Butterworth filter

About: Butterworth filter is a research topic. Over the lifetime, 6187 publications have been published within this topic receiving 69070 citations.

Analysis of filtering methods for 3D acceleration signals in body sensor network

Abstract: Development of denoising algorithm for 3D acceleration signals is essential to facilitate accurate assessment of human movement in body sensor networks (BSN). In this study, firstly 3D acceleration signals were captured by self-developed nine-axis wireless BSN platform during 12 subjects performing regular walking. Then, acceleration noise was filtered using four common filters respectively: median filter, Butterworth low-pass filter, discrete wavelet package shrinkage and Kalman filter. Finally, signal-to-noise ratio (SNR) and correlation coefficient(R) between filtered signal and reference signal were determined. We found that (1) Kalman filter showed the largest SNR and R values, followed by median filter, discrete wavelet package shrinkage and finally Butterworth low-pass filter; whereas, after correcting waveform delay for Butterworth low-pass filter, its performance was a little better than that of Kalman filter; (2) Real-time performance of median filter related to its window length; Decomposition level influenced real-time performance of discrete wavelet package shrinkage; Butterworth low-pass filter could bring large waveform delay if filter order and cut-off frequency were not properly selected. The algorithms of these filters would be further investigated to achieve best noise reduction of 3D acceleration signals in future.

Parameterized filters and signaling techniques

Abstract: Filter taps for filters are specified by filter coefficient parameters. The filter taps are greater in number than the coefficient parameters from which the filter taps are calculated. For example, two coefficient parameters are used to specify a four-tap filter. Filter information can be signaled in a bitstream, such as by signaling one or more family parameters for a filter family and, for each filter in a family, signaling one or more filter tap parameters from which filter taps can be derived. Family parameters can include a number of filters parameter, a resolution parameter, a scaling bits parameter, and/or a full integer position filter present parameter that indicates whether or not the filters include an integer position filter. Filter parameters can be signaled and used to determine coefficient parameters from which filter taps are calculated.

Switched-capacitor filter design using bilinear element modeling

Abstract: The low sensitivity of a doubly loaded reactance ladder to element-value variations is preserved in a switched-capacitor filter with the same graph if a one-to-one replacement of branch impedances is used to derive the switched filter from the reactance ladder This paper describes the design principles and some novel circuits based on this approach The frequency axes of the two filters are mapped into each other by the bilinear s{\leftrightarrow}z transformation; this results in advantageous sensitivity and selectivity properties for the resulting switched-capacitor circuit In addition, the number of active components is equal to the number of inductors replaced, and is hence small This results in very economical realization for the integrated filter

Tunable allpass filter for low voltage operation

Abstract: A novel high-performance first-order allpass filter with electronically adjustable filter parameters is presented. The core of the circuit is an inverting unity gain amplifier with electronically adjustable output resistance, which leads to an allpass filter realisation with tunable time constant. The circuit is composed of a simple CMOS cascode circuit and a level shifter and is also very suitable for low voltage operation, since it employs two active devices between its rails. SPICE simulation and experimental results verifying theoretical analyses are also given.

Cascadable allpass filter with a single DO-CCII and a grounded capacitor

Abstract: In the literature sufficient emphasis has not been given to dual-output current conveyors in all-pass filter designs. In this study, a cascadable voltage-mode all-pass filter with a grounded capacitor using a single dual-output current conveyor has been reported.