共查询到19条相似文献,搜索用时 187 毫秒
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该文以非合作水声脉冲信号为对象,研究非合作条件下水声信号的单水听器匹配场定位。首先根据水声脉冲信号的短时瞬态非平稳特性,设计具有自适应径向高斯核函数的时频分布进行频率估计。然后利用声场传播模型计算声场,求解海洋信道脉冲响应。由计算出的信道脉冲响应和水听器上的接收信号,使用时域最小二乘的方法得到搜索网格区域上的拷贝场信号。最后通过建立误差代价函数,获得表征目标位置的模糊表面,实现利用单个水听器对非合作水声脉冲信号的匹配场定位。通过仿真实验和实际海试数据的验证,证明了该方法的有效性。 相似文献
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分析了主动匹配场定位的必要性,提出了主动匹配场定位的方法。介绍了该方法的基本原理,对方法实现中的主要问题进行了讨论。基于简正波模型,利用KRAKEN程序计算出主动匹配场的拷贝场向量,根据主动定位的信号特点设计了主动匹配场处理器。利用现有的声场模型产生仿真数据,对该定位方法进行了计算机模拟仿真,仿真结果表明,本方法在复杂海洋环境下可以确定较远距离的目标反射体的位置。最后指出了主动匹配场技术的应用前景。 相似文献
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采用距离和信息的多基地雷达多目标投影定位算法中,距离向脉冲压缩后分辨率降低,需要已知空间中目标个数.针对此问题,提出了一种稀疏重建的多基地雷达多目标定位方法.该方法利用多个接收机中目标稀疏度相同的特点,通过构造平均重构残余误差变化率和平均散射系数变化率作为正交匹配追踪(OMP)算法迭代终止判定条件,自适应地终止OMP算法的同时获得稀疏重建信号以及信号稀疏度的估计值,提高了距离向分辨率,获得了对空间中目标个数的估计.仿真实验表明所提算法有效抑制了距离向主瓣展宽和旁瓣串扰,提高了距离向分辨率.同时,所提算法在不同噪声环境下能准确估计空间中目标个数并提取其空间位置,实现对空间中目标的准确定位. 相似文献
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现有的基于声场干涉结构特征的目标深度分类方法的频率适用范围有限,仅适用于目标线谱频率激发前2阶简正波的情况。针对上述问题,该文提出基于匹配场处理的目标深度分类算法,该算法将垂直复声强无功分量作为匹配量进行目标深度的匹配估计,利用目标深度的粗略估计结果辅助进行目标深度的二元分类。算法适用于线谱频率激发前3阶简正波的情况,有效拓展了算法的频率适用范围。仿真结果验证了算法的可行性和稳健性。该文分析了环境失配情况对算法性能的影响。所提算法具有较高的准确性和稳健性。 相似文献
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现有的基于声场干涉结构特征的目标深度分类方法的频率适用范围有限,仅适用于目标线谱频率激发前2阶简正波的情况.针对上述问题,该文提出基于匹配场处理的目标深度分类算法,该算法将垂直复声强无功分量作为匹配量进行目标深度的匹配估计,利用目标深度的粗略估计结果辅助进行目标深度的二元分类.算法适用于线谱频率激发前3阶简正波的情况,有效拓展了算法的频率适用范围.仿真结果验证了算法的可行性和稳健性.该文分析了环境失配情况对算法性能的影响.所提算法具有较高的准确性和稳健性. 相似文献
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深海直达声区声场存在明显的多途结构,可用于水下声源被动定位。本文根据一次南海实验获取的数据,研究基于双水听器接收信号互相关函数和单水听器接收信号自相关函数的水下声源距离深度联合估计方法。首先假设声源深度位于50m~300m之间,根据双水听器互相关函数提取直达波到达时间差估计水下声源距离,然后根据距离估计结果以及单水听器自相关函数提取的直达波与海面反射波时延差估计水下声源深度,最后计算声源深度估计结果的平均值再与双水听器互相关函数结合得到更为精确的距离估计结果。结果表明,采用此方法估计的水平距离相对误差在10.5%以内,声源深度相对误差小于13.3%。 相似文献
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北极水域信道特殊,匹配场处理作为一类可结合环境信息进行信号处理的目标定位方法,在模型匹配时可以准确估计出声源位置,但存在环境变化复杂且信息了解少的问题,导致模型很难完全匹配,从而出现位置估计不准确的问题。该文提出建立一种改进的压缩匹配场模型,并基于相位归一化原理对稀疏模型进行优化,利用归一化阵元域信息进行匹配,以消除声源频谱的影响,提高压缩匹配场的定位准确度。仿真结果表明,改进后方法比改进前方法的定位准确率更高;试验数据处理表明,单快拍下改进后方法比改进前方法在目标位置估计上误差更小,比常规匹配场方法的分辨率更高。 相似文献
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针对钛合金内部疲劳裂纹激光超声成像问题,提出了一种基于合成孔径聚焦技术的多模式组合成像方法。采用扫描激光源法,通过提取不同探测位置的时域模式回波信号,根据B-scan图中反射纵波与反射横波的幅值分布,将裂纹回波时域特征进行分区重组,对其进行反演聚焦完成了对内部裂纹的识别及图像重构。使用COMSOL Multiphysics对钛合金板材内部裂纹成像过程进行数值模拟并通过MATLAB图像算法验证了其可行性。与单一模式波成像相比,采用反射纵波与反射横波组合的成像方法有效减少了伪像,实现了对内部裂纹的定位及图像重构,重构裂纹位置X轴与Y轴相对误差均在3%以内。 相似文献
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A.S.M. Koeleman T.J. van den Akker H.H. Ros R.J. Janssen O. Rompelman 《Signal processing》1984,7(4):389-405
One of the main points of interest in the study of the dynamic behaviour of ECG time intervals is the accuracy with which characteristic moments can be estimated in the various waveform segments such as the P wave or QRS complex. In this study, the error involved in such estimation is regarded as due to the superposition of various types of disturbances (noise, hum and fluctuations in amplitude and symmetry) on a supposedly ideal ECG waveform. The effect of these disturbances on estimation accuracy is investigated for three estimation methods (peak estimation, double level estimation and