基于时频变换的雷达运动目标参数估计方法研究

Research on estimation method of radar moving target parameters based on time-frequency transform

针对机载合成孔径雷达(SAR)系统对地面目标检测时,目标回波的距离抖动与多普勒扩散造成的成像能量不聚焦现象,文中对对地的SAR成像方法进行了研究。针对SAR平台的正斜视模型,当进行距离脉压后,在距离方向上引入了快速傅里叶变换,对变换结果进行Keystone变换与慢时间反变换,最后使用方位上的快速傅里叶变换得到聚焦的成像结果。通过各种时间、频率变换方法的引入,在成像时解决了能量散焦的问题。可以精确估计地面目标的运动目标参数,算法在X波段SAR平台实测数据上的参数估计精度可达99.54%。此外,该算法不含遍历搜索方法,运算复杂度远小于二阶Keystone法与Deramp-Keystone等传统参数估计方法。

When the airborne synthetic aperture radar(SAR)system detects the ground target,the imaging energy caused by the range jitter and Doppler diffusion of the target echo is not focused.In view of this phenomenon,this paper studies the imaging method of ground SAR.For the forward squint model of SAR platform,fast Fourier transform is introduced in the range direction after pulse compression.Then the keystone transform and slow time inverse transform are applied to the transform results.Finally,the focused imaging results are obtained by using the fast Fourier transform in azimuth.Through the introduction of various time and frequency transformation methods,the problem of energy defocusing is solved during imaging,and the parameters of moving targets on the ground can be estimated accurately.The accuracy of the algorithm is 99.54%on the measured data of X-band SAR platform.In addition,the algorithm does not include the ergodic search method,and the computational complexity is far less than the traditional parameter estimation methods such as the second-order keystone method and the deramp-keystone method.