Patent ID: 8018794
Filing Date: 2011-09-13
Classification: G01S,Y10S

Abstract:
1. A device for independent determination of absolute geographic coordinates for an immersed moving body carrying the device, said device comprising: acoustic means for positioning the moving body, providing the relative position in distance and bearing from a fixed immersed acoustic beacon, said position in distance and bearing being defined from an acoustic signal transmitted by said fixed acoustic beacon; surface positioning means used by the moving body to determine absolute geographic coordinates of the moving body when the moving body is at the surface; a set of sensors that the moving body uses to determine its travel depth, horizontality, and the difference between a speed vector of the moving body and a fixed direction; onboard calculation means gathering information given by all of the acoustic means, surface positioning means and sensors, to calculate changes to the latitude, longitude, and elevation with respect to an origin position for which absolute geographic coordinates are previously memorized; said device being configured to operate according to the following different phases: a preparation phase during which, as the carrying body is at the surface, the device acquires the absolute coordinates of the initial position of the carrying moving body, using only said surface positioning means, an initialization phase during which, as the carrying body is brought close to the beacon, the said acoustic positioning means of the device are synchronized with the acoustic transmission signal of the beacon, an operating immersion phase during which, as the carrying body is in immersion, the onboard calculation means determine changes to the geographic position of the moving body with respect to an initial position of the moving body from the measurements given by acoustic positioning means and from the set of sensors, an operating surface phase during which, as the carrying body is at the surface, the device makes a new acquisition of the absolute geographic coordinates of the carrying moving body and, if necessary, updates the absolute position previously calculated during the immersion.