A Best Way To Crack Gorenment Job Exams

ECE Objective Questions { Digital Communication System }

64. Companding is used
A. to overcome quantizing noise in PCM
B. in PCM transmitters, to allow amplitude limiting in the receivers
C. to protect small signals in PCM from quantizing distortion
D. In PCM receiver, to overcome impulse noise.

65. Which one of the following system is analog
B. delta
C. differential PCM

66. If the sampling time is less than the Nyquist interval
A. simpler filters can be used to obtain the original signal
B. bandwidth increases
C. channel capacity increases
D. guard time becomes less

67. A signal of maximum frequency of 10 kHz is sampled at Nyquist rate. The time interval between two successive samples is
A. 50 ns
B. 100 gs
C. 1000 is
D. 5 is

68. A narrowband signal occupying a frequency range of nfo to (n + 1) fo is to be sampled. The maximum sampling rate is (Taken to be an integer)
A. 2nfo
B. 2(n + 1)f0
C. 2f0
D. None of the above

69. The minimum required bandwidth for transmission of n signals, each band-limited to fm Hz, is
A. fm Hz
B.2fm Hz
C.mfm Hz
D. 2nfm Hz

70. TDM is preferred because
A. it requiresless power
B. it needs lesser bandwidth
C. more than noe messages can be transmitted simultaneously over a common channel
D. none of these

Page 10 of 37

« 8 9  10  1112 »