Transmission Plan

TRANSMISSION PLAN

Transmission Systems - UHF - MARR - Microwave - Satellite - Digital Coaxial - OFC - New Transmission Systems etc.

Local Exchange

Tel.

TAX

MUX.

Trans Eqpt.

TRANSMISSION PLAN 1. Transmission Loss Plan

2. Transmission Noise Plan

3. Error Performance Plan

1. Transmission Loss Plan Telephone instrument should meet the following Reference Equivalents. Minimum SRE 3 dB Minimum ORE 2 dB Maximum ORE 13 dB Junction Loss - From Digital Local Exchange to Input of TAX should be 3.5 dB. - From tandem exchange to TAX/Tandem should be on transmission media (4W) with 0 dB loss. - Between two local exchanges (for local calls) should not exceed 9dB. - Between local exchange and tandem exchange (including hybrid loss) should not exceed 4.5 dB. - Local PCM system should be lined up for following losses. 2W switch to 2 W switch 3 dB 2 W switch to 4W switch 3.5 dB

- Analog long distance circuits should be lined up for 4W to 4W with 0 dB loss. - The loss between MUX centre and local exchange/TAX should not exceed 1 dB. (Preferably they should be collocated). - Relative level of channel at 4W point is -3.5 dB. - The traffic weighted mean ORE for the connection with these will be 14-16 dB and will meet the CCITT objectives.

2. Transmission Noise Plan : The following noise limits for analog circuits should be used : Distance

Commissioning Maintenance Limit (dBmop) Limit (dBmop)

Usable Limit (dBmop)

(a) Terrestrial Circuits 1161 321 641 10012501-

160 km 320 km 640 km 1000 km 2500 km 5000 km

-58 -55 -53 -51 -49 -46

-55 -52 -50 -48 -46 -43

-52 -49 -47 -45 -43 -41

(b) Satellite Circuit maintenance

-50

-48

-46

-47

-45

-43

Others

3. Error Performance Plan (Digital System) The digital transmission will have following three grades for different applications : (i) High grade

- Above level 1 TAXs (Digital Microwave, Coaxial and Optical Fibre). (ii) Medium grade - Between level 1 TAX and local exchanges (Digital Microwave, Coaxial, Optical Fibre, cable PCM and UHF). (iii) Local grade - Between local exchange and subscriber (Digital MARR, digital subscriber, VHF and subscriber PCM)

Hypothetical Reference Connections (HRX)-CCITT Rec. G.801 A Digital HRX is a model for formulation of Standards. HRX is of 27500 Km. of length., which includes two lengths of 1250 km. of local and medium grade circuit and 25000 km. high grade circuit. 27500 KM 1250 KM LOCAL NATIONAL 15%

25000 KM INTERNATIONAL

15%

40%

1250 KM NATIONAL LOCAL 15%

T INTERFACE THE INTERNATIONAL MODEL LINK FIGURE G.1

Hypothetical Reference Digital Section (HRDS)- Rec. G.801 For HRDS a length of 2500km is considered as suitable distance. Lengths of 280 km & 50 km have been chosen to be representative of digital sections likely to be encountered in real operational networks.

Unavailable Time: BER in one second is worse than 1x10-3 for a period of 10 consecutive seconds. Degraded Minutes: SES are excluded from the available seconds of observation and the remaining second intervals are grouped into packets of 60. No. of such packets which contain more than 4 errors are degraded minutes. Severely Error Seconds Within the available seconds, such of those seconds which have more than 64 errors, are defined as SES. Errored Seconds: Those seconds which contain at least one error in each second, within the available seconds.

The reference performance objective, commissioning limits and maintenance limits for 64 Kb/s digital section should be met for different grade of circuits. High Grade

Degraded Minutes (DM)

Errored Seconds (ES)

Severely Severely Err. Errored Seconds Seconds Opt. Microwave Fibre (SES) (SES)

Performance objective (2500 km)

0.400

0.320

0.054

0.0400

Performance objective (280 km)

0.045

0.036

0.006

0.00045

Commissioning limits (280 km)

0.023

0.018

0.003

0.00023

Maintenance

limits

< 625 km

0.075

0.06

0.01

0.00075

626-125 km

0.15

0.12

0.02

0.0015

1251-1875 Km 1976-2500 km

0.225 0.3

0.18 0.24

0.03 0.04

0.00225 0.0030

The values given above are in percentage.

Medium Grade Medium Grade Circuit will consist of class 1 (Systems include coaxial cable and fibre optic systems of various bit rates and 34 Mb/s and 140 Mb/s digital - microwave systems). The limits for class 1 systems will be same as for High Grade Circuits. The limits for class 3 and 4 systems will be :

Class 3

Class 4

Errored Seconds (ES)

Severely Errored Seconds (SES)

Errored Seconds (ES)

Severely Errored Seconds (SES)

Performance Objective (50 km)

0.16

0.006

0.40

0.015

Commissioning limit (per hop)

0.08

0.003

0.20

0.008

< 50 km

0.12

0.0045

0.30

0.0115

51-100

0.24

0.0090

0.60

0.0230

101-150 km

0.36

0.0135

0.90

0.0345

Maintenance limit

Note : For Digital UHF systems in 400 and 600 MHz frequency band Degraded Minutes (DM) not prescribed now.

Local Grade ES

SES

Performance objective

1.2

0.0150

Commissioning limit

0.6

0.0075

2.

Class 4 systems include 30 channel and 10 channel UHF

Maintenance limit

0.9

0.0110

3.

Local grade systems include Digital MARR, Digital subscriber and subs. cable PCM systems.

Notes :1. Class 3 systems include 120 channel UHF.

Satellite System DM

ES

SES

Performance objective

2.0

1.6

0.030

Commissioning limit

1.0

0.8

0.015

Maintenance limit

1.5

.12

0.023

Other Impairments : Other items influencing the quality of a telephone connections are : (a) Cross-talk (b) Side tone. (c) Attenuation distortion. (d) Group Delay distortion. (e) Frequency shift. (f) Propagation time. (g) Impulse noise (h) Phase jitter (i) Non-linearity of amplitude distortion (j) Gain/Phase change (k) Quantizing distortion (l) Single tone interference CCITT has recommended values for these. Equipment’s should conform to CCITT recommendations for these parameters.