Research Of Assessment Techniques About GNSS User Autonomous Integrity Monitoring System

GNSS have been becoming an important infrastructure for human development and technological progress. Nowadays, with the rapid development of Integrity monitoring technology, users autonomous integrity monitoring plays a vital role in the security of civil aviation. The research of the GNSS users autonomous integrity monitoring and the assessment methods will not only promote the performance indicators of navigation satellite system, improve and upgrade the performance of satellite navigation systems, enhance the interoperability of GNSS open services, but also provide a reference for the construction of BeiDou system:Based on the project of GNSS a utonomous integrity monitoring, this thes is researches deeply on the indicator syste m of user autonomous integrity monitoring and index we ights. The ma in w ork inc ludes :1. The principle of RAIM algorithm and its influencing factors are researched. The reasons of the faulted satellites are presented. The pseudo-range noise, integrity risk, RAIM availability, alarm time, alarm limits and other parameters are analysed. In addition, several models of satellite failures are discussed. By the parity vector method, the gradient model, step fault model and the mix model under the single satellite failure are simulated. Simulation results are consistent with the theoretical analysis.2. The evaluation index system of user autonomous integrity monitoring system is constructed. From the purpose and content of the assessment system, combined with the performance requirements of integrity monitoring system, through theoretical analysis, the more comprehensive multi- level evaluation index system are selected. According to the theoretical approach of the system evaluation, the commonly used methods of determining the index weight- AHP method and weight determination method based on the information entropy are analyzed. The principles and steps of these two methods are detailedly introduced and analyzed.3. By the entropy fuzzy comprehensive evaluation method, the User Autonomous Integrity Monitoring is assessed and analyzed. This method firstly combine the AHP method and the information entropy method, and find the weight value of the secondary indicators system and the results of this layer; then, according to the assessment level membership to solve the fuzzy matrix, and obtains the final evaluation results using fuzzy comprehensive evaluation method, evaluation results show the importance of its indicators were: integrity risk, alarm time, alarm limits; Finally, The evaluation system is presented through the visual interface by MATLAB-based GUI.