共查询到17条相似文献,搜索用时 203 毫秒
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基于IIR小波滤波器的涡街流量计数字信号处理系统 总被引:2,自引:1,他引:2
涡街流量计被广泛应用于过程工业,但是,由于易受由管道振动和流场扰动等因素干扰,现场测量精度无法保证,测量小流量困难。本文将小波滤波器组应用于涡街流量计信号处理中,研究基于小波滤波的涡街信号处理方法,分析了小波滤波器的幅频特性对信号分析的影响,构造了幅频特性好的IIR型小波滤波器组。本文研制了基于ADSP2181的涡街流量计数字信号处理系统,并进行了气体流量和水流量标定实验,实验结果表明,基于小波滤波的涡街流量计数字信号处理系统有良好的适配性能,性能指标优于常规的涡街流量计处理系统。 相似文献
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针对涡街流量计高精度、高量程比的要求,在分析涡街信号及其噪声特点的基础上,提出一种采用自适应采样频率和Welch功率谱估计相结合的涡街信号分析处理方法。该方法首先使用经典功率谱估计的FFT算法计算出信号频率的区间范围,然后将信号通过相应截止频率的低通滤波器以防止发生混叠现象,采用信号抽取的方法降低采样频率从而减小频谱的最小频率分辨率,最后采用Welch功率谱估计的方法进行谱分析提高信噪比、减少谱失真。仿真及实验结果表明:所提出的涡街信号处理方法能有效地抑制噪声,实现高精度的功率谱计算,对于提升和改进涡街流量计的性能有良好的效果。 相似文献
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传统涡街流量计由于抗干扰性差、测量精度低等难以满足实际测量的需求,研究和开发高抗扰型涡街流量计已成为当前流量测量领域的重要发展方向.针对现有产品存在的问题,设计了一种嵌入式涡街流量计,给出了硬件组成结构和相关电路原理图;并在信号处理算法上,采用Chirp-Z变换的频谱校正方法,对经FFT变换后的涡街信号的频谱主瓣进行局部细化,从而在运算量增加不多的情况下,提高了涡街流量计的测量精度.并通过Matlab仿真实验对该频谱校正方法进行有效性验证.仿真结果表明:该方法具有校正精度高,响应速度快和使用灵活的特点. 相似文献
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基于外差式随机共振的涡街频率检测方法 总被引:2,自引:1,他引:1
涡街频率检测是涡街流量计的关键技术问题,也是当前的研究热点.分析非线性双稳系统在噪声和单一频率信号、多频率信号作用下的随机共振特性,将外差式频谱分析与随机共振原理相结合,提出基于外差式随机共振的涡街频率检测方法.理论分析、数值仿真和试验结果表明,含噪的涡街信号通过随机共振能有效地提高涡街信号信噪比,准确获取涡街频率.该方法在涡街频率检测中的应用是可行和有效的,为提高涡街流量计现场适应性及小流量弱涡街信号频率检测提供了一种新的方法. 相似文献
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介绍基于带通滤波器匹配的涡街信号处理方法的原理,给出了用构建的涡街信号模型对该方法进行仿真的内容及结果.仿真结果表明该方法能快速准确地测量涡街信号频率. 相似文献
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漩涡频率检测是涡街流量计的关键技术之一。正比于流量的涡街频率信号变化范围较宽,对不同的测量介质和测量管道各不相同,在实际应用中并且混杂有各种干扰,因此,设法提高涡街频率的测量精度是一项非常困难但必要的工作。通过研究传统涡街频率检测电路,分析涡街频率信号的特点,在比较各种滤波方法和频率测量方法的基础上,提出通过自适应高阶低通滤波电路来削弱干扰信号,并采用自适应扩展周期方法来测量频率。该方法简单可行,仿真与实验结果表明,改进电路能有效削弱涡街流量信号的干扰,提高漩涡频率测量精度。 相似文献
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Xu KJ Luo QL Fang M Wang G Liu SS Kang YB Shi L 《The Review of scientific instruments》2011,82(9):096105
Some digital signal processing methods have been used to deal with the output signal of vortex flowmeter for extracting the flow rate frequency from the noisy output of vortex flow rate sensor and achieving the measurement of small flow rate. In applications, however, the power of noise is larger than that of flow rate sometimes. These strong disturbances are caused by pipe vibration mostly. Under this condition the previous digital signal processing methods will be unavailable. Therefore, an anti-strong-disturbance solution is studied for the vortex flowmeter with two sensors in this Note. In this solution, two piezoelectric sensors are installed in the vortex probe. One is called the flow rate sensor for measuring both the flow rate and vibration noise, and the other is called the vibration sensor for detecting the vibration noise and sensing the flow rate signal weakly at the same time. An anti-strong-disturbance signal processing method combining the frequency-domain substation algorithm with the frequency-variance calculation algorithm is proposed to identify the flow rate frequency. When the peak number of amplitude spectrum of the flow rate sensor is different from that of the vibration sensor, the