End-to-End with Return Reference Mode

TM 11-6625-922-15

applied to the line under test and his TS-2669/GCM will

delay of the line as a function of frequency can be

read the relative delay of the line.

determined.

f. Amplitude response measurements are made on

3-5. End-to-End with Return Reference Mode

the receiving TS-2669/GCM by having the operator at

this end of the line to monitor the dbm/% MODULATION

a. To perform a transmission line measurement

meter as the operator at the transmitting end varies the

using the return reference mode, it is necessary to have

carrier frequency.

a TS-2669/GCM on the input to the line (fig. 3-4). It is

also necessary to have a second line available to return

3-6. Loop Mode

the delay signal to the transmitting TS-2669/GCM.

a. To perform a transmission line measurement

b. The transmitting TS-2669/GCM, located at the

using the loop method, it is only necessary to use one

input end of the transmission line to be measured,

TS-2669/GCM at the input end of the line under test (fig.

produces a modulated carrier signal in the pass band of

3-5). At the far end of the line, the output is patched to

the line. The signal is transmitted down the line to a TS-

the input of a second line used to return the test signal

2669/GCM at the far end. The receiving TS-2669/GCM

back to the input terminal. The delay and amplitude

demodulates the test signal and uses this modulation

measurements are thus made over two transmission

signal to remodulate its own transmitting carrier signal

lines. If the two lines are of the same type, it is usually

as a reference carrier. This reference carrier is sent

assumed that the forward and return path delays and

back to the transmitting TS-2669/GCM by way of the

amplitude characteristics are equal.

auxiliary transmission line. The operator using the

transmitting TS-2669/GCM can now make delay

Connect the TRANSMIT jack of the TS-

measurements on his own unit.

2669/GCM to the input of line No. 1 and the RECEIVE

c. Connect the TRANSMIT jack of the transmitting

jack to the output of line No. 2.

TS-2669/GCM to the input of the transmission line under

c. Operate all switches and controls on the TS-

test. Connect the RECEIVE jack of the transmitting TS-

2669/GCM to the output of the auxiliary line (fig. 3-4).

2669/CCM as described in paragraph 3-3.

All controls and switches on the transmitting TS-

2669/GCM are to be operated as described in paragraph

d. Delay and amplitude measurements can now be

3-3.

made by the operator of the TS-2669/GCM.

d. Connect the output of the transmission line under

3-7. Operation under Unusual Conditions

test to the RECEIVE jack of the receiving TS-

2669/GCACI. Connect the input of auxiliary line to the

Although the TS-2669/GCM has been designed to

transmit jack of the receiving TS-2669/GCM (fig. 3-4).

operate over a wide range of temperature and humidity,

Operate the switches and controls on the receiving TS-

operation may be difficult in extreme cold, heat,

2669/GCM as follows:

humidity, moisture, and similar conditions. Observe the

following procedures when operating under adverse

(1) MODULATION FREQUENCY HZ switch to

conditions.

same modulating frequency used on the transmitting

TS-2669/GCM.

a. Cold Climates. Keep the equipment as warm

(2) END TO END-REF RETURN switch to REF

and dry as possible. If the equipment has been exposed

RETURN.

to the cold and then brought into a warm room, moisture

(3) SWEEP - CARRIER - REFERENCE switch

will gather on the equipment. When the equipment

to CARRIER.

reaches room temperature, dry it thoroughly.

(4) Operate CARRIER FREQUENCY control to

provide an output carrier in the middle of the desired

b. Hot Climates. When the equipment is installed

band.

in tents, huts, or underground dugouts, provide the best

(5) All other controls are to be operated as

ventilation. When the surrounding temperature drops,

instructed in paragraph 3-3.

moisture will form on the equipment. Always dry the

equipment thoroughly before operating it.

e. Delay measurements cal now be made on the

transmitting TS-2669/GCM.

The operator at the

c. Dry Climates. Keep the equipment as free from

transmitting end will control the carrier frequency

(lust as possible.

3-10