Analog Communication Laboratory Viva Questions 8

Theory_Questions:

1.What should be the possible SNR used in Telephone Networks?

a)5 dB

b) 15 dB

c) 25 dB

d)20 dB

Answer: [C] 25 dB

2. What should be the possible SNR used in Television?

a)50 dB

b) 5 dB

c) 15 dB

d) 25 dB

Answer: [A] 50 dB

3) Given that SNR is “-30 dB”. find the correct statement from the following?

a)Noise dominates signal by 1000 times

b) Noise dominates signal by 100 times

c) Signal dominates Noisel by 1000 times

d) Signal dominates Noisel by 1000 times

Answer: [A] Noise dominates signal by 1000 times

4)Given that DSB-SC signal is having power of 100 W. what is the Representation in dB and dBm?

a)20 dB and 50 dBm

b) 20 dB and 20 dBm

c) 10 dB and 50 dBm

d) 10 dB and 20 dBm

Answer: [A] 20 dB and 50 dBm

5) Identify the correct statement from the following?

a) White noise has same amplitude for all the time instances in its Time domain representation

b) White noise has Different amplitudes for all the frequencies in its power spectral density

c) White noise has same amplitudes for all the frequencies in its power spectral density

d)None

Answer: [C] White noise has same amplitudes for all the frequencies in its power spectral density

6)Identify the FM demodulator circuit from the following?

a)Ratio Detector

b)Foster Sealay Detector

c)both ‘a’ and ’b’

d)None

Answer: [C] both ‘a’ and ’b’

7)In the Noise analysis of DSB-SC, which component of noise present at the output of the demodulator

circuit ?

a) quadrature phase component

b) Inphase component

c)both

d)none

Answer: [B] Inphase component

8) What is the difference between spectrums of NBFM and AM ?

a) In NBFM the lower side band is phase shifted by 1800

b) In NBFM the upper side band is phase shifted by 1800

c) There is no difference

d)In NBFM both the lower side band and upper side bands are phase shifted by 1800

Answer: [A] In NBFM the lower side band is phase shifted by 1800

9) A FM signal 10cos(200Πt+5sin(20Πt)) is given to the mixer with local oscillator frequency 50 Hz.Then what is the modulation index of the resulting FM signal ?

a) 0

b) 5

c) 10

d) none

Answer: [B] 5

10) What is the approximate bandwidth for NBFM signal 10cos(100Πt+0.05sin(40Πt)) in Hz ?

a) 40

b) 20

c)42

d) Very Small

Answer: [A] 40