Patent ID: 6429814
Filing Date: 2002-08-06
Classification: G01S

Abstract:
A method for computing position comprising:supplying pseudorange measurements that approximate the distance from a location to a plurality of global positioning system (GPS) satellites; supplying a terrain model; and computing a three-dimensional position of said location in response to said pseudorange measurements and said terrain model, wherein said computing step comprises: (a) determining an upper altitude bound and a lower altitude bound; (b) selecting a first altitude between said upper and lower altitude bounds; (c) determining from said pseudorange measurements a longitude and a latitude corresponding to said first altitude; (d) determining a second altitude using said terrain model at said longitude and latitude; (e) if said second altitude is above said first altitude, replacing said lower altitude limit with said first altitude, otherwise replacing said upper altitude bound with said first altitude; and (f) repeating steps (b), (c), (d), (e) and (f) until a difference between said upper and lower altitude bounds is within a predefined value.