高质量LMSCT时频分析算法及其在雷达信号目标检测中的应用

A High Quality Algorithm of Time-Frequency Analysis and Its Application in Radar Signal Target Detection via LMSCT

针对线性调频小波变换(CT)引入的调频率参数不能完全匹配信号的瞬时频率及算法抗噪性能不佳等问题,提出高质量的局部最大值同步压缩线调频小波变换(LMSCT)算法,改善CT时频分布图能量扩散幅度出现的偏差.所提算法的核心思想是通过局部最大值同步压缩操作重新分配CT的频率点.实验结果表明,LMSCT算法具有较高的时频聚集度,并且能够较好地抑制噪声的干扰,在低信噪比的情况下仍然保持良好的时频聚集度.在IPIX处理雷达信号分析中,LMSCT算法能够较为清晰地描绘目标信号的时间-频率联合分布特性,并且确定目标出现的距离单元,为海杂波背景下的IPIX雷达信号小目标检测提供判断依据.

Aimed at the fact that the chirplet rate parameter of the chirplet transform(CT)cannot match the instantaneous frequency of the signal completely,and that the anti-noise performance of the algorithm is poor,this paper proposes a high-quality local maximum synchrosqueezing chirplet transform(LMSCT)algorithm to improve the deviation of energy diffusion amplitude in CT time-frequency(TF)distribution.The main idea of this algorithm is to reallocate CT frequency points by local maximum synchrosqueezing operation.The experiment results show that the LMSCT algorithm has a higher TF concentration and a strong ability to suppress the interference of noise.The method can maintain a better resolution of TF representation at a low signal-to-noise ratio.In the application analysis of IPIX processing radar signals,the LMSCT algorithm can clearly describe the TF joint distribution characteristic of target signal and determine the distance unit of target,which provides the judgement basis for small target detection of IPIX radar signal in the background of sea clutter.