Abstract
Different designs of receiver correlators and front ends will cause different biases in terms of the pseudorange. In this paper, we present an algorithm to derive GNSS receiver-dependent code biases by estimating an additional code bias for each satellite based on different orbit and clock products and apply the calibrated biases in user positioning. One-month data from 117 globally distributed multi-GNSS experiment stations are selected to analyze the characteristics of BeiDou Navigation Satellite System (BDS) code biases, including BDS-2 and BDS-3 satellites. It is shown that the BDS code biases on B1I and B3I signals differ by receiver type, receiver model, antenna type, or even unknown factors. The code biases on BDS-2 satellites can reach up to 4 ns from peak to peak, while they are within 2 ns for BDS-3 satellites. The receiver-dependent code biases are calibrated based on the broadcast ephemeris and the precise products. With a correlation coefficient of approximately 0.9, it is demonstrated that the calibrated code biases are in agreement not only among different products, but also with previous result of BDS-2. To validate the effect of the calibrated code biases, we apply them in single point positioning (SPP), precise point positioning (PPP), and real-time kinematic (RTK) positioning. It is proven that with corrected BDS code biases, SPP users will benefit from an overall improvement of 9.5%, 9.9%, and 27.4% at B1I, B3I, and B1I/B3I ionosphere-free frequencies. For the ionosphere-free based positioning using BDS-3 only, the impact of code biases cannot be ignored. The corrected code biases will accelerate the convergence performance in PPP. For RTK applications, especially for single-frequency users, the fixing rate and ratio values will also improve when the code biases are corrected.
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Data availability statement
The GNSS data are provided by the Multi-GNSS Experiment (MGEX), which are available from ftp://cddis.gsfc.nasa.gov/. The precise clock and orbits are provided by IGS analysis center Wuhan University at ftp://igs.gnsswhu.cn/. The DCB products are provided by the Chinese Academy of Science at ftp://ftp.gipp.org.cn/.
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Acknowledgments
This work is mainly funded by the Key R&D Program of Guangdong Province (No. 2018B030325001); the National Natural Science Foundation of China (No. 11673050); the Key Program of Special Development Funds of Zhangjiang National Innovation Demonstration Zone (No. ZJ2018-ZD-009), and the National Key R&D Program of China (No. 2018YFB0504300). The GNSS observation data and products provided by MGEX are acknowledged.
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YZ performed the research and wrote the paper. JC designed the research. NK and JC reviewed and revised the paper. AW helped analyzing the results.
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Zhang, Y., Kubo, N., Chen, J. et al. Calibration and analysis of BDS receiver-dependent code biases. J Geod 95, 43 (2021). https://doi.org/10.1007/s00190-021-01497-6
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DOI: https://doi.org/10.1007/s00190-021-01497-6