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Electronics and Communication Engineering - Communication Systems

Exercise : Communication Systems - Section 3
46.
In equally tampered scale, frequency of each tone equals the frequency of lower adjacent tone multiplied by
(2)1/7
(2)1/12
(2)1/6
(2)1/5
Answer: Option
Explanation:

Since these are 12 intervals in one octave, hence (2)1/12.

47.
A carrier is modulated by two modulating waves A and B having modulation indices of 0.6 and 0.8 respectively. The overall modulation index is
1
0.7
0.2
1.4
Answer: Option
Explanation:

.

48.
A communication channel disturbed by additive white, Gaussian noise has a bandwidth of 4 kHz and SNR of 15. The highest transmission rate that this channel can support (in k bits/sec) is
16
1.6
3.2
60
Answer: Option
Explanation:

Channel capacity = 4000 log2 (1 + 15) = 16000 bits/s.

49.
Which of the following microphones is used as a standard for calibration?
Moving coil
Carbon
Condenser
Ribbon
Answer: Option
Explanation:

Condenser microphone is taken as standard for calibration.

50.
The reactance of coupling capacitor for AC signals in an amplifier, should be
as low as possible
as high as possible
neither low nor high
either low or high
Answer: Option
Explanation:

XC for ac signal should be low so that the attenuation is minimum.

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