Investigation of PPP-AR algorithm based on uncombined model
Aiming at the problem of short wavelengths of narrow lane ambiguities in the wide lane(WL)-narrow lane(NL)ambiguity resolution(AR)method,the paper proposed a fixing method based on raw observation approach(N1-N2 AR):the observable-specific signal bias(OSB)products were utilized to eliminate satellite hardware delays,and precise point positioning was conducted through an uncombined model;then undifferenced ambiguities were converted into single-difference form for ambiguity resolution;finally,the performance of the N1-N2 AR method was compared with the WL-NL AR method under both static and simulated dynamic conditions.Experimental results showed that both methods would exhibit comparable performance in static tests,with fixation rates exceeding 96%;while in simulated dynamic tests,using only global positioning system(GPS)data,the fixation accuracy of the N1-N2 AR method would be approximately 15%higher than that of the WL-NL AR algorithm,and under the combined conditions of G/C/R/E,the effective fixation rate and fixation accuracy would be approximately 7%and 2%higher,respectively;in general,considering the trend towards multi-frequency and multi-system developments,the fixation method based on raw observation approach could have a broader application potential under conditions of high-precision pseudorange observations.
uncombined modelprecise point positioning(PPP)raw observationambiguity resolutionglobal positioning system(GPS)multi-system combination
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