一种FMCW SAR地面运动目标谱图域参数估计方法

对调频连续波(FMCW)合成孔径雷达(SAR)地面运动目标的参数估计方法进行了研究,采用相位中心偏置天线(DPCA)技术对地杂波进行抑制,分析了载机及地面运动目标连续运动对回波信号的影响,推导了采用DPCA技术引入的回波慢时间包络(STE)项与地面运动目标参数之间的关系。在此基础上,提出了一种地面运动目标谱图域参数估计方法,该方法首先利用Radon变换在谱图域估计导致回波信号距离走动的目标等效径向速度,并对距离走动进行校正;其次,在谱图域中提取运动目标回波幅度,根据STE项引起的回波幅度变化与目标方位向速度之间的关系,估计目标的方位向速度,并进一步求解相应的目标径向速度。所提方法能够在谱图域完成地面运动目标二维速度估计,最后的仿真实验验证了所提方法的有效性和可行性。

A ground moving target parameter estimation method in spectrogram for FMCW SAR

The ground moving target parameter estimation method for frequency modulated continuous wave (FMCW) synthetic aperture radar (SAR) is studied. The displaced phase center antenna (DPCA) technique is utilized to cancel the ground clutter, then the influence of the platform and target continuous movement to the echo are analysed, and the relationship between slow time envelope (STE) term and ground moving target parameter is deduced. On this basis, a ground moving target parameter estimation method in spectrogram is proposed. Firstly, the Radon transform is utilized to estimate the equivalent across-track velocity which leads to the range walk, and then the range walk is corrected. Secondly, amplitude of the received signals is extracted from spectrogram, and the change of the amplitude is related to the STE. According to the relationship between the amplitude and along-track velocity, the along-track velocity of target is estimated. Furthermore the across-track velocity of target is calculated. The 2D velocity of ground moving target can be accurately estimated in spectrogram with the proposed method. Finally, the feasibility and effectiveness of the proposed method are proved by the simulation results.