Lesson 2/Learning Event 3
This applies to circuit conditioners, technical controllers, and assisting
personnel alike. This knowledge is especially important for the technical
controller because he will often be directing an operation from a distance.
He must know the capabilities, limitations, and the normal method of
operation for each item of test equipment.
b. DCA circuit specifications.
The characteristics of circuits will
normally be specified by the DCA in the form of a Telecommunication Service
Order (TSO).
These characteristics are defined in DCA publications.
A
large variety of technical information is available from the DCA. All DCS
station headquarters maintain a library of these publications. They can be
ordered through channels from the Defense Communications Agency. Inspectors
normally examine the DCA publications library in each station to assure
c. Corrective devices and information. The principal corrective device
for VF circuits is an equalizer.
Each equalizer must have an instruction
book for the circuit conditioner to use since each equalizer is individually
calibrated.
An amplifier having sufficient bandwidth for the service
specified follows each equalizer in the circuit to make up total line and
equalizer loss. Part of the equalizer is an impedance-matching transformer
that is used to match the equalizer to the circuit.
d. Location.
Circuit conditioning is always performed at the
terminating point (receiving point) of a circuit, and the receiving
termination of most interface locations. When the overall circuit consists
of several sections having differing characteristics, each subordinate
circuit must be conditioned prior to interconnecting to the next circuit.
The purpose of this procedure is to make every section compatible with the
next in as many circuit parameters as possible. It is nearly impossible to
condition an entire circuit consisting of interconnected sections at only
one receiving termination of the overall circuit.
Learning Event 3: PRECAUTIONS IN TESTING VF CIRCUITS.
When using test techniques specified for circuit conditioning, the
technician must exercise precautions so as to gain satisfactory results
while at the same time insuring the safety of equipment and personnel
involved.
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