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
3-6.
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.
(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
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
