Comtech EF Data SNM-1002 - Manual (Page 121)

SNM-1002 LinkSync
 Modem
Revision 2
Maintenance MN/SNM1002.OM
5–13
5.2.3.1 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 Use interface loopback for isolating the problem. Verify
the frequency of the input data clock to be within the lock range of
100 PPM.
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.
MODEM REF ACT Modem REF ACT fault.
Indicates incorrect EXT REF frequency input.
MODEM REF PLL Modem REF PLL
Indicates phase lock loop is unable to lock to EXT REF.
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.
CONFIGURATION Modulator/Demodulator Configuration fault.
Indicates a fault in either the Modulator or Demodulator state.