共查询到20条相似文献,搜索用时 156 毫秒
1.
2.
3.
4.
一阶逼近格林瓦尔-莱特尼科夫(G-L)加权系数的计算具有准确快速的递推公式,而高阶逼近鲁比希加权系数的求解则复杂度高,计算消耗时间长。本文通过傅里叶变换证明了鲁比希算子的逼近阶,并基于移位鲁比希算子提出一类四阶逼近的加权移位鲁比希差分(WSLD)算子。从数字信号处理角度分析WSLD算子滤波特性,设计基于WSLD算子的分数阶数字FIR微分滤波器并进行数值仿真验证。对比Al-Alaoui、鲁比希2种典型分数阶算子,结果表明,利用WSLD算子求解分数阶数字FIR滤波器滤波系数的算法简单、高效,且相对其他算子能有效减小吉布斯效应影响。 相似文献
5.
6.
7.
基于两通道滤波器组构建的子带信号处理方法已在图像、语音信号处理中得到广泛的应用.本文从分数阶傅里叶域多抽样率信号处理基本理论和分数阶卷积定理出发,推导了分数阶傅里叶域两通道滤波器组准确重建的基本条件,并基于传统傅里叶域有限长标准正交镜像滤波器组和共轭正交镜像滤波器组的原型滤波器设计了分数阶傅里叶域标准正交镜像滤波器组和共轭正交镜像滤波器组.本文所提出的结论为分数阶傅里叶域滤波器组理论的建立提供了基本依据,同时也为分数阶傅里叶变换在图像、语音信号处理等工程实践中的应用奠定了理论基础.最后,仿真实验验证了所提分数阶傅里叶域滤波器设计方法的有效性. 相似文献
8.
为确定体声波(BAW)梯形滤波器的阶数,使用仿真法研究了滤波器的带外抑制与并、串联薄膜体声波谐振器(FBAR)的电容比Cps和滤波器阶数N的关系。基于FBAR的Mason 解析电路模型构建了1~6阶BAW梯形滤波器,Cps取值为1~6,对1~6阶BAW梯形滤波器进行仿真,取滤波器的左带外抑制进行统计并绘制曲线图。此外,BAW梯形滤波器的阶数可包括半阶数,用同样仿真法改变阶数(N=1.5,…,5.5)对滤波器进行仿真。仿真结果表明,当Cps一定时,带外抑制基本随滤波器的阶数等量增加。当滤波器的阶数一定时,带外抑制随Cps的增加而增加。在优化设计时,并、串联FBAR谐振器区面积比(即Cps)一般设置为1~4,在此范围内滤波器阶数每增加一阶,带外抑制平均增加约10 dB;滤波器的阶数增加半阶时,带外抑制约增加整阶数的一半,即5 dB,而此时通带内的插损基本保持不变。故设计滤波器时,根据设计指标中的带外抑制可初步确定滤波器的阶数。 相似文献
9.
陈家义 《智能计算机与应用》2011,(4):73-75,85
首先回顾了分数阶微积分、分数阶系统和分数阶PIλDμ控制器的数学描述,对于一类分数阶SISO被控对象,提出了一种基于整数阶微分算子的分数阶PIλDμ控制器的S平面状态空间实现.同时,在Matlab Simulink仿真平台实现了基于Oustaloup连续滤波器法的分数阶微分算子和该状态空间实现,并基于遗传算法整定了状态... 相似文献
10.
图像边缘细节包含重要的视觉感知信息,是进一步进行图像理解与场景感知的基础.针对常用的边缘梯度检测方法难以有效提取类似于分形纹理结构的复杂图像边缘问题,提出一种基于分数阶微分的图像边缘检测方法.该方法首先基于分数阶微分的性质进行图像拐点检测,并进一步结合拉格朗日多项式插值和Grumwald-Letnikov(G-L)分数阶微分的定义,推导出具有非整数步长像素信息的图像边缘检测算子.实验表明,该方法能有效提取图像中的边缘细节(拐点)特征.对被噪声严重污染的具有复杂边缘细节的图像,该算子同样具有较好的边缘细节检测能力,获得更好的视觉效果. 相似文献
11.
Optimum (in a maximally flat frequency response error sense) FIR digital differentiators of variable fractional sample delay are derived that calculate the derivative of an input uniformly sampled discrete-time signal with arbitrary centre frequency at an arbitrarily chosen instant of time within each sampling interval. The proposed class of differentiators includes maximally linear differentiators for low frequencies 相似文献
12.
This paper presents an easy and simple method to design variable fractional order digital FIR integrators and differentiators based on fractional order systems. First, closed-form digital IIR fractional order integrators and differentiators have been obtained from the analog rational functions approximations, in a given frequency band, of the fractional order integrator s ?m and differentiator s m (0?<?m?<?1) through the Tustin generating function. Then, closed-form digital FIR fractional order integrators and differentiators by truncation of the digital IIR ones have been derived. Next, polynomial interpolation has been used to design digital FIR variable fractional order integrators and differentiators that can be implemented by the Farrow structure. The main feature of variable fractional order operator is that its order can be changed without re-designing a new fractional order operator. Some examples have been presented through the paper to illustrate the performance and the effectiveness of the proposed design method. The results obtained have been discussed and have been compared to one of the most recent works in the literature using the same design parameters. 相似文献
13.
