
AC POWER
OFF
RF Panel
Antenna Relay Control Switch
NORMAL
Power Distribution Panel
All circuit breakers
Off
Test Interrogator Modules
MONITOR ANDINTERROGATOR ANDINTERROGATOR DCPOWER
ON
Transponder Power Supplies
TRANSPONDER TRANSPONDER DC POWER
ON
Transmitter Driver Modules
DRIVER DC POWER
ON
1kW PA Power Supplies
AMPLIFIER DC POWER
ON
d. Apply power to the beacon as in A.2.2. in A.2.2. e. On the CTU, press the MAINTENANCE pushbutton. MAINTENANCE pushbutton. This selects 'maintenance' operation in the ‘local ‘mode. The LOCAL and LOCAL and MAINTENANCE indicators MAINTENANCE indicators should be on. f.
On the CTU, press the SELECT MAIN, NO1 NO1 pushbutton. pushbutton. This activates the rack
HA72500
APPENDIX A
5. Move the coaxial cable connected to FWD-E on FWD-E on the lower directional coupler, to connect from FWD-C on FWD-C on the upper directional coupler to TI-1 TEST INTRGS. INTRGS. 6. Leave the coaxial coaxial cable from connector connector FWD-C on FWD-C on the lower directional coupler to TI-2 TEST INTRGS. INTRGS. 7. Connect a coaxial cable from connector ERP IN on IN on the rear of the upper transponder subrack to the 1 0d13 attenuator on connector FWD-A on FWD-A on the upper directional coupler. c. The following following table lists the settings of the front panel panel switches, switches, of Transponder 1, prior to placing the beacon in maintenance operation. These settings are independent of the final mode of operation of the beacon. UNIT AC Power Supplies
SWITCH
SETTING
AC POWER
OFF
RF Panel
Antenna Relay Control Switch
NORMAL
Power Distribution Panel
All circuit breakers
Off
Test Interrogator Modules
MONITOR ANDINTERROGATOR ANDINTERROGATOR DCPOWER
ON
Transponder Power Supplies
TRANSPONDER TRANSPONDER DC POWER
ON
Transmitter Driver Modules
DRIVER DC POWER
ON
1kW PA Power Supplies
AMPLIFIER DC POWER
ON
HA72500
APPENDIX A
1. Make sure that 10 dB attenuators are attached to connectors TI-1 REPLY DET, TI-2 REPLY DET, on the RF panel, and FWD-A on both directional couplers. 2. Leave 50 ohms terminations on connectors REV-A on both directional couplers. 3. Remove any coaxial cable connected to FWD-B and FWD-C of the upper directional coupler. 4. Make sure that a coaxial cable is connected from FWD-D on the lower directional coupler to the 10 dB attenuator on TI-1 REPLY DET on the RF panel. 5. Make sure that a coaxial cable is connected from FWD-B on the lower directional coupler to the 10 dB attenuator on TI-2 REPLY DET on the RF panel. 6. Make sure that a coaxial cable is connected from FWD-E on the lower directional coupler to TI-1 TEST INTRGS on the RF panel. 7. Make sure that a coaxial cable is connected from FWD-C on the lower directional coupler to TI-2 TEST INTRGS, on the RF panel. 8. Re-install the original wiring associated with connectors ERP IN on the rear of the transponder subracks
A.2.6
Recycle Operation
The recycling facility allows the beacon to automatically restart after a failure. Following
HA72500
APPENDIX A
circuit breakers to off and then on again. If the CTU fault indicator is still on, or flashing, then the CTU module should be replaced. d. If any of the ALARM REGISTER, PRIMARY or SECONDARY indicators turn on following switch-on, then one of the transponder operating parameters is out of tolerance; if this parameter is a primary fault, the transponder should shut down after the ALARM DELAY period. The indicators in the ALARM REGISTER can be used as a guide to locating the cause of t he fault condition, after the transponder has shut down. (See also Section 4.1.2 for LRU fault location)
A.2.8
Typical Test Results
The table below shows the normal readings which would be indicated on the Test Facility of the CTU, in an operating rack. For operation of t he Test Facility of the CTU refer to Section A.3.1.2. PARAMETER
LOWER LIMIT
UPPER LIMIT
X
49.8 µs
50.2 µs
Y
55.8 µs
56.2 µs
X
11.9 µS
12.1 µs
Y
29.9 µs
30.1 µs
POWER OUT
1.1 kW
1.3 kW
EFFICIENCY
70%
100%
95 pps
2850 pps
Varies with interrogation rate.
940 pps
2850 pps
Varies with interrogation rate.
DELAY SPACING
Decoded Pulse Rate Tx Pulse Rate
NOTES
Typical reply efficiency is 90%unless interrogation rate is high.
HA72500
APPENDIX A
A.3
CTU FACILITIES AND OPERATING PROCEDURE
The major human interface to the DME LDB-102 is provided by the Control and Test Unit (CTU). Although the implementation of some commands input via the CTU is installation-specific (that is, depending on the facilities and configuration of the particular installation) all the facilities provided by the CTU are explained here in order to give a detailed overview of the operational control facilities available. This procedure assumes that each individual module of the DME has been correctly configured and setup in accordance with the alignment and adjustment procedures described in Section 3 of this handbook.
