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Electronics and Communication Engineering - Communication Systems

Exercise : Communication Systems - Section 4
26.
For an ideal 3000 Hz channel, Nyquist rate is
3000 bps
6000 bps
9000 bps
12000 bps
Answer: Option
Explanation:

For 3000 Hz.

Nyquist rate is twice, i.e., 6000 bps.

27.

Assertion (A): Electromagnetic waves in free space spread uniformly in all directions from a point source

Reason (R): Free space has no interference or obstacles.

Both A and R are correct and R is correct explanation of A
Both A and R are correct but R is not correct explanation of A
A is correct but R is wrong
A is wrong but R is correct
Answer: Option
Explanation:

Since free space has no interference or obstacles, EM waves spread uniformly.

28.
In the FM wave described by equation v = 15 sin (4 x 108 t + 3 sin 1100 t), the maximum frequency deviation is
175 Hz
525 Hz
3 Hz
58.33 Hz
Answer: Option
Explanation:

.

Maximum frequency deviation = 3 x 175 = 525 Hz.

29.
The radar cross-section of a target depends an
frequency
polarization of incident wave
aspect of target
all of the above
Answer: Option
Explanation:

Effective area of target is called radar cross-section.

It depends on frequency polarization of incident wave and aspect of target.

30.
The Nyquist sampling interval, for the signal sin c (700t) + sin c (5000 t) is
Answer: Option
Explanation:

g(t) = sin c (700 t) + sin c (500 t)

[sin (p 700 t) + sin (p 500 t)]

fm = 350 Hz

fs = 700 Hz, Nyquist rate = .

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