Communication Systems - Study Mode

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[#156] A random process obeys Poisson's distribution. It is given that the mean of the process is 5. Then the variance of the process is

(A) 5

(B) 0.5

(C) 25

(D) 0

Correct Answer

(A) 5

[#157] For an AM signal, the bandwidth is 20 kHz and the highest frequency component present is 800 kHz. The carrier frequency used for this AM signal is

(A) 710 kHz

(B) 705 kHz

(C) 700 kHz

(D) 790 kHz

Correct Answer

(D) 790 kHz

[#158] Consider the following types of modulation 1. Amplitude modulation 2. Frequency modulation 3. Pulse modulation 4. Phase modulation Which of the above modulation are used for telecasting TV programmes?

(A) 3 and 4

(B) 2 and 3

(C) 1 and 2

(D) 1 and 4

Correct Answer

(C) 1 and 2

[#159] A signal with frequency f m modulates a carrier f c (where f c >> f m ), then the output of the AM-DSBSC signal will contain frequencies.

(A) 2f c , f c ± f m

(B) f c , f c ± 2f m

(C) f c ± f m

(D) f c , f c ± f m

Correct Answer

(C) f c ± f m

[#160] An FM signal with a deviation δ is passed through a mixer and has its frequency reduced five fold. The deviation in the output of the mixer is

(A) 5δ

(B) intermediate

(C) $$frac{delta }{5}$$

(D) δ

Correct Answer

(D) δ