共查询到19条相似文献,搜索用时 78 毫秒
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针对拖曳线列阵声呐平台噪声构成近场强干扰影响声呐弱目标探测的问题,利用近场平台噪声的多途传播特性,将匹配场定位技术和平面波目标方位估计技术结合,使用平台噪声到达接收阵的拷贝向量以及平面波方向向量共同设计平台噪声零响应约束空域矩阵滤波器,实现了平台噪声抑制.推导得出滤波器设计最优化问题的最优解,利用广义奇异值分解简化最优解表达式,并给出滤波器对平面波方向向量整体响应误差以及对平台噪声拷贝向量响应。利用平台噪声拷贝向量与远场平面波方向向量相关性,解释了平台噪声构成强干扰的原因,以及滤波后存在探测盲区的原因。由仿真可知,空域矩阵滤波处理可获得更小的探测盲区,同时获得盲区外更高的探测能力. 相似文献
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用于拖曳式线列阵的一种新的线谱增强系统 总被引:1,自引:1,他引:0
拖曳式线列阵是近来声呐信号处理领域中非常活跃的课题.自适应线谱增强器有可能用于拖曳式线列阵的信号处理系统.在利用LMS迭代算法的自适应线谱增强器中,由于存在迭代噪声,系统增益与输入信噪比有关.如果不抑制拖曳平台的噪声,线谱增强系统的效用就无法发挥出来,文中提出用自适应噪声抵消系统和自适应线谱增强器级联的概念.首先把拖曳平台的噪声作为干扰加以抑制,再对输出信号进行线谱增强,从而可以提取微弱信号的线谱分量. 相似文献
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水听器非轴线布放时的拖线阵流噪声响应 总被引:1,自引:1,他引:0
对拖线阵流噪声理论做出两项改进.(1)对Corcos/Carpenter两种压力起伏模型以及相应的拖线阵流噪声响应进行了全面的比较; (2)讨论了有限水听器非轴线布放时的拖线阵流噪声响应,并导出了噪声功率谱的解析表达式.结果表明,这两种压力起伏模型的波数谱、流噪声响应具有一定差别;流噪声响应与拖曳速度、套管外径以及轴线偏移距离有着密切关系.基于Carpenter模型的数值分析表明,拖曳速度提高一倍,噪声功率谱增加约24 dB,且随着套管外径的增大而减小、轴线偏移距离的增大而增大.套管外径以及轴线偏移距离对高频噪声的影响要大于其对低频噪声的影响. 相似文献
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针对传统拖线阵流噪声理论的局限性, 建立了完善的矢量拖线阵流噪声理论分析方法, 可全面准确地揭示矢量拖线阵流噪声响应特性. 基于细长圆柱的湍流边界层压力起伏Carpenter模型, 采用波数-频率谱分析方法对矢量拖线阵流噪声响应特性进行了理论研究, 导出了圆柱形矢量水听器流噪声响应的声压和振速自功率谱及其互功率谱的解析表达式, 定量分析了流噪声响应功率谱与拖曳速度、水听器尺寸、套管尺寸和材料等参数之间变化规律; 另外, 还讨论了圆柱形矢量水听器偏离护套轴线时矢量拖线阵流噪声响应, 导出了流噪声响应的声压、径向和轴向振速自功率谱及其互功率谱的解析表达式, 数值计算结果表明: 轴线偏移距离对声压和轴向振速的高频噪声的影响要大于对低频噪声的影响, 而对径向振速的全频段噪声都有明显影响, 且对振速分量影响要远大于对声压影响. 相似文献
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强干扰是制约中远程声呐性能的主要因素。对于大型声呐来说,由于过长的延时量以及过高的运算速率,抗强干扰问题始终未能解决,本文提出一种适用于大型基阵的全方位抗强干扰系统。它是自适应噪声抵消系统与一个可编程迪卡诺(DICANNE)系统的结合,在干扰与信号入射角之间的夹角比较小时,采用低采样速率的自适应噪声抵消系统;在此角度较大时,采用高采样率的DICANNE系统,从而使整个系统具有全方位抗干扰的性能。本方案在采用高性能的DSP器件时,易于实现。文中给出设计框图与硬件实施方法。 相似文献
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相对于大多数声纳,海洋环境噪声通常被视为背景干扰。水听器基阵的信噪比增益成为了基阵设计和性能估计的重要参数。从空间相关特性的角度看,当信号场已知时,阵增益可唯一由噪声场的空间相关特性来确定,这就是海洋环境噪声空间相关特性建模的动机。根据环境和声场之不同,文献中已给出几种不同的噪声场模型。为了阐明已有模型的特点及未来的研究方向,本文对噪声场空间相关特性建模做了简要综述。 相似文献
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提出了一种MVDR(最小方差无失真响应)的改进算法,用以解决常规MVDR算法由于阵形时变而出现的性能下降问题。在获得时变阵形估计数据的基础上,该算法以统计时段内的平均阵形为基准阵形,在每个扫描方向上根据实际阵形和基准阵形的差异对阵列互谱矩阵多样本进行相位补偿,从而实现统计时段内的互谱矩阵多样本相干累加和目标检测。数值仿真与海上实验数据处理结果表明:与传统MVDR算法相比,改进算法有效缓解了时变阵形下的目标测向角度模糊问题,可提高拖线阵目标左右舷分辨性能、增强弱目标检测能力。 相似文献
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LI Qihu LI Shuqiu SUN Changyu YU Huabing 《声学学报:英文版》2007,26(3):193-197
The interference characteristics of towed platform noise resulted from propeller and towed body for active/passive towed array is analyzed. It is shown that, in shallow water environment, the direct wave and bottom/sea surface reflected wave will seriously affect the performance of sonar system. The formula for calculating the direction of arrival (DOA) of interference in terms of various parameters, such as array depth, length of tow cable, is derived. The effect of interference noise for the detection performance of sonar system is described. The results of system simulation provide the method for reducing the effect of these kind of interferences. 相似文献
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《声学学报:英文版》2012,(2):189-201
