Influence of the GLONASS inter-frequency bias on differential code bias estimation and ionospheric modeling

摘要

Due to the application of frequency division multiple access, the signals of GLONASS satellites suffer from code and carrier phase inter-frequency biases (IFBs). In this study, the effects of GLONASS code IFBs on differential code bias (DCB) estimation and ionospheric modeling are investigated. The observational data from more than 130 MGEX stations for a period of 60 days are used to generate the DCB products, with and without considering the GLONASS code IFB. According to the results, residuals of the DCB estimation without GLONASS code IFB consideration exhibit frequency-dependent systematic errors, errors that can be eliminated when the GLONASS code IFB is taken into account. The GLONASS inter-frequency differential code bias (IFDCB), defined as the difference of the sum of satellite and receiver DCB estimates without and with GLONASS code IFB consideration, is taken to represent the difference between the two DCB estimation types. The IFDCBs are generally in the range of +/- 4 and +/- 2 ns for C1P-C2P and C1C-C1P, respectively, and the largest difference of the C1P-C2P IFDCBs between frequency channels is > 7 ns. The VTEC products of ionospheric modeling with and without the consideration of the GLONASS code IFB are also generated based on data from 30 days of MGEX and IGS networks. The mean difference and standard deviation between them are 0.53-1.13 and 0.98-1.75 TECU, respectively.