Accurate method to calculate space-borne SAR Doppler parameters
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摘要: 提出了一种基于空间坐标转换,利用卫星位置、速度参数精确估算星载SAR(Synthetic Aperture Radar)全观测带多普勒参数的方法.利用卫星速度、位置,通过星载SAR空间几何模型和坐标转换关系,建立SAR图像中斜距同卫星下视角之间的四次方程,解出下视角并进一步计算出该斜距处的多普勒参数值.仿真结果表明,该方法在无卫星位置、速度误差情况下估算精度达到0.02Hz(多普勒中心频率)和2×10-4Hz/s(多普勒调频率);存在卫星位置测量误差(300m)以及速度测量误差(0.3m/s)的情况下,估算精度达到0.8Hz(多普勒中心频率)和0.07Hz/s(多普勒调频率).该方法适用于单星SAR以及分布式SAR高精度多普勒参数的估算.Abstract: A new method which can calculate the whole swath Doppler parameters of space-borne SAR(synthetic aperture radar) was presented. The method, based on space coordinate transformation, made the satellite position and velocity as references. Using the space geometric model and the coordinate transformation, a quartic equation between the slant range and the look angle was founded. After solving the equation, the look angle value was got, and the Doppler parameters were then calculated. The simulation results show that the calculation precision of the method can reach below 0.02Hz(Doppler centroid) and 2×10-4Hz/s(Doppler rate) with no satellite position and velocity error. The precision can reach below 0.8Hz(Doppler centroid) and 0.07Hz/s(Doppler rate) even if there are measurement errors in satellite position (300m) and velocity (0.3m/s). This method is suitable for both single SAR and distributed SAR Doppler parameters precision calculations.
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Key words:
- synthetic aperture radar /
- signal processing /
- radar imaging /
- parameter estimate
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