COMPARISON OF GPS PSEUDORANGE AND BIASED DOPPLER RANGE MEASUREMENTS TO DEMONSTRATE SIGNAL MULTIPATH EFFECTS

Abstract

The TI 4100 Geodetic Global Positioning System (GPS) Receiver has been field tested in several environments. These include collocation rooftop tests near reflective equipment, isolated desert positioning tests, and shipboard survey tests. The receiver data consisted of pseudorange (code) and biased Doppler range (phase) measurements on both L1 and L2 frequency channels. This paper compares differences between ionospherically corrected pseudorange and biased Doppler range measurements to demonstrate the significant effects of signal multipath on the pseudorange measurements. That is, pseudorange signal multipath effects can be isolated, detected, and statistically modeled using only the above measurements. Examples are given for various receiver antenna locations. Day-to-day comparisons are made to demonstrate the repeated multipath effects due to repeated satellite-to-antenna geometries. The results can be used to analyze and statistically model pseudorange multipath effects for possible improved positioning and GPS satellite orbit determination accuracy.