Algorithm Of Generating VRS Data For Compass Navigation System

With the fast development of BDS(Compass Navigation System), higher precision of positioning and navigation become the important research aspect. Network Real Time Kinematic(NRTK) based on the continuous operating reference stations can realize the positioning with cm level and become the new technology of higher precision positioning. VRS (Virtual Reference Station) technology is a considerable mature technology to realize the NRTK.The research of BDS’VRS technology is still not so plentiful. Taking all those into consideration, this paper researches the methods of realizing VRS technology of BDS importantly.What’s more, based on the method, a software for generating the VRS observation data of BDS was developed.This paper describes the cycle slip testing methods, ionosphere delay model and troposphere delay model while processing the data of reference stations.While it is difficult to determine the wet troposphere delay, a real time troposphere wet zenith delay model was proposed which named TTZWD-Three-segment Piecewise Troposphere Zenith Wet Delay. Select the meteorological data of IGS stations for experiments. Compared with the Saastamoinen zenith wet delay model, TTZWD zenith wet delay model improved much.A detailed research on fixing the ambiguities of reference stations’network was engaged. The whole processing includes float ambiguities solution by using Kalman filtering and fixing integer ambiguities by using some search methods. Search methods for fixing integer ambiguities is crucial.A method named MLAMBDA (or LAMBDA) which was universally applied in kinematic positioning was illustrated. But de-correlating process by MLAMBDA method, some directions of the search space were sharp. So a modified approach was proposed which was named error ellipse search method (EES) and avoided some sharp search direction to shrink the search space effectively. Compared with the MLAMBDA(or LAMBDA),EES had higher successful rate and used less epochs to fix the integer ambiguities. However, there are at least three baselines and more data in a realistic NRTK. The experiments showed that MLAMBDA had a faster computational efficiency and was more suitable for fixing the ambiguity in NRTK than EES to fix the ambiguities of reference stations.This paper also has a detailed description for constructing the space error of virtual reference station. Some methods and evaluation for those methods were explained.Generating the observation data of VRS was analyzed. The data include range data and carrier phase data. Based on the whole process for generating the VRS observation data,a software for generating the VRS data of BDS was developed in the visual studio2010c++platform.At last, the realistic BDS data of NRTK were used to generate the VRS data and to take experiments. The experiments showed that the algorithm was effective and the rover station positioning by using the VRS data had a accuracy of6-9cm level no matter the ionosphere was effective. BDS VRS improved the accuracy of the long distance RTK. While at the same time, because of the peculiarities for BDS, the RTK results were not so even and smooth.