TM 55-1510-219-MTF
PROCEDURE TROUBLESHOOTING REFERENCE
F.
AVIONICS FLIGHT CHECKS (CONT)
d.
Establish communications with a ground station at least
150 miles distant on at least three frequencies (one each
from the lower, middle, and upper frequency ranges).
Establish two-way communications on AM and, when
possible, on USB. Obtain signal quality reports from the
other station and note received signal quality.
NOTE
The intelligibility of SSB voice operations becomes
degraded when the receiver and transmitter differ in
frequency by a small amount (approximately 50 Hz).
The voice pitch will sound either too high or too low.
The cause may be either the receiver or transmitter.
e. Frequency accuracy - Check as follows:
(1)
Station WWV - Select the frequency that provides the
best signal. The station broadcasts on 2. 5000,
5.0000, 15.0000, 20.0000, and 25.0000 MHz. The
higher the frequency selected, the more accurate the
frequency check will be.
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