Lesson 3/Learning Event 4
(8) Harmonic distortion.
(9) Phase jitter.
(10) Impulse noise hits and drop.
(11) Envelope delay.
(12) Phase hits and gain hits.
(13) Maximum change in audio frequency.
Learning Event 4: TIMS REPLACEMENT.
Even though it is possible to perform several test using the TIMS,
which may eliminate several pieces of test equipment, it is not feasible to
replace all the test equipment at the same time. In some cases it may take
several years at some facilities, therefore the remainder of this lesson
will be devoted to some of the other types of test equipments that may be in
use today in some of the technical control facilities.
Learning Event 5: TELEPHONE TEST SET AN/USM-181.
Telephone Test Set AN/USM-181, as shown in figure 4, is a self-
contained unit which can be operated from an AC source in a fixed
installation or it can be operated from internal battery in a mobile
situation with no access to AC power.
The AN/USM-181 consists of an
Oscillator, Model HP 204B, AC Voltmeter, Model HP 403B, and a Patch Panel,
Model HP 353A.
It is intended for measurement of transmission line and
system characteristics, such as attenuation, frequency response, signal
losses and gains. All three instruments are housed in an aluminum case and
response, are removable for servicing or for individual use. A common power
supply serves both the oscillator and the voltmeter.
The patch panel
requires no power for its operation.
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