【摘要】 合成孔径声纳成像时,需要从不同位置采集目标的回波,从而造成目标的阴影被模糊。传统的声纳图像增强方法没有利用合成孔径声纳的成像机理,难以对阴影进行有效增强。从合成孔径声纳信号处理的角度,给出了固定焦距阴影增强(FFSE)算法的严格证明过程,导出了不同变换域下阴影增强的处理方式。对于多子阵合成孔径声纳,使用不均匀分离快速傅里叶变换(NSFFT)消除方位向的不均匀采样,然后在距离多普勒域进行阴影增强。分别对海上试验和湖上试验的数据进行了分析。处理结果表明,该方法能够显著增强合成孔径声纳图像的阴影,具有较强的实用价值,对于后续的图像分割和目标识别具有重要意义。更多还原

【Abstract】 Synthetic aperture sonar needs to collect the echoes from a target at different locations,which blurs the contour of shadow cast of targets. The conventional methods cannot obtain good effects because of lack in exploitation of synthetic aperture principle. A rigorous derivation of fixed focus shadow enhancement( FFSE) algorithm is presented,and time domain,frequency domain and range-Doppler domain are conducted. For synthetic aperture sonars,many receivers are used to increase efficiency. Nonuniform fast Fourier transform( NSFFT) is used to eliminate non-uniform sampling in azimuth direction,and then shadow enhancement can be applied in range-Doppler domain. The method is applied to laketrial data set and sea-trial data set. Results show that the shadows of objects are enhanced evidently,which is great significance to image segmentation and target identification.更多还原