AM Transmitters and Receivers MCQ

1. A scheme in which several channels are interleaved and then transmitted together is known as

  1. frequency division multiplexing
  2. time-division multiplexing
  3. a group
  4. a super group
Answer. a

2. In a radio receiver, AGC works by

  1. Turning the local oscillator
  2. Turning off the audio section in the absence of a received signal
  3. Adjusting the gain of RF and IF amplifiers
  4. Limiting the signal level using a clipper in the audio section
Answer. c

3. In a super-heterodyne receiver, the frequency of local oscillator is

  1. half that of incoming signal.
  2. slightly less than that of incoming signal
  3. higher than that of incoming signal.
  4. equal to that of incoming signal.
Answer. c

4. The type of noise reduced by limiters in FM receivers is

  1. Avalanche noise
  2. Burst noise
  3. Narrow band-pass noise
  4. Impulse noise
Answer. d

5. All types of linear modulation can be detected by

  1. Product demodulator
  2. Envelop detector
  3. Filtering
  4. Linear detector
Answer. a

6. One of the main functions of RF stage amplifier in Super Heterodyne Radio Receiver is to

  1. provide improve tracking.
  2. permit better adjacent channel rejection.
  3. increase tuning range of the receiver
  4. improve rejection of image frequency.
Answer. d

7. If the turn on and turn off energy losses in a transmitter are 51 mJ and 76.8 mJ respectively and the mean power loss is limited to 200 W, what is the maximum switching rate that can be achieved?

  1. 15649 cycles/s
  2. 156.49 cycles/s
  3. 1564.9 cycles/s
  4. 15.649 cycles/s
Answer. c

8. Which one of the following statement is correct?

The threshold effect in demodulators is

  1. Exhibited by all receivers when the input SNR is low
  2. Exhibited only by correlation receivers
  3. The rapid fall in the output SNR when input SNR falls below a particular value
  4. The exponential rise in the output SNR when input SNR is increased above a particular value
Answer. c

9. The operating point of RF amplifier in an AM receiver is normally biased in

  1. Class-B
  2. Class-A
  3. Class BC condition
  4. Class-C
Answer. d

10. When a radio receiver is tuned to 555 kHz, its local oscillator provides the mixer with input at 1010 kHz. At the output, another signal is also received along with the desired signal. What is the frequency of the other station?

  1. 355 kHz
  2. 910 kHz
  3. 1465 kHz
  4. 455 kHz
Answer. c