Envelope-delay-distortion parameters (after equalization) are the most
important values to the circuit conditioner.
Relative delays prior to
equalization are important values in determining whether equalization is
necessary.
(7) Calibration and adjustment of controls.
The calibration
procedure necessary to prepare the TS-2669/GCM for use is too extensive to
include here. The technician must refer to the instruction manual for this
information.
Only those controls essential for performing the envelope-
delay-distortion test will be included here. Frequency calibration of the
two sets should be compared before starting the test.
(a) On the transmitting TS-2669/GCM, set the MODULATION FREQUENCY
HZ switch to the 83-1/3 position and the SWEEP/CARRIER/REFERENCE switch on
CARRIER. Adjust the CARRIER/FREQUENCY control to the first test frequency
as indicated on the FREQUENCY readout. Place the REF RETURN switch on the
END-TO-END position.
(b) With the receive signal patched to the BAL RECEIVE jack at the
receiving end of the circuit, adjust the RECEIVE LEVEL control for the
expected input level specified in the Telecommunications Service Order
(TSO). The receiving operator reads the level on the DBM scale of the level
meter, and the delay on the DELAY meter. He calls the values over the order
wire to the transmitting operator who controls the test in the sending
direction. The transmitting operator enters all values on the form.
(c) The receiving operator continues calling off the delay
readings at frequencies indicated on the envelope-delay data sheet (figure
2-2). The transmitting operator calculates the delay values (relative delay
before equalization, envelope delay after equalization).
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