合成孔径声呐系统相位修正

On Necessity of Phase Correction in Addition to Efficient Imaging Algorithm for Better Imaging Quality of Synthetic Aperture Sonar (SAS)

提出了一种合成孔径声呐 ( SAS)系统相位误差的修正方法 ,即在数据预处理以前用一个相位相乘来对由 Stop- and- Hop假设和移位相位中心假设引入的系统相位误差进行修正。采用 ω- k算法对相位校正前后的点目标成像进行比较 ,结果表明 ,这种修正方法正确可行。

Under conditions that will occur increasingly frequently in the future, Synthetic Aperture Sonar (SAS) system model can be terribly erroneous, making image quality terrible even when imaging algorithm is efficient. We propose a method for making the necessary phase correction to make the SAS system model acceptable. Section 1 discusses in some detail two conditions under which serious phase errors occur. Subsection 1.1 discusses the phase errors caused by the very widely used Stop and Hop assumption. The technical trend is that such phase errors will become increasingly serious as the distance between SAS and target becomes greater and greater. Subsection 1.2 discusses the phase errors caused by the also very widely used DPC (Displaced Phase Center) assumption. Section 2 explains how to correct the phase errors by a simple phase multiplication during data pre processing. The phase multiplications for Stop and Hop assumption (subsection 2.1) and DPC assumption (subsection 2.2) are only somewhat different in minor details. Section 3 gives a simulation example with imaging done with the efficient ω k algorithm. Fig.4 compares the imaging results before phase correction (Figs.4(a) and 4(c)) with those after phase correction (Figs.4(b) and 4(d)). The image quality after phase correction is obviously better.