SWEEP SYNCHRONIZATION

TM 11-5820-917-13

f. The monitored chirp sweep start time can then be determined relative to the

baseline time reference by computing the difference between the monitored frequencies

and 2 MHz, dividing that difference by the observed sweep rate, and subtracting the

resulting number of seconds from the recorded times. All observations should result

in the same start time within a one-second tolerance or additional observations are

necessary.

3-16. SWEEP SYNCHRONIZATION. The final step in synchronizing the receiver with

a transmitter is the fine adjustment of the receiver timing and sweep synchronization

to exactly match that of the transmitter. This is accomplished by using the automatic

synchronization procedure, paragraph 3-17, or by manual synchronization, paragraph

3-18.

NOTE

When the path clock start time is known relative to the PATH 1 clock or to

an external time reference, this information should be carefully noted as it

will facilitate the synchronization process should there be difficulty later.

3-17. AUTOMATIC SYNCHRONIZATION PROCEDURE. After the receiver programmer

and clocks have been set as described in paragraphs 3-12 thru 3-15, the AUTO SYNC

circuit is used to acquire and lock the receiver onto the transmitter signal.

Check the following:

(1) FREQ range switch is set to the appropriate 2-16 or 2-30 MHz position.

(2) ANTENNA SELECT thumbwheel switch is set appropriately.

(3) INPUT ATTEN is set to 0 dB, or 10 dB in high noise areas or when heavy

interference is expected.

(4) PATH PROGRAMMER switches are set correctly.

(5) Path clocks are set and running.

(6) BATT switch is ON.

b. When the next programmed sweep starts for the path to be synchronized,

perform the following:

(1) Place the MODE switch in the SET position corresponding to the path to be

synchronized.

(2) Press AUTO SYNC pushbutton to initiate automatic synchronization process.

The AUTO SYNC button should be pressed just before the sweep reaches the expected

propagating band for the path, if known. For example, if it is known that the

propagating frequencies for the path are 10 to 20 MHz, the AUTO SYNC button should

be pressed when the sweep reaches approximately 9 MHz. If the propagating band is

not known, press the AUTO SYNC button just after the sweep starts, around 2.5 MHz.

The AUTO SYNC indicator lamp flashes while synchronization is underway, and the

CRT load line indicator moves at a faster rate than the digital frequency readout

indicates.