Extraction and Application of Un-differenced Atmospheric Delays with Un-combined Precise Point Positioning Technique
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A new method for the extraction and application of un-differenced atmospheric delays with un-combined precise point positioning technique, is proposed based on the regional continuous operational reference system (CORS) network. The estimable state vector, which lets in the receiver clock offset, the ionospheric slant delay and zenith tropospheric wet delay (ZWD), is estimated epoch by epoch at every reference station. In addition, the least squares and the ionospheric regional polynomial model is also used to separate the DCB and the ionospheric delay. For improving the convergence time of the PPP, a new PPP algorithm, which was suited for single-frequency and dual-frequency receivers, was put forward. The algorithm took full use of the interpolation of regional atmospheric delay value as the quasi-observable, and the un-combined satellite-different observations were used to obtain the precise positioning results. Nevertheless, the method mentioned above is investigated and examined on the IGS tracking stations. The results show that all the satellites’ DCB are solved and compared with the products published by CODE, the disparity between them is mostly not greater than 0.2 ns. Furthermore, with the aim of the real-time fast precise point positioning based on the sparse regional CORS, results from American CORS data set is introduced and discussed. The positioning accuracy can reach 10 cm in the plane within 30 min for the single-frequency PPP user and the plane position result in 1–2 cm also can be accomplished after the convergence of the filter. For dual-frequency receiver, it takes approximately 10 min to get positions with accuracy better than 10 cm at the three directions for the dual-frequency PPP user. On the other hands, due to its epoch-by-epoch nature, the method proposed above is also suited for dynamic precise point positioning.
KeywordsUn-differences atmospheric delays Un-combined PPP DCB Ionosphere-weighted model
This work is supported by the Key Projects in the National Science & Technology Pillar Program during the Twelfth Five-year Plan Period.(2012BAJ23B01). The authors are very grateful to the anonymous reviewers for their constructive comments and suggestions.
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