SYNC-TIME MEASUREMENTS

TM 11-6625-3056-12

3-5.

SYNC-TIME MEASUREMENTS

General

To measure the length of time it takes the TD-1065 to acquire sync after an input signal is applied,

proceed as follows:

NOTE:

This test is normally not performed in the field. Erroneous results are possible with noisy signals.

Setup

At TD-1065, disconnect cable from MUX channel to be tested (1-4, 5-8, or 9-12). Under some

conditions with these cables connected, noise is introduced in the channel and is misinterpreted

by the TS-3981 as a signal. The result is a sync time reading much shorter (O to 4 ms) than the

actual sync time (5 to 20 ms).

Procedure

Set TS-3981 controls as follows:

POWER

PATTERN

LONG

OPERATION

CORRELATOR LOOP

OPEN

DATA ON/OFF

RATE SELECT

7 (32 kb/s)

DISPLAY SELECT

ERRORS

ACTIVITY indicator will be lit.

Press RESET:

Display will read 0.

If display does not stay at 0 and increases count rapidly, turn DATA ON/OFF back and forth

between ON and OFF several times. If display still increases count rapidly, polarity of DATA

OUT and/or DATA IN connectors may be reversed. Reconnect with opposite polarity and

repeat procedure.

Press SINGLE ERROR several times.

Display will advance 1 count each time SINGLE ERROR is pressed. This ensures setup is

operating properly.

Set DATA ON/OFF to OFF and DISPLAY SELECT to SYNC TIME MSEC.

Press RESET:

Display will read O.

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