Latched Alarms; Common Equipment Faults; Backward Alarms; Ibs Fault Conditions And Actions - Comtech EF Data DMD50 Installation And Operation Manual

DMD50 Univeral Satellite Modem
6.2.2.1.3

Common Equipment Faults

Common equipment faults indicate hardware or configuration problems in the modem that effect
both transmit and receive operation. Most common faults indicate a hardware failure within the
modem, such as a bad power supply. Common faults for the External Reference and External
Clock indicate a bad modem configuration, not a hardware failure.
6.2.2.2

Latched Alarms

Latched Alarms are used to catch intermittent failures. If a fault occurs, the fault indication will
be latched even if the alarm goes away. After the modem is configured and running, it is
recommended that the Latched Alarms be cleared as a final step.
6.2.2.3

Backward Alarms

Backward Alarms are alarms that are fed back to or received from the other end of the satellite
link. In IBS Mode (including Drop & Insert), Backward Alarm 1 is the only one used. It would
be received if the distant end demod drops lock.
6.3

IBS Fault Conditions and Actions

Figure 6-1 and Table 6-1 illustrate the IBS Fault Conditions and Actions to be taken at the Earth
Station, at the Terrestrial Data Stream, and the Satellite. These faults include those detected on
the Terrestrial link and those detected from the satellite.
MN-DMD50– Revision 3
Figure 6-1. IBS Alarm Concept
Maintenance and Troubleshooting
6–6