共查询到18条相似文献,搜索用时 78 毫秒
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为了解决强噪声背景下微弱光信号检测难的问题,介绍了一种基于锁相放大原理的微弱光信号检测系统。系统采用对1 550nm的DFB激光进行调制的方法产生前级信号,利用PIN光电二极管产生的电流信号作为原始信号,经过前级放大、锁相放大及低通滤波电路还原调制信号。系统采用OPA124作为前级运放,AD630作为锁相放大器,参考信号和调制信号均由DDS芯片AD9850产生。滤波电路、移相电路和调制电路均采用高精度运放OP07来设计。实验结果表明,该系统具有很高的线性度,灵敏度为4.51V/V,精度大于0.05%,是一种高精度、高实用性的微弱光信号检测系统。 相似文献
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基于复杂非线性系统相空间重构理论,提出了混沌背景中微弱信号检测的神经网络方法,利用神经网络强大的学习和非线性处理能力,建立了混沌背景噪声的一步预测模型,从预测误差中检测淹没在混沌背景噪声中的微弱目标信号(包括周期信号和瞬态信号),研究了混沌背景中存在白噪声时该方法的检测能力,指出了目标信号为瞬态信号和周期信号时检测原理的异同点,最后以Lorenz系统作为混沌背景噪声进行了仿真实验,实验表明该方法能有效地将混沌背景中极其微弱的信号检测出来.
关键词:
混沌
神经网络
信号检测 相似文献
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利用自治混沌系统的参数非共振激励混沌抑制原理实现强噪声背景下微弱方波信号的检测. 将频率远大于系统特征频率的方波信号作为内置激励信号,经平均法处理后,得到受控系统与原系统之间的参数等效关系,并由此确定使系统由混沌状态突变为周期状态的检测参数临界值. 数值仿真结果表明此系统可以达到极低的信噪比工作下限. 相比于利用参数共振微扰混沌抑制原理实现微弱信号检测的有关方法,此方案可根据严格的理论分析得到更准确的检测参数估计值,有利于在相关领域推广应用.
关键词:
自治混沌系统
参数激励
方波信号
检测 相似文献
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利用Duffing振 子从混沌到间歇混沌的相变及其对策动力和待检测信号频差较小的周期信号的敏感性, 研究了强海洋背景噪声下微弱周期信号的检测. 通过构造混沌振子列的方法对频率未知信号进行扫频, 从而提取待检测信号的频率范围, 最后利用希尔伯特变换, 实现对间歇混沌的包络检测, 并计算出待检测信号的频率. 计算机仿真与实测水声信号处理结果表明, 利用基于希尔伯特变换的间歇混沌振子对水声微弱信号检测, 其检测信噪比比一般的间歇混沌振子提高了至少4.4 dB, 验证了所提方法的有效性. 相似文献
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在计算机日益普及的今天,工程设计领域中,人们通过对研究对象建模,用计算机程序分析其各种性能,寻找出最优方案,然后再予以物理实现,这就是计算机仿真科学.计算机仿真及与此相关的CAA和CAD技术已经成为科学研究及工程设计的必要手段.在物理实验教学中,计算机也不仅仅局限于处理各种实验数据,提洪先进的测试手段,除此之外,它将成为我们模拟各种物理实验的平台,成为我们展示物质世界奥妙的有效手段.计算机模拟一方面可以节约经费,另外,可以实现许多采用实验手段难以完成的事情,例如,通过汁算机模拟,可以捕捉到稍纵即逝… 相似文献
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In this paper, a chaos system and proportional
differential control are both used to detect the frequency of an
unknown signal. In traditional methods the useful signal is obtained
through the Duffing equation or other chaotic oscillators. But these
methods are too complex because of using a lot of chaos oscillators.
