Digital Communication - Study Mode

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[#106] Which of the following pulse modulation are digital? 1. PCM 2. Differential PCM 3. PWM Select the correct answer using the options given below:

(A) 1 and 2 only

(B) 2 and 3 only

(C) 1 and 3 only

(D) 1, 2 and 3

Correct Answer

(A) 1 and 2 only

[#107] The Nyquist sampling rate for the signal $$sleft( t
ight) = frac{{sin left( {500pi t}
ight)}}{{pi t}} imes frac{{sin left( {700pi t}
ight)}}{{pi t}}$$ xa0 xa0 xa0is given by

(A) 400 Hz

(B) 600 Hz

(C) 1200 Hz

(D) 1400 Hz

Correct Answer

(C) 1200 Hz

[#108] The granular noise can be reduced by

(A) Increasing the step size

(B) Increasing input signal amplitude

(C) Reducing the step size

(D) Reducing input signal amplitude

Correct Answer

(C) Reducing the step size

[#109] Match List-I with List-II and select the correct answer as per the options: List-I List-II a. RF band is divided into small frequency bands 1. TDMA b. Store and forward system 2. FDMA c. Spread spectrum multiple access 3. Navigation technique d. Dead reckoning 4. CDMA

(A) a-1, b-2, c-3, d-4

(B) a-2, b-4, c-3, d-1

(C) a-3, b-2, c-1, d-4

(D) a-2, b-1, c-4, d-3

Correct Answer

(D) a-2, b-1, c-4, d-3

[#110] In a band limited channel higher bit rate can be transmitted with

(A) BPSK

(B) QPSK

(C) FM

(D) FSK

Correct Answer

(B) QPSK