# Digital communication

Digital communication
Question:-
Option (A)
Option (B)
5
Option (C)
0
Option (D)
Correct Option:
A
Question Solution:
Here carrier amplitude
Ac= 20 volts
So sideband voltage is
=
= 5 V
Hence its rms value is :
Question:-
Option (A)
4.7 b/character
Option (B)
0.18 b/character
Option (C)
3.2 b/character
Option (D)
5.3 b/character
Correct Option:
A
Question Solution:
Average information content for equally probable events is given as
H(X)=log2 M
HereM=26
therefore, H(X)=log2 26 = 4.7 b/character
Question:-
Option (A)
Option (B)
0
Option (C)
1
Option (D)
None of these
Correct Option:
C
Question Solution:
Directivity, D =
For isotropic antenna
ΩA=4π
therefore, D =
Thus directivity of an isotropic antenna is unity which is the smallest.
Question:-
Option (A)
R = 160 kbps ; SNRq = 20.4 dB
Option (B)
R = 160 kbps ; SNRq = 25.8 dB
Option (C)
R = 320 kbps ; SNRq = 25.8 dB
Option (D)
R = 320 kbps ; SNRq = 20.4 dB
Correct Option:
B
Question Solution:
16 levels => 16 = 24
therefore, n = 4 bits/sample
therefore, Bit rate = R =
= 160 kbps
SNRq = 1.76 + 6n
= 1.76 + 6 x 4
= 25.76 ≈ 25.8 dB