大测绘带合成孔径声呐斜距向分段运动补偿分析

Analysis of the Motion Compensation About Segmenting Method Along Slant Range for Wide-swath Synthetic Aperture Sonar

运动误差是限制合成孔径声呐实现高分辨率成像的重要因素。对运动误差在斜距向空变性特点进行分析,研究斜距向分段策略,提出适用于大测绘带合成孔径成像声呐的斜距向非均匀分段补偿方法。沿地距向对回波数据均匀分段,借助距离压缩效应可得到斜距向的非均匀子段,顺应运动误差“先快后慢”的空变规律,实现更准确的误差补偿。仿真结果表明,经过非均匀分段补偿后,目标方位向峰值旁瓣比降低,目标与背景的对比度增强,远近目标聚焦差异性减弱。实测数据结果表明,斜距向非均匀分段补偿使近距处浮球串目标聚焦效果更佳。斜距向非均匀分段补偿方法通过区别处理空变程度不同的远近距离处的回波数据,对大测绘带合成孔径声呐在近距处的成像结果改善尤其明显。

Motion error is the main factor that degrades the high resolution of synthetic aperture sonar (SAS). Based on the analysis of the characteristics of the range-variant motion error and the study of the segmenting strategies, a motion compensation method to divide echo data into non-uniform segments is proposed for wide-swath synthetic aperture sonar. By means of dividing uniformly along the ground range, non-uniform segments, which are consistent with the first-rapid-then-slow range variance of motion error and then could get compensated more accurately, can be obtained along the slant range through the effect of the range compression. Simulation results show that after non-uniform segmenting motion compensation, the peak side lobe ratio of the target declines, the contrast between the target and the background gets enhanced and the difference between the nearby targets and distant targets gets reduced. Lake trial results show that non-uniform segmenting motion compensation method makes the floating ball array targets at the near range focus better. The proposed non-uniform segmenting method takes different measures to deal with echo data with different range variance, which has an obviously improved performance especially for nearby targets in the application of the wide-swath synthetic aperture sonar.