Fast Convergence Ambiguity Resolution On-the-Fly for Dual Frequency GPS Receivers and the Flight Evaluation

Abstract

An algorithm of ambiguity resolution On-The-Fly (OTF) for dual frequency GPS receivers was proposed and flight experiments were conducted by National Aerospace Laboratory to evaluate its performance. As results of post flight analyses, the correct L1 ambiguities were resolved almost instantaneously with probability of better than 98% when 5 or more satellites were visible and the baseline length was shorter than 20km.
In the OTF algorithm, the least squares search method was adopted to resolve correct ambiguities. The number of potential solutions could be reduced to one-tenth by using three kinds of observable step by step, namely, carrier-smoothed pseudorange, widelane phase and L1 carrier phase. In order to reject the wrong candidates of ambiguity, we performed the statistical test not only in measurement domain but also in positioning domain.Moreover, in the positioning domain test, we propose a method to evaluate the horizontal position instead of the three dimensional position in order to resolve the ambiguities quickly and reliably. This OTF algorithm can be applied to the real time kinematic GPS for the aircraft approach and landing.