A comparative study of the integer ambiguity validation procedures

In GPS and GLONASS satellite-based positioning, the correct determination o f the integer carrier phase ambiguities is the key to achieve precise posit ioning results. The process of determining the ambiguities, called ambiguit y resolution, is usually separated into three steps: (a) estimating the flo at or real-valued ambiguities, (b) searching the best integer ambiguity set , (c) validating the best ambiguity set. Whilst the theory and methodology for ambiguity estimation and search are well documented, the ambiguity vali dation issue is still under investigation. Existing ambiguity validation pr ocedures are based on various statistical assumptions and therefore, may ha ve different performances in practical applications. In this paper, the maj or ambiguity validation procedures are analysed and their performances in b oth GPS and GLONASS ambiguity resolution are numerically compared. It is co ncluded that both the probability of estimating ambiguities correctly and c onfidence levels of the ambiguity discrimination tests are both important i ndicators of the reliability of ambiguity resolution.