软件GNSS信号模拟器架构与中频信号生成

Architecture of software-based GNSS signal simulator and implementation of its IF signals generation

软件GNSS(Global Navigation Satellite Systems)信号模拟器对于GNSS接收机的高效研发将做出重要贡献,因其结构灵活、开放性以及低成本.以GPS/Galileo组合系统为例,讨论了软件GNSS中频信号模拟器的架构,主要功能模块包括卫星星座仿真、接收机轨迹生成、传播通道特性仿真(包括电离层模型、对流层模型、多径模型等)、数字中频信号生成.在此基础上,着重阐述了数字中频信号生成模块的实现,功率谱图及分析结果验证了所生成的信号,包括GPS L1 C/A,Galileo E1 CBOC(Composite Binary Offset Carrier),Galileo E5a和E5b信号.

The software-based global navigation satellite systems （GNSS） signal simulator would be an enormous asset for the efficient development of GNSS receivers, due to its flexible structure, the possibility for easy updates and changes and low cost. A hybrid GPS/Galileo intermediate frequency（IF） software-based signal simulator was proposed. The architecture and implementation description for it are included. This hybrid IF signal simulator consists of the following main parts, i.e. GPS/Galileo satellite constellation simulation, receiver trajectory generation, propagation and disturbance channel （including the ionosphere model, the troposphere model, the multi-path model and etc. ）, and GPS/Galileo IF signals generation. Meanwhile, the hybrid GPS/Galileo IF signal generator was presented in detail, which provides the following signals： GPS L1 C/ A, Galileo E1 CBOC（composite binary offset carrier） , Galileo ESa and ESb signals. Finally, the power spectral density （PSD） curves for the IF signals obtained with the hybrid signal simulator were given. From the PSD point of view, the implementation of the hybrid signal simulator was validated.