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为了降低双基地距离模型的二阶级数近似给成像算法带来的误差,提出了求解距离-Dopple(RD)表达式的新方法。利用级数反演的方法,推导出具有闭合形式的方位向调制函数;利用RD域中瞬时Doppler频率与瞬时斜视角的对应关系,推导出精确的距离弯曲因子;利用双基地距离模型的二阶近似表达式,通过传统的三步变换法,推导出等效距离向调频斜率。通过新方法获得的方位向调制函数和距离弯曲因子具有更高的近似精度,能够提高并轨双基地chirp scaling算法的成像性能。仿真结果证明了该方法的有效性。
In order to reduce the error caused by the second order approximation of the bistatic distance model to the imaging algorithm, a new method to solve the distance-Dopple (RD) expression is proposed. Using the method of series inversion, the azimuth modulation function with closed form is deduced. Using the correspondence between instantaneous Doppler frequency and instantaneous oblique angle in RD domain, the accurate distance bending factor is deduced. By using the second order of bistatic distance model The approximate expression, through the traditional three-step transformation method, derives the equivalent range to FM slope. The azimuth modulation function and the distance bending factor obtained by the new method have higher approximate accuracy and can improve the imaging performance of the bilinear chirp scaling algorithm. Simulation results show the effectiveness of this method.