A signal m1 (t) is band limited to 3.6 kHz and the three other signals m2 (t), m3 (t) and m4 (t) are band limited to 1.2 kHz each, and these signals are transmitted by means of TDM. Then, what will be the transmission bandwidth of the channel.
A. 7.2 kHz
B. 14.4 kHz
C. 3.6 kHz
D. 2.4 kHz
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The bit rate of a digital communication system is 16 Mbps. The modulation scheme is QPSK. The baud rate of the system is:
A. 16 Mbps
B. 32 Mbps
C. 48 Mbps
D. 64 Mbps
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Which one of the following can be used for the detection of the non coherent BFSK signal?
A. Matched filter
B. Phase-locked loop
C. Envelope detector
D. Product demodulator
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The anti-aliasing filter has a higher cut-off frequency fm . Its output is sampled periodically every Ts seconds. For proper recovery of the signal at the receiver, Ts must be
A. T s ⩾ 2 f m 1
B. T s ⩽ 2 f m 1
C. T s ⩾ f m 2
D. T s ⩽ f m 2
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For QPSK
A. Error rate is lower than 16 MPSK
B. Error rate is higher than QASK
C. Signals are in time Quadrature
D. More-inter symbols interference compared to MSK
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In 512 QAM, the number of signal vectors of the signal constellation is:
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In a certain '12 channel TDM' system, it is found that channel number 3 and channel number 8 are connected to the same input signal. The technique
A. wastes the channel capacity
B. takes care of different sampling rates
C. is required when different bandwidth signals are to be transmitted
D. reduces noise
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The spectral efficiency and bandwidth of BPSK are . . . . . . . . and . . . . . . . . respectively.
A. 0.5 b/s/Hz, 2fb
B. 1 b/s/Hz, fb
C. 2 b/s/Hz, fb
D. 1 b/s/Hz, 2fb
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The bit rate of digital communication system is M kbps. The modulation used is 16-QAM. The minimum bandwidth required for ideal transmission is . . . . . . . .
A. M/2 kHz
B. M/16 kHz
C. M kHz
D. M/8 kHz
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Hamming codes are used for error detection and correction. If the minimum Hamming distance is m, then the number of errors correctable is
A. equal to m
B. less than 2 m
C. equal to 2 m
D. greater than m
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From the following relative amplitude vs frequency plot, identify the type of noise which the sections A, B, C and D depict.
List-I List-II
a. Section A
1. Thermal noise
b. Section B
2. Power line pick up
c. Section C
3. Power supply (EPC) switching noise
d. Section D
4. f 1
A. a-1, b-2, c-3, d-4
B. a-2, b-1, c-4, d-3
C. a-4, b-2, c-3, d-1
D. a-3, b-4, c-2, d-1
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For an ideal 3000 Hz channel, nyquist rate is
A. 3000 bps
B. 6000 bps
C. 9000 bps
D. 12000 bps
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Which of the following is not the modulation technique
A. PCM
B. AM
C. PSK
D. None of these
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The information rate to be transmitted is 900 bits/sec, FEC is 4 3
A. 225 symbols/sec
B. 450 symbols/sec
C. 600 symbols/sec
D. 675 symbols/sec
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Flat top sampling of low pass signals
A. gives rise to aperture effect
B. implies oversampling
C. leads to aliasing
D. introducing delay distortion
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In a binary PCM system, the maximum tolerable error is sample amplitudes is 0.5% of the peak input signal amplitude. The input signal bandwidth is 5 MHz. The minimum rate of transmission of the PCM coded bits is:
A. 70 Mbits/sec
B. 80 Mbits/sec
C. 90 Mbits/sec
D. 100 Mbits/sec
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The bit rate of a digital communication system is 34 Mbit/s. The modulation scheme is QPSK. The baud rate of the system is
A. 68 Mbit/s
B. 34 Mbit/s
C. 17 Mbit/s
D. 8.5 Mbit/s
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What is the process of utilizing one data link for transmission of a group of variable known as?
A. Encoding
B. Decoding
C. Demultiplexing
D. Multiplexing
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In a single error correcting Hamming code, the number of message bits in a block is 26. The number of check bits in the block would be
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A satellite system employs QPSK modulation with 40% excess bandwidth per carrier including guard band. The voice channels use 64 kbps PCM coding. The number of channels supported by 36 MHz bandwidth of the transponder in bandwidth limited case will be
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