Overview
GPS Assist is software that uses data from an existing maritime radar to estimate the lat/long position of a ship or unmanned surface vessel (USV) by comparing received radar data with expected radar returns that are predicted from the appearance of local terrain and shorelines. The calculated position is then compared with GPS-received position, with errors being used to infer missing, spoofed or jammed GPS signals. When such a condition is detected, GPS-Assist can raise an alarm and create its own stream of NMEA-based navigation data with the goal of providing emergency navigational information.