Partial Ambiguity Resolution for Low Cost GNSS Receiver in UAV Navigation Applications: A Comparative Study

Abstract

This paper compares several Ambiguity Resolution (AR) methods, including the Least square AMBiguity Decorrelation Adjustment (LAMBDA) method, the Modified LAMBDA (MLAMBDA) method, the Two-step Success Rate Criterion (TSRC) method with the low cost GNSS receivers. The algorithms were firstly tested with the low cost ublox F9P dual frequency multi-GNSS receivers in vehicle field test and UAV flight test. The ambiguity fix rate and the Time To First Fix (TTFF) are used as indices to compare the algorithms. Experiments show that the Co-LAMBDA algorithm achieves a TTFF of 480 epochs and a fix rate of 53.7%, and the TSRC algorithm achieves a TTFF of 112 epochs and a fix rate of 91.3%. It can be seen that TSRC algorithm has better performance in both TTFF and fix rate in the low cost GNSS UAV dynamic positioning applications. Then the algorithms were tested with a quasi-dynamic medium-long baseline Real-Time Kinematic (RTK) experiment, a total of 970 experimental results verify that the TSRC algorithm improves the median fix rate from 41.51% to 90.83%, and the median correct rate slightly degrades from 100% to 96.98%, which is reasonable since it computes the statistics from many more fixed-solution samples.