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 (f_m), the modulation index  m_p 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

Q.5. State true or false – PM is used in the broadcasting application

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 × 10⁶ t )

b. 5 sin 1000 t + 5 sin 10⁶ t

c. 5 sin ( 2 π × 10⁶ t + 10 sin 6280 t )

d. 5 sin ( 2 π × 10⁶ t – 10 sin 6280 t )

Ans. (c) 5 sin ( 2 π × 10⁶ t + 10 sin 6280 t )