Adaptive Tune The Zero-gps Receiver Software And Simulation To Achieve

More than twenty years have passed since the first commercial GPS receiver was available on the market. Since then, the receiver development has come a long way. With the development of modern science and technology, Global Positioning System (GPS) is a new generation of precision positioning technology that consist of aerospace technology, computer technology, satellite navigation and geodetic technology and satellite communication technology.All in all this work completed based on MATLAB. According to GPS signal structure and modulation characteristics, a GPS intermediate frequency digital signal is simulated under the condition of noise environment. Based on this data, the technology about adaptive processing, acquisition, tracking and decoding will be studied.At adaptive processing stage, the paper select power inversion (PI) algorithm after compared the MUSIC algorithm and PI algorithm. Suppose interference signal and useful signal inject on the array antenna in different directions, the PI algorithm is selected to weaken the interference signal. One feather of PI algorithm is that the stronger the interference signal is, the deeper the null depth is. So the paper improves the PI algorithm to get deeper null under the weak interference.At acquisition stage, based on C/A code autocorrelation and cross correlation, the paper analyzes key parameters in acquisition and contrast several algorithm. Then, we select parallel code phase search algorithm in acquisition. In order to make the track loop into lock quickly, the paper uses FFT spectral analysis to get fine frequency.At tracking stage, after analysis the characteristics of the In-phase code tracking loop, the paper uses the In-phase and Quadrature code tracking loop to track the code phase. Then we discuss the influence of frequency offset on code loop in the noisy environment. Finally, paper couple the code loop and carrier loop together to track GPS signal in close loop and analyze the tracking results under different signal strength.After get the output of the promote code arm and bit synchronization, the navigation data is demodulate. Compared the results with the raw navigation data, the algorithm of GPS software receiver is prove to be correct.