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The calculation of the length of the recovery area MDCs on the metal cable

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Аpsec - permissible security of the signal from the noise, determined by the rules on the permissible error probability рerr used the site of the primary network; Аesec - the expected security of the signal from the noise, determined by the actual ratio signal...

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2015-09-13

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16 The calculation of the length of the recovery area MDCs
on the metal cable.

The estimated length of the recovery area Lр defined from the equation

Аesec(Lр) = Аpsec(Lр),

где

Аpsec - permissible security of the signal from the noise, determined by the rules on the permissible error probability рerr used the site of the primary network;

Аesec - the expected security of the signal from the noise, determined by the actual ratio signal/noise ratio, which depends on the linear code, type of cable used, how to organize two-way communication, and other factors.

The determination of acceptable security Аpsec(L) provide for (2.41 - 2.43) training manual [5], with the account of the approximate evaluation of the impact of the length of a line L on the Аpsec(L), as follows:

Аpsec.х(L) = Аesec.peak + Рpeak.ш.х + Аesec.р

                                   - 0.5*Lg(L)

Here 

Аesec.peak - permissible security of the ideal of the heat exchanger in relation to a peak value of the noise. When using triplequazi linear codes Аesec.peak = 6 dB;

Аesec.р - the deterioration of the admissible the security of the real heat exchanger compared with the ideal by the action of the internal noise and instabilities. The numerical value of the Аesec.р is selected in accordance with (2.44) [5] or at the direction of a teacher, but not less than 1 dB;

 Рpeak.ш.х - peak factor interference linear path, which basically determines the expected probability of error. In a designation of pic-factor character "x" takes different values (with. b, d, etc) in accordance with what the noises mainly define the security (for own noise SN; b - to-noise linear conversion at the end of PL-Bq, etc). The

Рpeak.ш.с = 16 + 0.5*(C-10) дБ

Рpeak.ш.б = [11 + 5*Lg(B)] + 0.5*(C-10) дБ

Here «s» is the value of the negative powers of the number, characterizing the permissible error probability at 1 km of the projected path:

Рadd1 = 10-C 

So

С = Lg(1/рadd1)

As a permissible error probability of the projected path, set the ID of length L, we will use the BER subject only to the background errors ES (see Clause 15-4 and example 1 in Appendix II-15). Then

рadd1 =(BER considering only the background bugs ES)/ L

Below are given recommendations for the determination of the permissible and the expected protection for different transmission lines (detailed explanations see in [5]).

For coaxial cable (CC)

ШЛТр = СШ.

In this case

Аpsec.(L) = Аpsec.с(L) = 22+ 0.5*(C-10)+ Аesec.р - 0.5*Lg(L)

Аesec (L) = Азс(L)

Азс(L) = (рпер - рш.вх +2,36) - 0,876*[(fp)*L] –

- 3,96*10-3 *[(fp)*L]2

where 

рпер = 10*Lg[ U2вых *10 3 / Z]     дБ

рш.вх = -[105 - 10*Lg(fp)}         дБ


For single 4x symmetrical cable with the use of single cable duplex (1х4 СК + ОКД)

 ШЛТр = ЛП - БК.

In this case 

Аpsec.(L) = Аpsec.б(L)

Аpsec.б(L) = 16 + 5*Lg(В) + 0.5*(C-10) +

+ Аesec.р –  0.5*Lg(L)

Аesec(L) = Азб(L) )

Азб(L) ) = (А01 -  15*Lg(fp) + 7,5) –

-0,917*[(fp)*L] – 2,6*10-3 *[(fp)*L]2

А01   look in [5] Table S.2.2 on page 69.

For single 4x symmetrical cable with the use of double cable duplex (1х4 СК + ДКД) 

         ШЛТр =СШ + ЛП - ДК - ВВ

In this case 

Аpsec.(L) = Аpsec.с(L) = 22 + 0.5*(C-10) +

+ Аesec.р - 0.5*Lg(L)

Азож(L) = Азс(L) - А оп,

where

Азс(L) = (рпер - рш.вх +2,36) - 0,876*[(fp)*L] –

   -3,96*10-3 *[(fp)*L]2

А оп = 20*Lg[1/(1 - 10-0,05*А)]

А = А01 -[5+ 10*Lg(L)] - 40*Lg(fр) - Аesec.р

А01   look in [5] Table S.2.2 on page 69.

For multi 4x symmetrical cable with the use of single cable duplex (nх4 СК + ОКД).

 ШЛТр = (ШЛП-БК-МВ)*nв + (ШЛП-ДК - MВ)*(nв-1) + (ШЛП - ДК - ВВ) + СШ.

Because СШ(ШЛП - БК - МВ), and (ШЛП - ДК - MВ)  (ШЛП - ДК - ВВ), so

ШЛТр = (ЛП-БК-МВ)*nв+ (ЛП-ДК-ВВ).

Under big nв noise (ЛП - БК - МВ)*nв normalize and that’s why

Аpsec.(L) = 22+ 0.5*(C-10)+ Аesec.р - 0.5*Lg(L)

Аesec(L) = Азб(L) - Аpsec

where

Азб(L) = (А01 - 15*Lg(fр) - 10*Lg(nв)+7.5) –

    --0,917*[(fp)*L] – 2,6*10-3 *[(fp)*L]2

А оп = 20*Lg[1/(1 - 10-0,05*А)]

А = А01 -[5+ 10*Lg(L)] - 40*Lg(fр) - Аesec.р –

    -10*Lg(nв)

А01   look in [5] Table S.2.2 on page 69.

Here

For multi 4x symmetrical cable with the use of double cable duplex (nх4 СК + ДКД)

ШЛТр = (ЛП-ДК–МВ)*nв + ЛП-ДК-ВВ + СШ

Under big nв noise (ЛП - БК - МВ)*nв normalize and that’s why

Аpsec.(L) = 22 + 0.5*(C-10) + Аesec.р - 0.5*Lg(L)

Азож(L) = Азсдм(L) - Аоп(L)

Here

Азсдм(L) = 10*LOG[1/(10- 0.1*Азс(L) + 10- 0.1*Аздм(L))],

where

Азс(L) = (рпер - рш.вх +2,36) - 0,876*[(fp)*L] –

    -3,96*10-3 *[(fp)*L]2

Аздм(L) = А01 + 23,4 - 20*Lg(fр) - 10*Lg(L)) –

       -10*LOG(nв)

А оп(L) = 20*Lg[1/(1 - 10-0,05*А)], а

А(L) = А01 -[5+ 10*Lg(L)] - 40*Lg(fр) - Аesec.р

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