The design and implement of GPS software simulation platform

Due to different requirements of Global Positioning System (GPS) applications, performances of GPS receiver vary greatly. In order to evaluate a GPS receiverpsilas performances, a simulation platform build on Matlab has been developed by this research. This platform includes four elements: user interface, GPS signal simulator (intermediate frequency, IF), civilian (C/A) software receiver and noise generator. Design and implementation of the platform are discussed in details in this paper. Firstly, a mathematical model of intermediate frequency (IF) GPS signal simulator is introduced. After that, methods of determining visual satellites and computing transmission time by using existing ephemeris are also discussed. Secondly, key algorithms of the software receiver, including acquisition and tracking, are presented. Finally, an experiment is demonstrated to test the validity of this platform. The close correspondence between pre-designed user trajectories and position results of the software receiver certifies the validity of this platform. Compared with hardware simulation, this platform possesses more effective and flexible. The performances of the receiver can be tested completely by changing different scenes of signal simulator. All key techniques of this platform are modularized and coded with Matlab language. It is easy to understood and used. In this sense, this simulation platform can be an ideal tool for new beginners of this field to master GPS principles.