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Fast Digital filters for ECG Signals
Ráček, Tomáš ; Vítek, Martin (referee) ; Kozumplík, Jiří (advisor)
In the thesis there are described the implementations of various types of filters to remove disturbing signals, which often degrade the ECG signal. In particular, it is a zero isoline fluctuations and power network interference. It is used a principle of the Lynn’s linear filters. The individual filters are designed in a recursive and non-recursive implementation. Then there is described a time-varying linear Lynn's filter for removing drift of zero isoline signal. The thesis also includes filters with minimized calculating time of response, by sampling rate conversion method for both interference types. In conclusion there is an experimental study of the filter implementation for ECG signal with false and real interferences.
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ECG noise generator
Siegel, Jan ; Walek, Petr (referee) ; Smital, Lukáš (advisor)
The signal of ECG is interfered by the noise of different origin.. Most common are powerline interferences, baseline wandering, electromyographic and impuls noises. Such kind of noise is undesirable in signal since they decrease diagnostic yield in ECG. For effective removal of noise, we must detect the type of interference consequently use its theorists properties for specific filtration. The aim of this work is to creat a technical tool - ECG noise generator. ECG noise generator is being used for simulation of signal with defined parameters and type of noise. This noise generator can be employed for the verification of techniques designed for the elimination of interferences or the identification of the noise present in the unknown signal.
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Preprocessing of ECG signals for detection of significant points
Strouhal, Martin ; Smital, Lukáš (referee) ; Vítek, Martin (advisor)
This work aims to find out the best filter design method for getting out parasitic elements in ECG signal. There are defined origin and frequency qualities of these elements. Individua filter design methods are compared according to number of filter coefficients, effectivity and influenc to useful signal. I created several digital filters by various design methods and tested them on ten ECG signals. From the experiment ensued: all filters were able to get out brum, but filters designed by distribution of zeros and poles had the lowest number of coefficients. On the other hand same filters were disable to get out drift with very sheer course.
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Digital filtering of ECG signals
Ráček, Tomáš ; Kolář, Radim (referee) ; Kozumplík, Jiří (advisor)
In the thesis there are presented frequency features of disturbing signals as baseline fluctuation, power network interference and myopotentialstion. Methods for removing these signále are discussed too. It iis used a principle of the Lynn’s linear filters, mostly the Lynn’s high pass and Lynn’s band pass filters. For real-time ECG signal filtration there is optimal to use the filter with continuously changing cut-off frequency according to a measured heart rate. Then there is described a simple dynamic linear Lynn's filter with a varying impulse response according to the heart rate.
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Preprocessing of ECG signals for detection of significant points
Strouhal, Martin ; Smital, Lukáš (referee) ; Vítek, Martin (advisor)
This work aims to find out the best filter design method for getting out parasitic elements in ECG signal. There are defined origin and frequency qualities of these elements. Individua filter design methods are compared according to number of filter coefficients, effectivity and influenc to useful signal. I created several digital filters by various design methods and tested them on ten ECG signals. From the experiment ensued: all filters were able to get out brum, but filters designed by distribution of zeros and poles had the lowest number of coefficients. On the other hand same filters were disable to get out drift with very sheer course.
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Digital filtering of ECG signals
Ráček, Tomáš ; Kolář, Radim (referee) ; Kozumplík, Jiří (advisor)
The aim of the thesis is to out¬line the present state of digital pre¬processing (especially filtering) of ele¬ctrocardiograms. The frequency featu¬res of disturbing signals (baseline wandering, power network interferan¬ce, myopotentials) are mentioned and methods for removing of them are discussed. Based on this description, requirements for amplitude characterization of phase non-distorting filter for sup¬pressing the drift of isoelectric line of ECG signal are tentatively established. Several digital filters were created so that their application in testing would enable to give even more precision to requirements for amplitude characteristics. The expriments made it clear that ECG sig¬nal may be filtered through high pass filter with linear phase characteristic and cutt-off frequency 0.7 Hz and mi¬ximum attentuation in the filter transmission band 0.5 dB irrespective of rhythm regularity without significant distortion to occur. Also is describe an experiment by means of which they assessed the width of the frequency band of the ideal, not distorting band-stop filter for the suppression of the network hum in the ECG signal. It was found that the width of the band can be as much as +-3 Hz in the area surrounding the network frequency without cau¬sing excessive distortion of the useful signal. Also are discuss the properties, design and inlplementation of band-stop filters, based on the principle of Lynn's filters. It is optimal to use the filter with its cut-off fre¬quency continually changing according to measured heart rate for pre-processing ECG signal to decrease baseline drift by high-pass filter in real time. Easy rea¬lizable non-recursive Lynn's filter with time-varying impulse response adapted to the current frequently of ECG signal is described.