A.3.1
CTU Front Panel Controls
REFER Figure A-1. The controls on the CTU front panel can be divided into two groups; control switches and test switches. CONTROL SWITCHES
TEST SWITCHES
ALARM DELAY
Five multifunction test switches, beneath display, software programmable
RECYCLE
TIRATE
SOURCE MAINTENANCE
LOCAL REMOTE
1 kHz 10 kHz
ESCape
HA72500
Figure A-1
APPENDIX A
CTU Front Panel
HA72500
A.3.1.1
APPENDIX A
CTU Front Panel Control Switches - Description of Operation
Each CTU front panel control switch has an indicator associated with it, indicating the current setting of that particular switch. These do not indicate the current state of t he DME. This can be determined using the status indicators described in Section A.3.2.1. The most recent settings of these switches are stored in EEPROM. Therefore, when power is restored after any type of power interruption to the CTU the switch settings (and hence the state of the DME) will return to those which were in use immediately before the power interruption occurred.
A.3.1.1.1
ALARM DELAY Switch
The ALARM DELAY switch is a recessed 1 0-position rotary switch with positions labelled 1 through 10. This switch selects the delay in seconds from the moment a fault is first detected by the CTU until action is taken. The fault must be present for the duration of this period in order for the CTU to t ake action following the expiry of the delay period. The ALARM DELAY indicator will be lit if an alarm delay of less than 4 seconds is selected. This indicates that abbreviated postfault measurements will be performed if the RMM System option is installed. The CTU will respond immediately to changes in the position of this switch.
A.3.1.1.2
RECYCLE Switch
The RECYCLE switch is a pushbutton switch that toggles between two settings: ON and OFF. When recycle is selected, the CTU will attempt to restart the main transponder 30
HA72500
APPENDIX A
ALARM switch is set to INHIBIT, attempting to select REMOTE will result in the message << Turn MON INHIBIT off first >> being displayed.
A.3.1.1.4
MAINTENANCE Switch
The MAINTENANCE switch is a pushbutton switch that toggles between two settings: ON and OFF. The CTU will only respond to input from this switch when the SOURCE switches are set to LOCAL. MAINTENANCE may be selected if the DME is on or off. It may be turned off at any time by pressing the MAINTENANCE switch; it cannot be changed remotely. When the MAINTENANCE switch is ON, a dual DME is prevented from transferring to the standby transponder, thus allowing the standby transponder to be tested without alarms being generated by h modules. The main transponder may remain on-air, but will be shut down if a primary fault occurs. The 1kHz and 10 kHz interrogation rates (TI RATE) are only available when MAINTENANCE is ON.
A.3.1.1.5
MONITOR ALARM Switch
The MONITOR ALARM switch is a pushbutton switch that toggles between two settings: INHIBIT and NORMAL. The CTU will only respond to input from this switch when the SOURCE switches are set to LOCAL. Failure to do this will result in the <<< Select LOCAL first >>> message on the lower line of the CTU front panel display. It may be turned off at any time by pressing the MONITOR ALARM switch; it cannot be changed remotely. When the MONITOR ALARM switch is set to NORMAL, the DME is able to transfer or
HA72500 A.3.1.2
APPENDIX A Test Facility - Description of Operation
REFER Figure A-1. The test facility of the CTU is located in the top half of the CTU front panel. It provides facilities which allow the user to measure various parameters, sample status lines, and control and display some minor functions on the DME transponder(s). In maintenance mode (see Section A.3.1.1.4) these facilities can also measure the more important fault limits of the available monitor module(s). The front panel controls and displays associated with the test facility consist of: a. A 2x40-character liquid crystal display (LCD), which performs the following: •
•
•
On the top line of the LCD, status messages and measurement results are displayed. On the bottom line of the LCD, labels for the five multifunction pushbuttons are displayed. This forms the basis of the menu system described below. If a measurement is being performed, the corresponding switch label will flash. On the bottom line of the LCD, error messages are displayed. These are flashed four times at one-second intervals before returning to the previous display.
b. Five multifunction pushbuttons mounted directly below the LCD display, which are used to select the action, or select the next menu indicated by the label above it. These may also be referred to as 'softkeys' throughout the remainder of this Appendix.
