Receive Link Test Procedure

TM 11-5820-803-12

ERROR CODING switches to that position set SYMBOL

users. If the self-test requires setting

RATE switches to operational positions, and set INPUT

the INPUT DATA RATE switches to

DATA RATE switches to one-half the operational

any rate greater than the" operational

SYMBOL RATE.

Then perform the coder test in

rate, the terminal output power for

accordance with table 3-5

the carrier associated with the

g. If the TRANSMIT ERROR CODING switch is

modem under test should be

operationally set to INTERNAL or EXTERNAL set both

reduced.

ERROR CODING switches to that position, set INPUT

a. If modem is nonoperating, perform the

DATA RATE switches to operational positions, and set

preliminary starting procedure (para 3-4).

SYMBOL RATE switch to twice the INPUT DATA RATE.

b. Initiate the test by changing the modem switch

Then perform (or repeat) the coder test in accordance

settings as required to correspond to table 3-3.

with table 3-5.

c. Perform the self-test in accordance with table

3-4 and the following instructions:

3-6.

Transmit Link Test Setup

(1) In the sequence shown on the table, set

a. The following modem setup procedure allows

each front panel switch indicated in the first 36 column to

the terminal at the other end of the satellite

the corresponding setting(s) indicated in the second

communications link to perform a receive link test (para

column.

3-7). See paragraph 3-3 c for the transmit link test

(2) For each switch setting, observe the

requirements.

indicators(s) listed in the third column, and verify the

CAUTION

results required by the fourth column.

Performing this test interrupts digital

d. If operational INPUT DATA RATE (table 3-2) is

user communication on the transmit

not the same as operational SYMBOL RATE, set both

link.

switch groups to the operational SYMBOL RATE and

b. If modem is nonoperating, perform the

repeat procedures of table 3-4.

preliminary starting procedure (para 3-4).

e. If both ERROR CODING switches are

c. Set the following controls as indicated:

operationally set to NONE (table 3-2) omit procedures of

table 3-5.

f. If the RECEIVE ERROR CODING switch is

operationally set to INTERNAL or EXTERNAL, set both

Control

Position.

TRANSMIT SOURCE

LINK.

TRANSMIT ERROR CODING

Normal operational setting (table 3-2)

INPUT DATA RATE

Normal operational setting (table 3-2)

DIFF ENCODE

Normal operational setting (table 3-2)

ALARM

OFF.

b. If the modem is nonoperating, perform the

d. Momentarily depress the fault ALARM. switch to

RESET. Verify the TRANSMIT SECTION and both

preliminary starting procedure (para 3-4).

TRANSMIT FAULT indicators are extinguished when the

c. If the transmit communications link is in normal

switch is released.

operation, retain the TRANSMIT SOURCE switch in the

e. Maintain control settings for time period required

OPERATE position; otherwise, set the TRANSMIT

by site procedures or schedule.

SOURCE switch to the LINK position.

d. Set the following controls as indicated:

3-7.

Receive Link Test Procedure.

a. See paragraph 3-3d for the receive link test

requirements.

Control

Position

RECEIVE ERROR CODING

Normal operational setting (table 3-2)

SYMBOL RATE

Normal operational setting (table 3-2)

DIFF DECODE (behind front panel)

Normal operational setting (table 3-2)

METER

ERROR COUNT

MANUAL/OFF/AUTO (Monitor)

AUTO

3-7