The classical central difference approximations of the derivative of a function based on Taylor series are the same as type III maximally linear digital differentiators for low frequencies. A new finite difference formula is derived which can be implemented as a full band type IV maximally linear differentiator. The differentiator is compared with type III maximally linear and type IV equiripple minimax differentiators. A modification is proposed in the design to minimise the region of inaccuracy near the Nyquist frequency edge 相似文献
14.
Aggarwal Apoorva Kumar Manjeet Rawat Tarun K. Upadhyay D. K. 《Multidimensional Systems and Signal Processing》2017,28(4):1569-1587
Multidimensional Systems and Signal Processing - In this article, an optimal design of two-dimensional finite impulse response digital differentiators (2-D FIR-DD) with quadrantally odd symmetric... 相似文献
15.
J. Le Bihan 《Circuits, Systems, and Signal Processing》1995,14(5):633-637
A new efficient algorithm for calculating the weighting coefficients of maximally linear, FIR digital differentiators is presented. Simple closed-form explicit and recursive formulas are derived in a very straightforward manner. Moreover, a simple recursive equation is established, relating coefficients of two digital differentiators of adjacent ranks. 相似文献
16.
New compact and simple formulas for the design of digital differentiators based on the least squares method are proposed. The new expressions allow a very fast and precise computation of the filter coefficients. Furthermore, using the proposed analytical solution, the need to solve the system of linear equations for the case of fullband differentiators is avoided 相似文献
17.
Using fractional delay to control the magnitudes and phases of integrators and differentiators 总被引:1,自引:0,他引:1
The use of fractional delay to control the magnitudes and phases of integrators and differentiators has been addressed. Integrators and differentiators are the basic building blocks of many systems. Often applications in controls, wave-shaping, oscillators and communications require a constant 90deg phase for differentiators and -90deg phase for integrators. When the design neglects the phase, a phase equaliser is often needed to compensate for the phase error or a phase lock loop should be added. Applications to the first-order, Al-Alaoui integrator and differentiator are presented. A fractional delay is added to the integrator leading to an almost constant phase response of -90deg. Doubling the sampling rate improves the magnitude response. Combining the two actions improves both the magnitude and phase responses. The same approach is applied to the differentiator, with a fractional sample advance leading to an almost constant phase response of 90deg. The advance is, in fact, realised as the ratio of two delays. Filters approximating the fractional delay, the finite impulse response (FIR) Lagrange interpolator filters and the Thiran allpass infinite impulse response (IIR) filters are employed. Additionally, a new hybrid filter, a combination of the FIR Lagrange interpolator filter and the Thiran allpass IIR filter, is proposed. Methods to reduce the approximation error are discussed. 相似文献
18.
The finite-difference time-domain (FDTD) method has been widely used to simulate the electromagnetic wave propagation in biological tissues. The Cole-Cole model is a formulation which can describe many types of biological tissues accurately over a very wide frequency band. However, the implementation of the Cole-Cole model using the FDTD method is difficult because of the fractional order differentiators in the model. In this letter, a new FDTD formulation is presented for the modeling of electromagnetic wave propagation in dispersive biological tissues with the Cole-Cole model. The Z-transform is used to represent the frequency dependent dielectric properties. The fractional order differentiators in the Cole-Cole model is approximated by a polynomial. The coefficients of the polynomial are found using a least-squares fitting method 相似文献
19.
In this article, we propose the use of power function and least squares method for designing of a fractional order digital differentiator. The input signal is transformed into a power function by using Taylor series expansion, and its fractional derivative is computed using the Grunwald–Letnikov (G–L) definition. Next, the fractional order digital differentiator is modelled as a finite impulse response (FIR) system that yields fractional order derivative of the G–L type for a power function. The FIR system coefficients are obtained by using the least squares method. Two examples are used to demonstrate that the fractional derivative of the digital signals is computed by using the proposed technique. The results of the third and fourth examples reveal that the proposed technique gives superior performance in comparison with the existing techniques. 相似文献
20.
Multirate digital filters, filter banks, polyphase networks, andapplications: a tutorial 总被引:3,自引:0,他引:3
Vaidyanathan P.P. 《Proceedings of the IEEE. Institute of Electrical and Electronics Engineers》1990,78(1):56-93
The basic concepts and building blocks in multirate digital signal processing (DSP), including the digital polyphase representation, are reviewed. Recent progress, as reported by several authors in this area, is discussed. Several applications are described, including subband coding of waveforms, voice privacy systems, integral and fractional sampling rate conversion (such as in digital audio), digital crossover networks, and multirate coding of narrowband filter coefficients. The M -band quadrature mirror filter (QMF) bank is discussed in considerable detail, including an analysis of various errors and imperfections. Recent techniques for perfect signal reconstruction in such systems are reviewed. The connection between QMF banks and other related topics, such as block digital filtering and periodically time-varying systems, is examined in a pseudo-circulant-matrix framework. Unconventional applications of the polyphase concept are discussed 相似文献