A multi-frequency and multi-GNSS method for the retrieval of the ionospheric TEC and intraday variability of receiver DC
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ORIGINAL ARTICLE
A multi-frequency and multi-GNSS method for the retrieval of the ionospheric TEC and intraday variability of receiver DCBs Min Li1
· Yunbin Yuan1 · Xiao Zhang1,2 · Jiuping Zha1,2
Received: 27 May 2020 / Accepted: 10 September 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract As one of the important factors influencing the ionospheric total electron content (TEC) estimation accuracy, receiver differential code biases (DCBs) should be properly removed from global navigation satellite system (GNSS) measurements. The intraday variability in receiver DCBs (rDCBs), which is usually ignored in the commonly used ionospheric observable retrieval procedure, has been identified as one of the major errors degrading the accuracy of TEC estimation. The modified carrier-to-code leveling (MCCL) method can be adopted to eliminate the impact of the rDCB variability on the retrieval of the ionospheric TEC from dual-frequency (DF) GNSS observations. In this contribution, we extend the MCCL method from two aspects. First, the DF MCCL method is adapted to the multi-frequency (MF) case, in which DF, triple-frequency or even arbitrary-frequency observations can be readily processed to simultaneously estimate both the ionospheric TEC and rDCB variations. Second, the MCCL method is refined to enable the handling of GLONASS data by accounting for the effects of code inter-frequency biases induced by the frequency division multiple access (FDMA) technology. Based on the test results, the retrieval accuracy of the ionospheric TEC using our proposed method can be improved from 9.47 TECu to 2.67 TECu in the presence of significant intraday rDCB variations. We discovered that the maximum difference in the rDCB variations of the same satellite system between different frequency bands can be as large as 10 ns. The dependence of multi-GNSS and MF rDCB variations on the ambient temperature is further verified in this study. The results show that the temperature dependence of rDCB varies among different satellite systems and frequency bands. Compared to the Galileo, GPS and GLONASS satellite systems, the Beidou system (BDS) rDCB estimates exhibit a stronger correlation with the measured temperature. The percentages of stations with the mean absolute Pearson correlation coefficient value above 0.8 are 27.17% for GPS, 30.58% for GLONASS, 43.78% for BDS and 33.9% for Galileo, respectively. Keywords Multi-frequency and multi-GNSS · Total electron content (TEC) · Time-varying receiver differential code biases (rDCBs) · Modified carrier-to-code leveling (MCCL)
1 Introduction The accurate ionospheric total electron content (TEC) derived from global navigation satellite system (GNSS) observations can not only serve the needs of single-frequency GNSS users for the calibration of ionospheric delay errors but can also contribute to the improvement of the convergence behavior of precise point positioning (PPP) (Odijk 2000;
B
Yunbin Yuan [email protected]
1
State Key Laboratory of Geodesy and Earth’s Dynamics, In
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