雷达波谱仪信号仿真及海面各向异性的修正

摘要

In order to research the signal preprocessing and the inversion method of the ocean wave, the simulation model of a space-borne real aperture radar spectrometer based on signal flow is established. The block diagrams for the modulation spectrum and directional spectrum simulation are provided. Using the simulation model, different ocean wave spectrum model and ocean conditons are simulated. The results show that the retrieved modulation spectrum and referenced modulation spectrum are highly related. What is more, a method used to correct the influence of the ocean anisotropy is proposed. The ocean anisotropy can be corrected by using the normalized modulation coefficient. The simulation results show that the directional spectrum retrieval error is significantly reduced after modulation coefficient correction, especially in the conditon that wind wave and swell wave exist simultaneously and are vertical to each other. The energy integral error of directional spectrum reduces to 2%from 20%.%为研究星载真实孔径雷达波谱仪信号预处理及海浪谱反演方法，该文建立了雷达波谱仪信号仿真模型，阐述了海浪调制谱和方向谱的信号仿真流程。对不同海浪谱模型，不同海况条件下的海面进行仿真，结果表明反演得到的调制谱与参考调制谱具有良好的一致性。同时，海面各向异性对海浪方向谱的反演存在影响，进而提出了通过拟合不同方位向雷达后向散射系数随入射角的变化曲线的方法。利用归一化调制系数的方位向变化规律修正海面各向异性对海浪方向谱反演的影响。仿真结果表明，在噪声条件和无噪条件下，经过调制系数修正后，反演方向谱与参考方向谱的误差明显减小。尤其是在风浪和涌浪同时存在且方向互相垂直的海况条件下，方向谱积分能量误差由20%下降到2%以下。