Comtech EF Data C5 - Manual (Page 238)

System Checkout C5/K1/K3 Integrated Satellite Terminal System
Rev. 0 6-14
6.3.3.1 Transmitter 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.
MODEM
REFERENCE PLL Internal reference activity fault.
Indicates clock reference not detected.
MODEM REF PLL Modem Ref PLL fault.
Typically indicates that the Modem Ref PLL is missing or will not program.