Analog Communication Laboratory Viva Questions 11

Theory_Questions:

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

a) DSB-FC

b) DSB-SC

c) SSB

d) VSB

Answer: [B] DSB-SC

2. what is the Intermediate frequency used in FM?

a) 10.7 kHz

b) 10.7 MHz

c) 455 KHz

d) 5 MHz

Answer: [B] 10.7 MHz

3. Which of the following analog modulation scheme suitable for transmission of video signals

a) VSB

b) DSB-SC

c) SSB

d) AM

Answer: [A] VSB

4. Which of the following condition has to be satiesfied by VSB filter H(f) for perfect demodulation of VSB signal, Where fc is carrier frequency ?

a) H(f-fc)+H(f+fc)=0

b) H(f-fc)+H(f+fc)=constant

c) H(f-fc)-H(f+fc)=1

d) H(f-fc)-jH(f+fc)=H(fc)

Answer: [B] H(f-fc)+H(f+fc)=constant

5. In a superheterodyne AM receiver IF(intermediate frequency) is 450 KhZ and it is tuned to 1650 KhZ. Then what is Image Frequency in KhZ?

a) 455

b) 500

c) 1410

d) 2550

Answer: [D] 2550

6. In a superheterodyne AM receiver IF( intermediate frequency ) is 455 KhZ then what is the seperation between incoming signal frequency and it's image frequency in KhZ?

a) 910

b) 500

c) 1410

d) 100

Answer: [A] 910

7). An angle modulated signal is S(t)=cos2π(2*106t+30 sin 150t+40cos150t) the maximum frequency and phase deviation of S(t) are

a).80π, 7Khz

b).7.5Khz, 80π

c). 7Khz, 60π

d). 7.5Khz, 100π

Answer: [D] 7.5Khz, 100π

8) carrier signal c(t)= 5 cos 2π(106)t and m(t) = 4 cos (4π*103t)be the message signal they are used to generate an FM signal . if the maximum frequency deviation of FM is equal to the 3 times the transmission bandwidth of AM signal then what is amplitude of the component cos(2π(1008)*103t) in terms of based coefficient

a). 5 J2(6)

b). 5 J3(3)

c). 5J4(6)

d). 4J4(3)

Answer: [C] 5J4(6)

9). A carrier is phase modulated with frequency deviation of 10Khz by a single tone frequency of 1khz . if the single tone is increased to 2Khz then what is the frequency deviation of the phase modulated signal

a).10Khz

b). 5Khz

c).20Khz

d). 15 kHz

Answer: [C] 20Khz

10)how do We get Frequency modulated signal?

a)Differentiation followed by PM

b)integration followed by PM

c)PM followed by integration

d)PM followed by differentiation

Answer: [B] integration followed by PM