The Study On Algorithm Of GPS/GLONASS Combined Positioning

With the development of the GLONASS satellite constellation, the combinedpositioning of GPS and GLONASS attracts more and more attention. The combinationof the two systems can not only greatly increase the availability of satellite and thereliability of positioning, but also improve operational efficiency without reducingaccuracy. The paper introduces the GLONASS system first, and then does the workbased on GPS/GLONASS as follows:1．The combined GPS/GLONASS pseudorange positioning model and positioningproblems are studied.2．The method of processing GPS/GLONASS pseudorange positioning is introducedbase on the difference between GPS and GLONASS.3．Design program to process GPS/GLONASS combined positioning and pseudorangeobservations of GPS and combined GPS/GLONASS are respectively used to position,and then compare the results.4．The carrier phase observation equation of GLONASS is studied, and then deducethe single differential and double differential carrier phase equation.5．The main problems of the GLONASS carrier phase double differential ambiguityresolution are analyzed, and the ambiguity resolution method that suitable forGLONASS is introduced.6．The carrier phase observation equation of GPS/GLONASS is given and thendesign program to calculate the baseline using GPS/GLONASS combined observation,the result showed that the combined positioning can give good result even the GPSsatellite is less.7．The differential data communication format (RTCM) is described, and thendesign the decoding method of the latest version RTCM3.1.