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

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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

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

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

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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

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

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

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