HA72500
APPENDIX A
A.3.1.3
Test Facility - Menu System
A.3.1.3.1
Menu System - Introduction
REFER Figure A-2 and Figure A-3. The menu system on the CTU allows the implementation of a multifunction test control system with the minimum of controls and prompts the user with the allowable combinations. The menus are arranged in an hierarchical system, and t he behaviour, display and choices offered by the menus are modified if maintenance mode is selected. When the MAINTENANCE switch is not selected (MAINTENANCE indicator is off) the system is in an operational mode. The menu structure is as shown in Figure A-2 and the user is allowed to: a. Perform and display measurements from both transponder monitoring systems (test interrogator/monitor modules) at the same time. The name of the parameter being measured, the measured value for each channel (transponder), the unit of measurement and the pulse repetition rate of the test interrogator are shown on the top line of the front panel display. A typical parameter display is as shown below (but with the tiprf field blank). The tiprf is displayed only in maintenance mode. Name Delay
=
Ch1
Ch2
unit
tiprf
50.1
50.1
µs
100
b. Perform and display measurements that do not interfere with the operation of the transponder.
HA72500 Figure A-2
APPENDIX A Menu Structure in Operational Modes
HA72500 Figure A-3
APPENDIX A Menu Structure in Maintenance Mode
HA72500
APPENDIX A
A.3.1.3.2
Menu System in Operational Mode
A.3.1.3.2.1
Measurement Class Selection (Top Level Menu)
CTU Display Keys
LDB-102DME Param
Level
PS.Volt
Status
Misc.
a.
b.
c.
d.
e.
Actions performed when the corresponding softkey is pressed: a. Change display to the first of four parameter select menus (see A.3.1.3.2.2.1). b. Change display to first of two signal level select menus (see A.3.1.3.2.3.1). c. Change display to power supply select menu (see A.3.1.3.2.4). d. Change display to status select menu (see A.3.1.3.2.5). e. Change display to first of three miscellaneous selection menus (see A.3.1.3.2.6.1).
A.3.1.3.2.2
Transponder Parameter Selection
A.3.1.3.2.2.1 Parameter Select - First Menu CTU Display Keys
Spacing
Delay
Pwr.Out
Effncy
NEXT
a.
b.
c.
d.
e.
HA72500
APPENDIX A
A.3.1.3.2.2.3 Parameter Select - Third Menu CTU Display Keys
Width
Rise
Fall
PREV
NEXT
a.
b.
c.
d.
e.
Actions performed (for each of the monitor/test interrogator modules fitted) when the corresponding softkey is pressed: a. Measure and display 'Transmit Pulse Width' parameter. b. Measure and display 'Transmit Pulse Rise Time' parameter. c. Measure and display 'Transmit Pulse Fall Time' parameter. d. Change display to second parameter select menu (see A.3.1.3.2.2.2). e. Change display to fourth parameter select menu (see A.3.1.3.2.2.4).
NOTE
It is the characteristics of the second transmitted pulse that are measured and displayed
A.3.1.3.2.2.4 Parameter Select - Fourth Menu CTU Display Keys
V Cal
R cal
T cal
PREV
a.
b.
c.
d.
e.
Actions performed (for each of the monitor/test interrogator modules fitted) when the
HA72500
A.3.1.3.2.3
APPENDIX A
Transponder Signal Level Selection
A.3.1.3.2.3.1 Signal Level Select - First Menu CTU Display Keys
RV.Osc
RV.RF
TD.Drv
TD.Mod
NEXT
a.
b.
c.
d.
e.
Actions performed when the corresponding softkey is pressed: a. Measure and display 'Oscillator RF Level' parameter, from receiver video module(s). b. Measure and display Tx RF Drive Level' parameter, from receiver video module(s). c. Measure and display7D Drive Level' parameter, from transmitter driver module(s). d. Measure and display 'Pulse Modulation Level' parameter, from transmitter driver module(s). e. Change display to second signal level select menu (see A.3.1.3.2.3.2).
A.3.1.3.2.3.2 Signal Level Select - Second Menu CTU Display
PA.Mod
PA.Drv
PA.Out
TI.RF
PREV
HA72500
A.3.1.3.2.4
APPENDIX A
Power Supply Voltage Selection
CTU Display
AUX.24V
PA.HT
TP.15V
TP.18V
Drv.HT
a.
b.
c.
d.
e.
Keys
Actions performed when the corresponding softkey is pressed: a. Measure and display ‘+24 Volt input Supply' parameter, from monitor module(s). b. Measure and display ‘Power Amplifier HT Supply' (nominal 50 volts) parameter, from 1kW PA power supply module(s). c. Measure and display ‘+1 5 Volts Transponder Supply' parameter, from transponder power supply module(s). d. Measure and display ‘+18 Volts Transponder Supply' parameter, from transponder power supply module(s). e. Measure and display ‘Driver HT Transponder Supply' (nominal 42 volts) parameter, from transponder power supply module(s).
A.3.1.3.2.5
Status Selection
CTU Display Keys
MON PS
RV PS
TI PS
RV TRIG
a.
b.
c.
d.
Actions performed when the corresponding softkey is pressed:
e.
HA72500
A.3.1.3.2.6
APPENDIX A
Miscellaneous Selection
A.3.1.3.2.6.1 Miscellaneous - First Menu CTU Display Keys
Restart count = xxx Reset a.
b.
Alarm1
Alarm2
NEXT
c.
d.
e.
