METHOD AND APPARATUS FOR PRECISION ATTITUDE DETERMINATION

A technique for resolving whole-cycle ambiguity that is inherent in phase-angle measurements of signals received from multiple satellite-based transmitters in a global positioning system. The relative position of a secondary receiving antenna with respect to a reference antenna is approximately known or approximately initially determined and then measurements from a minimum number of satellites are used to determine an initial set of potential solutions to the relative position of the secondary antenna that fall within a region of uncertainty surrounding the approximate position. Redundant measurements are taken from one or more additional satellites and used to progressively reduce the number of potential solutions to close to one. Even if the number of potential solutions is not reduced to one true solution, the number can be further reduced by using additional measurements taken at different time intervals, at which different satellite geometries prevail. The disclosed technique produces rapid elimination of false solutions and permits realtime computation of angular orientation in attitude determination applications.