共查询到19条相似文献,搜索用时 359 毫秒
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在理论分析的基础上,构造了基于λ水平能量聚点的目标辐射噪声线谱的特征量模型.在利用中值痣波去除信号功率谱中“平台型”的λ水平能量聚点后,计算其λ水平能量聚点作为拟线谱频率,通过拟线谱频率对应周期的整周期延时叠加突出线谱特征,以提高辐射噪声线谱的检测率.理论分析和对仿真信号的计算结果表明,该算法是有效的. 相似文献
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本文对语音信号处理领域发展起来的一种二次谱方法进行了研究改进,应用于海上实艇信号的线谱检测。由一次谱经开根运算和付里叶变换所得的二次谱具有分离周期信号和随机噪声的特性,可提取信号,抑制噪声,提高信噪比。在PC机上编制了处理程序,对模拟信号和海上实艇信号进行了线谱检测。和自功谱方法的检测效果相比较,本方法对多谐波成份线谱信号提高了检测性能,对海洋起伏噪声具有抑制能力。 相似文献
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将功率谱和神经网络相结合,应用于高海况、低信噪比条件下,水中目标信号的特征提取中.文中首先对信号进行功率谱估计,利用目标信号功率主要集中在低频部分的特点,提取低频信号的能量作为特征,然后利用人工神经网络对目标信号进行检测.利用不同浪级情况下海洋水压场的仿真信号数据,对某型目标舰船的水压信号进行了检测计算,验证了该方法的有效性,尤其是达到了在高海况、低信噪比条件下,对目标信号检测率比较高、虚警率比较低的效果. 相似文献
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水声信号被动检测中广泛使用LOFAR图对接收信号进行处理和分析。针对LOFAR图中线谱信号检测问题,根据线谱信号特征设计特征函数,提出频域滑动窗线谱特征累积检测法。该方法在频率轴移动观察窗,用多步决策算法计算每个观察窗的最优解,得到最优路径,如果最优路径特征值大于阈值,则累积LOFAR图像素点被该最优路径经过的次数,次数越多对应点为线谱点的概率越大。仿真研究表明,该方法对频率时变、低信噪比的线谱信号具有良好的检测能力,可实现多根线谱的增强与检测。海试数据处理结果证明了该方法的可行性和稳健性。该算法对于辐射线谱信号的水下目标远距离探测识别有较高的参考价值。 相似文献
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端点检测技术是语音信号处理的关键技术之一,为提高低信噪比环境下端点检测的准确率和稳健性,提出了一种非平稳噪声抑制和调制域谱减结合功率归一化倒谱距离的端点检测算法。该算法首先通过抑制非平稳噪声再采用调制域谱减消除残余噪声来提升信噪比,减少语音失真。然后再提取每帧信号的功率归一化倒谱系数,计算每帧信号与背景噪声的功率归一化倒谱距离。最后将该倒谱距离作为检测参数,采用双门限判决方法进行端点检测。实验结果表明,该端点检测算法对语音帧和噪声帧具有较好的区分性。此外,在低信噪比环境下,所提出的算法对于不同类型的噪声都具有较好的稳健性。 相似文献
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Abstract A sinusoidal detector with adaptive thresholding CFAR (constant‐false‐alarm‐rate) processor operating in noise of changing statistics is analyzed for some very general situations. The detector contains FFT and a cell‐averaging processor, which can be easily implemented for real time applications, such as in pulse doppler radar. For signals in stationary noise in particular, the second‐order statistics of the FFT‐based periodogram of the windowed data are derived. In the AWGN case, this detector possesses the desired CFAR characteristics. For Gaussian colored noise, the detector performance is derived analytically with certain reasonable approximations. It is shown from some numerical examples that in this case the variation of the false alarm probability with respect to the unknown sinusoidal frequency and noise spectrum is not significant, which reveals the property of robustness. Moreover, the detection probability is satisfactory for most cases. 相似文献
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自主检测技术是实现水下无人航行器(Underwater Unmanned Vehicle,UUV)智能化的关键技术,是无人航行器能够自主执行水下预警、目标跟踪等任务的前提。针对当前基于均值类和有序统计类恒虚惊(Constant False Alarm Rate,CFAR)技术的自主检测方法在背景起伏严重、多目标情况下,背景噪声统计特性估计不准确、自主检测性能下降的问题,文章提出了一种基于方位-时间二维参考窗联合有序截断平均算法的自主检测方法。首先,该方法设计了一种方位-时间二维参考窗,解决了一维参考窗检测参考样本过少、噪声统计量估计不准的问题;其次,采用有序截断平均算法估计背景噪声统计量,对起伏背景进行均衡;最后,利用背景噪声均值和方差构造恒虚警检测器,采用检测前跟踪技术,实现起伏背景下、多目标自动检测与跟踪。湖上试验结果表明,在水下无人航行器的自噪声干扰下,该方法对多目标依然具有较好的自主检测效果。 相似文献
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Robust energy detection in cognitive radio 总被引:1,自引:0,他引:1
The success of advanced dynamic utilisation of the scarce spectrum in cognitive radio depends upon reliable primary signal detection where accurate noise power estimation plays a critical role. However, in practical scenarios, the noise power cannot be accurately estimated, which significantly degrades the performance of primary signal detection. To avoid inaccurate noise power estimation and associated accumulated problems. A novel two-stage Bayesian estimation-based energy detection algorithm is introduced here. This algorithm, as supported by simulation results, shows two main features: (a) a superior performance of 1 dB compared with previous methods; (b) the consistency of the algorithm has been proved indicating that 100 correct primary user signal detection can be approached as the number of samples tends to infinity. 相似文献