(where 'xxx' is the restart count) Actions performed when the corresponding softkey is pressed: a. Change display to submenu, to ask the user 'Are you sure T; if the response is 9 yes' then reset the' RESTART COUNT' both in RAM and EEPROM, otherwise return to this menu. b. No action. c. On the alarm register, display only those alarms that apply to Transponder 1 while this button is held down. d. On the alarm register, display only those alarms that apply to Transponder 2 while this button is held down. e. Change display to second miscellaneous select menu (see).
A.3.1.3.2.6.2 Miscellaneous - Second Menu CTU Display
HA72500
APPENDIX A
A.3.1.3.2.6.3 Miscellaneous - Third Menu CTU Display
Ident Source : xxx Mon 1
Mon 2
2240Hz
OFF
a. b. c. d. Keys (where 'xxx' is the current audio source for the internal CTU speaker)
PREV e.
Actions performed when the corresponding softkey is pressed: a. Select the Monitor 1 audio source. b. Select the Monitor 2 audio source. c. Select 2240 Hz as the audio source. d. Turn audio source off. e. Change display to second miscellaneous select menu (see A.3.1.3.2.6.2).
A.3.1.3.3
Menu System in Maintenance Mode
A.3.1.3.3.1
TI/Monitor Selection (Top Level Menu)
CTU Display Keys
LDB-102 DME - Maintenance Mode Ch.1
Ch.2
a.
b.
c.
Actions performed when the corresponding softkey is pressed:
d.
e.
HA72500
A.3.1.3.3.2
APPENDIX A
Measurement Class Selection
CTU Display Keys
Param
Level
PS.Volt
Status
F1tLimit
a.
b.
c.
d.
e.
Actions performed when the corresponding softkey is pressed: a. Change display to first parameter select menu, same menu as when maintenance is not selected, except that only one value is measured and displayed (see A.3.1.3.2.2.1). For the 'Efficiency' measurement submenu of the 'Param' selection, see A.3.1.3.3.2.2. b. Change display to first signal level select menu, same menu as when maintenance is not selected, except that only one value is measured and displayed (see A.3.1.3.2.3.1). c. Change display to first power supply select menu, same menu as when maintenance is not selected, except that only one value is measured and displayed (see A.3.1.3.2.4). d. Change display to first status select menu, same menu as when maintenance is not selected, except that only one value is measured and displayed (see A.3.1.3.2.5). e. Change display to monitor fault limit select menu (see A.3.1.3.3.2.1).
A.3.1.3.3.2.1 Monitor Fault Limit Select Menu
HA72500
APPENDIX A
A.3.1.3.3.2.2 Efficiency Reading Select Menu CTU Display Keys
1kHz Effncy
Hi Eff
Lo Eff
PREV
a.
b.
c.
d.
e.
Actions performed when the corresponding softkey is pressed: a. Perform a normal Efficiency measurement, alternating high and low level test interrogations, using the selected test interrogator/monitor modules. b. Perform an Efficiency measurement, using high level only test interrogations, in the selected test interrogator/monitor modules. c. Perform an Efficiency measurement, using low level only test interrogations, in the selected test interrogator/monitor modules. d. Return to the first parameter select menu (see A.3.1.3.2.2.1). e. No action.
HA72500
A.3.2
APPENDIX A
CTU Front Panel Indicators
REFER Figure A-1.
A.3.2.1
Status Indicators
There are six status indicators on the CTU front panel: •
•
•
•
•
NO1 ON (green). Will be lit if Transponder 1 is powered on and is the currently operating transponder. This does not indicate that Transponder 1 is selected as main. NO2 ON (green). Will be lit if Transponder 2 is powered on and is the currently operating transponder. This does not indicate that Transponder 2 is selected as main. NORMAL (green). The DME will be in the normal state when the selected main transponder (that is, the transponder selected using the SELECT MAIN switches) is on and operating. The DME is not in the normal state if the MONITOR ALARM switch is set to INHIBIT or the MAINTENANCE switch is ON or if any alarms are present. TRANSFER (yellow). The DME will be in the transfer state if it is a dual DME and the standby transponder is on and operating (the standby transponder is the transponder that is not selected as main on the SELECT MAIN switches). SHUTDOWN (red). The DME will be in the shutdown state when all transponders are off due to a
HA72500
•
APPENDIX A
AC PWR NORM (green). If AC power is being applied to battery charger 1, then this status indicator will be on.
A.3.2.3
Test Status Indicators
There are two TEST status indicators on the CTU front panel: •
•
MODULES (red). Will be on if any one of the transponder modules has its control switch out of the NORMAL position. ANT RELAY (red). Will be on if the antenna control switch is not in the NORMAL position. The antenna test switch is located on the RF panel behind the CTU, and can be accessed from the rear of the rack.
A.3.2.4
Alarm Register
The ALARM REGISTER display indicates the faults (in all transponders) that were present at the time the most recent shutdown or transfer decision was made by the CTU. The alarms corresponding to individual transponders can be selected from the menu system (see Section A.3.1.3.2.6.1). In a single DME, the alarms shown on this display are derived from the monitor faults. In a dual DME, the alarms shown on this display are the result of the monitor 'voting' specified on the internal option switch S2 on the CTU processor board (see Table A-4). This display is cleared when the main transponder is selected from the OFF state.
