Table 3-2. Operational Switch Settings.

TM 11-5820-803-12

Control section

Switch

Setting

Notes

FAULT

ALARM

............................ Per site requirements

TRANSMIT

INPUT DATA RATE

............................ Equal to digital user's output data rate

ERROR CODING

............................ Per site requirements

SOURCE

OPERATE

MONITOR

TEST

METER

SIG/NOISE

MANUAL/OFF/AUTO

AUTO

RECEIVE

SYMBOL RATE

............................ Equal to digital user's input data rate with no

receive error correction coding; equal to

twice digital user's input data rate with

receive error coding.

ERROR CODING

............................ Per site requirements

POWER

ON/off

Behind front panel

STD/CLK/ICF

............................ Per site requirements

DIFF ENCODE

............................ Per site requirements

DIFF DECODE

............................ Per site requirements

or upon request to aid in locating a communications

scheduling. Also, the site transmit/receive equipment

system malfunction.

may be arranged so that its own transmissions are

c. Transmit Link Test. The transmit link test setup

received via satellite.

(para 3-6) is performed to determine the quality of the

e. Normal Duplex Link Communications. Duplex

data received at the remote end of the link. This test is

Link Communications (para 3-8) is the normal mode of

performed as a part of the routine site maintenance

operation in which the modem provides the required

procedure, the site procedure for establishing a

interface between an earth terminal and a digital user.

communications link, or upon request to aid in locating a

3-4.

Preliminary Starting Procedure

communications system malfunction.

CAUTION

d. Receive Link Test. The receive link test (para

When power is applied to a modem in

3-7) is performed to determine the quality of the data

an operating terminal, the carrier is

received from the remote end of the link. This test is

immediately transmitted. Improper

performed as a part of the routine site maintenance

upconverter settings or INPUT DATA

procedure, the site procedure for establishing a

RATE switch settings will cause

communications link, or upon request to aid in locating a

interference with other satellite users.

communications system malfunction. Performing this

a. Prior to applying power to the PSK modem, set

test requires the PSK modem at the remote end of the

the following controls as indicated.

link to be set up or a transmit link test. This is generally

accomplished either by direct request or by prior

Control

Position

TRANSMIT SOURCE

LINK.

TRANSMIT ERROR CODING

Normal operational setting (table 3-2)

INPUT DATA RATE

Normal operational setting (table 3-2)

ALARM

OFF.

b. Set the POWER switch to the ON position, and

3-5.

Self-Test

allow 30 minutes for warm-up.

CAUTION

NOTE

Performing self-test on a modem

If mission requirements do not permit

while the system is operating

a proper warm-up period, the modem

interrupts

digital

user

can be operated (with possible

communications on both the transmit

degraded performance) immediately

and receive links.

after application of power.

CAUTION

c. Perform a self-test per paragraph 3-5.

Performing self-test on a modem

while the system is operating may

cause interference with other satellite

3-5