Comtech EF Data SNM-1010L - Manual (Page 192)

SNM-1010L Data/Control Modem Revision 0
System Checkout MN/SNM1010L.OM
7.2.2.2 Demodulator Faults
Fault/Alarm Possible Problem and Action
CARRIER DETECT Carrier detect fault.
Indicates the decoder is not locked. This is the most common fault
displayed in the modem. Any problem from the input data on the
modulator end of the circuit to the output of the decoder can cause this
alarm.
First, ensure the demodulator has an RF input at the proper frequency
and power level. Ensure the demodulator data rate is properly
programmed. Refer to the fault isolation procedure for Data Clock Syn
in the modulator section. Verify the frequency of the data transmitted
from the modulator is within 100 PPM.
IF SYNTHESIZER Demodulator IF synthesizer fault.
Indicates the demodulator IF synthesizer is faulted.
This fault is a hardware failure. Contact the Comtech EF Data Network
Customer Support Department.
I CHANNEL Indicates a loss of activity in the I channel of the quadrature
demodulator.
Typically indicates a problem in the modulator side of the circuit.
Check for proper RF input to the demodulator. If the input to the
demodulator is correct, then the problem is in the baseband processing.
Q CHANNEL Indicates a loss of activity in the Q channel of the quadrature
demodulator.
Follow the same procedure for the I channel fault.
BER THRESHOLD Indicates the preset BER threshold has been exceeded.
Setting of this alarm is done in the Utility menu. This is an alarm based
on the corrected BER reading on the front panel.
MODULE Demodulator module fault.
Typically indicates that the demodulator module is missing or will not
program. Contact the Comtech EF Data Network Customer Support
Department.
CONFIGURATION Modulator/Demodulator Configuration fault.
Indicates a fault in either the Modulator or Demodulator state.
LNB CURRENT Indicates a LNB Fault.
Typically indicates either Under or Over current. Contact Comtech EF
Data Network Customer Support Department.
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