Speed comparison among methods for restoring signals with missing high-frequency components using two different low-pass-filter matrix dimensions

1985 ◽  
Vol 10 (8) ◽  
pp. 372
Author(s):  
Nabih N. Abdelmalek ◽  
Nobuyuko Otsu
Keyword(s):  
High Frequency ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Low Pass ◽  
Frequency Components

A modified Bessel filter for amplitude demodulation of respiratory electromyograms

1998 ◽  
Vol 84 (1) ◽  
pp. 378-388 ◽  
Author(s):  
Ronald S. Platt ◽  
Eric A. Hajduk ◽  
Manuel Hulliger ◽  
Paul A. Easton
Keyword(s):  
High Frequency ◽  
Stop Band ◽  
Pass Band ◽  
Third Order ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Transient Characteristics ◽  
Low Pass ◽  
Seventh Order ◽  
Frequency Components

Platt, Ronald S., Eric A. Hajduk, Manuel Hulliger, and Paul A. Easton. A modified Bessel filter for amplitude demodulation of respiratory electromyograms. J. Appl. Physiol. 84(1): 378–388, 1998.—We studied a device that is commonly used for amplitude demodulation of respiratory muscle electromyograms (EMG). This device contains a rectifier and a low-pass filter called a modified third-order Paynter filter. We characterized this filter and found that it has good transient characteristics that suit its task as an EMG demodulator, but it has poor high-frequency attenuation that passes interfering, higher frequency components to the output waveform. Therefore, we designed and constructed a new filter with transient characteristics that are comparable to those of the modified Paynter filter but with superior high-frequency attenuation. This new filter is a modified seventh-order Bessel filter. We also identified a simple technique to convert an existing modified Paynter filter back to an original Paynter filter. The original Paynter filter has a wider pass band than the modified Paynter filter but superior stop-band attenuation.

Weaknesses of the Baxter-King Filter: Is a Pattern-Based Filter an Alternative? / Schwächen des Baxter-King Filters: Ist ein musterbasierter Filter eine Alternative?

2005 ◽  
Vol 225 (4) ◽  
Author(s):  
Georg Goldrian
Keyword(s):  
Time Series ◽  
High Frequency ◽  
Degree Of Approximation ◽  
Trigonometric Function ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Low Pass ◽  
Frequency Components ◽  
Slow Moving ◽  
Ideal Filter

SummaryThe Baxter-King filter shows some weaknesses, particularly with regard to monthly time series. This procedure involves not only a loss of data for the border areas of time series, but suppresses inadequately high frequency components and shows as a low-pass filter only the performance of ordinary moving averages. Another important finding is that the maximal lag Κ not only determines the degree of approximation to an ideal filter, as Baxter and King argue, but also the ability to extract a slow moving component. A pattern-based filter, whose weights are generated by a trigonometric function as well, does not possess such weaknesses, and is thus a real alternative to the Baxter-King filter.

Aliasing Effects on Nodal Acceleration Output From Nonlinear Finite Element Simulations

2000 ◽  
Author(s):  
Mark O. Neal ◽  
Chin-Hsu Lin ◽  
J. T. Wang
Keyword(s):  
Finite Element ◽  
High Frequency ◽  
Nonlinear Finite Element ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Low Pass ◽  
Frequency Components ◽  
Averaging Filter ◽  
Very High ◽  
Acceleration Output

Abstract Nodal acceleration output from nonlinear finite element crash simulations often contains high frequency components. If this output is not sampled frequently enough the high frequency components will be aliased and the resulting acceleration output will be inaccurate. It is recommended in this paper that a low-pass filter be installed in the crashworthiness finite element codes which would remove the high frequency components of the nodal accelerations before they are sampled for output. This would completely eliminate aliasing error in acceleration output. Prior to this installation, there are several options for reducing the effects of aliasing on acceleration output. One option is to request very high sampling rates for acceleration output; however this will result in very large output files. Another option is to calculate the accelerations by differentiating the output velocities. This option, which effectively is an averaging filter acting on the accelerations, is available in the finite element code DYNA3D. The properties of this filter are examined in this paper and it is shown that this filter is very effective in reducing the effects of aliasing on acceleration output, although it should not be expected to completely eliminate potential aliasing problems. Finally, guidelines are presented for selecting nodes and sampling rates based on local natural frequencies that will reduce the effect of aliasing of the acceleration output.

Rapid Recovery of Wide-Bandwidth Photothermal Signals via Homodyne Photothermal Spectrometry: Theory and Methodology

1993 ◽  
Vol 47 (4) ◽  
pp. 489-500 ◽  
Author(s):  
J. F. Power ◽  
M. C. Prystay
Keyword(s):  
High Frequency ◽  
Low Cost ◽  
Signal Recovery ◽  
Wide Bandwidth ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Filter Output ◽  
Low Pass ◽  
Four Quadrant ◽  
Lock In

Homodyne photothermal spectrometry (HPS) is a very wide bandwidth signal recovery technique which uses many of the elements of lock-in detection at very low cost. The method uses a frequency sweep, with a high-frequency bandwidth of up to 10 MHz, to excite a linear photothermal system. The response sweep of the photothermal system is downshifted into a bandwidth of a few kilohertz by means of in-phase mixing with the excitation sweep with the use of a four-quadrant double-balanced mixer and a low-pass filter. Under conditions derived from theory, the filter output gives a good approximation to the real part of the photothermal system's frequency response, dispersed as a function of time. From a recording of this signal, the frequency and impulse response of the photothermal system are rapidly recovered at very high resolution. The method has been tested with the use of laser photopyroelectric effect spectrometry and provides an inexpensive, convenient method for the recovery of high-frequency photothermal signals.

