在GNSS—R海洋遥感探测中,机载试验是一种重要手段;针对GNSS-R机载试验需要耗费巨大人力、物力以及可重复性差的问题,研究并设计了一种反射信号软件模拟器,介绍了模拟器的总体结构、流程图、关键参数、主要模块及用户界面;该模拟器在GNSS直射信号模拟器的基础上,在直射通道之外并行增加了反射信号通道;通过分析导航卫星反射信号的特点,并利用基于Z—V模型的GNSS海洋反射信号模型,配置机载GNSS海洋反射信号的时延、功率和多普勒频率等参数,从而模拟产生多颗星的多条反射信号;该模拟器可分别生成直射、反射信号两个数字中频文件,直接送人GNss—R软件接收机进行接收处理;实验结果表明GNSS-R软件接收机的接收处理结果与设定的基于Z—V模型的相关功率曲线的相关系数为0.9977,模拟器产生的反射信号与真实信号相关特性几乎一致,能根据用户输入的不同参数模拟输出导航卫星反射信号。
Airborne experiment is an important way of GNSS-R ocean remote sensing. In order to solve the problem that GNSS-R air- borne experiment requires huge manpower and material resources and it has a poor repeatability, this paper studied and designed a kind of GNSS reflected signal simulator, and the structure, flow chart, key parameters, components and user interface of the simulator were presen- ted. This reflected signal simulator software based on the direct GNSS signal simulator, and both have direct signal channels and reflected signal channels parallel. Through analyzed the characteristics of navigation satellite reflected signal, and used a GNSS sea reflected signal model that is based on Z-V model, set time delay, Doppler frequency and power parameters of airborne GNSS ocean reflection signal, to simulate more multiple reflections of different satellites. This simulator could generate two intermediate frequency files of direct and reflected signals respectively that can be send to GNSS-R software receiver. The simulation experiment results show that the correlation coefficient between the Z-V model theory curve and the result of the reflection signal simulator is 0. 9977, the reflected signals of simulator have a same correlated characteristic with the real signals, and it can according to the different parameters of user~ s input analog output navigation satel- lite reflected signal.