Comtech CRS 1:N Redundancy Switches for Legacy Modems

INTRODUCTION
The Comtech EF Data 1:N Modem Redundancy Switches provide full protection of traffic circuits in the case of equipment failure. They are primarily intended for hub applications, and are compatible with a variety of Comtech EF Data Satellite Modems. The protection system consists of traffic modems (up to ten for the CRS-200 and up to eight for the CRS-400), plus a redundant modem, and a redundancy switch. An optional IF switch, CRS-280 or CRS-280L, is available as a companion switch for multiple transponder or multiple satellite applications.

COMPATIBILITY
These 1:N redundancy Switches support a wide-range of terrestrial data interface types including: EIA -422, V.35, EIA-232 and HSSI signals.

KEY RELIABILITY FEATURES
• Twin, independent AC supplies
• Passive back-plane for signal path
• Normal traffic is not interrupted upon power failure
• Non-interruption of user data when other traffic modem Interface circuit cards are removed
• Data and clock are provided to the redundant modem when in bridged mode
• Programmable holdoff times to backup or restore
• Audible alarm programmable to activate based on various changes in status
• Provides single-point remote Monitor and Control (M&C) to switch and traffic modems
• Simplified configuration and control
• 2 line x 24 character vacuum fluorescent display
• Front panel keypad
• LED system status display showing unit and modem status, online/offline status and bridge status

SUPERIOR FUNCTIONALITY
The configuration of each traffic modem is stored in the 1:N controller. This information is used to program the redundant modem if the traffic modem fails. The modem information is copied to the controller through a serial cable. The 1:N controller also controls the traffic and redundant modem IF output. All modem outputs are ON if the CRS-280/CRS-280L IF switch is used in the system. The downlink path through the CRS-280/CRS-280L is completely passive.
External monitor and control may be connected to the CRS-230 controller board. The switch and each traffic modem may be monitored or controlled through this remote serial interface.
The data and clock signals to and from a traffic modems are routed through a Traffic Modem Interface (TMI), via a set of relays. This allows the data signals to pass directly through to the traffic modem in the event of a power failure. If the system’s power supplies are lost, or if a TMI carrying traffic is removed, no interruption of traffic takes place.
The bridge mode may be used to verify the user data on a specific traffic modem. The redundant modem locks to the traffic modem receive IF input signal. The operator can program a delay interval for the backup modem to wait before coming on line when a traffic modem failure occurs.

MODULAR CONSTRUCTION
The redundancy switches are modular in construction.
All replaceable modules insert into slots in the back panel, including the controller, Traffic Modem Interfaces (TMIs), Redundant Modem Interfaces (RMIs) and Power Supply Units (PSUs). Power consumption is so low, even for fully populated units, that no fan cooling is required.