# bandwidth required for the transmission line of aPCM

#### muni

Joined Jul 29, 2008
45
bandwidth required for the transmission line of a PCM signal increases by afactor of------------------------------- when the number of quantisation levels are increased from 4 to 64.

sir request answer with little explanation.

in the book it is given some thing like this way

V1 = log (base 2) 4 =2
C= 2b LOG (BASE 2) N; B=C/4

V2 = log (base 2) 64 =6; B= C/12

therefore BW = (C/12) / (C/3) =1/4

request little more clear explanation on this

#### studiot

Joined Nov 9, 2007
4,998
_{}Not sure where your difficulty lies.

The quantized signal is mapped to a binary word
Obviously the greater the number of quantizing levels the longer the binary word.

Each of the M levels is mapped to one of N bits in the binary word

N = log$$_{2}$$(M) or M = 2$$^{N}$$

The rest is simply calculating this for M= 4 and M =64 and taking the ratio to obtain the fraction required.

#### muni

Joined Jul 29, 2008
45
sir, thankyou for giving me explanation and the formulae. though i was knowing this formulae, i wasn't clear how to use over this problem.

once again thank you sir