Location determination using signals from fewer than four satellites

摘要

Method and apparatus for determining the location of a point on a rotating body, using location determination (LD) signals received from as few as one satellite, preferably non-geosynchronous. Where signals from two or more satellites are received, one may be geosynchronous. Pseudoranges are measured from one or more satellites at two or more selected, spaced apart observation times, and the simultaneous rotations of the body and the satellite(s) relative to each other result in different body-satellite constellations for which the initial location coordinates (and, optionally, signal receiver time offset) of the selected point are determined exactly, without approximation or iteration. The selected point may be motionless or may be allowed to move with known coordinate differences between the initial unknown location and the present location at each observation time. Pseudoranges from different satellites, or even from different satellite systems (GPS, GLONASS, LEO, etc.) can be measured and used in this procedure.