e1theory

Technical Seminar ‘99E1THEORY.ppt Slide 1


AgendaAgenda

Multiplexing and TDM Theory

PCM Technique

E1 Theory (+ T1)


What is Multiplexer?What is Multiplexer?

A Device allows multiple logical signals to be transmitted simultaneously across a signal physical channel

Simply call it as MUX


MultiplexingMultiplexingBefore

After

Modem Modem

Multiplexer Multiplexer

Modem Modem

Modem Modem

Modem Modem


What is TDM?What is TDM?

TDM is Time Division Multiplexer Transmitting multiple digitized data, voice signals

simultaneously over one communication media by interleaving pulses

Simply many inputs can share one output


TDM TheoryTDM Theory Allocation of fixed length time slots to data sub-channels

Group of channels or Time slots called Frames

In each frame, one or more time slots are dedicated to each data source (channel)

One Data Frame

CH1 SYN CH3 CH2 CH1 SYN

M MTDMMultiplexer

TDMMultiplexer

CH1

CH2

CH3

CH4

CH1

CH2

CH3

CH4

CH4

SYN CH2 CH3 CH4 SYNCH1 CH1



PCM TechniquePCM Technique


PCM Voice DigitizationPCM Voice Digitization(Pulse Code Modulation)(Pulse Code Modulation)

CODEC

300-3400 HzANALOG

64,000 bpsDIGITAL

CODEC is an analog to digital and digital to analog converter


What is PCM?What is PCM?

Pulse code modulation is a way to convert sound or analog information to binary information (i.e. 0 or 1s) by taking samples of the sound and record the resulting number as binary information

Sampling is nothing but measurements of signal


PCM TechniquePCM Techniquev

t (sec.)1Analog Signal



8000 samples per 1 second



sampled pulse


0 and 1s0 and 1s

Pulse is 1 and Non pulse is 0



1 1 1 1 1 1 1 1

0 0 0 0 0 0 0 0

Digital character of 8 bits



8000 samples x 8bits = 64 kbps

(E1 64 kbps x 32 = 2048 kbps)


PCM Voice Digitization - SummaryPCM Voice Digitization - Summary

Incoming analog signals are sampled 8000 samples/sec.

Sampled values are converted into pulses

The height of each pulse is assigned an equivalent 8-bit digital value

Creation of 64 kbps (no. of samples/sec x no. of bits per sample, or 8000 x 8 = 64,000 bps)

CODEC

300-3400 HzANALOG

64,000 bpsDIGITAL



E1 – Basic CharacteristicsE1 – Basic Characteristics

Digital communications standard for transmission of Voice, Data, LAN and Video signals at a rate of 2.048 Mbps

E1 is a European digital transmission format derived by ITU-T

Designed for transmission of 30 telephone channels

PCM voice digitizing technique using 64 kbps for each channel

The E1 is defined as 32 8-bit channels (timeslots)


E1 (cont.)E1 (cont.)

Specifications defined in ITU recommendations:

– G.704/G.732 Frame definition

– G.703 Pulse mask

– G.823 Jitter requirements

Signaling information is sent in a special timeslot (16) Synchronization is sent in dedicated timeslot (zero).


Digital Hierarchy Digital Hierarchy G.702, G.703G.702, G.703

LevelLevel Bit RateBit Rate CircuitsCircuits HierarchyHierarchy

0 64 kbps 1

1 2.048 Mbps 30 E1

2 8.448 Mbps 120 E2

3 34.368 Mbps 480 E3

4 139.264 Mbps 1920 E4


32 Time slots / Frame

E1 Signal Structure – G.704E1 Signal Structure – G.704

TS31

TS30

TS29

TS28

TS27

TS26

TS25

TS24

TS23

TS22

TS21

TS20

TS19

TS18

TS17

TS16

TS15

TS14

TS13

TS12

TS11

TS10

TS9

TS8

TS7

TS6

TS5

TS4

TS3

TS2

TS1

TS0

1 2 5 6 7 83 4

Channel Data

Timeslots 1-15, 17-31

1 1 N N N NA N

Odd frames (1, 3, 5-15)

1 0 1 0 0 10 1

Even frames (0, 2, 4-14)

FAS

Timeslot 0

NOTESI International BitN National Bits (Sa4 - Sa8)A Remote Alarm Indication (RAI) SignalFAS Frame Alignment Signal, occupies alternate

(but not necessarily even) frames

ABCD ABCD Signaling BitsX Extra BitY Loss of Multiframe AlignmentMAS Multiframe Alignment Signal


CAS Channel Associated Signaling (TS 16)

CCS Common Channel Signaling (any TS)

AIS Alarm Indication Signal (all ones)

Red Alarm Sync Loss (from T1)

Yellow Alarm Remote Sync Loss (from T1)

OOS Out Of Service

CRC Cyclic Redundancy Code


e1theory

Documents

t1 technical seminar

mux technical seminar

output technical seminar

ts alarm indication

data frame technical

bitstechnical seminar

secondtechnical seminar

pulsetechnical seminar