Comtech EF Data SNM-1000 - Manual (Page 137)

SNM-1000 Node Control Modem Revision 3
Maintenance MN/SNM1000.IOM
5–7
5.1.3.1 Modulator Faults
Fault/Alarm Possible Problem and Action
IF SYNTHESIZER Modulator IF synthesizer fault.
This is considered a major alarm, and will turn off the modulator
output. Return the modem for repair.
DATA CLOCK SYN Transmit data clock synthesizer fault.
This fault indicates that the internal clock VCO has not locked to the
incoming data clock, or the internal clock synthesizer has not locked
to the internal reference. This is considered a major alarm, and will
turn off the modulator output. Ensure the proper data rate has been
set up and selected, and the incoming data rate matches the modem
selections.
I CHANNEL Activity alarm for the I channel digital filter.
This alarm is considered a major alarm, and will turn off the
modulator IF output. An alarm in this position indicates either a fault
in the scrambler, or if the scrambler is disabled, the alarm indicates a
loss of incoming data. If the fault is active with the scrambler turned
off, check for input data at the DATA I/O connector.
Q CHANNEL Activity alarm for the Q channel digital filter.
Use the I channel procedure.
AGC LEVEL Output power AGC level fault.
Indicates the level at the modulator output is not the programmed
level.
INTERNAL SCT SYN Internal TX data clock synthesizer fault.
The SCT has failed to lock to the internal reference.
EXT REF ACT External reference activity fault.
Indicates clock reference not detected.
MODULE Modulator module fault.
Typically indicates that the modulator module is missing or will not
program.