Research On GPS/BD-Ⅱ Integrated Positioning Technology

Currently, there are four global satellite navigation systems: GPS system, GLONASSsystem, the Beidou satellite navigation system and the Galileo system in the world. AlthoughGPS satellite navigation system technology is more mature, but in some areas there is still alot of problems. Therefore, in order to meet higher navigation positioning accuracy andperformance, using combined navigation system would greatly increases the observables ofnavigation and positioning, improve the quality of navigation and positioning services, andbroaden satellite navigation the field of application. In recent years, with the rapiddevelopment of the satellite navigation system, the integrated use of two and more satellitenavigation systems had become a major research direction in the field of satellite navigation.Therefore, this paper put forward the idea that the observations of GPS system and BD-2system can be integrated to enhance the performance of navigation system and mainly studiesGPS/BD-2integrated positioning technology:First of all, this paper analyses compatibility and interoperability between GPS and BD-2,demonstrates the need for the compatible use of the two systems with common theory andthen analyses public signal compatibility with simulation, gives the results of public siginalspectrum overlap and mutual interference. These results proved that GPS system and BD-2system is compatible in the non-overlapping portion of signal band and can be interoperablein the overlapping portion of the signal band; this paper also snalyses the differences about thetime system and the coordinate system, proposes the method to interoperate.Secondly, this paper deduces the observation and measurement error model ofGPS/BD-2integrated system and gives the inhibition methods of measurement error. Thispaper advances least squares positioning algorithm of GPS/BD-2integrated system based ontraditional least squares positioning algorithm and analyses the methods of confirming weightmatrix. Three methods with positioning results of the determination of the weight matrices aregiven: satellite elevation angle method, carrier-to-noise ratio method and posterior estimationmethod.Thirdly, this paper introduces STK simulation software for BD-2system model, analysesthe impact of the BD-2regional enhancement for users. This paper also simulates the degreewhich GPS/BD-2integrated system relative to single system improves performance insatellite geometric distribution, availity availability and continuity to the global users withMatlab. According to the simulation results, the combined system about these three performance indicators is superior to any one of navigation system, and Beidou II systemabout these three performance indicators is superior to the GPS system.Finally, this paper proposes GPS/BD-2integrated system RAIM algorithm based on thetraditional RAIM algorithm, studies the methods of determining the availability for RAIMalgorithm and simulates the availability of single system and integrated system, gives thedegree which GPS/BD-2integrated system relative to single system improves availability forRAIM algorithm. According to simulation results, the combined system in the RAIMalgorithm of availability is stronger than any one of navigation system, Beidou II system inthe RAIM algorithm of availability is better than GPS system.