Digital Communication - Study Mode

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[#131] Four voice signals, each limited to 4 kHz and sampled at Nyquist rate, are converted into binary PCM signal using 256 quantization levels. The bit transmission rate for the timex02division multiplexed signal will be

(A) 8 kbps

(B) 64 kbps

(C) 256 kbps

(D) 512 kbps

Correct Answer

(C) 256 kbps

[#132] A coherent binary phase-shift keyed (BPSK) transmitter operates at a bit rate of 20 Mbps. For a probability of error (P e ) of 10 -4 and given carrier-to-noise $$left( {frac{{ ext{C}}}{{ ext{N}}}}
ight)$$xa0density ratio of 8.8 dB, determine energy of bit-to-noise $$left( {frac{{{{ ext{E}}_{ ext{b}}}}}{{{{ ext{N}}_0}}}}
ight)$$xa0density ratio for a receiver bandwidth equal to the minimum double-sided Nyquist bandwidth.

(A) 23 dB

(B) 2.3 dB

(C) 8.8 dB

(D) 0.88 dB

Correct Answer

(C) 8.8 dB

[#133] In . . . . . . . . the position of a pulse relative to its unmodulated time of occurrence is varied in accordance with the message signal.

(A) PWM

(B) PCM

(C) PDM

(D) PPM

Correct Answer

(D) PPM

[#134] An analog signal has significant spectral components from 1 kHz to 5 kHz. What is the Nyquist sampling rate of this signal?

(A) 5 k samples/s

(B) 4 k samples/s

(C) 8 k samples/s

(D) 10 k samples/s

Correct Answer

(D) 10 k samples/s

[#135] In PCM if the transmission path is very long

(A) repeater stations are used

(B) pulse width may be increased

(C) pulse amplitude is increased

(D) pulse spacing is reduced

Correct Answer

(A) repeater stations are used