On orthogonal realizations for adaptive IIR filters

Convergence speed is one of the main concerns in adaptive IIR filters. Fast convergence can be closely related to adaptive filter realization. However, with the exception of the lattice realization that is based on the nice properties of Szëgo orthonormal polynomials, no other adaptive IIR filter realization using orthonormal characteristics seems to be extensively studied in the literature. Furthermore, many orthogonal realizations for adaptive FIR filters, that are particularly suitable for rational modelling, have been proposed in the past years. Since rational orthogonal basis functions are a powerful tool for efficient system representation they seem attractive for adaptive IIR filters. In this paper, we present some theoretical results related to the properties of a generalized orthonormal realization when used for mean‐square output error minimization in a system identification application. One result is related to the low computational complexity of the updating gradient algorithm when some properties of the orthonormal realization are used. An additional result establishes conditions for the stationary points of the proposed updating algorithm. In order to confirm the expected performance of the new realization, some simulations and comparisons with competing realizations in terms of computational complexity and convergence speed are presented. Copyright © 2000 John Wiley & Sons, Ltd.     

Design of IIR multiple notch filters

A new method for designing IIR multiple notch filters is presented, which satisfies the notch frequency specifications exactly and realizes 3 dB rejection bandwidths which are lower than those specified. An allpass filter-based realization has been worked out to make the design relatively insensitive to coefficient inaccuracies. Illustrative examples are given. © 1998 John Wiley & Sons, Ltd.     

On the design of two channel perfect construction QMF filters

This paper presents two rapidly convergent methods for the design of two‐channel odd degree linear phase FIR banks as well as IIR filter banks. In both cases, zeros of arbitrary multiplicity are assumed at z = −1, to ensure regularity of the generated wavelet basis. It is shown that in the FIR case, the problem reduces to the solution of an eigenvalue problem. A simple minimization method is proposed for its solution to reduce most of the computational complexities of eigenvalue evaluations. In the IIR case, a simple rapidly convergent algorithm is also described for the determination of a perfect as well as pseudo‐perfect reconstruction stable IIR function having equiripple pass and stop band responses and with almost constant group delay. It is also shown that the analysis and synthesis banks are of same complexities, and as a result of being expressed as sum of two all‐pass functions, they are realized in a lattice form. Therefore, they are immune from quantization effects. Illustrative examples are also given. Copyright © 2000 John Wiley & Sons, Ltd.     

双相信号发生器的设计

分析了采用地址计数器原理实现的双相信号发生器的局限性，介绍了应用直接数字合成技术（DDS）基本原理、采用可编程逻辑器件实现的双相信号发生器的方法。该技术可以扩展信号发生器的频段，提高相位分辨率，还可以实现两路独立信号发生器的功能，大大提高了仪器的应用范围。     

IIR陷波滤波器设计

从实际应用的要求出发，以IIR数字滤波器的基本理论为依据，按照层次化、模块化、参数化的设计思路，采用VHDL硬件描述语言和原理图两种设计技术进行了IIR陷波滤波器的硬件设计，并在制作的实验电路中进行了实际滤波效果测试，测试结果表明该IIR陷波滤波器具有很好的滤波效果，验证了设计的正确性。     

IIR低通滤波器在谐波监测中的应用

以IIR数字滤波器的基本理论为依据，结合滤波器的传递函数分子、分母系数固定这一事实，通过选用高密度可编程逻辑器件确定了IIR数字滤波器的硬件实现方案，并按照层次化、模块化、参数化的设计思路，采用VHDL硬件描述语言和原理图两种设计技术进行了IIR滤波器的硬件设计；对设计的低通滤波器进行了系数量化并对其影响进行了分柝最后进行了实际滤波效果测试，验证了设计的正确性。     

On the design of multi notch filters

A methodology for designing FIR multi notch filters (NFs) derived from second‐order prototype IIR NFs is suggested. Rejection bandwidth for the designed filter can be controlled by suitable choice of ‘r’, the pole radius of the IIR prototype NFs. The suggested multi NF can also be adapted to eliminate second‐, third‐ and fourth‐order harmonics of periodic noise besides the fundamental noise frequency component. A special case when two notch frequencies ω₁ and ω₂ are such that [(cosω₁)(cosω₂) = ? 1/2] has also been discussed. The IIR multi NF design for this special case results in reduction of the number of multipliers without affecting the response of the desired NF. For the aforereferred condition, the required coefficients of impulse response of FIR multi notch filter get reduced to almost half in number resulting in reduced computations. The number of zero coefficients further reduces with increase in ‘r’ value. In addition, the frequency response becomes better, with reduced ripples in the pass bands, when ‘r’ is increased and length ‘L’ of the FIR NF is chosen appropriately. Copyright © 2010 John Wiley & Sons, Ltd.     

