TM 11-6625-3041-12/TO 33A1-8-908-1
3-12. FAULT INDICATORS (cont)
Logic Card
Sensors
Each logic card contains sensors that monitor important signals
on the card (fault sensors). In addition, the Transmit 1 and
Receive 1 cards contain sensors that monitor external input
signals (input sensors).
Two sensors are peak detectors (.49/.55 Hz and 512/576 kHz
clocks) and indicate a fault immediately whenever the monitored
signal drops below a preset level. When the signal returns to
normal, the indicator immediately returns to a no-fault condi-
tion.
The remaining sensors (both fault and input) are digital and
are read approximately every half second (2 seconds on the
Receive 2 card). Whenever the signal they monitor disappears,
it can be one-half or 2 seconds before a fault is indicated.
When the signal returns, it can be one-half or 2 seconds before
the indication returns to a no-fault condition.
Because of the 2-second read interval on the Receive 2 card,
two sensors are inhibited at the lower data rates (red-end
sensor at 128 kb/s and below 9.6 kb/s and yellow-end sensor
below 576 kb/s).
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