SYNCHRONIZATION

TM 11-5820-917-13

(4) When the receiver starts showing Chirp traces on the CRT, place the

MANUAL SYNC switch either to ADV position to raise the traces on the CRT or to RET

position to lower the trace. The traces move as the receiver changes synchronization

by 1 ms for every second the ADV/RET switch is activated. The total CRT display

range is 5 ms for the 2-30 MHz sweep (or 10 ms for the 2-16 MHz sweep). Thus,

activating the MANUAL SYNC switch for 1 second (at the 1 ms/sec slip rate) moves

the CRT display by 20% of its range when operating on a 2-30 MHz sweep.

(5) After recentering, place MODE switch in PROG position.

The receiver synchronization may be changed at any time, even when not sweeping.

However, the change in synchronization is only immediately visible at the CRT load

line cursor while sweeping. If the receiver synchronization is changed when the

sweep is stopped or during a portion of the sweep where there are no chirp traces,

there will be no immediate indication on the CRT that the synchronization has changed.

The result of the change will be visible only when the sweep advances to the propagat-

ing band where the change in trace position will be visible.

NOTE

Do not change the synchronization of a path while the receiver is sweeping

a different path (i.e. do not slip PATH 1 while sweeping PATH 2).

SYNCHRONIZATION

3-11. The RF sweeps of the RCS-4B and TCS-4B must be synchronized in time to an

accuracy of about one millisecond for proper operation. Because it would be extremely

difficult to directly synchronize the receiver and transmitter program timers to this

accuracy, a four-step procedure is used that makes synchronization relatively easy.

This four-step procedure, summarized in steps a thru d below, is described in para-

graphs 3-12 thru 3-19:

a. Establish the TCS-4 sweep program and determine which 5 minute segments

of the hour a particular transmitter is transmitting and set the receiver PATH

PROGRAMMER to the same segments. For example, path 1 sweep may be set for 00,

15, 30 and 45 minutes; path 2 set for 05, 20, 35 and 50 minutes; and path 3 set

for 10, 25, 40 and 55 minutes.

b. Establish the transmitter clock timing relative to real time. For example, the

clock could be started 1 minute and 14 seconds after the 00 minute and 00 second of

the real time hour. When operating a multiple (2 or more paths) sounding network

it is recommended that the transmitter clock start times be offset from one another

by a minimum of two seconds (even when the individual path sweeps are programmed

for different 5 minute segments of the hour) to avoid any possibility of accidently

synchronizing the receiver on the wrong transmitter. For example, path 1 start

time mav be four seconds after the time reference (e.g. WWV); path 2 at seven

seconds after; and path 3 at 15 seconds after. To insure reception of all three paths

without loss of data, the path start time offsets should be within a 20-second "win-

dow".

c. Manually start one of the RCS-4B receiver path clocks to match the desired

transmitter start time from step b. The receiver path clock must be started with a

second accuracy.