4.
Part of the circuit preparation for the envelope-delay-distortion test
specifies that the equalizers must be strapped out of circuits. This
procedure is necessary because equalizers
a.
cause loss of signal in the operator's order wire.
b.
generate test signals that may interfere with readings.
c.
may introduce delays that interfere with test accuracy.
d.
might be damaged by the high signal levels used in the test.
5.
The modulating frequencies used by the TS-2669/GCM in making envelope-
delay-distortion measurements are generated within the test set. The
modulation frequency most often chosen to make the test in 83-1/3 Hz
because this frequency provides the
a.
strongest of the three signals.
b.
lowest modulating frequency in the group.
c.
best compromise between accuracy and stability.
d.
most uniform modulation envelope of the three frequencies.
SITUATION
Assume that you are determining envelope-delay distortion on a
telephone line extending from station A to B.
You are the transmitting
operator at station A.
You have selected the end-to-end method, using
Envelope Delay Distortion Measuring Set TS-2669/GCM.
Preliminary circuit
tests yield the following results:
Maximum initial line delay = 2.140 ms at 500 Hz
Minimum initial line delay = 1.860 ms at 2,700 Hz
The TSO specifies parameter S3, which is illustrated
in figure 2-7.
Relative
delays
(before
or
envelope
delays
(after
equalization) are as follows:
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