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ECE Objective Questions { Digital Communication System }



43. Which of the following pulse modulating system is analog?
A. PCM
B. PWM
C. Both (a) and (b) above
D. None of the above

44. For transmission of normal speech signal, the PCM channel needs a bandwidth of
A. 64 kHz
B. 8 kHz
C. 4 kHz
D. 2 kHz

45. Which of the following system is digital?
A. PPM
B.PCM
C. PFM
D. PWM

46. In sampling theorem the Nyquist interval is given by
A. T = ?fm
B. T = It
C. T =
D. T = ?Tcf

47. Which of the following statement is true?
A. Pulse modulation has low power efficiency and narrow bandwidth
B. The PAM system has the best signal to noise ratio
C. Blocked-grid keying is similar to frequency-shift keying
D. None of the above

48. Which one of the following communication system is digital?
A. FM
B. AM
C.PCM
D. PAM

49. Quantizing noise occurs in
A. time-division-multiplexing
B. PCM
C. PPM
D. frequency-division-multiplexing

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