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由于全球导航卫星系统反射(GNSS-R)机载试验耗费大和重复性差,需研制GNSS-R信号模拟器,但没有相应的反射信号模型。提出了一种基于数据拟合的机载GNSS海洋反射信号建模方法。首先,对复杂的GNSS海面反射信号进行近似简化。然后利用ZV模型生成的时延相关功率曲线,通过最小二乘拟合和非线性拟合,建立了多条等时延间隔的海洋反射信号功率衰减模型,从而得到机载GNSS海洋反射信号的时延、功率、多普勒频率参数。最后,对多条反射信号的合路信号进行相关的仿真验证。验证的结果表明模拟的14条反射信号的相关功率曲线与ZV模型理论曲线的相关系数优于0.99,能够有效地用于GNSS海洋反射信号的生成。该方法可根据海面风场、浪高、波高等海面信息,模拟不同海况的海洋反射信号,为GNSS-R信号模拟器的研制奠定基础。
Due to the high cost and repeatability of GNSS-R airborne tests, a GNSS-R simulator was developed but no corresponding reflected signal model was developed. A method of airborne GNSS ocean reflection signal modeling based on data fitting is proposed. First, approximate the complex GNSS sea surface reflections. Then using the delay-dependent power curve generated by the ZV model, a series of power attenuation models of ocean reflection signal with equal time delay interval are established by least-squares fitting and nonlinear fitting to obtain the time-dependent GNSS ocean reflection signal Delay, power, Doppler frequency parameters. Finally, the combined signals of multiple reflection signals are verified by simulation. The verification results show that the correlation coefficients between the correlation power curves of the 14 simulated reflection signals and the ZV model theoretical curve are better than 0.99, which can be effectively used for generating the GNSS ocean reflection signal. The method can simulate sea reflection signals in different sea states based on sea surface wind field, wave height and wave height, and lay a foundation for the development of GNSS-R signal simulator.