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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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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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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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