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Electronics and Communication Engineering - Communication Systems

Exercise : Communication Systems - Section 1
6.
The colour subcarrier and sidebands produced by its modulation with the chrominance signals are accommodated in the standard channel width by the process of
frequency adjustment
frequency interleaving
frequency changing
frequency amalgamation
Answer: Option
Explanation:

In frequency interleaving the space between bundles is used for colour signal.

7.
In FM signal with a modulation index mf is passed through a frequency tripler. The wave in the output of the tripler will have a modulation index of
mf
3mf
mf/3
mf/9
Answer: Option
Explanation:

Frequency multiplier increase the deviation,

.

8.
In colour TV receiver, varactor diode is used for
detection
rectification
tuning
both (a) and (b)
Answer: Option
Explanation:

In varactor diode the applied reverse bias controls the width and therefore capacitance of depletion layer.

This capacitance is used for tuning.

9.
The number of noise sources in a BJT are
3
2
1
4
Answer: Option
Explanation:

Shot noise, partition noise and thermal noise.

10.
Energy content of atmospheric noise
does not depend on frequency
decreases as frequency is increased
increases as frequency is increased
either (a) or (c) depending on the temperature
Answer: Option
Explanation:

Atmospheric noise decreases as frequency is increased.

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