Vibrational Fatigue Analysis of a Strain Loading Using the Frequency and Wavelet Filtering Methods

2011 ◽  
Vol 462-463 ◽  
pp. 124-129
Author(s):  
Shahrum Abdullah ◽  
Edisah Putra Teuku ◽  
Zaki Nuawi Mohd. ◽  
Mohd. Nopiah Zulkifli
Keyword(s):  
High Frequency ◽  
Filter Design ◽  
High Amplitude ◽  
Morlet Wavelet ◽  
Wavelet Filtering ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Automotive Components ◽  
Low Pass ◽  
Low Amplitude

This paper presents a comparison work between the filtering methods of fatigue strain loadings using the frequency spectrum and the wavelet transform (WT), in which a raw loading signal can be simplified for purpose of simulation. For this reason, the Fast Fourier Transform (FFT) and the Morlet wavelet algorithms were used in order to transform the vibrational fatigue time series into the frequency domain signal, leading to the observation of the frequency characteristics of the signal. To retain high amplitude cycles in the FFT algorithm, a low pass filter technique was applied to remove the high frequency signals with small amplitude that are non-damaging. The departure of high frequency information smoothed the low amplitude cycles at high frequency events in the fatigue signal. The Butterworth filter was selected as the most efficient filter design as it retained most of the fatigue damage and also had the capability to remove 30 % of the original low amplitude cycles. On the other hand, the Morlet wavelet managed to remove 64 % of the original 59 second signal. This wavelet filtering method removed 34 % more than the similar procedure applied through the FFT approach. Hence, this fatigue data summarising algorithm can be used for studying the durability characteristics of automotive components.

Closed horizontal wire loop as a low–pass filter in tem measuring systems

2020 ◽  
Author(s):  
Nikolay O. Kozhevnikov ◽  
Keyword(s):  
Frequency Response ◽  
High Frequency ◽  
External Noise ◽  
Measuring System ◽  
Electromagnetic Noise ◽  
Measuring Systems ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Low Pass ◽  
Horizontal Wire

The paper discusses the possibility of using a closed horizontal loop in a TEM measuring system to reduce the external high–frequency electromagnetic noise induced in a receiving loop. It is shown that the effect of an additional loop on the frequency response of the TEM measuring system is similar to that of a low–pass filter. In order to effectively reduce external noise, one should locate the auxiliary loop as close as possible to the receiver one.

Design of the Broadband Standard Signal Generator for Laser Locating System of the Mine Hoisting Container

2013 ◽  
Vol 427-429 ◽  
pp. 2033-2036
Author(s):  
Di Fan ◽  
Yan Gao ◽  
Yue Zhao
Keyword(s):  
High Frequency ◽  
Low Frequency ◽  
Frequency Standard ◽  
Analog Filters ◽  
Laser Ranging ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Noise Disturbance ◽  
Standard Signal ◽  
Low Pass

As the key junction between the ground and underground, hoisting systems as well as mines themselves are of vital importance to coalmine production. Laser ranging method is studied as a new solution of getting the real-time position directly. Furthermore, multi-scale phase based laser ranging principles are utilized in the system. The paper is aimed to conduct research into the problems existing in standard signal generating while using laser to locating the hoisting container, and to design standard sine generator circuits with DDS technology and DDS devices AD9850 to generate multiple frequency standard signals. In view of the serious noise disturbance in high frequency output, 4-order Chebyshev low-pass filter is designed, by using the integrated analog filters LT 6600-15, to filter the sine signals from AD9850 and to effectively weaken the noise disturbance. The established practical circuits are tested, obtaining trillion level high frequency and low frequency sine signals and fulfilling the requirements for the location system of hoisting containers.

Suprathreshold Intrinsic Dynamics of the Human Visual System

2003 ◽  
Vol 15 (12) ◽  
pp. 2883-2908 ◽  
Author(s):  
Gopathy Purushothaman ◽  
Haluk Öğmen ◽  
Harold E. Bedell
Keyword(s):  
Visual System ◽  
Human Visual System ◽  
High Frequency ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Cortical Dynamics ◽  
Neural Activities ◽  
Low Pass ◽  
Psychophysical Studies ◽  
Spatiotemporal Integration

Intrinsic high-frequency neural activities have been observed in the visual system of several species, but their functional significance for visual perception remains a fundamental puzzle in cognitive neuroscience. Spatiotemporal integration in the human visual system acts as a low-pass filter and makes the psychophysical observation of high-frequency activities very difficult. A computational model of retino-cortical dynamics (RECOD) is used to derive experimental paradigms that allow psychophysical studies of high-frequency neural activities. A reduced-parameter version of the model is used to quantitatively relate psychophysical data collected in two of these experimental paradigms. Statistical analysis shows that the model's account of the variance in the data is, in general, highly significant. We suggest that psychophysically measured oscillations reflect intrinsic neuronal oscillations observed in the visual cortex.

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