c. unaffected by line loss.
d. reinforced by the other echoes.
9. Assume that a long-distance telephone network uses echo suppressors.
An
echo will not be heard by the talker as long as he speaks because the
a. send channel controls the send gate.
b. send channel controls the receive gate.
c. receive channel controls the send gate.
d. receive channel controls the receive gate.
10. Assume that echo suppressors are not usable in a long-distance telephone
network passing data signals.
One effective method for passing the traffic
without developing echoes is to use
a. hybrid coils.
c. four-wire trunks.
b. two-wire trunks.
d. repeating amplifiers.
11. Host telephones are designed to transmit the bandwidth from approximately
200 to 3,200 Hz because
a. compandors work most effectively in this range.
b. noise and crosstalk have the least effect in this range.
c. all the vocal tones in a human voice are included in this range.
d. most of the energy of speech signals is concentrated in this range.
12. The overall action of a compressor during telephone transmission is to
a. attenuate weak and strong signals equally.
b. raise the power level of both weak and strong signals equally.
c. raise the power level of weak signals and attenuate strong signals.
d. attenuate the weak signals and raise the power level of strong signals.
13. A compandor is useful in improving the signal-to-noise ratio in
a
telephone communication system. It is called a remedial device because it
a. gives relief from the effects of noise on weak signals.
b. eliminates any noise and crosstalk from the incoming signal.
c. filters out the noise above and below the voice-frequency range.
d. shifts the frequency of voice components which lie beyond the voice
frequency range.
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