Applicability of Combined Microwave and Optical Data for Surface Water Quality Retrievals

In a redundant controller system having an active controller (112) with an active data base and a standby controller (115) with a standby data base, the active controller (112) operably coupled to the standby controller (115), the active data base including a plurality of records, the plurality of records subject to modification, a method of updating the standby data base to mirror the active data base including modifying a record, the record including a record checksum, incorporating the record checksum into a virtual checksum (322) for the active data base, communicating the record including the record checksum to the standby data base (324), incorporating the record checksum into a standby checksum (410, 412) for the standby data base, and comparing the standby checksum to the virtual checksum (312) to insure the standby data base mirrors the active data base.