Acta Geodaetica et Cartographica Sinica ›› 2015, Vol. 44 ›› Issue (2): 150-159.doi: 10.11947/j.AGCS.2015.20130800

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Estimation of GLONASS Code Inter-frequency Biases with Multiple Parameters Based on a Single Station and Its Impact on Combined Precise Point Positioning

LIU Zhiqiang1 2, WANG Jiexian2, DUAN Bingbing2   

  1. 1. School of Earth Sciences and Engineering, Hohai University, Nanjing 210098, China;
    2. College of Surveying and Geo-infomatics, Tongji University, Shanghai 200092, China
  • Received:2014-01-02 Revised:2014-07-01 Online:2015-02-20 Published:2015-02-14
  • Supported by:
    The National Natural Science Foundation of China (Nos. 41174023;41174002);the Natural Science Foundation of Jiangsu Province (No. BK20130831)

Abstract: The disadvantages of ignoring GLONASS receiver code inter-frequency biases(IFBs) in GPS/GLONASS combined precise point positioning (PPP) are analysed in this contribution. A new algorithm of combined PPP and code IFBs estimation based on "multiple parameters" is proposed where inter-system bias parameter is merged with code IFB. Multiple independent inter-system and inter-frequency bias (ISFB) parameters are introduced to the observation equations which could compensate the GLONASS code IFBs in the function model. In the meantime, the GLONASS code IFBs can be estimated precisely based on a single station. GPS/GLONASS observation data from 30 IGS sites which involves 6 different GNSS receiver manufacturers is processed with the proposed algorithm. The results show that the GLONASS code IFBs could be several meters and a significant correlation exists between code IFB and signal frequency. It seems to be difficult to provide a priori code IFB precisely with simple function model. GLONASS code IFBs with the same receiver manufacturer mostly show similar characteristics, however, abnormal behaviors are also found in some receivers. It is worth to note that GLONASS code IFBs could be quite different with two receivers even if their receiver types, firmware versions and antenna types are all the same. The PPP results demonstrate that the new algorithm can significantly accelerate the convergence of combined PPP by compensating the GLONASS code IFBs efficiently. The combined PPP accuracy of "multiple parameters" method is comparable with that of traditional "single parameter" method and almost unaffected by freedom reduction of the function model.

Key words: GPS, GLONASS, precise point positioning, inter-system bias, inter-frequency bias, inter-system and inter-frequency bias

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