Active Alarms; Major Alarms; Minor Alarms; Common Equipment Alarms - Radyne DMD20 Installation And Operation Manual

DMD20 Universal Satellite Modem Maintenance and Troubleshooting
When an alarm is masked, the Front Panel LEDs and the Fault Relays do not get asserted, but
the Alarm will still be displayed. This feature is very helpful during debugging or to lock out a
failure that the user is already aware of.

6.1.2.1 Active Alarms

6.1.2.1.1 Major Alarms

Major Alarms indicate a modem hardware failure. Major Alarms may flash briefly during modem
configuration changes and during power-up but should not stay illuminated. Alarms are grouped
into Transmit and Receive Alarms - Transmit and Receive are completely independent.

6.1.2.1.2 Minor Alarms

Minor Alarms indicate that a problem may persist outside the modem such as loss of Terrestrial
Clock, loss of terrestrial data activity, or a detected transmit or receive AIS condition.
Alarms are grouped into Transmit and Receive Alarms - Transmit and Receive are completely
independent.

6.1.2.1.3 Common Equipment Alarms

TBD

6.1.2.2 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.

6.1.2.3 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.

6.2 DMD20 Fault Tree Matrices

TBD

6.2.1 Interpreting the Matrices

The first vertical column in the Tables represents the various Faults that the modem may identify.
The top horizontal column indicates the various actions that the modem will undertake. These
actions may be in the form of a relay, a switch or an LED.

6.2.2 IBS Fault Conditions and Actions

Figure 6-10 and Table 6-4 illustrates 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.
TM103 – Rev. 1.1 6-7