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FIR Filter (fir + filter)

Distribution by Scientific Domains

Engineering	66%

Selected Abstracts

Design of an FIR filter for the displacement reconstruction using measured acceleration in low-frequency dominant structures

INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 4 2010
Hae Sung Lee
Abstract This paper presents a new class of displacement reconstruction scheme using only acceleration measured from a structure. For a given set of acceleration data, the reconstruction problem is formulated as a boundary value problem in which the acceleration is approximated by the second-order central finite difference of displacement. The displacement is reconstructed by minimizing the least-squared errors between measured and approximated acceleration within a finite time interval. An overlapping time window is introduced to improve the accuracy of the reconstructed displacement. The displacement reconstruction problem becomes ill-posed because the boundary conditions at both ends of each time window are not known a priori. Furthermore, random noise in measured acceleration causes physically inadmissible errors in the reconstructed displacement. A Tikhonov regularization scheme is adopted to alleviate the ill-posedness. It is shown that the proposed method is equivalent to an FIR filter designed in the time domain. The fundamental characteristics of the proposed method are presented in the frequency domain using the transfer function and the accuracy function. The validity of the proposed method is demonstrated by a numerical example, a laboratory experiment and a field test. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Design of a near-optimal adaptive filter in digital signal processor for active noise control

INTERNATIONAL JOURNAL OF ADAPTIVE CONTROL AND SIGNAL PROCESSING, Issue 1 2008
S. M. Yang
Abstract Adaptive filter has been applied in adaptive feedback and feedforward control systems, where the filter dimension is often determined by trial-and-error. The controller design based on a near-optimal adaptive filter in digital signal processor (DSP) is developed in this paper for real-time applications. The design integrates the adaptive filter and the experimental design such that their advantages in stability and robustness can be combined. The near-optimal set of controller parameters, including the sampling rate, the dimension of system identification model, the dimension (order) of adaptive controller in the form of an FIR filter, and the convergence rate of adaptation is shown to achieve the best possible system performance. In addition, the sensitivity of each design parameter can be determined by analysis of means and analysis of variance. Effectiveness of the adaptive controller on a DSP is validated by an active noise control experiment. Copyright © 2007 John Wiley & Sons, Ltd. [source]

Microphotonic wideband tapped optical delay line FIR filter noise analysis

MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 6 2005
R. D. Jeffery
Abstract MicroPhotonic broadband RF signal processors utilize true-time-delay methods to perform processing functions that cannot be achieved by conventional electronic methods. Using a tapped optical-delay line, a low-cost adaptive wideband FIR filter can be realized. We analyse the sources of noise for such a filter using commercially available VCSEL sources, PIN diodes, and transimpedance amplifiers. The power at each tap can be equal by using a suitably graded coating, or if the reflectivity is constant, there is an optimum reflectivity that maximizes the signal-to-noise ratio for a given number of taps, as we show in this paper. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 45: 476,480, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20857 [source]

An automated quantitation of short echo time MRS spectra in an open source software environment: AQSES

NMR IN BIOMEDICINE, Issue 5 2007
Jean-Baptiste Poullet
Abstract This paper describes a new quantitation method called AQSES for short echo time magnetic resonance spectra. This method is embedded in a software package available online from www.esat.kuleuven.be/sista/members/biomed/new/ with a graphical user interface, under an open source license, which means that the source code is freely available and easy to adapt to specific needs of the user. The quantitation problem is mathematically formulated as a separable nonlinear least-squares fitting problem, which is numerically solved using a modified variable-projection procedure. A macromolecular baseline is incorporated into the fit via nonparametric modelling, efficiently implemented using penalized splines. Unwanted components such as residual water are removed with a maximum-phase FIR filter. Constraints on the phases, dampings and frequencies of the metabolites can be imposed. AQSES has been tested on simulated MR spectra with several types of disturbance and on short echo time in vivo proton MR spectra. Results show that AQSES is robust, easy to use and very flexible. Copyright © 2006 John Wiley & Sons, Ltd. [source]

FIR filter design problems of simultaneous approximation of magnitude and phase and magnitude and group delay

MATHEMATICAL METHODS IN THE APPLIED SCIENCES, Issue 8 2001
Rembert Reemtsen
Two of the four central design problems for FIR filters in the frequency domain are the problems of simultaneous approximation of prescribed magnitude and phase responses and prescribed magnitude and group delay responses, respectively. In the past, these problems have almost always been approached in indirect and approximative ways only. Especially (approximate) solutions of the simpler frequency response approximation problem have served as substitutes for solutions of the magnitude-phase problem. In this paper, at first a rigorous mathematical formulation of both problems is developed and then, for these problems, the existence of solutions and results on the convergence of the approximation errors are proved. (A method to solve both problems is simultaneously suggested in Görner et al. (Optimization and Engineering 2000; 1:123,154).) Also the improvement, obtained by use of a direct solution of the magnitude-phase response problem instead of a solution of the frequency response problem, is quantified by computable bounds. In the study, the approximation errors are measured by an arbitrary Lp -normresp. lp -norm with 1,p,,, and constraints on the filter coefficients are permitted. Copyright © 2001 John Wiley & Sons, Ltd. [source]