Electronics and Communication Engineering - Communication Systems

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

A. frequency adjustment
B. frequency interleaving
C. frequency changing
D. frequency amalgamation

Answer: Option B

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

A. mf
B. 3mf
C. mf/3
D. mf/9

Answer: Option B

Explanation:

Frequency multiplier increase the deviation,

.


8. 

In colour TV receiver, varactor diode is used for

A. detection
B. rectification
C. tuning
D. both (a) and (b)

Answer: Option C

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

A. 3
B. 2
C. 1
D. 4

Answer: Option A

Explanation:

Shot noise, partition noise and thermal noise.


10. 

Energy content of atmospheric noise

A. does not depend on frequency
B. decreases as frequency is increased
C. increases as frequency is increased
D. either (a) or (c) depending on the temperature

Answer: Option B

Explanation:

Atmospheric noise decreases as frequency is increased.