AUTOMATIC SYNCHRONIZATION PROCEDURE

TM 11-5820-917-13

(3) The AUTO SYNC switch-indicator stops flashing and remains lit when

internal criteria for probable signal acquisition are met. If no signal acquisition

occurs, the AUTO SYNC feature terminates just before the upper frequency limit is

reached.

(4) Verify that proper signal acquisition and synchronization has occurred

by listening for an audio tone from the speaker and looking for a Chirpsounder record

to appear on the CRT. Make sure to select CRT display path number that is the same

as path being synchronized.

(5) If no tone is heard and no Chirpsounder record is displayed, the signal

acquisition circuit has been falsely triggered. After a false sync the path clock may

have to be reset. Check the receiver clock timing relative to reference and correct

if necessary. Refer to paragraph 3-12 h. If the clock timing is correct, the auto sync

process can be restarted by pressing the AUTO SYNC button again. The auto sync

process can be repeated (or restarted) as many times as necessary to achieve synchro-

nization as long as the receiver path clock timing is correct, and the receiver is making

a programmed sweep for the path to be synchronized when the AUTO SYNC button is

pushed. On rare occasions, the AUTO SYNC circuit will be falsely triggered repeated-

ly in the same frequency range by the presence of a large number of interference

signals. To avoid this situation, try turning the INPUT ATTEN to 10 dB .

(6) When signal acquisition ocurs, the Chirpsounder record may be moved to

the desired position on the CRT screen bv setting the MANUAL SYNC-SLIP RATE

switch to the 1 millisecond per second position and pushing the ADV/RET switch to

move the display up or down. (Refer to paragraph 3-18 g).

NOTE

The Chirpsounder record obtained immediately after auto synchronization

will not be registered correctly with the frequency calibration on the CRT.

Do not use this first record for frequency management data. The next

complete Chirpsounder record will be registered correctly.

(7) Occasionally the AUTO SYNC circuit will lock onto the chirp signal and the

chirp tone will be heard in the receiver audio, but no traces will be visible on the

CRT display. When this happens the signal traces are just above the top of the CRT

display area and can be brought back down on screen as follows:

(a) Set Controls:

Mode = SET (of path synchronized)

SLIP RATE = 1 ms/sec

CRT DISPLAY = Path being synchronized

(b) Listen for chirp audio tone and depress MANUAL SYNC toggle to RETard

while watching CRT.

top of the CRT.

3-16