well as an envelope-delay characteristic curve from readings obtained in the
two preceding tests. This provides him with a visual aid to guide him in
(1) Adjust FREQUENCY KHZ controls so that the delay inserted by the
CN-1234A/GCC is greatest where the telephone line has the least delay. The
initial settings depend upon the maximum delay time determined by analysis
of the delay characteristic curve.
The settings are afterward varied,
(a) When maximum initial delay is 3 ms or less, the FREQUENCY KHZ
controls are adjusted to one set of values.
(b) When maximum initial delay is between 4 and 7 ms, these
controls are adjusted to a different set of values. A line having greater
than 7 ms delays should not be used for data.
(c) When maximum initial delay is
between 3 and 4 ms, these
controls are varied slightly to establish
the best set of operating
(d) Recommended FREQUENCY KHZ control setting are given below.
(2) Using the receiving TS-2669/GCM to monitor delay, increase
amount of delay in the equalizer at the midband frequencies to equal
delay at the ends of the frequency band. Remember that the basic intent
delay equalization is not to eliminate delay, but rather to minimize
variation in delay across the band of interest.
(3) Keeping the modulation rate constant,