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?

a)4

b)2

c)1

d)0.5

Answer: [A] 2

2) To modulation voice signal, which of the following modulation technique is best suited?

a)AM

b)SSB

c) DSB-S C

d) VSB

Answer: [B] SSB

3). To modulate video signals, which of the following modulation technique is best suited?

a).AM

b). SSB

c).DSB-SC

d). VSB

Answer: [D] VSB

4). A super heterodyne receiver is to operate in the frequency range 550Khz—1650Khz,with intermediate frequency of 450Khz, Let R=Cmax/Cmin denote the required capacitance ratio of the local oscillator then what is the value of R?

a).R=4.41

b).R=2.1

c).R=3.0

d).R=9

Answer: [A] R=4.41

5) In the above problem ,if I denote the image frequency (in Khz) of the incoming signal ,if the receiver is tuned to 800khz then

a).I=1700

b).I=1600

c). I=1150

d).I=1800

Answer: [A] .I=1700

6).what is the bandwidth of the IF filter in a super heterodyne receiver

a)5Khz

b)10Khz

c) 15Khz

d) 20Khz

Answer: [B] 10Khz

7). What is the condition on the filter characteristics ,used in a VSB technique?

a).H(f—fc)-H(f+fc)=K

b).H(f—fc)-H(f+fc)=kf

c).H(f—fc)+H(f+fc)=k

d).H(f—fc)+H(f+fc)=kf

Answer: [C] H(f—fc)+H(f+fc)=k

8).The problem of quadrature null effect occurs in which modulation?

a).DSB-SC

b). SSB

c)VSB

d) both a &b

Answer: [A] DSB-SC

9) If the receiver is tuned to 1200 Khz and image frequency is 3000 Khz, then what is the intermediate frequency ?

a) 455Khz

b) 900Khz

c) 1800Khz

d) 3000Khz

Answer: [B] 900Khz

10) Filter method is used to generate which analog modulation technique?

a) VSB

b) DSB-SC

c) SSB

d) None

Answer: [C] SSB