Exercise: Communication Systems

Questions for: Communication Systems

The output resistance of a microphone is 20 ohms. It is to feed a line of impedance 320 ohms. To ensure maximum power transfer, the turn ratio of transformer is
A:
16
B:
256
C:
2
D:
4
Answer: D

(20)(4)2 = 320 ohms.

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The function of blend control in stereo system is
A:
to dilute left channel
B:
to dilute right channel
C:
to dilute any of the channels
D:
none of the above
Answer: C

Dilution of the effect of any channel to give balanced output from left and right channels is called blind control.

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The number of channels available in MF band (300 kHz - 3 MHz) for AM modulating signal of 20 kHz is
A:
70
B:
67
C:
100
D:
150
Answer: B

In MF band, frequency space available

= 3000 - 300 2700 kHz

when AM is used Bandwidth of each channel.

= 2 x 20 kHz = 40 kHz

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The generally used value of EHV supply in TV receivers is
A:
1 kV per diagonal cm
B:
1 kV per diagonal inch
C:
0.5 kV per diagonal cm
D:
0, 5 kV per diagonal inch
Answer: B

It is 1 kV per diagonal inch.

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In ionosphere incidence angle is 60°. The maximum usable frequency fm is equal to
A:
2fc
B:
fc
C:
0.5 fc
D:
3 fc
Answer: A

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