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.

Answer the questions from 1 to 3 with the above given data.

1)What is the multiplication factor before and After frequency Mixer respectively?

a)125,60

b)25,300

c)250,30

d)30.250

Answer: [A] 125,60

2)what should be the local oscillator frequency?

a)10.586 MHz

b)10.356 MHz

c)10.865 MHz

d)10.99 M Hz

Answer: [C] 10.865 MHz

3)what should be the overall multiplication factor?

a)7200

b)7500

c)5000

d)10000

Answer: [B] 10.865 MHz

The Design of an Armstrong indirect FM modulator to generate an FM carrier with a carrier frequency of 96 MHz and frequency deviation of 20 kHz. A Narrow band FM generator is available at a carrier

frequency of 200 KHz and a frequency deviation of 9.7656 Hz is available.The local oscillator with an

adjustable frequency in the range of 9 MHz to 10 MHz.there is aband pass filter with any center frequency,only frequency doublers are available.

Answer the questions from 4 to 6 with the above given data.

4) What is the multiplication factor before and after frequency Mixer respectively?

a)32,64

b)16,128

C)128,16

d)64.32

Answer: [D] 64.32

5)what should be the local oscillator frequency?

a)9.386 MHz

b)9.29 MHz

c) 9.5 MHz

d)9.8 M Hz

Answer: [D] 9.8 M Hz

6)In the design total howmany doublers are required?

a)10

b)11

c)12

d)9

Answer: [B] 11

7) find out the correct statement from the below?

a) PM demodulator followed by integrator serves as FM demodulator

b) PM demodulator followed by differentiator serves as FM demodulator

c) Integrator followed by PM demodulator serves as FM demodulator

d)None

Answer: [B] PM demodulator followed by differentiator serves as FM demodulator

8) Find out the correct statement from the below?

a) FM demodulator followed by integrator serves as PM demodulator, when m(t) has no discontinuities

b) FM demodulator followed by differentiator serves as PM demodulator, when m(t) has no discontinuities

c) differentiator followed by FM demodulator serves as PM demodulator, when m(t) has no discontinuities

d) None

Answer: [A] FM demodulator followed by integrator serves as PM demodulator, when m(t) has no discontinuities

9)The purpose of having Band pass Limiter at the receiver is?

a) To Limit the phase variations

b) To Limit the frequency variations.

c) ) To Limit the amplitude variations produced due to channel

d) None

Answer: [C] To Limit the amplitude variations produced due to channel

10) How can we realize a differentiator at the receiver of Angle modulated signal?

a) Using a simple time delay

b) Using a band pass filter

c) Both a & b

d) None

Answer: [C] Both a & b