Theory, Algorithms And Implementation Of Network Real-Time Kinematic Positioning Based On Continuously Operating Reference Stations

While compared with Standard Real-Time Kinematic (SRTK) technology, Network Real-Time Kinematic (NRTK) positioning technology, which is based on Continuously Operating Reference Stations (CORS), has the following advantages:1. The characteristic of continuously operating. The CORS can provide redundant observations, also it can mitigate the sidereal, seasonal as well as anniversary periodic errors largely, and thus it could provide users with all-weather continuous precise navigation and positioning services.2. The characteristic of multiple reference stations (MRS). Because of the use of multiple reference stations, the redundant observations can be gained and the spatial dependent errors can be precisely modeled, so the accuracy and availability of navigation and positioning are improved greatly; in order to ensure the reliability and continuity of services, MRS can also backup each other when necessary; in addition, while with a large scale coverage, MRS can provide wide-area navigation and positioning services seamlessly.By all appearances, the CORS-based NRTK technology embodies many unmatchable merits when compared with SRTK. Many evidences show that spatial data infrastructure, which is with CORS-based NRTK as a leading technology, will be posed upon an emphasis in the further national infrastructure construction; furthermore, the CORS-based NRTK navigation and positioning services will become the extremely potential application in the future, therefore, development and studies for CORS-based NRTK algorithms have many high applied and academic values.Firstly, the errors which affect NRTK positioning precision and availability are investigated comprehensively so as to implement a system which is capable of continuously operating, concurrent accessing with abilities of wide-area coverage, high precision and reliability as well as high availability. Then, the optimized network construction, real time data preprocessing, network ambiguity resolution and network parameter (including spatial dependent errors) estimation, network correction generation and distribution are anatomized one by one, and simultaneously a series of innovative and improved algorithms have been proposed and that a great deal of experiments have been carried out to prove the efficiency and feasibility of the proposed algorithms. A VRS-based NRTK software package, namely VENUS (Vrs-Enhanced Network Utility Solution), has been developed, tested and evaluated. The results show the correctness and efficiency of the presented algorithms.The main contents of this paper consist of the following two parts:1. Studies of theories and algorithms. In this paper, a new network constructing and updating algorithms for large scale CORS have been proposed, furthermore, several algorithms for removing and mitigating all kinds of spatial dependent and independent errors have been proposed and improved after these errors are analyzed in detail; otherwise, effective least-square cycle-slip estimation algorithm based on kalman-filter has been addressed and optimized system of equations over multiple-baselines are set up and a algorithm for integrated fast ambiguity resolution has been advanced with linear independence of observations and the dependence of ambiguities analyzed carefully; in addition, a new integrated NRTK technology - Augmentation Reference Station (ARS) has been put forward and also a correction encoding format based on RTCM, which has small transmission is recommended for supporting it while comprehensively analyzing the shortcomings of VRS, MAC and FKP technology for network parameters estimation as well as network correction generation and distribution.2. A NRTK system, based on VRS technology, called VENUS, has been developed by our team which implements the presented algorithms. The experiments have been carried out to test and assess the performance of the software systematically. The results show that VENUS has equivalent performance when compared to GPSNet^TM and SpiderNet^TM capable of continuous operation, concurrent accessing services with abilities of wide-area coverage, high precision and reliability as well as high availability.