Geoacoustic inversion is important for acoustic field predictions and matched field localizations in shallow water.Combing the Matched-field inversion(MFI) and the Reflectionloss inversion,a multi-step Bayesian inversion for geoacoustic parameters was presented.This method applied the posterior probability density(PPD) or inversion results from one inversion as prior information for subsequent inversion.First,the sensitive parameters were determined by the MFI.Second,the insensitive parameters were determined by the Reflection-loss inversion based on the PPD and inversion results from the MFI.The PPD results indicated that the multi-step inversion method was performed better than direct matched-field inversion,and the inversion results of some parameters were improved significantly.To demonstrate the advantages of the multi-step inversion method on the sound field prediction,the statistical properties of transmission loss based on the posterior probability were introduced.The transmission loss distribution showed that the predicted acoustic fields based on the multi-step inversion method had smaller errors. 相似文献
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Thode A Skinner J Scott P Roswell J Straley J Folkert K 《The Journal of the Acoustical Society of America》2010,128(5):2681-2694
Passive acoustic towed linear arrays are increasingly used to detect marine mammal sounds during mobile anthropogenic activities. However, these arrays cannot resolve between signals arriving from the port or starboard without vessel course changes or multiple cable deployments, and their performance is degraded by vessel self-noise and non-acoustic mechanical vibration. In principle acoustic vector sensors can resolve these directional ambiguities, as well as flag the presence of non-acoustic contamination, provided that the vibration-sensitive sensors can be successfully integrated into compact tow modules. Here a vector sensor module attached to the end of a 800 m towed array is used to detect and localize 1813 sperm whale "clicks" off the coast of Sitka, AK. Three methods were used to identify frequency regimes relatively free of non-acoustic noise contamination, and then the active intensity (propagating energy) of the signal was computed between 4-10 kHz along three orthogonal directions, providing unambiguous bearing estimates of two sperm whales over time. These bearing estimates are consistent with those obtained via conventional methods, but the standard deviations of the vector sensor bearing estimates are twice those of the conventionally-derived bearings. The resolved ambiguities of the bearings deduced from vessel course changes match the vector sensor predictions. 相似文献
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针对拖船转弯时,弯曲的拖曳线列阵的波束形成和方位估计,提出了一种先盲捕获信号,再校准阵形并估计目标方位的方法。该方法首先利用多级恒模阵对多个独立的目标信号进行盲分离,并估计出拖线阵对目标的方向向量;然后再根据方向向量对拖线阵阵形进行校准并估计出目标方位。其中,阵形自校准时的核心问题——一个多维非线性约束最小二乘问题采用了遗传算法进行求解。文中还推导了对阵元位置和目标方位估计的克拉美罗界。针对较大弯曲度拖线阵的计算机仿真实验,结果表明该方法不依赖于阵形就可实现对目标信号的捕获与分离,具有自适应抑制其它方向入射干扰信号的能力,并可以对阵形和目标方位进行有效估计。仿真结果验证了方法的正确性和有效性。 相似文献
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Song HC Cho S Kang T Hodgkiss WS Preston JR 《The Journal of the Acoustical Society of America》2011,129(3):EL71-EL75
In September 2010 a long-range acoustic communication (LRAC10) experiment was carried out in deep water off the Southern California Coast. The experiment involved two mobile components: (1) a source towed slowly at a speed of 2-3 knots at ~75-m depth and (2) a horizontal line array towed at 3.5 knots at a depth of ~200 m. Phase-coherent communication sequences were transmitted in the frequency band of 200-300 Hz at various ranges (100-700 km). Initial analysis of the LRAC10 data demonstrates that an information rate of 50 bits/s can be achieved over ~550-km range using quadrature-phase shift-keying (QPSK) modulation and error-correction coding combined with beamforming. 相似文献