HA72500
A.4
APPENDIX A
OPERATOR CONTROLS AND INDICATORS
Information on CTU controls and indicators are contained in Sections A.3.1 and A.3.2 respectively. The front panel controls and indicators on the main transponder modules are listed in Table A-3, following. Table A-3
Transponder Front Panel Controls and Indicators
MAJOR ASSEMBLY/ SUBASSEMBLY TYPE NAME No. 1A72510 Monitor Module
CONTROL/INDICATION FUNCTION DETAILS TYPE Toggle switch
LEGEND MONITOR OUTPUTS
FUNCTION/SETTING/INDICATION FAILED
NORMAL
Green LED Green LED Green LED Green LED Green LED Green LED Green LED Green LED Yellow LED
DELAY SPACING EFFICIENCY RATE POWER IDENT ANTENNA SHAPE SELF TEST
All monitor outputs are set to their fault condition (high) which invokes a FAILED condition for all front panel indicators and all fault lines read by the CTU. The TEST indicator is turned on. Monitor module operates normally and TEST indicator is off.
When on, indicates that the named parameter is within preset limits.
Indicates that the CTU is performing
HA72500 MAJOR ASSEMBLY/ SUBASSEMBLY TYPE NAME No.
APPENDIX A CONTROL/INDICATION FUNCTION DETAILS TYPE
LEGEND
Pushbutton CHECK switch DETECTOR COINCIDENCE
Toggle switch, centre off
Toggle switch, centre off
16-way rotary switches Toggle switch,
FUNCTION/SETTING/INDICATION
Connects the output of the RF generator into the reply detector, bypassing the transponder. Is used to check that the detector stages in the transponder have the same delay. The signals at the INTERROGATIONS TIMING and REPLY TIMING test jacks should match each other when this switch is pressed. This switch will interfere with the normal operation of the monitor module connected to the test interrogator under test. TEST REJECT +2µs Afters the interrogating TRANSPONDER pulse spacing outside DECODING acceptable limits to test -2µs the transponder pulse decoder rejection. ACCEPT +1µs Alters the interrogating pulse spacing within acceptable limits to test -1µs the transponder pulse decoder acceptance. REPLY GATE Sets accept gate timing; variable between 0 DELAY and 60 microseconds. COARSE 16 microseconds increments. FINE 1 microsecond increments. MONITOR AND ON The power supply output is INTERROGATOR connected to the test interrogator
HA72500 MAJOR ASSEMBLY/ SUBASSEMBLY TYPE NAME No.
APPENDIX A CONTROL/INDICATION FUNCTION DETAILS TYPE Test jack
EARTH
Test jack
EARTH
Test jack
INTERROGATIONS TIMING EARTH
Test jack
1A72520
Receiver Video
LEGEND
Test jack REPLY TIMING Yellow LED REPLIES INHIBITED Red LED
TEST
Green LED
DC POWER ON
16-position switches 16-position switch Toggle switch centre off
BEACON DELAY REPLY PULSE SEPARATION IDENT
FUNCTION/SETTING/INDICATION Common earth of all supply voltages and outputs. Common earth of all supply voltages and outputs. Output pulses from the RF generator detector. Common earth of all supply voltages and outputs. Buffered output pulses of the reply detector. Flashes on and off when the receiver video is being over-interrogated. On continuously when replies are inhibited. Indicates that the IDENT switch is not in the NORMAL position. Indicates that DC power is applied to the module. COARSE Sets the Delay parameter of the receiver video. FINE Sets the Spacing parameter of the receiver video. NORMAL Normal mode of operation. OFF CONTINUOUS
No ident is generated. Ident is generated continuously.
HA72500 MAJOR ASSEMBLY/ SUBASSEMBLY TYPE NAME No.
1A72525
Transponder Power Supply
APPENDIX A CONTROL/INDICATION FUNCTION DETAILS TYPE
LEGEND
Test jack Test jack
+15V EARTH
Test jack
EARTH
Test jack
RF LEVEL
Test jack
ON CHANNEL VIDEO
Test jack
EARTH
Test jack Green LED
DETECTED LOG VIDEO POWERON
Red LED
TEST
Toggle switch, centre off
TRANSPONDER DC POWER
FUNCTION/SETTING/INDICATION Buffered output from the +1 5V regulator. Common earth of all supply voltages and outputs. Common earth of all supply voltages and outputs. DC output proportional to the output TX RF DRIVE. Buffered output of the narrow band detected on-channel gate from the IF amplifier (15 volts pulses forming an envelope around the detected log video pulses, normally 3 microseconds wide). Common earth of all supply voltages and outputs. Buffered output from the wideband logarithmic amplifiers of the IF amplifier. Indicates that power is applied to the module. Indicates that the TRANSPONDER POWER switch is not in the NORMAL position. ON All supply outputs are on, regardless of CTU commands. This is required during testing and maintenance. OFF All power supply outputs are oft. NORMAL Power supply outputs are under CTU control.
