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针对矿井环境恶劣、干扰严重和传统信号有线传输的现状,设计了基于ZigBee无线传感器网络的矿井环境监测系统;系统由井下ZigBee传感器终端节点、路由器、协调器和井上监测上位机构成,其中传感器终端节点对井下瓦斯、一氧化碳、温度等信号进行采集,利用ZigBee无线组网技术将信号送给井上PC机,井上管理人员通过PC机能够随时掌握井下设备和环境的状况;与传统的信号有线传输监测方法相比,该系统低功耗、低成本、抗干扰;实验结果表明,该系统运行稳定可靠,精度高,具有一定的实用性和推广价值。 相似文献
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在扩频测距技术中,伪随机(Pseudo-Noise)码捕获时间长,扩频信号需要高带宽信道,井下多径效应还会引起PN码相位延迟,因而使得扩频测距技术难以在煤矿井下应用。为了将扩频测距技术应用于井下,设计了一种并行的PN码同步精测算法,利用FPGA高速的并行处理能力,开辟L-1条相位彼此相差一个PN码片的相关通道,在各相关通道中分别对扩频码调制的数字基带信号相关运算后进行高频率采样,大幅度提高了信号处理带宽,能够在粗同步的基础上直接得到更高的时间分辨率。仿真结果表明,所提出的方法能够抑制井下严重的多径干扰,能将测距PN码所占带宽限制在50MHZ以下而测距精度达到1米以内,是适应煤矿井下特殊环境的一种高效扩频测距方法。 相似文献
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针对目前煤矿井下巷道人力牵引敷设电缆方式劳动强度大、电缆易磨损及工作效率低等问题,依据井下巷道环境以及井下电缆安装车的结构,设计并开发了井下巷道电缆安装车自适应挂缆控制系统,以机械化、自动化技术解放工人的繁重劳动;系统以C8051F020单片机为主控单元,采用手动控制和自动控制结合、手动控制优先的控制策略,融入记忆学习的智能思想,实现井下巷道电缆自动悬挂;阐述了系统的工作原理、软硬件设计及实现;实验室性能测试结果表明,位移测量误差±2%以内,挂缆机械手能够按照手动、自动的要求正确动作并准确挂缆,实现电缆的自适应悬挂。 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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反应离散子波变换进行污染云团红外光谱信号分析及特征提取,离散子波变换具有时-频分析特性,能将信号的细微变化反映出来,对实时遥感获取的目标云团作离散子波变换分析的结果表明:离散子波变换可明显提高目标云团的特性,十分有利于光谱的识别。 相似文献
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R. S. Kaler 《Fiber and Integrated Optics》2006,25(1):41-57
In this article, the comparison of large signal theory and small signal theory has been done with dispersive propagation of optical signal with IMDD (Intensity Modulation Direct Detection) systems for semiconductor lasers with higher-order dispersion terms. The expressions for an exact large signal theory and small signal theory including higher-order dispersion terms for propagation of an optical wave with sinusoidal amplitude and frequency modulation in a dispersive fiber have been derived. It is observed that small signal theory is more sensitive compared to large signal theory in terms of intensity modulation/direct detection systems. Also, it is reported that for large signal analysis the higher-order effects of dispersion can be ignored, whereas for small signal theory, the higher-order effects can be ignored for lower modulation frequencies only. The variation in the transfer function for various values of modulation indices are greater for small signal analysis than for large signal analysis. Also, as the intensity modulation index is increased, there is a decrease in the value of transfer function. The large signal model approximates the small signal model for lower values of the intensity modulation index. 相似文献
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R. S. Kaler 《Fiber and Integrated Optics》2013,32(1):41-57
In this article, the comparison of large signal theory and small signal theory has been done with dispersive propagation of optical signal with IMDD (Intensity Modulation Direct Detection) systems for semiconductor lasers with higher-order dispersion terms. The expressions for an exact large signal theory and small signal theory including higher-order dispersion terms for propagation of an optical wave with sinusoidal amplitude and frequency modulation in a dispersive fiber have been derived. It is observed that small signal theory is more sensitive compared to large signal theory in terms of intensity modulation/direct detection systems. Also, it is reported that for large signal analysis the higher-order effects of dispersion can be ignored, whereas for small signal theory, the higher-order effects can be ignored for lower modulation frequencies only. The variation in the transfer function for various values of modulation indices are greater for small signal analysis than for large signal analysis. Also, as the intensity modulation index is increased, there is a decrease in the value of transfer function. The large signal model approximates the small signal model for lower values of the intensity modulation index. 相似文献
