Research Of GNSS Receiver Fast-positioning Technology

With the development of global navigation satellite system,the range of application for satellite positioning and navigation technology becomes more extensive.It is able to provide high precision locating and timing information and also navigation service for user worldwide.The time to first fix(TTFF)of GNSS receiver is a significant indicator when measure its performance.To decrease TTFF,the article made an analysis and research of fast-positioning technology.Firstly,the thesis introduced the basic concepts of GNSS,in order to provide theoretical foundation to improve the fast-positioning algorithm and optimize the process.Secondly,the thesis analyzed three start modes(cold-start,warm-start and hot-start)in GNSS receiver,and discussed the work procedure in hot-start mode when there was(or not)a real time clock(RTC).The algorithm of satellite transmitting time recombination,satellite location and velocity calculation,and receiver location computing were investigated emphatically.Then,the paper suggested a transmitting time estimation method to solve the problem when RTC error was large.Besides,the paper also proposed another locating method based on BeiDou Navigation Satellite System(BDS),which can realize fast positioning without RTC.In addition,the thesis gave an optimization proposal to classify all the satellites into certain types and search their signals in order of priority that can achieve making full advantage of given information and hardware resources.Finally,on the GNSS receiver platform developed by our laboratory,did tests to the fast-positioning algorithm and the optimized scheme and proved their feasibility and effectiveness.For the research of GNSS receiver fast-positioning technology,this article had the theoretic importance and practice value.