frequency-domain subtraction algorithm will be adopted; when the peak number of amplitude spectrum of the flow rate sensor is the same as that of the vibration sensor, the frequency-variance calculation algorithm will be employed. The whole algorithm is implemented in real time by an ultralow power micro control unit (MCU) to meet requirements of process instrumentation. The experimental results show that this method can obtain the flow rate frequency correctly even if the power of the pipe vibration noise is larger than that of the vortex flow rate signal. 相似文献
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涡街流量计信号估计的自适应陷波方法 总被引:17,自引:3,他引:14
本文提出采用自适应陷波方法计算涡街流量计输信号的频率,并给出实验结果。流量计信号为一窄带信号,自适应陷波抑制一个特定的涡街频率,并且几乎不受位于带宽以外频率的影响。此自适应陷波器只需估计一个参数,频率计算非常简单,与以前的频率估计方法相比,它以前的频率估计方法相比,它有许多优点,是一种有效的新方法。 相似文献
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数字式智能涡街流量计系统的设计 总被引:2,自引:0,他引:2
设计了以TMS320LF2407A为信号采集处理单元,P89LPC932为控制单元,配有LCD液晶显示模块和红外通讯接口的主从式数字式智能涡街流量计系统。针对目前涡街流量计易受干扰,精度不高的问题,信号采集处理单元采用基于DFT的频率估计方法,实现对传感器信号频率的估计。 相似文献
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分析自适应滤波和小波滤波的原理与方法,建立非平稳信号的自适应滤波的小波模型和滤波方法。利用小波变换的多尺度分解,将分离出来的噪声成分作为自适应滤波器的输入信号。通过自适应滤波器组能同时实现对多种噪声成分的最佳滤波,是实现信噪分离的最佳滤波方法,具有优良的滤波性能。模型验证和工程实例应用表明,该方法能实现非平稳信号在同频段对噪声成分和有用信号的最佳估计。 相似文献
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SWT based separation method for periodic signal with non-stationary noise and its application in EMF
Periodic signal superimposed with strong non-stationary noise that follows an approximate 1/f distribution cannot be easily separated with traditional signal processing methods. Using the stationary wavelet transform, the noisy signal is decomposed into wavelet coefficients including both the detail and approximate coefficients. According to its periodic feature, detail coefficients on each scale are extracted to form the same-phase sequences which consist of coefficients with the same phase values in each cycle. The amplitude probability distribution functions of same-phase sequences follow approximate Gaussian distribution. Therefore, noise in the same-phase sequences can be removed with the non-linear median filter and moving average filter. Since non-stationary noise follows approximate 1/f distribution, the approximate coefficients on the lowest frequency level have strong non-stationary property. Due to spectrum leakage of different frequency sections, the leakage signal components are superimposed on the approximate coefficients. Three different filtering methods are proposed to process the approximate coefficients in order to extract the useful signal components and to reconstruct the periodic signal accurately. Finally the proposed method is used to process the output signal of electromagnetic flowmeter during slurry flow measurement under different slurry concentrations and different flow rates. Results show that the proposed method is effective in the separation of periodic signal and strong non-stationary noise which follows the approximate 1/f distribution. 相似文献
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介绍利用8031单片机对涡街流量计输出脉冲信号采取计时与计频方式相结合的测频方法。重点介绍测量原理和硬软件设计思想。 相似文献