# Multiple Choice Questions and Answers on Phase Modulation

#### Q.1. In PM  the information is transmitted using _______ .

a. Change in frequency

b. Change in amplitude

c. Change in phase of the carrier

Ans. (c) Change in phase of the carrier

#### Q.2. With change in modulating frequency (fm), the modulation index  mp of a phase modulated signal will ______.

a. increase

b. decrease

c. remain constant

Ans. (c) remain constant

#### Q.3. FM can be generated using PM by _______ .

a. Passing the modulating signal through a low pass filter

b. Passing the modulating signal through a high pass filter

c. Using the pre-emphasis

d. Using the de-emphasis

Ans. (a) Passing the modulating signal through a low pass filter

#### Q.4. Noise immunity of PM is _______.

a. Better than AM and FM

b. Worse than AM and FM

C. Better than AM but worse than FM

Ans. (c) Better than AM but worse than FM

Ans. False

#### Q.6. The frequency deviation in PM is proportional to ________.

a. Modulating voltage

b. Modulating frequency

c. Modulating frequency and voltage

Ans. (c) Modulating frequency and voltage

#### Q.7. Amplitude of PM wave ______

a. remain constant

b. change in proportion with the modulating voltage

c. change in proportion with the modulating frequency

Ans. (a) remain constant

#### Q.8. The equation for the modulated PM wave is given by

a. 5 sin (2 π × 10t )

b. 5 sin 1000 t + 5 sin 10t

c. 5 sin ( 2 π × 10t + 10 sin 6280 t )

d. 5 sin ( 2 π × 10t – 10 sin 6280 t )

Ans. (c) 5 sin ( 2 π × 10t + 10 sin 6280 t )