Digitel - Digital Transmission

8/10/2019 Digitel - Digital Transmission

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Digital Transmission(TRANS101)


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Objectives

At the end of this module, participants should beable to:

Explain the telephone voice signal.

Calculate the DSO capacity.

Dierentiate the !"Carrier from E"Carrier System.


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The Telephone Signal

$ending the signal in an analog form for long transmission and

switching purposes is not efficient.

%&pensive and huge euipments are needed to ma'e this happen.(ue to these limitations, digital transmission was developed in )*+3.

This was done by conveying multiple telegraphy sources into singletelegraph cable.

t was then patented by -estern %lectric in )/.


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Sampling

This is the process of stripping the voice signal which is 4 Khz by*,000 samples per second of time.

%ach sample of signal is digitized or coded into *bit of pulses.

Total bandwidth of an analog voice in digital form is * bits & *,000samples which is euivalent to 4,000 bits per second.


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Time Slot Multiplexing

%ach *bit of information "octet# is sent to the main line by the time

allocation. This process continues for all channels or lines "telephone lines#

which could be either 30 or /4 channels depending to what carrierstandard is used "T2arrier or %2arrier#.


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T-Carrier System

The 5nited $tates 6ell $ystem activated the first commercial digital

carrier system in )/

%lectrical noise from hightension lines and automotive ignitionsinterfered with analog systems.

The system was designated T), with the T standing for Terrestrialto

distinguish the land transmission from satellite transmission.

T)

T/

T3

T4

T)2


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T-Carrier

Tcarrier was designed for a fourwire twistedpair circuit,although the ($7) interface is mediumindependent.

Table T-1: orth American Digital !ierarchy: T-carrier

Digital Signal "DS#$evel

Data %ate&'-(bps

Channels "DS-)s#

*+uivalent T1s

DS-0 64 Kbps 1 1/24

DS-1 (T1) 1.544 Mbps 24 1

DS-1C (T1C) 3.152 Mbps 48 2

DS-2 (T2) 6.312 Mbps 96 4

DS-3 (T3) 44.736 Mbps 672 28

DS-4 (T4) 274.176 Mbps 4,032 168

DS-5 (T5) 400.352 Mbps 5,760 250


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*-Carrier System

E"carrier is based on the original !"carrier digital carrier system.

E"carrier has improved certain electrical characteristics such assignaling rates, framing conventions, line coding techni#ue, and$C% techni#ue.

E"& supports '( DS"( payload channels, compared )ith !& at *+channels, and the higher E"carrier levels build on that dierence.

*-carrier$evel

Data %ate"Mbps#

umber o, &'bpsChannels

"DS-)s#

umber o, *-1s

E-1 2.048 30 1

E-2 8.448 120 4

E-3 34.368 480 16

E-4 139.268 1920 64

E-5 565.148 7680 256


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TDM Stan.ar.s

C O U N T R Y

S A - C A A D A

E / 0 A D

/ E 1 % A 2

3 1 A C E

4 ! A 0 2

5 A $ A

M U L T I P L E X I N S T E P

1 S T ! N D " R D # T $ % T $

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s

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x + x 9 x 7

x & +

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M U L T I P L E X I N $ I E R A R C $ Y


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Test

-hat is the freuency range of the telephone signal8

9 300 hz to 3,400 hz

The process of conversion, transmission of telephone signal fromanalog to digital and vice versa8

9 (igital Transmission

-hat is the sampling freuency8

9 * Khz

:ow many channels are their in ($) level with %2arrier8

9 30 ch

:ow do you calculate 4 Kbps89 * bits & *,000

:ow many voice channel in a T)8

9 /4 ch

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