HP 11757B Manual page 6

HP 11757B Digital Radio Testing
to connect the \ERROR PULSE" of the BERT to the
ERROR PULSE INPUT of the Fader, you must also
connect an Alarm line from either your radio or your
BERT to the ALARM INPUT line of the Fader. This
is because when no errors are present on the ERROR
PULSE INPUT line, the Fader cannot tell the di erence
between an out-of-lock situation and one were the bit
error rate is truly zero. The Fader needs the ALARM
INPUT line to determine which of these situations is
occurring.
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