8/13/2019 Lab3 Pulse Code Modulalation

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Laboratory Procedure

I . PCM Fa!"!ar!#at!o$

" The aalo$ to %i$ital coversio -ro-erties of the P&M as ivesti$ate% i the laste-eri'et"

The 4start bit a% the 6 %ata bits a% to 4sto- bits ere i%etifie%" It as also fo*% that if the

-arit sitch is o7 the the 1ststo- bit is cha$e% to a eve -arit bit" That is7 the 6 %ata bits

-l*s the -arit bit ill alas be a eve *'ber (refer to figure 8 B)

" et *- 9i$*re 8" the M): +*ati;atio sitches are to be i'-le'ete% *si$ the

a'-le a% hol% a%

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figure 8A (b) Input to PCM timing

The o*t-*t '*e% ith the i-*t is sho i fi$*re belo

figure 8A (c) Output Muxed with Input for PCM timing

The bloc( -ara'eters of the +*ati;er is sho belo

figure 8A (d) Quantizer boc! parameter"

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The hole P&M ti'i$ bloc( i'-le'etatio is sho belo

figure 8A (e) PCM timing# $u impementation

@ere are the bloc( -ara'ters of the +*ati;er eco%e a% the %eco%e bloc(s" The tri$er si$al is

-rovi%e% *si$ a -*lse $eerator"

figure 8A (f) Boc! Parameter" %nabed &uantizer encode

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i'ilarl the bloc( -ara'eters for the +*ati;atio %eco%e is sho belo"

figure 8A (g) Boc! Parameter" %nabed &uantizer decode

The %i$ital o*t-*t si$al is as sho belo"

figure 8A (h) Boc! Parameter" %nabed &uantizer decode

The +*ati;atio val*es are sho belo

figure 8A (i) Quantization 'aue"

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The %istortio is sho belo

figure 8A () i"tortion of the "igna

The fial o*t-*t of the %eco%er is sho belo

figure 8A (!) Output in compari"ion with the input

&" The sitches i the P&M)alo$ 'o%*le as set to

AN& / AN& ))) AN&

%j*st the aalo$ i-*t si$al for a 1 (@; sice ave" The o*t-*t of the P&M %eco%er

as observe%" The o*t-*t as also fe% to a :P9 to recostr*ct the si$al" The effect of

the :P9 to si$al recostr*ctio is i'-ortat sice it cha$es the a'-lit*%e of the

fre+*ec %o'ai si$al"

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figure 8B (b) Output of PCM channe in *oi"e

The bloc( -ara'eters of the a% li'ite% hite oise loo(s li(e this

figure 8B (c) Boc! Parameter" of Band imited +hite *oi"e

The other 'o%*le o*t-*ts are sho belo

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The %i$ital si$al $eerate% loo(s li(e this

figure 8B (d) Output of the digita "igna generator

The +*ati;atio val*es a% the error is sho belo

figure 8B (e) Quantization 'aue"

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figure 8B (f) i"tortion

1" Receive% -arit is eve! It ill be ass*'e% that o error as 'a%e i the chael"2" Receive% -arit is o%%! error has bee 'a%e"

a" &o'-esatio >! The 'ost recet eve -arit sa'-le ill be retaie% at the o*t-*t"

B No this is alas *se%"C

The abilit to co'-esate to icrease the o*t-*t NR of the P&M sste' as observe% a% a

-lot si'ilar to the -revio*s ti'e as %oe"

&" The -arit sitch as t*re% off a% the sste' has bee o-erati$ i a 4schroo*s

'o%e" That is7 the ti'i$ sste' is co''o to both eco%er a% %eco%er" schroo*s

'o%e ill *tili;e the start a% sto- bits of the P&M or% for obtaii$ or% ti'i$" The

loss of the start bit %*e to chael oise ill ot ol ca*ses a or% error7 b*t also ca*ses

loss of schroi;atio" It this ha--es7 it 'a ta(e several P&M or%s to reestablish

schroi;atio res*lti$ i a loer o*t-*t NR" This as verifie%"

III AS%NCRONOUS PCM TRANSMISSION

To lab $ro*-s coor%iate% this -ortio of the e-eri'et" To se-arate co)aial cables ere

-re-are% lo$ eo*$h to reach the to &M. 'aifra'es" The o*t-*t of o*t alo$)P&M

'o%*le as coecte% tot he i-*t of their P&M)alo$ 'o%*le" a'-li$ fre+*ecies asclose to the sa'e fre+*ec of 5(@; for aschroo*s o-eratio" to)a co''*icatio as

establishe% betee the to -arties" It as observe% that the sste's %o?t or( i AN& 'o%e"

I& T'O C(ANNEL TDM PCM S%STEM

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chael T.M P&M sste' b*ilt *si$ &M. as sho i fi$*re 8. as *se%" The overall

sste' -ara'eters7 s*ch as NR -ro-erties a% the cross chael se-aratio thro*$ho*t the

sste' a% sste' -erfor'ace as a f*ctio of the sste' sa'-li$ fre+*ec ere

ivesti$ate%"

figure 8 (f),wo channe ,M- PCM ./"tem

The ave for's are as sho belo at %ifferet sta$es

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figure 8 (b),wo channe ,M- PCM ./"tem 0 igita .igna

figure 8 (c),wo channe ,M- PCM ./"tem 0 &uantization 'aue"

figure 8 (d),wo channe ,M- PCM ./"tem 0 boc! parameter"

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figure 8 (e),wo channe ,M- PCM ./"tem 0 Output "igna 1

figure 8 (f),wo channe ,M- PCM ./"tem 0 Output "igna 2

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figure 8 (g),wo channe ,M- PCM ./"tem 0.igna before demuxing

& Report

The re-ort ith all the +*estios i the lab -roce%*re ere asere% a% the -lot of the NR

c*rves a% the eval*atios of the vario*s sste's ere %oe"