脉冲压缩与互相关联合的合成孔径声呐回波时延补偿

针对合成孔径声呐中阵元相位不一致导致互相关时延补偿算法对成像质量提升效果有限的问题,提出了一种脉冲压缩与互相关联合的回波时延补偿算法.该算法利用脉冲压缩回波的互相关对原始回波相位畸变进行校正,实现粗补偿;联合脉冲压缩与偏移相位中心算法实现精细时延补偿,对不同合成孔径位置各阵元回波时延差实现了较为准确的估计,增强了成像效果。试验数据经该算法处理后,回波时延得到较为精确的补偿,地貌成像结果的亮度、对比度等统计特性得到不同程度的提高,且纹理细节增多;典型线缆目标的成像聚焦加深,成像长度误差约由5%减小为0.8%。试验结果显示,该算法对互相关时延补偿方法改进效果明显,验证了算法的可行性、有效性。 

An echo time-delay compensation method combining correlation with pulse compression for synthetic aperture sonar

A raw echo time-delay compensation method combining pulse compression with correlation function is proposed to solve the problem that the improvement effect of cross-correlation time-delay compensation algorithm for SAS(synthetic aperture sonar) image quality is limited by decreasing phase congruence of the array elements.Phase distortion of the raw echo is compensated by its pulse compression echo.Subsequently,the echo with rough time-delay compensation can be obtained.Then the echo with accurate time-delay compensation can be got by combining pulse compression with Displaced Phase Center(DPC) algorithm.Moreover,the time-delay of each array element echo at different positions during aperture synthetizing can be achieved.Finally,the proposed algorithm can improve the image quality much better than only using the DPC algorithm.After the processing of experiment data,the raw echo obtains more accurate time-delay compensation by the proposed method.The new image result of anthropogenic landform shows that the brightness and contrast ratio are increased significantly and more details can be seen.The cable-target was focused more deeply and its length error was reduced from 5%to 0.8% approximately after used the proposed method.Results of experiment show that the proposed algorithm can promote the cross-correlation time-delay compensation algorithm significantly;the feasibility and validity of the method are consequently demonstrated.