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Inter-System Differencing between GPS and BDS for Medium-Baseline RTK Positioning

Gao, Wang; Gao, Chengfa; Pan, Shuguo; Meng, Xiaolin; Xia, Yan

Inter-System Differencing between GPS and BDS for Medium-Baseline RTK Positioning Thumbnail


Wang Gao

Chengfa Gao

Shuguo Pan

Xiaolin Meng

Yan Xia


An inter-system differencing model between two Global Navigation Satellite Systems (GNSS) enables only one reference satellite for all observations. If the associated differential inter-system biases (DISBs) are priori known, double-differenced (DD) ambiguities between overlapping frequencies from different GNSS constellations can also be fixed to integers. This can provide more redundancies for the observation model, and thus will be beneficial to ambiguity resolution (AR) and real-time kinematic (RTK) positioning. However, for Global Positioning System (GPS) and the regional BeiDou Navigation Satellite System (BDS-2), there are no overlapping frequencies. Tight combination of GPS and BDS needs to process not only the DISBs but also the single-difference ambiguity of the reference satellite, which is caused by the influence of different frequencies. In this paper, we propose a tightly combined dual-frequency GPS and BDS RTK positioning model for medium baselines with real-time estimation of DISBs. The stability of the pseudorange and phase DISBs is analyzed firstly using several baselines with the same or different receiver types. The dual-frequency ionosphere-free model with parameterization of GPS-BDS DISBs is proposed, where the single-difference ambiguity is estimated jointly with the phase DISB parameter from epoch to epoch. The performance of combined GPS and BDS RTK positioning for medium baselines is evaluated with simulated obstructed environments. Experimental results show that with the inter-system differencing model, the accuracy and reliability of RTK positioning can be effectively improved, especially for the obstructed environments with a small number of satellites available.


Gao, W., Gao, C., Pan, S., Meng, X., & Xia, Y. (2017). Inter-System Differencing between GPS and BDS for Medium-Baseline RTK Positioning. Remote Sensing, 9(9), 948.

Journal Article Type Article
Acceptance Date Sep 11, 2017
Online Publication Date Sep 13, 2017
Publication Date Sep 13, 2017
Deposit Date Jan 26, 2019
Publicly Available Date Jan 28, 2019
Journal Remote Sensing
Publisher MDPI
Peer Reviewed Peer Reviewed
Volume 9
Issue 9
Pages 948
Keywords GPS and BDS; inter-system differencing; differential inter-system biases (DISBs); real-time kinematic (RTK) positioning; medium baselines
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