Question

A date with a rate of 400 kbps is to be transmitted using M-ary PSK modulation through a channel whose bandwidth is $100kHz.$ If the baseband modelling of the data is done by a raised cosine filter with a roll-off factr of 0.50, then the minimum value of 'M' required for feasible transmission will be

• A.
  $64$
• B.
  $32$
• C.
  $16$
• D.
  $128$

Answer 1

The correct option is A

$64$
BW of the M-PSK signal, when the baseband modelling is done by a raised cosine filter is,

$(BW{)}_{M,PSK}\le (BW{)}_{channel}(BW{)}_{M-PSK}\le 100kHz\frac{400(1+0.50)}{lo{g}_2\left(M\right)}\le 100lo{g}_2(M)\ge 4(1.50)=6M\ge 2^6=64M_{min}=64$