一种基于局域中心频率的SAR图像舰船方位向速度估计方法

Ship Azimuthal Speed Estimation Method Based on Local Region Doppler Centroid in SAR Images

针对现有船速估计算法大多数只能估计出舰船距离向速度的问题,该文提出一种基于合成孔径雷达(SAR)图像局域中心频率的舰船方位向速度估计方法。首先分析了动目标在SAR图像局域多普勒中心频率的变化规律,并推导了利用中心频率变化率估计目标方位向速度的理论公式。然后给出了根据SAR图像局域方位向功率谱的概率密度函数,利用最大似然估计算法估计中心频率变化率的方法。同时,对所提方法的精度与适用性应用性进行分析。最后,通过仿真和实测数据,将该方法的估计结果与直接计算调频率获得的结果进行对比分析。结果表明,相对于调频率法,该方法具有更高的估计精度,验证了所提方法的有效性。

To deal with the problem that most of the existing ship speed estimation algorithms can only estimate the slant range speeds of ships, a ship azimuthal speed estimation method based on local region Doppler centroid for Synthetic Aperture Radar （SAR） images is proposed. Firstly, the variation of Doppler centroid of moving target in local region of SAR image is analyzed and the theoretical formula for estimating the azimuthal speed using the slope of Doppler ccntroid variation is derived. Then, based on the probability density function of azimuthal power spectrum, an estimation method for the slope of Doppler centroid variation using the maximum likelihood estimation algorithm is presented. Moreover, the estimation accuracy and the applicability of the proposed method are also analyzed. Finally, the proposed method is implemented on simulated and filed data and the estimation results are compared with those obtained by directly calculating the frequency modulation rate. The results show that the proposed method has high estimation accuracy, which verifies the effectiveness of the proposed method.