Comtech EF Data CPA - Manual (Page 123)

B–1
Appendix B. ISSPA REDUNDANT
OPERATIONS
B.1 Introduction
Comtech EF Data’s CPA ISSPAs are designed to automatically sense and configure
into Redundancy Mode when the redundant loop cable is connected. Polling on the
dedicated redundancy bus will not begin until the redundancy loop cable is
connected. Each ISSPA’s designation in a redundant subsystem is determined
automatically via the redundancy interface cable connected between the two (i.e.,
1:1) or three (i.e., 1:2) ISSPAs in the redundant configuration.
All Comtech EF Data CPA ISSPAs are designed to operate in both standalone and redundant
configurations. The ISSPA has the ability to automatically detect whether it is in a standalone or
redundancy system. This feature greatly simplifies redundancy configurations from both the
cost and operational complexity standpoints.
Every ISSPA contains the circuitry and logic necessary to perform all the functions of a backup
controller for either a 1:1 or a 1:2 configuration. This includes the ability to monitor and control
up to two RF waveguide switch assemblies.
In a redundant configuration, the Backup SSPA in the redundancy subsystem automatically
monitors the configuration and status for each of the Primary (chained) ISSPAs. This information is
communicated via the dedicated serial interface between the ISSPAs.
If a Primary SSPA fails, the backup detects this event and automatically reconfigures itself to the
proper attenuation setting, and positions the waveguide switch to provide minimal loss of traffic.
A result of this design is to greatly lessen the throughput requirements (i.e., the polling rate) of
earth station monitor and control systems. The Backup SSPA handles all of the time-critical tasks,
allowing the earth station monitor and control system to focus on less intelligent subsystems.