Phase errors in synthetic aperture sonar (SAS) imaging must be reduced to less than one eighth of a wavelength so as to avoid image destruction. Most of the phase errors occur as a result of platform motion errors, fo...Phase errors in synthetic aperture sonar (SAS) imaging must be reduced to less than one eighth of a wavelength so as to avoid image destruction. Most of the phase errors occur as a result of platform motion errors, for example, sway yaw and surge that are the most important error sources. The phase error of a wide band synthetic aperture sonar is modeled and solutions to sway yaw and surge motion estimation based on the raw sonar echo data with a Displaced Phase Center Antenna (DPCA) method are proposed and their implementations are detailed in this paper. It is shown that the sway estimates can be obtained from the correlation lag and phase difference between the returns at coincident phase centers. An estimate of yaw is also possible if such a technique is applied to more than one overlapping phase center positions. Surge estimates can be obtained by identifying pairs of phase centers with a maximum correlation coefficient. The method works only if the platform velocity is low enough such that a number of phase centers from adjacent pings overlap.展开更多
针对现有斜视多子阵合成孔径声呐成像算法忽略了"非停走停"假设的孔径依赖性和阵元依赖性,导致中等斜视时成像效果差的问题,提出了一种基于级数反演方法(Method of Series Reversion, MSR)的中等斜视多子阵合成孔径声呐距离...针对现有斜视多子阵合成孔径声呐成像算法忽略了"非停走停"假设的孔径依赖性和阵元依赖性,导致中等斜视时成像效果差的问题,提出了一种基于级数反演方法(Method of Series Reversion, MSR)的中等斜视多子阵合成孔径声呐距离多普勒算法(Range Doppler Algorithm, RDA)。首先,为了解决"非停走停"假设孔径依赖的问题,直接对精确距离史在波束中心处进行泰勒级数展开,得到近似距离史,并借用MSR求得近似距离史对应窄带回波信号的二维谱解析解。然后,为了解决阵元依赖的问题,使用基于MSR的RDA分别对每个子阵单独成像,再通过将每个子阵的成像结果进行相干叠加的方式消除单个子阵欠采样带来的混叠现象,得到完整的成像结果。最后,通过与现有算法的仿真对比实验,验证了该算法的有效性。展开更多
文摘Phase errors in synthetic aperture sonar (SAS) imaging must be reduced to less than one eighth of a wavelength so as to avoid image destruction. Most of the phase errors occur as a result of platform motion errors, for example, sway yaw and surge that are the most important error sources. The phase error of a wide band synthetic aperture sonar is modeled and solutions to sway yaw and surge motion estimation based on the raw sonar echo data with a Displaced Phase Center Antenna (DPCA) method are proposed and their implementations are detailed in this paper. It is shown that the sway estimates can be obtained from the correlation lag and phase difference between the returns at coincident phase centers. An estimate of yaw is also possible if such a technique is applied to more than one overlapping phase center positions. Surge estimates can be obtained by identifying pairs of phase centers with a maximum correlation coefficient. The method works only if the platform velocity is low enough such that a number of phase centers from adjacent pings overlap.
文摘针对现有斜视多子阵合成孔径声呐成像算法忽略了"非停走停"假设的孔径依赖性和阵元依赖性,导致中等斜视时成像效果差的问题,提出了一种基于级数反演方法(Method of Series Reversion, MSR)的中等斜视多子阵合成孔径声呐距离多普勒算法(Range Doppler Algorithm, RDA)。首先,为了解决"非停走停"假设孔径依赖的问题,直接对精确距离史在波束中心处进行泰勒级数展开,得到近似距离史,并借用MSR求得近似距离史对应窄带回波信号的二维谱解析解。然后,为了解决阵元依赖的问题,使用基于MSR的RDA分别对每个子阵单独成像,再通过将每个子阵的成像结果进行相干叠加的方式消除单个子阵欠采样带来的混叠现象,得到完整的成像结果。最后,通过与现有算法的仿真对比实验,验证了该算法的有效性。
