(4) Output impedance of 600 to 900 ohms,
a. Scope of Testing. Test procedures in this chapter
(5) Input of level meter is 600 or 900 ohms.
cover station to station (quality control) and in-station
c. Envelope Delay Test Set. The envelope delay test
(maintenance) testing. However, testing at a particular
set consists of a transmitter and receiver. It measures
facility should not be limited to the testing described
signal delay and amplitude versus frequency. It has
by this chapter nor should all facilities necessarily
the following performance characteristics:
perform all the tests described in this chapter. The
(1) Carrier frequency adjustable from 200 Hz to
number and types of tests performed at a specific tech-
nical control facility depends on the type of service
(2) Modulation frequencies of 25, 83 1/3, and 250
provided by the facility and on the technical services
schedule for that facility. The tests in this chapter are
(3) Amplitude accuracy of ± 0.5 db.
primarily intended for checking multiplex voice-chan-
(4) Delay accuracy of ±25 microseconds at 25 Hz
nel breakout to multiplex voice-channel breakout links
or ± 2 microseconds at 250 Hz modulation.
with single or multiple hop paths.
d. Frequency Counter. The frequency counter has a
b. Quality Control Tests. Quality control or station
range of 200 to 4000 Hz and a sensitivity of 100 milli-
to station tests should be performed regularly as speci-
volts. It has an accuracy of ± 1 count.
fied in chapter 4. These tests are used for evaluation of
e. Frequency Selective Voltmeter. The frequency
the performance of a circuit and in end-to-end circuit
selective voltmeter operates in the range of 5 to 1600
KHz with an accuracy of 0.5 db. It is sensitive from
c. Maintenance Tests. Maintenance or in-station
-90 to +30 dbm and has two bandwidths (250 or
tests should be performed prior to putting a circuit
into operation if the circuit has just been built or re-
f. Impulse Noise Counter. The impulse noise count-
paired. They are also used in troubleshooting station
er has three adjustable ranges and is capable of count-
ing impulses above the three adjusted levels. It is
6-2. Description of Test Equipment
equipped with a timer and a storage capacity of at
The test equipment described below is required to
least four digits while counting up to 10 counts per sec-
perform the tests specified by this chapter. The
descriptions given are of a general nature since the
g. Oscilloscope. The oscilloscope may be either a
test equipment at each facility varies with the func-
single or a dual trace with a minimum rise time of 10
tions of that facility and the services it provides.
microseconds or less.
a. Noise Measuring Test Set. The noise measuring
h. Phase Jitter Meter. The phase jitter meter meas-
test set is used to measure noise and signal levels to
ures the phase jitter of a single frequency signal. It has
-85 dbm. It has a frequency range of 50 to 5000 Hz
a minimum level range of -30 to 0 dbm with a meas-
and may be balanced for either 600 or 900 ohms
uring range of at least 0 to 30 degrees peak to peak jit-
impedance. If a Universal Transmission Measuring
ter. The readout is in degrees peak to peak jitter.
System is available, it may be used in place of the noise
i. Dual-Channel Recorder. The dual-channel
measuring test set.
recorder is capable of measuring 0.1 to 500 volts with
b. Transmission Test Set. The transmission test set
a sensitivity of 0.1 volts per millimeter. The chart
speed is adjustable.
and a level meter. It has the following
j. Signal Test Set. The signal test set measures pulse
speed and percent of break. The test set also generates
(1) Minimum frequency range of 20 Hz to PO KHz
pulses used to test signaling circuits and may be used
(2) Frequency-Amplitude response of less than 0.5
as a pulse repeater or converter.
db variation over 20 Hz to 10 KHz into a matching
k. Test Set, Teletypewriter AN/GGM-15(V)1. This
test set provides a capability for measuring signals in
(3) Minimum output level range of + 5 to -30
dc teleprinter/data loops and for transmitting digital
test messages over these loops. The test set includes a