通信系统的不可靠性会造成SAR卫星下发数据出现误码或丢失,从而导致几何参数的解译、计算出现较大的误差或者缺失,限制了SAR数据成像处理及后续利用。针对该问题,提出一种基于回波数据的成像参数联合估计方法。首先通过回波数据进行多普勒中心频率估计和多普勒调频斜率估计;然后,根据SAR多普勒参数特性,建立多普勒参数与几何参数之间的超定方程组,并利用多普勒参数估计值求解方程组反演几何参数;最后,利用多普勒参数估计值和几何参数估计值完成SAR数据成像处理。实验结果表明,本文方法可以获得可靠的多普勒参数估计值和几何参数估计值,从而有效地解决像参数欠缺情况下的星载SAR成像处理问题。

The unreliability of communication systems may result in bit error or loss in the auxiliary data received by ground stations from satellites. In such cases, it is impossible to obtain accurate geometric parameters by interpreting and calculating from auxiliary data, which will impede SAR imaging processing. To resolve the problem of deficient imaging parameters in spaceborne SAR imaging processing, this paper proposes a joint estimation scheme of imaging parameters based on SAR echo data. In this proposed scheme, the Doppler centroid and Doppler chirp rate are estimated using SAR data. The over-determined equations of both Doppler parameters and imaging geometrical parameters are then established, which take advantage of the Doppler properties of the spaceborne SAR. The Doppler parameter estimates are used to resolve the appropriate geometric parameter equations. Lastly, SAR imaging processing is accomplished by using the Doppler parameter estimates and geometric parameter estimates. Experimental results show that reliable estimates of both Doppler and geometric parameters are obtained using the proposed method, effectively solving the problem of deficient imaging parameters in spaceborne SAR image processing.