Gps If Satellite Signal Simulation

With the increasing widely application of GPS,the users of the GPS receiver have higher performance requirements on GPS receiver. The development of various GPS receiver of high performance to meet the needs of the users becomes an inevitable trend. To test various properties of the receiver,signal simulator is needed to generate various real satellite signals.So the study on GPS receiver all begins from digital IF signal.In this context,GPS IF Signal Simulator model is derived,a software simulation platform is built.the software program is given,and the performance of signal generation algorithm is verified.In this paper,our target is to realize GPS IF digital signal simulation,which is based on Matlab/Simulink platform.The generation algorithm and the receiver algorithm of IF signal in real environment is studied and simulated.This paper discusses the mathematical model of the GPS IF digital signal,the error model of navigation signal in detail,presents several key issues we should pay attention to when we simulate signals,gives the software structure of the IF signal simulator. Meanwhile, the paper also carries out a simple receiver algorithm research on IF signal and verifies the tracking and acquisition performance of software receiver using the IF digital signal generated by simulation.Experimental results show that the system basically realizes the generation and reception function of IF GPS signal, and the receiver can despread and demodulate correctly. Initial phase of PN code and carrier frequency can be obtained under certain accuracy.In addition, the traditional P-code acquisition technique get P code information from the C/A code, and then capture P code, but when the C/A code is not available, we must capture the P code directly.Therefore P code generator was simulated and its performance is simplely analysed in this article,which lay a foundation for future study on direct capture technology of P code. The simulation results show that the simulated P-code generator can produce correct P-code sequences,which can provide simulation environment for the development and test assessment of P code direct acquisition receiver.