Exercise: Communication Systems

Questions for: Communication Systems

Radio broadcasts are generally
A:
amplitude modulation
B:
frequency modulation
C:
both amplitude and frequency modulation
D:
neither amplitude nor frequency modulation
Answer: B

Frequency modulation gives noise free reception and is used for radio broadcasts.

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Space wave may be a direct wave or wave reflected from earth.
A:
True
B:
False
C:
D:
Answer: B

Strength of space wave depends on distance as it suffers attenuation.

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In sound recording the degree of pre-emphasis is about 6 dB/ octave.
A:
True
B:
False
C:
D:
Answer: B

It erases the matter already existing on the tape.

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A generator is feeding power to a transmission line of characteristic impedance Z0. The line is terminated in impedance ZL. Standing waves will be set up if
A:
ZL = Z0
B:
ZL < Z0
C:
ZL > Z0
D:
both (b) and (c)
Answer: D

Both the case, i.e., ZL > Z0 and ZL < Z0 give rise to standing waves.

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Signal to noise ratio of microphone is defined as the ratio of output when the sound pressure is __________ to the output in the absence of any sound signal.
A:
0.5 Pa
B:
0.2 Pa
C:
0.1 Pa
D:
0.01 Pa
Answer: C

0.1 Pa (= 0.5 x 10-4 W/m2) is taken as standard sound pressure for defining S/N ratio of microphones.

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