Ocean acoustic phase shift estimation using strapdown navigation techniques

An underwater navigator system is proposed which will allow a precise measurement of acoustic phase shifts due to the medium stability of the surrounding ocean environment of any suitably instrumented undersea sonar range. The prime components of the system comprise a strapdown inertial measurement unit (SIMU), a shipborne general purpose computer, a sonar transmitter, a geometric array of bottom-mounted hydrophones and a link for sending sonar derived position fixes from a shore-based computer to the shipborne computer. A feasibility study is presented to show that a specified relative positional accuracy goal can be met taking into account the statistical nature of the sonar fix and of the inertial sensors.