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多尺度分析在激光微多普勒效应特征提取中的应用 总被引:1,自引:0,他引:1
由于小波变换具有准确度高、抗噪性好等优点,在微多普勒效应探测方面具有很好的应用前景。利用多尺度分析(MRA)将信号进行分解并提取出含有微多普勒效应的低频平滑信息,获取了目标微小振动引起的微多普勒效应。用频谱分析和基于瞬时频率(Instfreq)的时-频域联合分析方法对原始信号及通过MRA分解得到的结果进行了对比研究。结果表明:利用时-频分析对MRA处理后的低频信号进行分析,可更加有效地提取微多普勒效应中振动信号的特征,为目标特征的识别、分类和探测提供了便利。 相似文献
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本文依据小波变换原理 ,提出利用小波变换技术对汽车车灯光源色测量中实时采集的光源光谱信号进行多分辨分解 ,有效地消除噪声 ,提高了光谱的信噪比。由CCD接收的标准A光源谱进行了多层分解 ,讨论了不同小波基和分解阶次对信号分析结果的影响。选取最佳小波基 ,为光谱信号消噪平滑处理提供了较有效的数据处理方法。通过对CCD接收的光谱信号进行了消噪和平滑处理 ,解决了实时采集光谱信号在分析和数据处理上的困难 ,该研究充分体现了小波变换在数据处理方面的优势 ,在依赖于光谱信号的颜色测量领域中起重要的作用。 相似文献
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Classical time-frequency analysis is based on the amplitude responses of bandpass filters, discarding phase information. Instantaneous frequency analysis, in contrast, is based on the derivatives of these phases. This method of frequency calculation is of interest for its high precision and for reasons of similarity to cochlear encoding of sound. This article describes a methodology for high resolution analysis of sparse sounds, based on instantaneous frequencies. In this method, a comparison between tonotopic and instantaneous frequency information is introduced to select filter positions that are well matched to the signal. Second, a cross-check that compares frequency estimates from neighboring channels is used to optimize filter bandwidth, and to signal the quality of the analysis. These cross-checks lead to an optimal time-frequency representation without requiring any prior information about the signal. When applied to a signal that is sufficiently sparse, the method decomposes the signal into separate time-frequency contours that are tracked with high precision. Alternatively, if the signal is spectrally too dense, neighboring channels generate inconsistent estimates-a feature that allows the method to assess its own validity in particular contexts. Similar optimization principles may be present in cochlear encoding. 相似文献
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综述了小波分析的发展现状,通过对比小波变换与短时傅里叶变换之间的差异,指出小波分析是一种多分辨分析方法,特别适合于非平稳信号的分析与处理,并且应用该方法对遥测速变信号进行处理,取得了较好的效果。 相似文献
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Muhammad Taher Abuelma'Atti 《Fiber and Integrated Optics》2004,23(6):467-478
Large signal analysis of the electroabsorption modulator driven by a mutisinusoidal RF signal is presented. The special case of a two-tone equal-amplitude RF signal is considered in detail, and the results are compared with previously published results. 相似文献
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Muhammad Taher Abuelma'Atti 《Fiber and Integrated Optics》2003,22(5):333-342
Large signal analysis of the dual-parallel electroabsorption modulator driven by a mutisinusoidal RF signal is presented. The special case of a two-tone equal-amplitude RF signal is considered in detail, and the results are compared with previously published results. 相似文献
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小波变换及其应用 总被引:3,自引:0,他引:3
傅里叶变换是信号分析的最基本工具和方法之一,但其本身仍然存在较大的缺陷,例如不能提供信号在时域上的特征.短时傅里叶变换虽然可以在一定程度上弥补该缺陷,但是它的频率分辨率和时间分辨率都十分有限,只是一种折衷的解决办法.小波变换是一种快速发展和比较流行的信号分析方法,它精确地揭示了信号在时间和频率方面的分布特点,可以同时分析信号在时域和频域中的特征,并可用多种分辨率来分析信号,实现信号的有损和无损传送.文章简要地回顾了小波变换的发展历史,介绍了小波变换的基本思想、主要概念、计算方法和计算流程.最后以四个典型的实例,展示了小波变换在现代工程中的应用和它独特的优势. 相似文献