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Approaches for using Three Dimensional sonar as a supplemental sensor to GNSS

The core of an underwater vehicle's navigation suite is the Inertial Navigation System (INS). Using a series of sensors, the INS estimates the position of the vehicle. One of the sensors is the Global Positioning System (GPS) receiver, which provides a position fix. Typically, a series of GPS position fixes are taken just before a vehicle submerges. After that, the INS must rely on other sensors such as the fathometer, speed log, and Doppler sonar to dead reckon (DR).