Pulse Modulation MCQ

31. For a 10-bit PCM system, the signal to quantization noise ratio is 62 dB. If the number of bits increased by 2, then how would the signal quantization noise ratio change?

  1. Increase by 6 dB
  2. Decrease by 6 dB
  3. Increase by 12 dB
  4. Decrease by 12 dB
Answer
Answer. c

32. Consider the following statements about analog data-digital signal

  1. Amplifiers used in repeaters produce additive noise.
  2. FDM is used for digital signals whereas TDM is used for analog signals.
  3. With TDM there is no intermodulation noise whereas this is a concern for FDM.
  4. Conversion to digital signalling allows the use of efficient digital switching techniques

Which of these statements are correct?

  1. i and ii
  2. iii and iv
  3. i, ii and iii
  4. i, ii, iii and iv
Answer
Answer. b

33. Quantization noise occurs in

  1. Pulse amplitude modulation
  2. Pulse width modulation
  3. Pulse code modulation
  4. Pulse position modulation
Answer
Answer. c

34. To overcome slope overload problem, which type of the integrator is used in delta modulation?

  1. Fixed slope integrator
  2. Variable slope integrator
  3. Linear slope integrator
  4. Bipolar integrator
Answer
Answer. b

35. Analog data having highest harmonic at 30 kHz generated by a sensor has been digitized using 6-level PCM. What will be the rate of digital signal generated?

  1. 120 kbps
  2. 200 kbps
  3. 240 kbps
  4. 180 kbps
Answer
Answer. d

36. Which one of the following statement is correct?

Quantising noise is produced in

  1. all pulse modulation systems
  2. PCM
  3. all modulation systems
  4. FDM
Answer
Answer. b

37. Which one of the following statement is correct?

In TDM, non-essential frequency components of the modulating signal are removed by

  1. sampler
  2. attenuator
  3. pre-alias filter
  4. modulator
Answer
Answer. c

38. Which one of the following multiplexing techniques involves signals composed of light beams?

  1. FDM
  2. CDM
  3. WDM
  4. TDM
Answer
Answer. c

39. One disadvantage of adaptive delta modulation over linear delta modulation is that it

  1. requires more bandwidth
  2. is more vulnerable to channel errors
  3. requires a large number of comparators in the encoder
  4. is not suitable for signals with periodic components
Answer
Answer. c

40. The performance of the DPCM-Coder improves as the

  1. input probability density becomes more and more Gaussian
  2. input power spectral density tends to be white
  3. input dynamic range increases
  4. sample-to-sample correlation of the input increases
Answer
Answer. d

41. The maximum number of quantized amplitude levels, in a 3-digit ternary PCM system can be used to represent is

  1. 9
  2. 8
  3. 81
  4. 27
Answer
Answer. b

42. A 4GHz carrier is amplitude-modulated by a low-pass signal of the maximum cut off frequency 1 MHz. If this signal is to be ideally sampled, the minimum sampling frequency should be nearly

  1. 4 GHz
  2. 4 MHz
  3. 8 GHz
  4. 8 MHz
Answer
Answer. b

43. “Slope overload” occurs in delta modulation when the

  1. frequency of the clock pulses is too low
  2. rate of change of analog waveform is too large
  3. step size is too small
  4. analog signal varies very slowly with time
Answer
Answer. b

44. Time-division multiplexing is used when the data to be transmitted is

  1. slow-changing
  2. of small bandwidth
  3. slow-changing and has a small bandwidth
  4. fast-changing and has a wide bandwidth
Answer
Answer. c
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