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In pre-processing of spectral data, advancements are yet to be made to discover the most efficient filter and establish parameters which define efficiency. In this paper, a unique method of using the Kalman filter for filtering the spectral data is proposed. Not only is it found that the performance of the Kalman filter is better but also observed that the filter provides better noise suppression...
A noise analysis is conducted on a DC powered dual diaphragm air pump. Using a sound level meter, data acquisition chassis and a LabVIEW based fast Fourier Transform tool, the acoustic spectrum of the pump operating under nominal conditions is obtained. The majority of the acoustic energy propagating from the pump is within the 20 to 2000 Hertz range, classifying the pump acoustics as low pitched...
Since the groundbreaking work of the Kalman filter in the 1960s, considerable effort has been devoted to discrete time filters for dynamic state estimation, especially including a variety of suboptimal implementations of the Bayesian filter. The essence of the Bayesian filter is to make the (sub)optimum fusion of the observation information in time sequence based on the hidden Markov model of the...
Single- and multi-target tracking are both typically based on the hidden Markov chain (HMC) model. That is, the target process is a Markov chain, observed by an independent observation process. Since HMC independence assumptions are invalid in many practical applications, the pairwise Markov chain (PMC) model has been proposed as an approach for weakening them. Petetin and Desbouvries subsequently...
There is serious conducted electromagnetic interference (EMI) in the application of medium-power variable-frequency drive (VFD) systems. The EMI passive filters which can suppress the noise can make the VFD systems comply with the relevant electromagnetic compatibility (EMC) standards. In this paper, combined with the experiment and measuring experience in related subjects, it describes the proper...
A bandpass delta-sigma modulator with a widely tunable center frequency range for direct digitization of IF or RF signals can be a key building block for highly digitized radio receivers. The performance of the bandpass modulator is highly dependent on the accuracy of the noise transfer function zero locations in the presence of process spread. An automatic calibration method is proposed to calibrate...
Fetal electrocardiograms (ECGs) are useful for monitoring fetal health during pregnancy. Previously published results demonstrated that a sequential combination of adaptive linear prediction (LPC), adaptive noise cancellation (ANC), and IIR comb filtering (CF) is an effective strategy to remove maternal interference from fetal ECGs. This paper presents a theory of how LPC-ANC sequential processing...
A novel integration structure of EMI filter based on multilayer ceramic is proposed in this paper. The inductors and capacitors of the new structure can be designed separately, which is advantageous to manufacture. Besides, the Insertion Loss(IL) is usually measured under the condition of the source impedance and load impedance are both 50Ω, which is different from the actual situation. In the process...
The planar EMI filter has great engineering significance to power electronic systems integration and miniaturization. However, for some special occasion like the EMI noise is serious, the single-stage EMI filter can not meet the demand of noise suppression, and the multi-stage EMI filter is an important choice to solve this trouble at this time. This paper proposes a design method of multi-stage EMI...
To develop common mode filter design, a tri-section quarter wavelength resonator common mode filter is introduced in this paper. The step impedance quarter wavelength resonator in common mode provides capabilities of tunable suppression bands by controlling the 1st and 3rd resonant frequency. In addition, the transmission zero in differential mode due to the difference of phase velocity between common...
In this paper, we propose an adaptive scheme to design directional second order derivatives orthogonally and tangentially to the local edge. The principle lies on the definition of two adaptive filter masks which estimate the two derivatives along the normal (n) and tangential (t) directions. Both filter masks are controlled by an adaptive mask whose coefficients are tuned in accordance with the local...
The paper investigates a three stage filtering scheme, namely: 1) signal decomposition, 2) filtering and 3) signal reconstruction. If marginal rank order filtering is used in step 2, the derived filtering scheme generalizes the classical order statistics one. Based on this idea, a new family of nonlinear filters, called decomposition filters, is proposed and investigated. The most interesting feature...
The concept of cost function (CF) in the context of image filtering is put under investigation in this work. Optimal behaviour of the resulting filters in respect with noise attenuation and edge preservation is sought through the minimization of these functions. This behaviour can be controlled by proper adjustment of certain parameters in some cases. Function combinations are also considered. Finally,...
A novel approach for speech segmentation is proposed, based on Multilevel Hybrid (mean{}/min{}) Filters (MHF) with the following features: • An accurate transition location. • Good performance in noisy environments (gaussian & impulsive noise). The proposed method is based on spectral changes, with the goal of segmenting the voice into homogeneous acoustic segments. This algorithm is being used...
This contribution deals with the textured images segmentation. The model exploits morphological operators and order filters properties. A morphological decomposition filters bank is built to isolate elementary patterns by decomposing the textural image characteristics. The 1 and 2 order statistic moments and the gradient means are computed in order to select the best feature component image which...
A novel operator for the enhancement of the quality of document images is presented in this paper. This operator, which is a quadratic one, is based on the Unsharp Masking (UM) technique, but it is able to limit noise amplification because every pixel of the processed image depends upon a large portion of the input image; in the same time a good response on details is obtained. A formal description...
We study the output variance of a class of nonlinear filters, called da-filters. In general, it is impossible to obtain an explicit expression of the output variance because of the implicit Input/Output relationship, except for α=1 (median filter), α=2 (mean filter) and α=∞ (midrange filter). In this paper, we develop a new approach to the computation of the filter output variance. It is based on...
Much research attention in recent years has been focussed on the subject of oversampled analogue-to-digital and digital-to-analogue conversion, based on the principle of sigma-delta modulation. Theoretical analysis of these conversion methods has been complicated by their nonlinear nature, precluding the application of standard linear circuit analysis methods. In recent years a number of researchers...
A novel type of distance weighted multichannel filter is used to filter correlated multichannel 1-D seismic electric signals. These signals are weak, short time variations of the geoelectric field occurring prior to an earthquake. The new filters use intersample distances to compute coefficients. Both vector and componentwise correlation is utilised in the computation. The new composite distance filters...
In this paper, we introduce a new technique for multidimensional filtering of irregularly sampled seismic data. In this context filtering may be used for coherent noise and interference attenuation, as well as the generation of seismic images. The filtering operation consists of the convolution of the filter operator with the seismic data. The filter operator is usually computed on a regular grid...
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