Troubleshooting; Alarm Faults; Major Tx Alarms - Comtech EF Data DMD50 Installation And Operation Manual

DMD50 Univeral Satellite Modem
6.2

Troubleshooting

Should a unit be suspected of a defect in field operations after all interface signals are verified,
the correct procedure is to replace the unit with another known working unit. If this does not cure
the problem, wiring or power should be suspect.
The following is a brief list of possible problems that could be caused by failures of the modem or
by improper setup and configuration for the type of service. The list is arranged by possible
symptoms exhibited by the modem.
Symptom
The Modem will not acquire the incoming
carrier:
The Async Port is not configured correctly.

6.2.1 Alarm Faults

6.2.1.1 Major Tx Alarms

Alarm Possible Cause
FPGA CFG Indicates a transmit FPGA hardware failure.
DSP CFG Indicates a transmit FPGA failure.
SCT Clock Indicates that the Tx SCT Clock PLL is not locked. This alarm will flash on during
PLL certain modem parameter changes. A solid indication points toward a configuration
problem within the modem.
SYM Clock Indicates that the Tx Symbol Clock PLL is not locked. This alarm will flash on during
PLL certain modem parameter changes. A solid indication points toward a problem with
the incoming clock to the modem (SCTE).
LB Synth PLL Indicates that the Tx L-Band Synthesizer is not locked. This alarm will flash on during
certain modem parameter changes. A solid indication points toward a configuration
problem within the modem.
IF Synth PLL Indicates that the Tx IF Synthesizer is not locked. This alarm will flash on during
certain modem parameter changes. A solid indication points toward a configuration
problem within the modem.
Ethernet WAN Indicates that the WAN Port is down.
MN-DMD50– Revision 3
Possible Cause
There is an improper receive input to modem.
The Receive Carrier Level is too low.
The Receive Carrier Frequency is outside of the
acquisition range.
The Transmit Carrier is incompatible.
Modem is in Test Mode.
The switches may not be set in the correct positions.
Maintenance and Troubleshooting
6–2