Comtech EF Data SNM-1001 - Manual (Page 55)

Maintenance SNM-1001 Network Control Modem
5–10 Rev. 1
5.2.1 Modulator Faults
5.2.1.1 Continuous Mode
Fault/Alarm Possible Problem and Action
IF SYNTHESIZER Modulator IF synthesizer is faulted.
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 is an indication 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.
Check to see that the proper data rate has been set up and selected. Verify that
the incoming data rate matches what has been selected in the modem. Verify
the frequency of the input data clock to be within the lock range of 100 PPM.
If the inputs to the modem are all correct and the problem still exists, replace
the modem and return for repair.
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, it indicates a loss of incoming data. If the fault is active
with the scrambler turned OFF, check to see that there is input data at the data
I/O connector. If data is present, the problem could be in the interface section.
If the fault is active with the scrambler turned ON, the problem could be in
the modulator section. Return the modem for repair.
Q CHANNEL Activity alarm for the Q channel digital filter.
Follow the same procedure as for the I channel.
AGC LEVEL Output power AGC level fault.
Indicates that the level at the modulator output is not the level that is
programmed. Replace the modem and return it for repair.
MODULE Modulator module fault.
Typically indicates the modulator will not program. This could indicate a
problem in the interface between the modulator and M&C due to modulator
firmware being installed incorrectly, or a pin not making contact. Verify the
modulator firmware is correctly installed. If the problem still exists, return the
modem for repair.