A Key Technology Study Of Compass/GPS Dual-mode Positioning

Satellite navigation is a method, which we use satellite positioning system todetermine the position (longitude, latitude and altitude) and time precisely on theearth. Satellite navigation is not only provides high-precision, three-dimensionalposition and velocity in global and near-earth space, but also has stronganti-interference ability. Satellite navigation receiver can provide multiple purposes,such as: measurements (geodetic, engineering surveying), traffic navigation, precisetime measurement, rescue, commercial location and so on. Satellite navigationsystems have important significance in the military and civilian.Firstly, this paper makes a brief introduction for the construction of the GPS andCompass satellite navigation system. And then describes the development stage ofGNSS receiver abroad. Besides, this paper makes a simple description of the receiverchip and navigation module production process.This paper does research about GPS and Compass navigation message parsing,and gives the way of frame synchronization, parity (GPS use parity check, Compassuse BCH (15,11,1) error correction decoding), and analysis. According to thesemethods solve out the GPS and Compass satellite ephemeris. This paper calculates thepseudo-range between the satellite and the receiver. Following, we make somecorrection on the pseudo-range such as: satellite clock error, the error ionosphericeffects, tropospheric effects, relativistic effect. The simulation results show thesecorrection model is correct.This article describes several time systems and coordinate system, and then usethe satellite ephemeris calculate the GPS and Compass satellite position and velocityin ECEF coordinate system respectively according to the calculation formula. In thecompletion of the satellite position, velocity and corrected pseudo-range the studylists GPS and Compass observation equations based on the rear positioning principles,then, combines the GPS and Compass observation equation to calculate the receiverposition and velocity in the ECEF coordinate system according to the least squaresalgorithm. Finally, this paper use matlab make a simulation solution for these algorithms and assess the accuracy of the positioning and speeding which are solvedby the matlab.