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电离层频率调制导致地表面杂波的多谱勒展宽,极大地限制了高频天波雷达的目标探测性能。本文针对这种电离层频率调制,给出了一种级联的两步校正处理的方法。在第一步校正中,首先分析这种时变信号的时频分布,并设计了一种谱峰追踪方法从时频分布中获得粗糙的电离层频率调制估计。然后采用基于分段多项式相位模型的参数化方法作二次校正处理,消除残余调制污染。模拟结果表明,即使对Bragg峰发生混叠的重污染的情形,这种级联的校正方法都具有非常好的效果。
Ionospheric frequency modulation leads to Doppler spread of surface clutter, which greatly limits the target detection performance of HF sky-wave radar. In this paper, we propose a cascaded two-step correction method for this ionospheric frequency modulation. In the first step, we first analyze the time-frequency distribution of this time-varying signal and design a spectral peak tracking method to obtain coarse ionospheric frequency modulation estimates from the time-frequency distribution. Then, a parametric method based on piecewise polynomial phase model is used for secondary calibration to eliminate residual modulation pollution. The simulation results show that this method of cascade correction has a very good effect even with heavily contaminated Bragg peaks.