并列式多入多出声纳宽带高分辨波束形成方法

并列式多入多出(Multiple-Input Multiple-Output,MIMO)声纳可以通过高分辨波束形成方法进一步提高方位分辨能力。本文通过对窄带方法的扩展,提出一种宽带高分辨波束形成的方法,数值仿真分析了该方法的性能,并通过湖试数据进行了验证。结果表明,该方法可以对并列式MIMO声纳进行宽带高分辨波束形成,高信噪比情况下可以得到较高的方位分辨能力,但方位分辨力随信噪比减小下降较快,且运算量远大于常规波束形成方法,在运算能力满足要求且信噪比较高时,用本方法可显著提高系统的方位分辨性能。     

球面单形平方根无迹粒子滤波在拖曳合成孔径声纳组合导航中的应用

惯性导航设备修正回波数据作为合成孔径声纳(SAS)运动补偿的一种重要方法,其中的关键技术是研究和利用高精度的滤波算法以及组合导航系统为运动补偿提供导航数据信息。在标准粒子滤波算法的基础上进行改进,提出了一种球面单形平方根无迹粒子滤波算法(SS-SRUPF),并将之应用于SINS、多普勒计程仪(DVL)组成的水下组合导航系统,输出的导航数据再传输给SAS成像系统。仿真结果表明,SS-SRUPF算法可将一个合成孔径时间内的组合导航位置均方误差精度提高到0.013m,小于SAS距离向分辨力0.019 m,满足SAS运动补偿的要求。     

Investigation of long-range sound propagation in surface ducts

Understanding the effect of source-receiver geometry on sound propagation in surface ducts can improve the performance of near-surface sonar in deep water. The Lloyd-mirror and normal mode theories are used to analyze the features of surface-duct propagation in this paper. Firstly, according to the Lloyd-mirror theory, a shallow point source generates directional lobes, whose grazing angles are determined by the source depth and frequency. By assuming a part of the first lobe to be just trapped in the surface duct, a method to calculate the minimum cutoff frequency （MCF） is obtained. The presented method is source depth dependent and thus is helpful for determining the working depth for sonar. Secondly, it is found that under certain environments there exists a layer of low transmission loss （TL） in the surface duct, whose thickness is related to the source geometry and can be calculated by the Lloyd-mirror method. The receiver should be placed in this layer to minimize the TL. Finally, the arrival angle on a vertical linear array （VLA） in the surface duct is analyzed based on normal mode theory, which provides a priori knowledge of the beam direction of passive sonar.     

高分辨侧扫及合成孔径声纳图像与回波中类似水雷目标计算机检测与分类

计算机辅助目标识别与分类技术有可能可靠地在海底发现水雷及其它感兴趣的目标,高效省时,一致性强,不受操作员个体因素影响。自90年代以来,是多个研究部门的热点课题。近年来,合成孔径侧扫声纳技术日趋成熟,能提供更高分辨率的声图,更是促进了自动识别与分类的发展。 本文综合评述了高分辨侧扫及合成孔径声纳图像与回波中类似水雷目标- MLO (Mine Like Object)-计算机检测与分类-CAD/CAC（Computer Aided Detection/ Computer Aided Classification）-研究的发展,现状及趋向。     

Research on a port and starboard ambiguity conjugate cancelling method for twin-line array

It is always an important problem in sonar signal processing for towed array to distinguish the target between port and starboard.It is studied in this paper the normalized beam output function for the parallel twin-line array and found a method that can enhance its port and starboard ambiguity suppression by equalizing the amplitude and phase of the beam output from the conventional beam forming.This method gets the weight value by analyzing the normalized beam output function,and then uses the amplitude weight and phase compensation for beam outputs of the twin arrays to cancel the conjugate（mirror） output. Therefore,the port and starboard restrain ratio is maximized.Both the computer simulation and sea trial data showed that this is a simple and practical method,can better enhance the port and starboard restrain ratio,especially when the band is wide.     

声纳导流罩吸声障板声学特性的研究

本文研究内容属于舰艇声兼容性技术研究的一部分。应用声学软件SYSNOISE计算了,声纳定向发射时某试验用声纳导流罩及尾部吸声障板的声场特性,同时进行相同工况的水下模型试验。计算结果与试验结果吻合良好,说明应用声学软件对声纳声场进行计算是一种可行的方法,有可能推广至其他的水下模型的声场计算。结果数据反映了吸声障板对声纳定向发射时声场的影响,为舰艇总体声纳导流罩内吸声障板的结构设计、声兼容设计提供依据。     

基于多分辨分析的合成孔径声纳相干斑抑制研究

相干斑噪声的存在使合成孔径声纳图像不能正确反映目标的反射特性,严重影响了图像的质量,降低了对图像的分析和理解性能。一个良好的合成孔径声纳图像相干斑抑制算法,必须在有效抑制相干斑噪声的同时,尽量保持图像中的边缘、点目标等细节信息。小波变换具有多分辨特性,可以利用其多分辨特性进行图像噪声消除。由于合成孔径声纳图像相干斑具有乘性噪声的性质,这就需要对其合成孔径声纳图像进行对数变换,把乘性噪声转换成加性噪声。然后对加性噪声进行小波多分辨分析和阈值处理,剔除小于阈值的小波系数后进行逆小波变换和指数变换,从而获得抑制相干斑噪声后的新的合成孔径声纳图像。从相干斑抑制的结果可以看出,基于多分辨分析的相干斑噪声抑制算法能够有效降低合成孔径声纳图像中的相干斑噪声。     

基于舷侧阵声纳的鱼雷远程自导性能研究

针对鱼雷的远程自导问题,研究了恶劣水文条件下浅海波导中鱼雷舷侧阵声纳对主动声纳信号的探测能力和测向精度,计算结果表明:在潜艇反舰作战中,通过利用水面舰艇发射的主动声纳信号,可实现潜射鱼雷对目标的远程被动探测,其被动测向精度一般可满足自导精度要求。     

浅谈声纳

随着科学技术的发展,电磁波已被广泛用来进行远距离信息传输与遥感、遥测．然而,最强的电磁波与激光束也很难穿透几百米深的海水．但海洋是声波良好的传导媒介,于是声纳应运而生．声纳是利用水中声波进行深测、定位和通信的电子设备．由于其原理与雷达相似,所以又称声波雷达．     

Design of sonar transducer based on the laser-induced sound

A design of a kind of sonar transducers was presented. An experimental system was developed for producing the sound signal based on the laser-induced breakdown and bubble oscillation. The power spectrum and the ambiguity function were analyzed. The range resolution and the Doppler resolution constant of the sound signal were determined. It is basically proved in theory that both the range resolution and directivity of the sonar transducer are very high. The transducer can be a sound source of high-resolution sonars.