Knowledge Bank

Geodetic positioning using range, integrated Doppler, and interferometric observations from a constellation of twenty-four Global Positioning System satellites is analyzed. A summary of the proposals for geodetic positioning and baseline determination is given which includes a description of measurement techniques and comments on rank deficiency and error sources. An analysis of variance comparison of range, Doppler, and interferometric time delay to determine their relative geometric strength for baseline determination is included. An analytic examination of the effect of a priori constraints on positioning using simultaneous observations from two stations is presented. Dynamic point positioning and baseline determination using range and Doppler is examined in detail. Models for the error sources influencing dynamic positioning are developed. Included is a discussion of atomic clock stability, and range and Doppler observation error statistics based on random correlated atomic clock error are derived. Criteria for establishing observation schedules for optimum geometric strength for positioning solutions are examined. Results of geodetic positioning simulation studies are presented. Satellite interferometry results based on the double differencing of simultaneous interferometric phase measurements from two satellites are given. The effects of ephemeris and refraction errors and the nonsimultaneity of observation are considered.