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为了解决红外预警系统在受到地物、云层、飞鸟等干扰点的影响下,目标探测虚警率高的问题,提出一种基于目标点角坐标变化的检测算法.该算法是先通过分析系统扫描到的目标点角速度变化情况,将可能的目标点从含有噪声的背景中分离出来;然后利用内点惩罚函数及最速下降法相结合的最优值算法求出每个目标点的航路;最后,对航路的真实性进行判断,从而检测出运动目标.通过实验证明了该算法抗噪声干扰能力强,易于硬件实现,能够有效地降低红外预警系统的虚警率. 相似文献
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极化合成孔径雷达图像船舶目标检测算法 总被引:3,自引:0,他引:3
结合区域划分和结构检测模板提出了改进极化白化滤波(IPWF)算法,利用IPWF算法融合极化合成孔径雷达(POL-SAR)中各极化通道图像,同时抑制相干斑,然后利用双参数恒虚警率(CFAR)检测方法对融合后的图像进行船舶目标检测.本文利用香港地区SIR-C全极化单视复数据进行了实验,结果表明IPWF算法更好地降低了相干斑因子,提高了船舶目标的检测率、控制了虚警率,同时可以更好地保持船舶目标的结构信息. 相似文献
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Chien CF Cheng YC Lin TT 《Journal of the Optical Society of America. A, Optics, image science, and vision》2011,28(4):581-589
In this research we propose a fast and robust ellipse detection algorithm based on a multipass Hough transform and an image pyramid data structure. The algorithm starts with an exhaustive search on a low-resolution image in the image pyramid using elliptical Hough transform. Then the image resolution is iteratively increased while the candidate ellipses with higher resolution are updated at each step until the original image resolution is reached. After removing the detected ellipses, the Hough transform is repeatedly applied in multiple passes to search for remaining ellipses, and terminates when no more ellipses are found. This approach significantly reduces the false positive error of ellipse detection as compared with the conventional randomized Hough transform method. The analysis shows that the computing complexity of this algorithm is Θ(n(5/2)), and thus the computation time and memory requirement are significantly reduced. The developed algorithm was tested with images containing various numbers of ellipses. The effects of noise-to-signal ratio combined with various ellipse sizes on the detection accuracy were analyzed and discussed. Experimental results revealed that the algorithm is robust to noise. The average detection accuracies were all above 90% for images with less than seven ellipses, and slightly decreased to about 80% for images with more ellipses. The average false positive error was less than 2%. 相似文献
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The performance of the ordered-statistic greatest of (OSGO) constant false alarm rate (CFAR) scheme with binary integration for M non-coherent sweeps in Weibull background was investigated for homogeneous and non-homogeneous backgrounds, with an assumption of known shape parameter. This kind of processing is based on the fact that the clutter can be segmented in regions in many real radar scenarios where a timevarying two-parameter distribution function family can be fitted, but the clutter power may vary locally inside the region. Under the assumption of known shape parameter, the authors examined the changes of the false alarm rate and detection probability of the OSGO-CFAR with binary integration when the shape parameter differs from the nominal one, and compared them to those of the OSGO-CFAR with single pulse processing. The authors have derived analytic expressions of the detection probability and false alarm rate during clutter power transitions for the OSGO-CFAR with binary integration in Weibull background. It is shown that the OSGO-CFAR with binary integration can not only improve the detection performance significantly, but it also control the rise of the false alarm rate at clutter edges more effectively compared to the OSGO-CFAR with single pulse processing. Moreover, it exhibits a good immunity to the variation of the shape parameter. 相似文献
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针对浅海随机噪声与混响背景下蛙人等弱回波强度、慢速小目标的检测问题,提出一种基于声呐历程累积图像的目标检测方法。首先根据声呐图像时域、空域相关性,采用背景空时归一化处理技术,抑制声呐背景中的静态混响、突发性噪声等强回波干扰。声呐历程累积图像集成了多帧声呐图像的信息,目标回波亮点由于运动连续性形成亮线特征,利用该特征,采用Radon恒虚警率(Radon Constant False Alarm Rate,Radon-CFAR)检测声呐历程累积图像中的目标短时运动轨迹,能够检测到低信噪比的目标。分析了空时归一化处理和检测算法的性能,并通过海试数据验证了该算法的有效性,可以检测到低信噪比的蛙人目标回波。 相似文献