matched filter estimation) by two different approaches; one based on use of a highly simplified theoretical model permitting the derivation of mathematical expressions for the estimation error, and one involving computer-aided simulation of ECG waveforms, based on real ECG data, with various types of disturbances on the basis of recorded ECG data. Both approaches indicate that noise and hum make the main contribution to estimation error, and that matched filter estimation is likely to give best estimation accuracy for both P waves and QRS complexes. 相似文献
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This paper presents a physically constrained maximum-likelihood (PCML) method for spatial covariance matrix and power spectral density estimation as a reduced-rank adaptive array processing algorithm. The physical constraints of propagating energy imposed by the wave equation and the statistical nature of the snapshots are exploited to estimate the ldquotruerdquo maximum-likelihood covariance matrix that is full rank and physically realizable. The resultant matrix may then be used in adaptive processing for interference cancellation and improved power estimation in nonstationary environments where the amount of available data is limited. Minimum variance distortionless response (MVDR) power estimates are computed for a given environment at different levels of snapshot support using the PCML method and several other reduced-rank techniques. The MVDR power estimates from the PCML method are shown to have less bias and lower standard deviation at a given level of snapshot support than any of the other reduced-rank methods used. Furthermore, the estimated power spectral density from the PCML method is shown to offer better low-level source detection than the MVDR power estimates. 相似文献
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介绍了粒子滤波的基本思想和具体算法实现步骤,并将粒子滤波算法应用在声源定位中,解决了在高斯噪声环境下的声源定位问题。所提出的基于粒子滤波的声源定位方法,在高斯噪声情况下,甚至在低信噪比(SNR〈-20dB)情况下,定位的均方根误差RMSE值均小于0.2m。 相似文献
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Zaridze R. Bit-Babik G. Tavzarashvili K. Economou D.P. Uzunoglu N.K. 《Antennas and Propagation, IEEE Transactions on》2002,50(1):50-58
It is known that any scattered wave field carrying energy into infinity must have source singularity centers within a bounded space. Otherwise, the scattered field should be identically equal to zero everywhere (Kupradze 1935). In this paper, attention is paid to localization of these singularities under the assumption that every scattered wave is determined uniquely by its own singularities. Investigations have shown that these singularities are distributed as "bright centers" and the distance between them depends on frequency. To determine the position (localization) of the scattered wave field singularities, the functions describing converging and diverging waves are used. Based on these concepts and the method of auxiliary sources, an efficient numerical method to reconstruct a field up to its singularities is suggested. The localization of singularities is used for partial representation of the scattered fields, which reduces significantly the number of unknowns in describing the scattering process and leading into optimized inverse scattering problem solutions 相似文献