HA72500 MAJOR ASSEMBLY/ SUBASSEMBLY TYPE NAME No.
1A72540
1kW PA Power Supply
APPENDIX A CONTROL/INDICATION FUNCTION DETAILS TYPE
LEGEND
FUNCTION/SETTING/INDICATION
Test jack
FUNCTION GENERATOR
The buffered output of the pulse-shaping integrator on the pulse shaper.
Test jack
SHAPED PULSE MODULATION
Test jack Test jack
+15V EARTH
Test jack
EARTH
Green LED
POWERON
Red LED
TEST
Green LED
HT ON
A buffered high-level modulation output representing the signal from the pulse shaper to the modulation stage. The buffered input + 1 5V supply. Common earth of all supply voltages and outputs. Common earth of all supply voltages and outputs. Indicates that DC power is supplied to the module. Indicates that the AMPLIFIER POWER switch is not in the NORMAL position. Indicates that the HT supply is available, and within limits. ON HT output voltage is supplied to the1kW RF power amplifier regardless of the power control signal state. This is required only during testing and maintenance. OFF There is no power output from the1kW PA power supply. NORMAL There is HT output from the module while the power control signal from the CTU is active
Toggle switch, centre off
AMPLIFIER POWER
HA72500
APPENDIX A
A.5 MODULE PRESET CONTROLS, SWITCHES, LINKS AND INDICATORS This section lists all the preset controls, switches, links and indicators that are located internally on the equipment (that is, not accessible at the front panel). These are used to set up operating conditions and functional modes of the equipment either prior to commissioning or as part of alignment or adjustment procedures. The major mode selection functions are selected by CTU internal controls, which are described in Section A.5.1. The internal indicators of the CTU are described in Section A.5.2. The internal controls for the transponder modules and boards are described in Section A.5.3.
A.5.1
CTU Internal Controls
A.5.1.1
Option Switches
REFER Figure A-4. There are two 8-way dual-in-line switches (S1 and S2) located on the CTU Processor PWB Assembly (1A72552). These switches are used to modify the CTU's behaviour for key functions, as described in Table A-4.
HA72500 Table A-4 SWITCH S1
S2
APPENDIX A CTU Processor Board Option Switch Settings FUNCTION SELECTED IF SWITCH ON IF SWITCH OFF
DESCRIPTION OF FUNCTION
SW1
Normal Operation
Production Tests
Used to select normal operation of the CTU or test routines that are used (in association with a test jig) during production testing. Indicates if Navaid Maintenance Processor (NMP) used in the RMM system is fitted. If S1:2 Is set to ON (NMP Present), but no NMP Is connected, there may be a significant delay before the CTU responds to any commands.
SW2
NMP Present NOTE
No NMP
SW3
No action
SW4
No action
SW5
No Statistics Menu
Subtract from Subtracts 0.1 microseconds from delay monitor fault limit MFLT2 delay readings (see alignment procedure) on Monitor Module 2. Add to MFLT2 Adds 0.1 microseconds to delay monitor fault limit readings delay (see alignment procedure) on Monitor Module 2. Delay Enables mean and standard deviation statistics to be Statistics Menu accumulated for delay readings. Available
SW6
No action
SW7
No action
SW8 SW1
SW2
Subtract from MFLT1 delay Add to MFLT1 delay
Subtracts 0.1 microseconds from delay monitor fault limit readings (see alignment procedure) on Monitor Module 1. Adds 0.1 microseconds to delay monitor fault limit readings(see alignment procedure) on Monitor Module 1.
Single Main AND Vote
Dual Main OR Vote
Select single or dual transponder operation. In a dual transponder this selects the type of voting to be used between the monitor module fault lines when the selected 'main' transponder is ON. This has no effect in a single transponder.
Standby
Standby OR
In a dual transponder, this selects the type of voting to be
HA72500 A.5.1.2
APPENDIX A Low Voltage Shutdown Preset
REFER Figure A-4. This adjustable preset control (R32) is used to set the lower limit of the battery voltage for normal transponder operation. This limit is adjustable between 19 volts and 22 volts. If the battery voltage fails below this limit, the transponders are switched off. Normal operation is restored when the battery voltage rises above this limit and either battery charger is normal. There is a small amount of hysteresis in the comparator to mask noise that may be present.
A.5.1.3
Internal Speaker Volume Preset
REFER Figure A-4. This preset control (R33) is used to adjust the audio volume from the internal CTU speaker (B1), and is located on the CTU processor board. A test tone of 2440 Hz may be selected from the menu system or via link XN8 on the CTU processor board. The internal speaker is normally used for recovered ident tone.
