基于FRFT域自适应滤波的脉冲压缩技术

摘要

Usually,there is a serious interference in radar echo.In the pulse compression radar system with linear frequency modulation signal,the result of pulse compression with radar echo is not ideal frequently.In this paper,according to the strong energy clustering of LFM in FRFT domain,the mixed radar echo consists of interference and target signal is processed by the adaptive filtering in FRFT domain first,then the processed echo is transformed to time domain and processed by pulse compression.The adaptive filter algorithm adopted variable step-size NLMS algorithm,it made improvements to the traditional NLMS algorithm.The simulation results indicate that the radar echo processed by the adaptive filter algorithm in FRFT domain gets better result of pulse compression,and the performance of the pulse compression radar is obviously enhanced.%雷达回波中往往存在严重的干扰,采用线性调频信号(linear frequency modulation,LFM)的脉冲压缩雷达系统中,直接对回波信号进行脉冲压缩往往得不到好的效果.文中利用线性调频信号在分数阶傅里叶变换(fractional fourier transform,FRFT)中的强能量聚集性的特点,在分数阶傅里叶域对混合回波进行自适应滤波,再将滤波后的信号变换回时域进行脉冲压缩处理.自适应滤波算法采用一种改进的变步长NLMS算法,相对于传统固定步长NLMS算法有较好的滤波结果.仿真结果表明,经过分数阶傅里叶域自适应滤波后的信号在脉冲压缩后的目标检测结果有了很大的改善,明显提高了脉冲压缩雷达的检测性能.