涌浪及降雨影响下的GNSS海面反射信号建模

全球导航卫星系统（GNSS）海面反射信号的模拟仿真采用的海浪谱多为风驱模型，而忽略了真实复杂环境中涌浪、降雨的影响。为此，提出了一种涌浪、降雨影响下的GNSS海面反射信号模型。首先，对Elfouhaily海浪谱、涌浪谱、降雨谱分别进行仿真，从海浪谱的角度分析涌浪、降雨对GNSS反射信号的影响。然后，设计了引入涌浪、降雨影响因子后的GNSS反射信号建模的方法，并建立噪声模型。最后，对星载场景下仿真得到的二维时延-多普勒相关功率分布图像（DDM）、时延相关功率波形（DW）进行分析，并与英国技术演示卫星（UK TDS-1）实测数据的处理结果进行了对比验证。结果表明:涌浪主要形成对GNSS反射信号影响较大的大尺度粗糙海面，而降雨对GNSS反射信号影响较小；仿真的DDM与实测数据结果的波形有很好的一致性，DW对比的相关系数达到0.92，优于未修正模型的对比结果，模拟的反射信号更为真实，证明了提出的GNSS反射信号建模方法的可行性、有效性。对真实复杂环境下的GNSS反射信号建模及GNSS反射信号星载探测应用研究具有一定的参考意义和实用价值。 

Modeling of GNSS-R signal under effects of swell and rain

The simulation of global navigation satellite system (GNSS) signal reflected from the ocean surface mostly uses wind-driven wave spectrum, which ignores the effect of swell and rain in real complex environment. For this reason, a model of GNSS signal reflected from the ocean surface under the effect of swell and rain is proposed. First, Elfouhaily spectrum, swell spectrum and rain spectrum are simulated respectively. The effects of swell and rain on GNSS-R signal are analyzed form the perspective of wave spectrum. Then, the method of modeling the GNSS-R signal after introducing the factors of swell and rain is designed. The noise model is established. Finally, the delay-Doppler maps(DDM) and dely waveform(DW) simulated in the spaceborne scenario are analyzed and compared with the results of the UK TDS-1 measured data. The validation results show that the swell mainly forms the large-scale rough sea surface which has great influence on the GNSS-R signal, while the rain has little influence on the GNSS-R signal. The simulated DDM has good consistency with the measured data, and the correlation coefficient between simulated DW and measured data is 0.92, which is better than the comparison result of the uncorrected model. The simulated reflected signal is more real, which proves the feasibility and effectiveness of the proposed GNSS-R signal modeling method. It has certain reference significance and practical value for the modeling of GNSS-R signal in real complex environment and the application of GNSS-R spaceborne detection.