低成本X波段超宽带LFMCW-SAR信号源与非线性矫正

Nonlinearity correction of low cost UWB X-band LFMCW-SAR source

本文针对近距离宽带LFMCW-SAR成像的应用背景,提出了一种基于YIG振荡器的X波段5.1 GHz带宽线性调频连续波信号源方案,该方案结构简单、价格低廉,缺点是线性度较低,导致距离分辨率下降.传统非线性估计方法在低信干噪比或多目标混叠情况下,估计精度将严重下降甚至失败.针对这个问题,本文提出一种基于宽窄带滤波器相结合的二次迭代高阶模糊函数非线性误差估计与插值重采非线性矫正方法,该方法在低信干噪比情况下仍能有效估计并矫正发射信号的非线性.论文分别采用仿真数据、延迟线数据以及轨道SAR实测数据对算法进行了验证.

For the application of near range imaging with wideband LFMCW-SAR imaging, this paper presents a scheme to generate X-band signal with 5.1 GHz bandwidth based on a YIG oscillator. This method has a simple structure and low cost. However, it introduces a certain degree of nonlinearity, resulting in range-resolution degradation. Conventional nonlinearity estimation methods do not work well or fail with low SINR. To solve this problem, a two-step high order ambiguity function method, based on wide and narrow band filters, is used to estimate the nonlinear error. The nonlinearity is corrected by resampling. In the end, the nonlinear correction algorithm is validated with simulation data, delay-line data, and rail-SAR data.