UNIVERSITY OF THE EAST College of Engineering ECE Department
EXPERIMENT NO.9
TIME-DIVISION MULTIPLEXING
SUBMITTED BY:
GRADE
Ma. Lerrevina C. Legaspi 2012-11-39193 NEC 512 1-ECF SUBMITTED TO:
Engr. Edelito Handig
DATE PERFORMED:
September 03, 2016
DATE SUBMITTED:
September 10, 2016
DATA:
REVIEW QUESTIONS: 1.
Briefly explain why the digital voice signals in the central office are time multiplexed. Time-division multiplexing is used primarily for digital signals in which two or more signals or bit streams are transferred appearing simultaneously as sub-channels in one communication channel, but are physically taking turns on the channel. The time domain is divided into several recurrent time slots of fixed length, one for each sub-channel. A sample byte or data block of sub-channel 1 is transmitted during time slot 1, sub-channel 2 during timeslot 2. One TDM frame consists of one time slot per sub-channel plus a synchronization channel and sometimes error correction channel before the synchronization.
2.
Briefly describe the DS1 multiplexing format used in North America and Japan.
In the United States and Japan, the DS-1 transmission format has evolved for multiplexing 24 voice channels together.
3.
Briefly describe the E1 multiplexing format used in Europe and most of the rest of the world.
In most countries and in Europe, the E1 multiplexing format adopted by the rest community uses 30 traffic channels, plus a synchronizing channel and a signaling channel each with 64 kbps giving an aggregate bit rate of 2.048 Mbps .
4.
What is a time slot? Time slot is defined as interval, or slot, of time recognizable by devices and designated for a specific purpose or operation.
5.
Describe the TXE signal produced by the TSAC of each of each analog line interface as well as the role of this signal.
TXE signal is one of the line interfaces and the serial PCM codes on the corresponding RX line. It will allow to understand how digitized voice signals from several line interfaces are time-division multiplexed to a single transmission line. It is also used to determine the time slot assigned to the line interface for transmitting the digitized voice signals.
DISCUSSION Experiment no.8 is about Time-Division Multiplexing. It is defined as a method of transmitting and receiving independent signals over a common signal path by means of synchronized switches at each end of the transmission line so that each signal appears on the line only a fraction of time in an alternating pattern. It is divided into two parts: the Transmit enable signal and the Received enable signal.
The experiment allows us to understand the frame synchronization relating to sampling frequency.
Framing is the process by which, while receiving a stream
of framed data, incoming frame alignment signals are identified, permitting the data bits within the frame to be extracted for decoding or retransmission. First part of the experiment is about the Transmit enable signal. From the experiment again, we understand that TXE established a connection between two telephone sets. It will be observed that the TXE signal is one of the line interfaces and the serial PCM codes on the corresponding TX line. It is also allowed to understand how digitized voice signals from several line interfaces are time-division multiplexed to a single transmission line. It is also used to determine the time slot assigned to the line interface for transmitting the digitized voice signal.
Second part of the experiment is about the Received signal enable. It is observed that RXE signal is one of the line interfaces and the serial PCM codes on the corresponding RX line. It is also allowed us to understand how digitized voice signal is received through a single transmission line are demultiplexed. The signals are use to determine the time slot assigned to the line interface for receiving the digitized voice signal. It is also observed from the experiment the signals on the TX and RX lines of a line interface during a normal telephone conversation which demonstrates the time division multiplexing for several digitized voice signals to be exchanged by a single line.
CONCLUSION From this experiment, I therefore conclude that Time-Division Multiplexing is about how transmitter and receiver will interface in a normal telephone conversation which allow several digitized voice signals to be exchanged in a single line. The duration of the pulse is changing same with its address. Most often said about the experiment is about the time slot. What is Time slot is about? It is said that Time slot is defined as the interval, or slot , of time recognizable by devices and designated for a specific purpose or operation.
It is also observe here how many voice channels are needed for the supplied voltage. The higher the voltage the lesser the number of voice channels obtained. From that, we can say that there are several formats such as DS-1 T1 multiplexing format which is built around 24 channels which contain 8-bits samples repeated 8000 times per second. We can also conclude that for each countries, there are different time division multiplexing standards. In the Unites States of America, Japan, and Canada, the DS-1 transmission has evolved for multiplexing 24 channels and for other countries there are 30 channels. From the experiment again, I therefore conclude that additional bits are incorporated in the frame to allow synchronization and for the signaling associated with the voice channels.
As a summary, signals received and transmit can be changed. Nothing is permanent in their positions or values measured such as their signal pulse duration. The time slot is the most changing and unstable. There are time that the two time slot were interchanging positions due to address changing. Well, that how everything been in the process. The technique is you have to let yourself understand how each part of the experiment may change or come back to their original positions. There are reasons behind actually but the most irritating part here is you can’t conclude anything. You can’t come up for the idea
GLOSSARY
FRAME SYNC
The
process
asynchronization source.
of
synchronizing When
several
display
pixel
systems
are
scanning
to
connected,
a synchronization signal is fed from a master system to the other systems in the network, and the displays are synchronized with each other.
MULTIPLEXER
A device that selects one of several analog or digital input signals and forwards the selected input into a single line.
PULSE DURATION
The interval between the time, during the first transition, that the amplitude of the pulse reaches a specified fraction (level) of its final amplitude, and the time the pulse amplitude drops, on the last transition, to the same level.
RECEIVE ENABLE (RXE) SIGNAL
Allowing signal to be received.
VOICE CHANNELS
A channel with a bandwidth sufficiently great to accommodate speech.
TIME SLOT
A defined interval, or slot, of time recognizable by devices and designated for a specific purpose or operation.
TIME-DIVISION MULTIPLEXING
A method of transmitting and receiving independent signals over a common signal path by means of synchronized switches at each end of the transmission line so that each signal appears on the line only a fraction of time in an alternating pattern.
TRANSMIT ENABLE (TXE) SIGNAL
Allowing signal to be transmitted.
REFERENCE
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http://broom02.revolvy.com/main/index.php?s=Timedivision%20multiplex ing&item_type=topic
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http://www.yourdictionary.com/time-slot
