Digital Communication - Study Mode

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[#176] 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

Correct Answer

(B) takes care of different sampling rates

[#177] The spectral efficiency and bandwidth of BPSK are . . . . . . . . and . . . . . . . . respectively.

(A) 0.5 b/s/Hz, 2f b

(B) 1 b/s/Hz, f b

(C) 2 b/s/Hz, f b

(D) 1 b/s/Hz, 2f b

Correct Answer

(A) 0.5 b/s/Hz, 2f b

[#178] 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

Correct Answer

(D) M/8 kHz

[#179] 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 $$frac{{ ext{m}}}{2}$$

(C) equal to 2 m

(D) greater than m

Correct Answer

(B) less than $$frac{{ ext{m}}}{2}$$

[#180] A 4 GHz carrier is DSB-SC modulated by a low pass message signal with maximum frequency of 2 MHz. The resultant signal is to be ideally sampled. The minimum frequency of the sampling impulse train should be

(A) 4 MHz

(B) 8 MHz

(C) 8 GHz

(D) 8.004 GHz

Correct Answer

(B) 8 MHz