Communication Systems MCQ Questions & Answers

81

The signal power and noise power are denoted by S and N respectively. If the signal power increases to 3S and the noise power reduces by half, the ratio of old SNR to the new SNR is given by . . . . . . . .

A) 6 B) $$\frac{2}{3}$$ C) 1.5 D) $$\frac{1}{6}$$

Discuss

Answer & Solution

Answer: Option D

No explanation is given for this question. Let's Discuss on Board

82

In PLL, the range of input frequency for which the initially unlocked loop will lock on an input signal is known as

A) Cut-off range B) Lock range C) Capture range D) Space range

Discuss

Answer & Solution

Answer: Option C

No explanation is given for this question. Let's Discuss on Board

83

In a super heterodyne receiver, which stage produces IF signal?

A) Grand condenser B) RF amplifier C) Mixer D) None of these

Discuss

Answer & Solution

Answer: Option C

No explanation is given for this question. Let's Discuss on Board

84

The . . . . . . . . function gives a quantitative measure of the closeners or similarity between samples of a speech signal as a function of their time separation.

A) Probability density B) Power spectral density C) Auto correlation D) All the above

Discuss

Answer & Solution

Answer: Option C

No explanation is given for this question. Let's Discuss on Board

85

The saving in power in a DSB-SC system modulated at 80% is

A) Nil B) 80% C) 75.76% D) 50%

Discuss

Answer & Solution

Answer: Option C

No explanation is given for this question. Let's Discuss on Board

86

If m_t is modulation index of FM. What is the value of ratio $$\frac{{{{\left( {\frac{{\text{S}}}{{\text{N}}}} \right)}_{{\text{WBFM}}}}}}{{{{\left( {\frac{{\text{S}}}{{\text{N}}}} \right)}_{{\text{AM}}}}}}$$ for 100% amplitude modulation with identical total transmitted power?

A) $$\frac{9}{2}{\text{m}}_{\text{f}}^2$$ B) $$\frac{3}{2}{\text{m}}_{\text{f}}^2$$ C) $$\frac{3}{2}{\text{m}}_{\text{f}}^3$$ D) $$\frac{9}{2}{\text{m}}_{\text{f}}^3$$

Discuss

Answer & Solution

Answer: Option A

No explanation is given for this question. Let's Discuss on Board

87

Which is not true about frequency deviation in PM

A) ∆f decreases with f_m increasing B) ∆f independent of f_m C) ∆f increases with f_m increasing D) ∆f increases with f_m decreasing

Discuss

Answer & Solution

Answer: Option C

No explanation is given for this question. Let's Discuss on Board

88

An amplitude modulated amplifier has a radio frequency output of 50 W at 100% modulation. The internal loss in the modulator is 10 W. The unmodulated carrier power is

A) 40 W B) 50 W C) 60 W D) 80 W

Discuss

Answer & Solution

Answer: Option A

No explanation is given for this question. Let's Discuss on Board

89

What is the assigned bandwidth of each of the channels in the AM broadcast band?

A) 5 kHz B) 15 kHz C) 10 kHz D) 200 kHz

Discuss

Answer & Solution

Answer: Option C

No explanation is given for this question. Let's Discuss on Board

90

A carrier wave is phase modulated with frequency deviation of 20 kHz by a single tone frequency of 2 kHz. If the single tone frequency is increased to 2 kHz, assuming that phase deviation remains unchanged, bandwidth of the PM signal is

A) 20 kHz B) 32 kHz C) 22 kHz D) 44 kHz

Discuss

Answer & Solution

Answer: Option D

No explanation is given for this question. Let's Discuss on Board

Communication Systems MCQ Questions & Answers | ECE