The CS4400 Frequency Converter System is a digitally controlled frequency agile converter for troposcatter and line-of-sight microwave radio. The system incorporates two transmit channels, four receive channels and redundant rubidium reference oscillators supporting quad diversity communications, and is field tunable over the 4.4 to 5.0 GHz band. All filters are motor driven and tuned under the control of the redundant system controllers in the CS4400. All functions including frequency changes can be controlled from the front panel or remotely via SNMP or M&C port. Redundant architecture and modular construction are utilized throughout for maximum availability. When combined with Comtech’s CS67200 20 Mb/s modem and CSM8800 E1/IP mulitplexer, the CS4400 is an integral part of a complete microwave terminal used for beyond-line-of-sight or line-of-sight communication systems.