Self Tests

TM 11-5895-1179-13 EE132-EA-OMP-010/E106 KY883 TO 31S1-2GSC-161

2-6.

Self Tests

Self-test procedures should be performed daily before operating the encoder-decoder to make sure the encoder-decoder

is operating properly. Self-tests should also be performed when a problem is discovered during operation. The self-tests

consist of four individual tests: on-line self-test, off-line self-test, lamp test, and link test.

On-Line Self-Test. The on-line self-test monitors the performance of the encoder-decoder during normal

operation and requires no operator action. The on-line self-test indicates a problem by turning on one or more of the ON

LINE FAULT INDICATORS and sounding the electronic signal. If this condition happens during operation, the off-line self-

test should be run to find the problem area.

(1) The static on-line self-test monitors the output of the power supply and the presence of an over-voltage, low

line voltage, high temperature or excess current condition. Any one of these conditions causes the POWER SUPPLY on-

line fault indicator to come on.

(2) The on-line dynamic test circuits consist of the following:

(a) K=2 and K=8 encoder fault detectors, which turn on the associated ON LINE FAULT INDICATOR, when

a transmit fault is found.

(b) Viterbi and feedback decoder fault detectors, which turn on the associated ON LINE FAULT

INDICATOR, when a receive fault is found.

(c)

Interleaver and de-interleaver fault detectors, which turn on the associated ON LINE FAULT

INDICATOR, when a fault is found.

(d) Clock fault detector which turns on the associated fault indicator when the encoder or decoder input clock

signal is interrupted.

Off-Line Self-Test. The off-line self-test is used to make sure the encoder-decoder is operating properly and to

help locate problem areas in the encoder-decoder. The off-line self-test isolates problems to the circuit card assembly

level. The off-line self-test should be run daily before operation to make sure the encoder-decoder is operating properly. If

the encoder-decoder must be kept in continuous operation, run this test only when the equipment can be shut down

without interrupting the communications link. The off-line self-test can be run with the ENCODER or DECODER MODE

select switches in any position.

CAUTION

Performing the off-line self-test on the encoder-decoder will interrupt digital user communication on

either link, transmit or receive.

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