基于频率采样法的线性相位滤波器设计及Matlab仿真

根据第1个频率采样点的不同有2种频率采样法来设计线形相位有限脉冲响应(FIR)滤波器,分别对应2种传输函数。传统的频率采样法设计线性相位滤波器时要考虑采样点的相位特性。通过研究傅里叶变换性质,对其步骤进行了改进,可以不考虑采样点的相位特性,通过对频率采样点向量H(k)乘以移位因子来直接进行滤波器的设计,算法简单易行。用Matlab进行仿真,结果表明该方法可按要求实现4种线性相位FIR滤波器。     

On the design of adaptive notch filters

In instrumentation and other applications, the on‐line estimation of the frequency and amplitude of a noise‐corrupted sinewave is of great practical interest. Recently an adaptive notch filter (ANF) with global convergence properties has been developed, and is a candidate approach to our problem. This paper analyses the transient and noise properties of this ANF and equips the method with design equations. Using frequency ranges greater than (up to 2 decades) and signal/noise ratios less than (down to ?16 dB) those commonly found in the ANF literature, it is verified by extensive simulations that the new frequency estimator has excellent tracking and noise‐rejection properties, provided that the signal/noise ratio is not too small. A comparison is made of its behaviour with that of a phase‐locked loop, a method commonly used in practice. Copyright © 2001 John Wiley & Sons, Ltd.     

YIG调谐带阻滤波器的新应用

首先介绍了YIG调谐滤波器的工作原理、特点和常规应用.在此基础上创造性地提出了YIG调谐带阻滤波器的新型用法,包括梳谱式阻带可变滤波器、多路幅相一致带阻滤波器以及开关滤波器,不仅拓展了YIG调谐滤波器的功能,而且改善了YIG器件扫速等固有的缺陷,为YIG调谐带阻滤波器更为广泛的应用找到了新的思路和方向.     

Q‐factor evaluation,design and accurate EM performance of multilayer dielectric filters

In this contribution we present the design of an optical dielectric multilayered filter by using a transmission‐line prototype. Each resonator of the prototype is realized by means of a stack of dielectric layers by equating the Q‐factor of the stack with that of the corresponding resonator of the prototype. We then compare the analytical results with numerical ones obtained by the finite element method (FEM). We extend the theory to a structure formed by periodic multilayer resonators. Copyright © 2006 John Wiley & Sons, Ltd.     

Optimal harmonic filters design of the Taiwan high speed rail traction system of distributer generation system with specially connected transformers

This paper presents a method for combining a particle swarm optimization with nonlinear time-varying evolution and orthogonal arrays (PSO-NTVEOA) in the planning of harmonic filters for the high speed railway traction system of Distributed Generation (DG) system with specially connected transformers in unbalanced three-phase power systems. The objective is to minimize the cost of the filter, the filters loss, the total harmonic distortion of currents and voltages at each bus simultaneously. An orthogonal array is first conducted to obtain the initial solution set. The set is then treated as the initial training sample. Next, the PSO-NTVEOA method parameters are determined by using matrix experiments with an orthogonal array, in which a minimal number of experiments would have an effect that approximates the full factorial experiments. This PSO-NTVEOA method is then applied to design optimal harmonic filters in Taiwan HSR traction system, where both rectifiers and inverters with IGBT are used. From the results of the illustrative examples, the feasibility of the PSO-NTVEOA to design an optimal passive harmonic filter of Taiwan HSR system is verified and the design approach can greatly reduce the harmonic distortion. Three design schemes are compared that V–V connection suppressing the 3rd order harmonic and Scott connection for the harmonic improvement is better than those of V–V and Le Blanc connection.     

Numerical analysis of waveguide bandpass filters using singular integral equations and construction of simple design formulas

A powerful numerical solution is presented for bandpass filters in rectangular waveguides. The filters are composed of cascading of perfectly conducting inductive obstacles with zero thickness: asymmetrical windows, symmetrical windows, or symmetrical strips. The problem is reduced to a set of singular integral equations, which is solved by an extension of Lewin's quasi‐static procedure. After the accuracy of the classical formulas for the equivalent reactance is investigated, the simple inverse formulas are constructed to yield proper window widths for desired equivalent parameters. Their effectiveness is demonstrated by designing practical filters having maximally flat or equal‐ripple characteristics. © 2004 Wiley Periodicals, Inc. Electr Eng Jpn, 148(4): 17–25, 2004; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10251     

Efficient optimization‐oriented design methodology of high‐order 3‐D filters using 2‐D and 3‐D electromagnetic simulators

This paper proposes a computationally highly efficient interface between two‐dimensional (2‐D) and three‐dimensional (3‐D) electromagnetic (EM) simulators for the optimization‐oriented design of high‐order 3‐D filters. In a first step, the novel optimization‐oriented design methodology aligns the 3‐D EM simulator response with the 2‐D EM simulator response of a low‐order 3‐D filter by using an inverse linear space mapping optimization technique. Then, a second mapping performs a calibration with the optimal 2‐D and 3‐D design parameters obtained from the first mapping. The optimization of high‐order filters is carried out using only the efficient 2‐D EM simulator, and the calibration equations directly give the design parameters of the 3‐D filter. The potential and the effectiveness of the proposed optimization‐oriented design methodology are demonstrated through the design of C‐band 3‐D evanescent rectangular waveguide bandpass filters with increasing orders from three to eight. Copyright © 2014 John Wiley & Sons, Ltd.