The GPDU is a Form-Fit-Functional replacement for the Evershed Electro-Dynamics R535 Display Unit used onboard the Victoria Class Submarines. The GPDU plugs into the existing Navigational Information Display Console (NIDC) wiring harness, and automatically detects and displays the Synchro input signal as a depth, speed, or angle (heading or bearing).
The GPDU can also use an EIA RS-422A input instead of the standard Synchro input to display select information from NMEA-0183 messages (GPS, INS, etc). The Synchro-to-Digital conversion circuitry of the GPDU is based on a custom designed optical-isolated 16-bit converter that provides improved accuracy over conventional transformer isolated designs.