初相捷变波形优化设计与信号处理方法研究
Research on Optimization Design and Signal Processing Methods of Initial Phase Agility Waveform
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摘要: 捷变波形具备一定的距离和速度模糊抑制能力,同时兼具优良的低截获和抗干扰性能,为雷达系统提供了新的信号处理维度。初相捷变波形相对简单,工程实现难度小,为实现波形设计和信号处理闭环,本文开展了初相捷变波形优化设计与信号处理方法研究。首先,介绍了初相捷变波形的距离选通特性,进而构建了基于距离选通特性的初相捷变波形优化设计模型,并通过Majorization-Minimization算法和牛顿法进行求解。所提算法可采用平方迭代法加快收敛速度,经仿真验证,与随机产生的初相捷变波形相比,所提算法可以显著改善优化后初相捷变波形的距离选通特性。其次,基于初相捷变波形的抗折叠杂波性能,探讨了基于距离选通特性的自适应杂波抑制算法,即利用初相捷变波形空时维导向矢量的距离选通特点,实现分距离段杂波抑制,使得近距主副瓣杂波不会折叠到远距离段,经仿真与实测数据验证,所提算法在强杂波环境下具备良好的远距低速目标探测能力。最后,研究了基于距离选通和交替反演的干扰抑制算法,利用远距支援干扰滞后于目标回波的特点,并基于初相捷变波形的距离选通特性,通过距离段间交替投影实现干扰与目标回波的分距离段重构,经仿真验证,所提算法可以实现对远距支援干扰的有效抑制。Abstract: The agile waveform has a certain ability to suppress range and velocity ambiguity and expand the difference between jamming and target, while also possesses excellent low interception and anti-jamming performance. Compared to waveforms with fixed parameters, the agile waveform provides a new signal processing dimension for radar systems. The initial phase agility waveform (IPAW) is relatively simple and it is also easy to engineering implementation with low hardware requirements. To achieve waveform design and signal processing closed loop, this article conducts the research on optimization design and signal processing methods of the IPAW. Firstly, the range gating characteristic of the IPAW is introduced, and an optimizing model for IPAW design based on the range gating characteristic is constructed. The solution of the model is achieved through the Majorization-Minimization algorithm and the Newton, and squared iterative method can be easily applied to the proposed method in this article. After simulation verification, compared with the randomly generated IPAW, the proposed algorithm can significantly improve the range gating characteristic of the optimized IPAW. Then, according to the ability to suppress folded clutter, an adaptive clutter suppression algorithm based on range gating characteristic is explored. By utilizing the range gating characteristic of the space-time steer vector of the IPAW, clutter suppression in each range segment is achieved. So that the main and side lobe clutter in near-distance does not fold to the long-distance range segment. Through simulation and measured data, the detection performance of the algorithm for long-distance and low-speed targets in strong clutter environment has been verified. Finally, in view of the range gating characteristic and alternating inversion, a deceptive jamming suppression algorithm is proposed. Exploiting the characteristic of long-distance support jamming lagging behind the target echo, and based on the range gating characteristic of the IPAW, jamming and target exhibit significant energy distribution difference in the range Doppler dimension. Therefore, range segment reconstruction results of jamming and target echo is achieved through alternating projection between range segments. The effectiveness in suppressing long-distance support jamming is demonstrated through simulation.