【摘要】 卫星导航信号源是卫星导航接收机研制过程中的重要测试设备。采用软件无线电技术,实现了一种基于DSP+FPGA的多通道GPS中频信号源。基于GPS中频信号数学模型,给出了系统整体设计方案。采用模块化设计,详细阐述了DSP与FPGA的数据交互逻辑、总线接口模块、载波NCO模块、码模块和导航电文缓冲模块等系统关键部分的实现及重要参数设置的依据,并给出Model Sim-Altera 6.4a下各模块的仿真结果。实测结果表明,信号源生成中频信号波形、频谱符合GPS信号体制规范,且能够被软件接收机正确捕获、跟踪。该信号源具有良好的实时性和可扩展性,成本可控,可有效应用于实验室环境下接收机的性能测试。更多还原

【Abstract】 Satellite navigation signal source is an important test equipment for the development of satellite navigation receiver. Using software defined radio technology,a multi-channel GPS intermediate-frequency( IF) signal source was developed based on DSP and FPGA. According to the mathematical model of GPS IF signal,the system overall design scheme is given. Using block-based design,the key parts of the signal source and the bases of settings for significant parameters are fully detailed,including the data exchange logic between DSP and FPGA,bus interface module,carrier NCO module,code module and navigation message buffer module. The simulation results of these modules in Model Sim-Altera 6. 4a are also presented. The practical test results show that waveform and spectrum of the IF signal generated by the signal source is in line with GPS signal specification and the IF signal can be acquired and tracked correctly by software receiver. The signal source has good real-time performance and scalability with controllable cost,which is able to be effectively used in the lab for the performance test of the receiver.更多还原