A.5.1.4
Internal Test Jumpers
REFER Figure A-4. The internal CTU jumpers are used during production or field test procedures. XN5 and XN10 may be fitted, depending on the installation configuration. For normal operation, all other test jumpers should be removed. Table A-5
CTU Processor Board Test Jumpers
HA72500 A.5.1.6
APPENDIX A Alarm Power On Inhibit Switch
REFER Figure A-5. This preset rotary switch (S11) is read by the software to determine the period to ignore transponder alarms, after a transponder has been switched on, for cold standby. The delay can be preset between 2 and 20 seconds in 2-second steps. (The delay, in seconds, is 2 times the switch setting, plus 2)
NOTE
For warm standby operation the alarm power on delay is preset to 2 seconds, and is independent of this switch
A.5.1.7
External Ident Level Preset
REFER Figure A-6. This preset control (R1) is used to adjust the output audible level of the recovered ident signal. It is located on the RCMS interface board.
A.5.2
CTU Internal Displays
Internal status indicators are provided to display useful information during production tests and normal operation.
A.5.2.1
CTU Processor Board
REFER Figure A-4. The indicators provided on the CTU processor board are: H1 Driven from A19 address line.
HA72500 Figure A-4
APPENDIX A CTU Processor Board - Control and Indicator Locations
HA72500 Figure A-5
APPENDIX A CTU Front Panel Board - Control and Indicator Locations
HA72500 Figure A-6
APPENDIX A CTU RMS Interface Board - Control and Indicator Locations
HA72500
A.5.3
APPENDIX A
Transponder Internal Controls
This section gives details of the internal switches, presets and adjustments for each of the module assemblies. Table A-6 SUBASSY
Internal Controls : Monitor Module 1A72510 TYPE
1A72511 Main PWB Assembly, Monitor Module
Preset resistor 8-way DIL switch
The Monitor Fault Limit switches S1-4 and S8-10, S12 and S13 are binary coded, with switch 1 of the DIL
8-way DIL switch
REF
CONTROL FUNCTIONS LEGEND FUNCTIONISETTING/INDICATION
R87 S1
S2
PULSE WIDTH LOWER REJECT LIMIT
FALL TIME UPPER REJECT LIMIT
Sets the ERP monitor fault alarm reference level to 0 dB at commissioning. 1 2 3 4 5 6 7 8 ON OFF Multiply the required lower reject limit (in microseconds) by 10 and subtract 1. Encode the switches for this value. For a lower reject limit of 2.9 microseconds the switches are encoded for a number of 28, as shown above. 1 2 3 4 5 6 7 8 ON OFF Multiply the required upper reject limit (in microseconds) by 10 and subtract 2. Encode the switches for this value. For an upper reject limit of 3.6 microseconds the switches are encoded for a number of 34, as shown above.
HA72500
SUBASSY 1A72511 Main PWB Assembly, Monitor Module
APPENDIX A
TYPE 8-way DIL switch
8-way DIL switch
REF S8
S9
CONTROL FUNCTIONS LEGEND FUNCTIONISETTING/INDICATION IDENT GAP UPPER REJECT LIMIT
DELAY REJECT WINDOW
1
2
3
4
5
6
7
8 ON OFF
Subtract 2 from the required upper reject limit (in seconds). Encode the switches for this value. For an upper reject limit of 62 seconds the switches are encoded for a number of 60, as shown above. 1 2 3 4 5 6 7 8 ON OFF Multiply the difference between the required upper and lower reject limits (in microseconds) by 10 and subtract 1 . Encode the switches for this value. For an upper reject limit of 50.5 microseconds the difference between the limits is 1.0 microsecond and the switches are encoded for a number of 9, as shown above.
8-way DIL switch
S10
SPACING REJECT WINDOW
1
2
3
4
5
6
7
8 ON OFF
Multiply the difference between the required upper and lower reject limits (in microseconds) by 10 and subtract 1 . Encode the switches for
HA72500
APPENDIX A
Table A-7 SUBASSY 1A72515 Main PWB Assembly. Test Interrogator 1A72516 RF Generator
Internal Controls : Test Interrogator 1A72514 TYPE
REF
CONTROL/INDICATION FUNCTION DETAILS LEGEND FUNCTION/SETTING/INDICATION
Slide switch
S4
mode
Preset resistor
R7
TPNDR OP LVL CAL
Variable capacitors Inductor 6-way DIL switch
C10, 10, 14,18, 22 L1 S1
SW1 SW2 SW3 SW4 SW5 SW6
1A72517 RF Filter 1A72518 Modulator and
Variable capacitors
C1, C2
Preset resistors
R13 R20
Pulse amplitude Pulse shape
R37
Pulse pedestal
X Sets pulse spacing for X channel operation. Y Sets pulse spacing for Y channel operation. Used to calibrate the transmitted pulse peak power. Used to align the RF generator to the operating interrogator frequencies (see Section 3.4.12). Selects interrogations at the nominal interrogation frequency. Selects interrogations at 160 kHz above the nominal interrogation frequency. Selects interrogations at 160 kHz below the nominal interrogation frequency. Selects interrogations at 900 kHz above the nominal interrogation frequency. Selects interrogations at 900 kHz below the nominal interrogation frequency. Adds a CW signal to the interrogation pules at -10 dB. Used to align the RF filter (see Section 3.4.13). Used to align the pulse shape of the interrogations produced by the RF generator (see Section 3.4.14).
