10
Figure 1-13. NSU2-B75/S50, NSU2-B50/S50 or NSU2-S50/S50 RF Connections
1.2.4 DEFINITIONS
Redundancy Chain
The Redundancy Chain is a series of units that have their signal paths linked together
via four-port transfer switches to achieve higher overall system reliability. This is
accomplished by having a Backup Unit standing by. In the event that a Primary Unit fails
the Control Unit will automatically place the backup unit online in the primary path and
the primary unit into the standby path by controlling the Switch Modules in the
Redundancy Chain.
The Redundancy Chain includes up to twelve primary positions and one backup
position. Each primary position includes one frequency converter and one Switch
Module. The backup position includes one frequency converter and may contain a
Switch Module for switching polarization. The NSU1 and NSU2 are fixed configurations
and cannot be expanded nor can they support polarization switching.
NSU System
The NSU1 is a 1:1 configuration with the switch modules integrated into a 1 rack unit
with the control unit. A polarization switch module cannot be added to the NSU1
System.
The NSU2 is a 1:2 configuration with the switch modules integrated into the 1 rack
control unit chassis. A polarization switch module cannot be added to the NSU2
System.