MANUAL SYNCHRONIZATION PROCEDURE

TM 11-5820-917-13

(d) Release RETard switch when traces are approximately centered or slightly

below center of CRT. Audio tones should be approximately 1000 Hz in pitch.

(8) Place MODE switch in PROG position.

MANUAL

SYNCHRONIZATION

PROCEDURE

a. Perform all steps (1 thru 6) of paragraph 3-17 a above, and then place the

MODE switch in the SET position corresponding to the path to be synchronized.

b. Place MANUAL SYNC-SLIP RATE switch in the 50 millisecond per second

position. Adjust AUDIO GAIN to hear signal when acquired.

c. Search for the transmitted signal by pushing ADV/RET (advance-retard)

switch to ADV position for 20 seconds, then RET position for 40 seconds, then

alternate to ADV and RET positions for 40 seconds each until signal is acquired.

NOTE

At the 50 millisecond per second slip rate, the procedure of step c causes

the receiver sweep timing to advance and retard over a plus or minus 1-

second window relative to the original start time. The original start

position is reached by holding the last sweep advance or retard action for

20 seconds. If the receiver operator is convinced his start time is matched

to the transmitter start time within a smaller window, he may reduce the

time he holds the ADV/RET switch in each position. In any event, interrup-

tion of the advance/retard routine may cause loss of the original start point.

If this occurs, recovery is best achieved by checking the clock timing and

repeating step c at the start of the next sweep.

d. While advancing or retarding the receiver sweep, listen carefully for any

chirp tone sliding in pitch, as opposed to the popping sounds making up the back-

ground noise. The received chirpsounder signal is in the receiver passband 100-200

milliseconds (depending on the sweep rate) 20 times longer than any background inter-

ference.

When any chirp tone is heard, immediately release the ADV/RET switch.

f. If the switch is released quickly enough in step e, the tone should remain

audible. If not, rotate MANUAL SYNC-SLIP RATE switch to the 10 position and

continue the search by pressing the ADV/RET switch to the opposite position from

that last used in the 50 position. Hold the switch for 5 seconds, then alternate

advance and retard actions for 10 second periods until the chirp tone is acquired,

or until the operator is convinced that a legitimate chirp tone was not heard. If no

tone is heard, hold last switch position for 5 seconds to return timing to original

point; then return MANUAL SYNC-SLIP RATE switch to 50 and pick up search where

it was interrupted at step e above.

g. When the tone remains in audio passband, the transmitter signal is acquired.

Rotate MANUAL SYNC-SLIP RATE switch to 1 position. Momentarily place ADV/RET

switch in ADV position. The pitch of the tone should increase, and the Chirpsounder