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Electronics and Communication Engineering - Communication Systems

Exercise : Communication Systems - Section 2
11.
If the oscillator output is modulated by audio frequencies upto 10 kHz, the frequency range occupied by the side bands will be
711.9 kHz to 712.1 kHz
702 kHz to 722 kHz
692 kHz to 732 kHz
71.2 kHz to 71.20 kHz
Answer: Option
Explanation:

L = 50 mH, C = ln F

.

12.
The power to the portable unit of a cordless telephone is provided by
pencil cells
dry cells
rechargeable cells
AC mains
Answer: Option
Explanation:

Rechargeable cells feed the portable unit.

13.
In a AM wave the carrier and one of the side bands is suppressed. If m = 0.5, the percentage saving in power is
50%
83.3%
94.4%
100%
Answer: Option
Explanation:

.

14.
Computer communication networks have
star configuration
tree configuration
loop/mesh configuration
All of the above
Answer: Option
Explanation:

All the three configurations are used.

15.

Assertion (A): A balun is an RF impedance matching transformer.

Reason (R): Sometimes a booster amplifier is used with a TV set.

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:

Balun gives a 4 : 1 impedance transformation. In areas where TV reception is poor, booster is used to strengthen a TV signal.

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