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Digital filtering of ECG signals
Ráček, Tomáš ; Kolář, Radim (referee) ; Kozumplík, Jiří (advisor)
The aim of the thesis is to out¬line the present state of digital pre¬processing (especially filtering) of ele¬ctrocardiograms. The frequency featu¬res of disturbing signals (baseline wandering, power network interferan¬ce, myopotentials) are mentioned and methods for removing of them are discussed. Based on this description, requirements for amplitude characterization of phase non-distorting filter for sup¬pressing the drift of isoelectric line of ECG signal are tentatively established. Several digital filters were created so that their application in testing would enable to give even more precision to requirements for amplitude characteristics. The expriments made it clear that ECG sig¬nal may be filtered through high pass filter with linear phase characteristic and cutt-off frequency 0.7 Hz and mi¬ximum attentuation in the filter transmission band 0.5 dB irrespective of rhythm regularity without significant distortion to occur. Also is describe an experiment by means of which they assessed the width of the frequency band of the ideal, not distorting band-stop filter for the suppression of the network hum in the ECG signal. It was found that the width of the band can be as much as +-3 Hz in the area surrounding the network frequency without cau¬sing excessive distortion of the useful signal. Also are discuss the properties, design and inlplementation of band-stop filters, based on the principle of Lynn's filters. It is optimal to use the filter with its cut-off fre¬quency continually changing according to measured heart rate for pre-processing ECG signal to decrease baseline drift by high-pass filter in real time. Easy rea¬lizable non-recursive Lynn's filter with time-varying impulse response adapted to the current frequently of ECG signal is described.
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Preprocessing of ECG signals for detection of significant points
Strouhal, Martin ; Smital, Lukáš (referee) ; Vítek, Martin (advisor)
This work aims to find out the best filter design method for getting out parasitic elements in ECG signal. There are defined origin and frequency qualities of these elements. Individua filter design methods are compared according to number of filter coefficients, effectivity and influenc to useful signal. I created several digital filters by various design methods and tested them on ten ECG signals. From the experiment ensued: all filters were able to get out brum, but filters designed by distribution of zeros and poles had the lowest number of coefficients. On the other hand same filters were disable to get out drift with very sheer course.
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Preprocessing of ECG signals for detection of significant points
Strouhal, Martin ; Smital, Lukáš (referee) ; Vítek, Martin (advisor)
This work aims to find out the best filter design method for getting out parasitic elements in ECG signal. There are defined origin and frequency qualities of these elements. Individua filter design methods are compared according to number of filter coefficients, effectivity and influenc to useful signal. I created several digital filters by various design methods and tested them on ten ECG signals. From the experiment ensued: all filters were able to get out brum, but filters designed by distribution of zeros and poles had the lowest number of coefficients. On the other hand same filters were disable to get out drift with very sheer course.
|
|
|
ECG noise generator
Siegel, Jan ; Walek, Petr (referee) ; Smital, Lukáš (advisor)
The signal of ECG is interfered by the noise of different origin.. Most common are powerline interferences, baseline wandering, electromyographic and impuls noises. Such kind of noise is undesirable in signal since they decrease diagnostic yield in ECG. For effective removal of noise, we must detect the type of interference consequently use its theorists properties for specific filtration. The aim of this work is to creat a technical tool - ECG noise generator. ECG noise generator is being used for simulation of signal with defined parameters and type of noise. This noise generator can be employed for the verification of techniques designed for the elimination of interferences or the identification of the noise present in the unknown signal.
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