Switching position and range-domain carrier-smoothing-code filtering for GNSS positioning in harsh environments with intermittent satellite deficiencies |
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| Authors: | Guobin Chang Tianhe Xu Chao Chen Bing Ji Shengquan Li |
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| Institution: | 1. School of Environmental Science and Spatial Informatics, China University of Mining and Technology, Xuzhou 221116, China;2. Institute of Space Science, Shandong University, Weihai 264209, China;3. State Key Laboratory of Geo-information Engineering, Xi''an Research Institute of Surveying and Mapping, Xi''an 710054, China;4. Department of Navigation Engineering, Naval University of Engineering, Wuhan 430033, China;5. Acoustic Science and Technology Laboratory, College of Underwater Acoustic Engineering, Harbin Engineering University, Harbin 150001, China |
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| Abstract: | Carrier-smoothing-code filtering (CSCF) is widely used in GNSS signal processing to combine code pseudoranges and carrier phases. Position-domain (PD) CSCF is generally more accurate and less sensitive to visible satellite changes than range-domain (RD) CSCF. However, PD-CSCF necessitates at least four visible satellites. Intermittent satellite deficiency with less than four visible satellites is not uncommon in harsh environments like urban canyons. At such deficiency epochs, the PD-CSCF convergence has to break off. This study aims to bridge intermittent deficiency epochs in PD-CSCF without introducing any external information. The proposed solution is called switching RD and PD CSCF in which PD filter is replaced by RD filter at deficiency epochs. Besides detailing the seamless switching algorithms from PD/RD to RD/PD filters, a global RD filter, different from the conventional one, is developed to preserve the correlations among smoothed pseudoranges corresponding to different satellites. Compared to the conventional PD and RD CSCF algorithms, smoother results can be expected from the proposed switching filter, especially after the intermittent deficiency epochs. Experiments are conducted using real BDS signals. Cases with different kinds of deficiency are considered. Superiority of the proposed method is clearly observed from the results. |
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| Keywords: | Corresponding author at: School of Environmental Science and Spatial Informatics China University of Mining and Technology |
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