Communication Systems

Exercise: Communication Systems

The power to the base unit of a cordless telephone is supplied by

battery

AC mains

both battery and AC mains

either battery or AC mains

Answer: B

Base unit is fed from ac mains and portable unit from battery.

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CCIR system B employs

625 lines

625 lines with 2 : 1 interlace

625 lines with 4 : 1 interlace

500 lines with 2 : 1 interlace

Answer: B

625 lines divided into odd and even fields, i.e., 2 : 1 interlace.

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The material used for the magnet of moving coil cone type loudspeaker is

steel alloy

soft iron

hard steel

Alnico

Answer: D

Alnico produces a strong magnetic field.

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An S/N ratio of 3 expressed in db is

4.8 dB

2.4 dB

0.48 dB

0.24 dB

Answer: A

10 log₁₀ 3 = 4.8 .

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Assertion (A): For satellites and space probes, PRF of a radar is pretty low.

Reason (R): PRF of a radar depends on the range of a radar.

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: B

PRF means Pulse Repetition Frequency.

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