Angle Modulation MCQ

31. Which one of the following statements is correct?

One hundred percent modulation of the carrier for the broadcast FM radio band is achieved when

  1. carrier frequency changes by ± 100%
  2. carrier-envelope changes by ± 100%
  3. carrier frequency changes by ± 75 kHz
  4. audio frequency changes by ± 15 kHz
Answer
Answer. c

32. In TV transmission, the modulation schemes for Video and Audio are, respectively

  1. FM and AM
  2. FM and FM
  3. AM and FM
  4. AM and AM
Answer
Answer. c

33. An FM wave uses a 2-5 V, 500 Hz modulating frequency and has a modulation index of 50. The deviation is

  1. 500 Hz
  2. 100 Hz
  3. 1250 Hz
  4. 25000 Hz
Answer
Answer. d

34. Let x(t) = 5 cos (50t + Sin 5t). Its instantaneous frequency (in rad/s) at t = 0 has the value

  1. 5
  2. 50
  3. 55
  4. 250
Answer
Answer. c

35. The waveform A cos(ω1t+ k cosω2t) is

  1. amplitude modulated
  2. frequency modulated
  3. phase-modulated
  4. frequency as well as phase-modulated
Answer
Answer. d

36. In the frequency modulation if fm is modulating frequency, Δf is maximum frequency deviation and B is bandwidth, then

  1. B = Δf – fm
  2. B = Δf + fm
  3. B= 2(Δf – fm)
  4. B=2(Δf + fm)
Answer
Answer. d
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