Method and apparatus for measuring displacement of object using GPS

The present invention is a method for measuring a distance between a GPS receiver installed in a floating body and a GPS satellite, subjecting this measured distance data to a moving averaging process, removing from the measured distance data, distance data corresponding to a distance to a satellite orbit to determine a variance of the GPS receiver, removing wind wave-induced noise from the data, then determining three linear equations that use three-dimensional coordinates of the GPS receiver as unknown numbers, based on variances relative to GPS satellites and an azimuth and an elevation of each GPS satellite, and then solving these simultaneous equations to determine displacement of the GPS receiver corresponding to its variation component quantities on three-dimensional coordinate axes.