基于星历和回波的分布式卫星SAR系统沿航迹基线计算方法

摘要

针对分布式卫星SAR系统中混合基线和雷达斜视导致沿航迹基线难以精确计算的问题,提出了一种基于星历和回波数据的沿航迹基线计算方法.在将分布式卫星航迹补偿为平行航迹的基础上,建立了存在混合基线及雷达斜视条件下的观测几何模型,推导了沿航迹基线的计算公式.根据雷达回波数据估计多普勒中心频率,并由此得到计算沿航迹基线所需的斜视角.在空间基线较长、斜视角较大条件下,该方法相比近似计算方式而言,能获得高精度的沿航迹基线估计.仿真结果表明,用该方法计算得到的沿航迹基线长度作为测速定位的基线参数,可以获得高精度的动目标测速定位结果.%Three-dimensional sparse distribution of the antennas and squint SAR in distributed-satellite SAR systems makes it difficult to estimate the along-track baseline accurately. Thus, an along-track baseline determination method is proposed based on ephemeris data and radar echoes. The geometric model of squint SAR systems with satellites distributed in three-dimensional space is established after the non-parallel track compensation. And the formula for calculating the along-track baseline is deduced. The squint angle is obtained according to the Doppler centroid estimated from the radar echoes. Compared with some approximate methods, more accurate results can be achieved with this method in the case of long baseline and large squint angle. Simulation results illustrate that accurate velocity estimation and relocation of moving targets can be obtained by using the proposed method to determinate the along-track baseline.