Algorithm And Implementation Of GPS Ephemeris Demodulation And UTC Time Conversion

Global Positioning System(GPS) has many advantages,such as global, all-weather,high precision and three-dimensional positioning,etc.,so it is the most advanced satellite navigation and positioning system which is widely used.So it's necessary to research it,which will be useful for Chinaese navigation and positioning technology.This paper focuses on GPS ephemeris demodulation and UTC time conversion. Compared with the traditional design of GPS ephemeris demodulation and UTC time conversion,the design in this paper cost less at the aspect of hardware.In the design of GPS ephemeris demodulator,it also contains single-bit error correction,multi-bit overturning error correction and a new algorithm of the sub-frame synchronization in addition to the basic features.This paper mainly contains the following topics:First,the basic theory of the GPS system and the navigation message are introduced in this paper.Second,this paper describes a basic algorithm of GPS ephemeris demodulation, then it introduces single-bit error correction and multi-bit overturning error correction. At the same time,this paper gives out a new algorithm of the sub-frame synchronization. The new algorithm can achieve the accuracy rate of the traditional algorithm with higher speed of sub-frame synchronization.Last,the algorithm of UTC time conversion is verifyed by use of Matlab platform and realized on the platform of FPGA development board.Then the data of UTC time that converted from GPS time is sended to PC through the serial port.