基于四阶传递函数大斜视角SAR成像算法

An Imaging Algorithm of SAR in Large Squint Mode Based on Fourth-order Transform Function

针对研究SAR大斜视工作时,为增加天线实时侦察效果,对低阶ETF(Exact transfer function)算法处理方位向相位的近似误差进行改进,在传统ETF成像算法基础上研究了四阶传递函数算法。采用四阶距离模型,分析了距离向聚焦深度为分块数据处理提供了依据,同时在距离多普勒域对非参考距离处目标进行了相位补偿。通过场景目标仿真对算法有效性进行了验证。仿真结果表明,算法可有效补偿大斜视角时方位向近似误差,提高了精度,满足大斜视时成像要求,同时避免插值处理,计算量小,便于实时成像。

For SAR in large squint mode, the azimuth phase approximation error in low order ETF algorithm increases. Based on the conventional ETF algorithm, a fourth order transform function algorithm is proposed. Fourth order range model is adopted. Range focus depth useful for block processing is analyzed. Meanwhile in range Doppler domain, the phase error of the targets away from the reference range is compensated. The validity of the algorithm is verified based on the simulation of the scene targets. Simulation results illustrate that it can efficiently compensate the approximation phase error in azimuth, possess high precision and can satisfy the requirement of imaging quality for SAR in large squint mode. Besides, it needs no interpolation and can perform real - time imaging of SAR.