Communication Systems MCQ Questions & Answers

51

Consider the frequency modulated signal 10cos[2π × 10^t + 5sin(2π + 1500t) + 7.5sin(2π × 1000t)] with carrier frequency of 10⁵ Hz. The modulation index is

A) 12.5 B) 10 C) 7.5 D) 5

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Answer & Solution

Answer: Option B

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52

For a frequency-modulated signal, the modulation index is doubled. The average power of the modulated signal is

A) quadrupled B) doubled C) unaltered D) none of these

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Answer & Solution

Answer: Option C

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53

Let U and V be two independent zero mean Gaussian random variables of variances $$\frac{1}{4}$$ and $$\frac{1}{9}$$ respectively. The probability P(3V ≥ 2U) is

A) $$\frac{4}{9}$$ B) $$\frac{1}{2}$$ C) $$\frac{2}{3}$$ D) $$\frac{5}{9}$$

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Answer & Solution

Answer: Option B

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54

For an angle modulated signal, x(t) = 6cos[2π × 10⁶ t + 2sin(8000πt) + 4cos(8000πt)]V.
The average power of x(t) is

A) 10 W B) 18 W C) 20 W D) 28 W

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Answer & Solution

Answer: Option B

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55

A random process is called ergodic process if-

A) Ensemble average is half of the time average B) Time average is half of the ensemble average C) Time average is equal to ensemble average D) Time average is more than ensemble average

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Answer & Solution

Answer: Option C

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56

In case of double side band side AM, power contained in upper side band is

A) $$\frac{{E_c^2}}{{2R}}$$ B) $$\frac{{{m^2}E_c^2}}{{4R}}$$ C) $$\frac{{E_c^2\left( {1 + \frac{{{m^2}}}{2}} \right)}}{R}$$ D) $$\frac{{{m^2}E_c^2}}{{8R}}$$

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Answer & Solution

Answer: Option D

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57

What is the total power carried by sidebands of the AM wave (DSB) for tone modulation for µ = 0.4?

A) 7.4% B) 11.11% C) 4.3% D) 8.3%

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Answer & Solution

Answer: Option A

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58

Mean of two batsmen A and B are $${\overline X _A} = 48$$ and $${\overline X _B} = 46.$$ Their coefficient of variation are 0.37 and 0.26 respectively. Then which of the following is correct?

A) A is better scorer and more consistent than B B) B is better scorer and more consistent than A C) B is better scorer and less consistent than A D) A is better scorer and B is more consistent than A

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Answer & Solution

Answer: Option A

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59

A signal with two frequency components at 6 kHz and 12 kHz, is sampled at the rate of 16 kHz and then passed through a Low Pass filter having a cut-off frequency of 16 kHz. The output signal of the filter

A) Is an undistorted version of the original signal B) Contains the 6 kHz component and a spurious component of 4 kHz C) Contains only the 6 kHz components D) Contains both the components of the original signal and two spurious components of 4 kHz and 10 kHz

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Answer & Solution

Answer: Option D

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60

Light is good for telecommunications because it is:

A) a high-frequency carrier B) not modulated C) a very low-frequency carrier D) a low-frequency carrier

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Answer & Solution

Answer: Option A

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Communication Systems MCQ Questions & Answers | ECE