14. An FM transmitter has a deviation of 20 kHz, and a modulation index of 20
when modulated by a 1-kHz rectangular wave. If the transmitter is to have the same
bandwidth when modulated by a 1-kHz triangular wave, it must have a deviation of 3
kHz and a modulation index of
a. 0.3.
c.
3.0.
b. 1.5.
d.
20.
15. When a given FM transmitter is modulated by a 1.5-kHz sine wave, the
If the
transmitter is modulated by a rectangular pulse having a pulse repetition rate of
1.5 kHz and the frequency deviation is held at 7.5 kHz, the modulation index
remains at 5 and the effective bandwidth will be
a. 24 kHz.
c.
60 kHz.
b. 48 kHz.
d.
75 kHz.
16. Assume that the preemphasis network in A of figure 1-2 is altered to have a
time constant of 75 microseconds.
The deemphasis circuit to be used in the
receiver is shown in B of figure 1-2.
The value of capacitance used in this
circuit should be
a. 0.0015 microfarad.
b. 0.0020 microfarad.
c. 0.0100 microfarad.
d. 0.0375 microfarad.
Figure 1-2.
Preemphasis and deemphasis circuits.
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