1.Which of the following modulation techniques comes under angle modulation?

1.Which of the following modulation techniques comes under angle modulation?

A. Amplitude modulation

B. Frequency modulation

C. Phase modulation

D. Both b and c

2.When the modulating signal amplitude is zero, the FM signal frequency will be __________.

A. equal to zero

B. at maximum deviation

C. at minimum deviation

D. same as carrier frequency

3.In FM, how many pairs of sidebands are produced with the modulation index of 3? 

A. 6

B. 12

C. 7

D. 14

4.In standard FM broadcasting maximum allowed deviation is __________.

A. 10kHz

B. 50kHz

C. 75kHz

D. 200kHz

5.Pre-emphasis and de-emphasis circuits are ___________ and ___________ filters.

A. Low pass, High pass

B. High pass, Low pass

C. Low pass, band pass

D. High pass, band stop

6.As the voltage across a reverse biased varactor diode increases, the capacitance value _______.

A. increases

B. decreases

C. remain constant

D. will be zero

7.Which one of the following circuit output frequency can be controlled by external voltage?

A. Frequency multipliers

B. PLL

C. VCO

D. Schmitt trigger

8.The range of frequencies over which a PLL can track the input signal and remain locked is called as _________.

A. free running frequency

B. bandwidth

C. capture range

D. lock range

9.The purpose of buffer amplifier in a transmitter is to __________

A. prevent overloading

B. amplify the incoming signal

C. provide isolation from the remaining stages

D. both a and c

10.Which of the following oscillators produces very stable oscillations?

A. Local oscillator

B. Crystal oscillator

C. Frequency oscillators

D. Frequency synthesizers