12
Priority
Each of the primary frequency converters can be assigned a priority. The NSU will grant
communication channels access to the backup converter on a prioritized basis. A
priority setting of 1 is for the most crucial communication channels. A priority setting of
12 is the least significant. In the case where the primary converters are set to the same
priority the backup is available on a first-come, first serve basis. The backup converter
has no priority.
Switch Module
The signal paths of the units in the Redundancy Chain are linked together by the Switch
Modules. The Switch Module is fixed in a redundancy chain position with a frequency
converter. The Switch Module contains an IF frequency and/or an RF frequency four-
port transfer switch. The Switch Module is connected to the Control Unit via the Switch
Module Bus. The Switch Module depicted below has both an RF and an IF four-port
transfer switch. The push-wheel is set from zero to twelve to indicate redundancy chain
position of the Switch Module (Zero is reserved for the Polarization switch). The LED
will light green for online, amber for standby, and red if there is an internal fault. There
are two connectors provided for daisy-chaining the Switch Module Bus.
Figure 1-14. Front Panel, Switch Module (NSUN Only)
Active Fault
An Active Fault indicates the NSU is presently experiencing a failure that is impeding
ideal operation of the NSU. An active fault will cause the “STATUS” button on the front
panel to light red and the status contacts will indicate a fault. The Event Log will contain
information about the fault condition and the time and date that the fault occurred.
The Types of Active Faults that can be reported are:
•
Power Supply ’A’ fault
•
Power Supply ’B’ fault
•
Converter bus fault
•
Converter Contact Failure fault
•
Switch fault
•
Switch Bus fault