HA72500
APPENDIX A
Table A-8
Internal Controls : Receiver Video 1A72520
SUBASSY TYPE 1A72521 Main PWB Assembly, Receiver Video
REF
CONTROL FUNCTIONS LEGEND FUNCTION/SETTING/INDICATION
Preset resistor
R37
CODE SPEED
Varies the ident code speed, which is set to 8 Hz.
Preset resistor Preset resistor
R39
CODE REPTN
R45
ADJUST 6 dB OFFSET
Preset resistor
R46
LONG DISTANCE ECHO SUPP LEVEL
Varies the ident repetition rate, which is set to 1.5 Hz. Set to 0.24 volts during factory test, but may need to be varied at module test level (see Sections 3.3.8, 3.4.17). Varies the LDES DC level.
Slide switch
S4
SELECT ENCODER MODE
Slide switch
S5
SELECT DECODER MODE
16-way rotary switch 16-way rotary switch Slide switch
S6 S7
SET LDES PERIOD SET DEAD TIME
S8
SDES
Slide switch
S9
LDES
8-way switch
S13 to
CODE ELEMENT
X Y X
Selects X mode operation for the encoder. Selects Y mode operation for the encoder. Selects X mode operation for the decoder.
Y Selects Y mode operation for the decoder. Sets the LDES period in multiples of 12.15 microseconds. Sets the dead time period in multiples of 11.57 microseconds. ON Enables SDES operation. OFF Disables SDES operation. ON Enables LDES operation. OFF Disables LDES operation. Set the ident Morse code characters.
HA72500
APPENDIX A
The Ident code element switches S13, S14, S15 and S16 on the Main PWB Assembly, Receiver Video set the ident code as follows: a. Convert the required Ident letters into International Morse Code, using the following table. LETTER
MORSE SYMBOL
LETTER
MORSE SYMBOL
A B
dot dash dash dot dot dot
N 0
dash dot dash dash dash
C
dash dot dash dot
P
dot dash dash dot
D E F
dash dot dot dot dot dot dash dot
Q R S
dash dash dot dash dot dash dot dot dot dot
G H 1
dash dash dot dot dot dot dot dot dot
T U V
dash dot dot dash dot dot dot dash
J K L
dot dash dash dash dot dash dot dash dot dot
W X Y
dot dash dash dash dot dot dash dash dot dash dash
M
dash dash
Z
dash dash dot dot
b. Set the switches using the following code (shading indicates switch position).
HA72500
Table A-10 SUBASSY 1A72531 Pulse Shaper PWB Assembly
APPENDIX A
Internal Controls : Transmitter Driver 1A72530 TYPE Preset resistors
REF R3, 5, 7, 9, 11, 13 R17 R36 R52 R54
R58 R62 R69 R85 R97 R1 15 Toggle
S1
CONTROL FUNCTIONS LEGEND FUNCTION/SETTING/INDICATION PULSE SHAPE
These vary the slope of th e segments of the function generator output from base (R3) to apex (R13). INTEGRATOR Adjusts the balance of the function generator BALANCE integrator. BACKPORCH Adjusts the spacing between the modulation pulses. PEDESTAL Adjusts the DC level of the shaped modulation VOLTAGE pulse. 2ND PULSE Adjusts the height of the second pulse of the EQUALISING pulse pair to equalise it with the height of the first pulse. MOD PULSE Adjusts the amplitude of the shaped modulation AMPLITUDE pulse. ALC LEVEL (RF OUTPUT) POWER MOD AMP DC
With S2 (ALC LOOP) in it s closed position, adjusts the shaped modulation pulse amplitude. Adjusts the power modulation amplifier DC level.
1W PULSE EXCITER DC MED POWER DRIVER DC DRIVER DC
Adjusts the pulse modulation amplitude. Adjusts the exciter DC level. Adjusts the medium power driver DC level. OFF
Power supply to exciter is off.
HA72500
Table A-11
APPENDIX A
Internal Controls: 1kW PA Power Supply 1A72540
SUBASSY
CONTROL FUNCTIONS TYPE
1A72541 Control and Status PWB Assembly 1A72542 DC-DC Converter PWB Assembly 1A72543 Regulator PWB Assembly
REF
Preset resistor Preset resistor
R45
Preset resistor
R112
R16
FUNCTION/SETTINGP/INDICATION Varies the centre of the HT ON window between approximately 48.5 and 51.9 volts. Calibrates the input circuit monitoring of the DC-DC converter section 3.4.33). Sets the HT output voltage to the 1kW RF power amplifier.
HA72500
A.6
APPENDIX A
DEPOT TEST FACILITY OPERATION
Operating procedures for the Depot Test Facility 3A72500 are contained in Appendix K.
Pelorus AustralAsia
Pelorus AustralAsia
Pelorus AustralAsia
