Exercise: Communication Systems

Questions for: Communication Systems

The minimum step size required for a Delta modulator operating at 36 samples/sec to track the signal (here u(t) is the unit step function) x(t) = 125t (u(t) - u(t - 1)) + (250 - 125t) (u(t - 1) - u(t - 2)) So that slope overload is avoided, would be
A:
2-10
B:
2-8
C:
2-6
D:
2-4
Answer: B

To avoid slope overload

|m(t)| ≥ Δ . fs or |x(t)| ≥ Δ . fs

125 ≤ Δ . 25 . 210

27 ≤ Δ . 215 Δ ≥ 2-8.

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If the ratio of ac to dc load impedance of a diode detector is low, the result will be
A:
poor AGC operation
B:
poor AF response
C:
negative peak clipping
D:
diagonal clipping
Answer: C

Negative peak will be clipped.

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The first pulse in a TV remote control is
A:
start pulse
B:
preliminary pulse
C:
either start pulse or preliminary pulse
D:
erase pulse
Answer: B

The first pulse is preliminary pulse followed by start pulse.

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Trinitron is a monochrome picture tube.
A:
True
B:
False
C:
D:
Answer: B

Frequency band for local programs is fixed.

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In a high speed modem the data rate handled is about
A:
1000 bps
B:
5000 bps
C:
20000 bps
D:
50000 bps
Answer: B

When data rate is in the range of 2400 to about 10800 bits per second, modem is designated as high speed.

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