In this paper a new method is presented that uses the R?ssler
equation and proportional differential control to detect a weak
signal frequency. Substituting the detected signal frequency into
the R?ssler equation leads the R?ssler phase state to be
considerably changed. The chaos state can be controlled through the
proportional differential method. Through its phase diagram and
spectrum analysis, the unknown frequency is obtained. The simulation
results verify that the presented method is feasible and that the
detection accuracy is higher than those of other methods. 相似文献
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对于一类同时存在扩散耦合和梯度耦合的非线性振子系统, 通过空间傅里叶变换,得到具有不同波矢的各运动模式的相互独立的运动方程. 计算各横截模的Lyapunov指数, 可在耦合参数平面上确定同步混沌的稳定区域. 在稳定区域边界, 一对共轭横截模式失稳,导致同步混沌的Hopf分岔. 对耦合Lorenz振子系统进行了数值模拟,并设计了耦合Lorenz振子系统的电路, 进行耦合振子系统同步混沌Hopf分岔的电路仿真实验. 计算和仿真的结果表明,Hopf分岔的特征频率等于失稳横截模式的振荡频率.
关键词:
耦合非线性振子
同步混沌
横截模式
电路仿真 相似文献
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构造了一个三维混沌系统, 简要分析了该混沌系统的平衡点性质、混沌吸引子相图和Lyapunov指数等特性. 在此基础上, 利用反馈同步思想设计了一种利用混沌信号部分信息实现混沌同步的方法, 完成了三维混沌系统的同步. 该方法仅利用混沌信号幅值信息即可实现两个混沌系统的同步, 其同步建立与混沌信号的极性无关, 此特性可有效提高混沌通信质量. 通过分析系统的条件Lyapunov指数证实该方法的有效性, 数值仿真表明该方法与利用混沌信号全部信息的线性反馈同步法相比, 同步建立时间基本相同. 相似文献
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Phase space reconstruction is the first step to recognizing
the chaos from observed time series. On the basis of differential
entropy, this paper introduces an efficient method to estimate the
embedding dimension and the time delay simultaneously. The
differential entropy is used to characterize the disorder degree of
the reconstructed attractor. The minimum value of the differential
entropy corresponds to the optimum set of the reconstructed
parameters. Simulated experiments show that the original phase space
can be effectively reconstructed from time series, and the
accuracy of the invariants in phase space reconstruction is greatly
improved. It provides a new method for the identification of chaotic
signals from time series. 相似文献
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Weak signal detection has been widely used in many fields such as military and national economy. Aiming at the problem that the traditional stochastic resonance (SR) method can’t obtain the signal amplitude when detecting weak signals, the frequency and amplitude of the weak signal are obtained by combining the SR and chaos characteristics of the two-dimensional Duffing system. Firstly, the effects of two-dimensional Duffing system parameters a, b, k, noise intensity D on the Kramers rate and signal-to-noise ratio (SNR) are analyzed under the Gaussian white noise environment. The results show that the damping ratio K can hinder the SR effect of the system to some extent. Secondly, to solve the misjudgment of the state method of the weak signal amplitude in the detection, the Lyapunov exponent is used to assure the threshold's range, and the threshold of the chaotic critical state is found. Finally, the paper gives the processes of frequency and amplitude detection of multiple high-frequency signals, which realizes the effective detection of the frequency and amplitude of multiple high-frequency signals in a Gaussian white noise environment, and successfully applies the method to the accurate detection of boundary voltage amplitude in electrical impedance tomography. 相似文献
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在前期实验工作的基础上,从理论分析的角度,提出了利用Duffing振子从大周期态向混沌态的相变 作为判据的微弱周期信号检测方法,给出了检测原理,并论证了其可行性;从过渡带影响和检测概率两方面 将该方法与传统的检测方法进行了比较分析,并对两者的检测性能进行了仿真对比.分析和仿真结果都显示,相同条件下, Duffing振子从大周期态向混沌态的相变受过渡带影响更小,所提方法具有更好的检测性能. 实验数据还表明, Duffing振子检测微弱信号只能基于单向相变, 利用阵发混沌进行频差检测只适用于待测信号信噪比较高的情况.
关键词:
Duffing
混沌
检测
过渡带 相似文献
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Using the wave packet theory,we obtain all the solutions of the weakly damped nonlinear Schrodinger equation.These solutions are the static solution,and solutions of planar wave,solitary wave,shock wave and elliptic function wave and chaos.The bifurcation phenomenon exists in both steady and non-steady solutions.The chaotic and periodic motions can coexist in a certain parametric space region. 相似文献