Analog Communication Laboratory Viva Questions 11

Theory_Questions:

1. Ring modulator is used to generate, which modulation scheme?

Analog Communication Laboratory Viva Questions 10

Theory_Questions:

1.The power required to transmit an SSB signal and DSB-SC signal are?

a)PmPc/2, PmPc

b) PmPc/2, PmPc/2

c) PmPc, PmPc

d) PmPc ,PmPc/2

Answer: [A] PmPc/2, PmPc

2) In an Envelope detector, the load resistance is 1KΩ, carrier frequency is 1MHz and the message signal is having a B.W of 4 KHz, then what is the appropriate value of the capacitor?

A)50nF

B) 300nF

C) 250nF

d) 1nF

Answer: [A] 50nF

3)What must be the condition on the charging time for the proper operation of Envelope Detector?

a)1/fc<<RsC<<1/fm

b)1/fc<<RsC

c) RsC<<1/fc

d) 1/fm<<RsC<<1/fc

Answer: [C] RsC<<1/fc

4)Receiver Complexity is less in case of which modulation scheme?

a)VSB

b)SSB

c)DSB-SC

d)AM

Answer: [D] AM

5)What is the Auto correlation function and spectral density of White Noise?

a) constant & impulse function

b) impulse function & constant

c) Ramp function & constant

d) impulse function & ramp function

Answer: [B] impulse function & constant

6)In AM ,if the carrier amplitude is 10V and message signal is sinusoidal, having peak value 2V,what is the modulation index and total transmitted power?

a)0.8,36W

b)0.8,72W

c)0.2,51W

d)0.2,52W

Answer: [C] 0.2,51W

7)suppose a voice signal is having peak value of 2V and power of 2W,with carrier peak value of 6V,is DSB modulated,then what is the total power in side bands?

a)36W

b)72W

c)1W

d)2W

Answer: [A] 36W

8)In the above problem,if the message is Amplitude modulated,instead of DSB-SC,then what is the total power in Side bands?

a)36W

b)72W

c)1W

d)2W

Answer: [C] 1W

9)if the input to the Envelope detector is m(t)cos(2πfct)+mh(t)sin(2πfct),then what is the output of the envelope detector?(Assume m(t)=Amcos(2πfmt) and mh(t) is the hilbert transform of m(t))

a) Amcos(2πfmt)

b) Amsin(2πfmt)

c)Am

d) Am/2

Answer: [C] Am

10)Two DSB signals with bandwidth 20 KHz is passed using quadrature carrier multiplexing,then what is the bandwidth of resulting signal?

a)10KHz

b)20KHz

c)40KHz

d)30KHz

Answer: [B] 20KHz

Analog Communication Laboratory Viva Questions 9

Theory_Questions:

A SSB signal plus noise is demodulated by synchronous detection. Find the SNR at the output in dB. Given that the transmitted signal power is 1mW and is passed through a cable that has loss of 60 dB, message signal bandwidth is 1 MHz and the two sided noise spectral density is 10-20/2 W/Hz

Analog Communication Laboratory Viva Questions 8

Theory_Questions:

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

Analog Communication Laboratory Viva Questions 7

Theory_Questions:

The Design of an Armstrong indirect FM modulator to generate an FM carrier with a carrier frequency of 98.1 MHz and frequency deviation of 75 kHz. A Narrow band FM generator is available at a carrier

frequency of 100 KHz and a frequency deviation of 10 Hz.The local oscillator with an adjustable frequency in the range of 10 Mhz to 11MHz.

Analog Communication Laboratory Viva Questions 6

Theory_Questions:

1). Identify the Non-linear modulation Technique?

Analog Communication Laboratory Viva Questions 5

Theory_Questions:

1. Which of the following analog modulation scheme requires the minimum transmitted power and minimum channel bandwidth ?

Analog Communication Laboratory Viva Questions 4

Theory_Questions:

1). Consider the amplitude modulated signal Accoswct+4coswm+coswct. For demodulating the signal using Envelope detector, the minimum value of Ac would be?

Analog Communication Laboratory Viva Questions 3

Theory_Questions:

1) What are the amplitude response H(f) and phase response β(f) of a distortion less system respectively?

Analog Communication Laboratory Viva Questions 2

Theory_Questions:

1. The Hilbert transform of a signal g(t) is 1/πt, then what is the name

of the signal g(t)?

Analog Communication Laboratory Viva Questions 1

Theory_Questions:

1) What is bandwidth of T.V Signal ?