Single-channel Gps Analog Signal Source Design Study

GPS (Navigation Satellite Timing and Ranging/Global Positioning System) is based on wireless and possess capability of global, round-the-clock, precise and three-dimensional satellite navigation and orientation. With the purpose of testing the performance of GPS signal simulator is needed that can be used to simulate the real GPS signals under all kinds of the conditions. This paper studies single channel GPS signal generator which is based on software radio.The concept, characteristics and structure of GPS system are firstly introduced in brief in this paper, gives a particular description of GPS signal structure and navigation message. Investigates the techniques for Direct Sequence Spread Spectrum(DSSS) communication system, which involves the selection and generation of pseudonoise sequence(PN code), the processing of spread spectrum signal. Discuss BPSK modulated algorithm and integer interpolation theory. A signal generator based on DSP+DDS is designed. We simulates the whole of system with matlab tools. The algorithm design and interface design which relate the system are written by C language. Software and hardware design work is going along on a hardware platform. The results of experimentation can meet demands and validate the system.Some defects among designing and suggestions for the following jobs are raised at the end of the paper.