ECG Filter Using Scaled Kronecker Delta Pulses
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Solution Overview
Problem
Existing electrocardiographic (ECG) signal filtering techniques either distort the waveform or introduce delays while attempting to correct baseline wander, and require additional hardware or software to accelerate settling behavior.
Innovation Solution
A digital filtering unit using a finite impulse response filter with an impulse response formed by consecutive scaled Kronecker delta pulses, which effectively rejects low-frequency components and minimizes distortion, allowing for real-time display of ECG signals without aggressive hardware or software modifications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a single-pole high-pass filter with corner frequency of 0.05Hz is used to remove baseline wander, then low-frequency noise is reduced, but the filter requires several seconds to settle and introduces delay in display presentation
Solution Approach 1:
The filter impulse response is segmented into multiple discrete samples (900-160000 samples) of the input signal, each scaled by appropriate factors. This segmentation allows the filter to process baseline wander removal through a finite sequence of signal samples rather than requiring continuous settling time, thereby reducing the time delay while effectively removing low-frequency noise.
Solution Approach 2:
The filter uses scalable impulse response coefficients that can be adjusted to change the filter's characteristics. By modifying the scaling factors applied to different segments of the input signal, the filter can adaptively remove baseline wander while controlling the settling behavior, thus reducing time loss without sacrificing noise removal effectiveness.
2Object-affected harmful factors
If filtering techniques aggressively remove baseline drift, then low-frequency noise is reduced, but the ECG waveform becomes distorted and ST segment is affected
Solution Approach 1:
The filter applies partial filtering action by processing only a finite number of signal samples (900-160000 samples) rather than continuously filtering all incoming signals. This partial action allows sufficient baseline drift removal while avoiding excessive filtering that would distort the ECG waveform and affect the ST segment, thereby maintaining waveform accuracy.
Solution Approach 2:
The filter operates by periodically processing blocks of input signal samples through the finite impulse response. This periodic action allows the filter to remove baseline drift in a controlled manner, preventing waveform distortion while maintaining the integrity of critical ECG features like the ST segment.
3Speed
If additional hardware or software monitoring and signal-modification units are added to accelerate settling behavior, then display range settling is improved, but device complexity increases
Solution Approach 1:
The invention extracts and removes the need for additional hardware monitoring units and software signal-modification units by implementing the settling acceleration function directly within the finite impulse response filter structure. The filter's inherent design with scalable coefficients performs both baseline wander removal and settling acceleration in a single integrated unit, thereby reducing device complexity while maintaining fast settling speed.
Data Source
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AI summary
The invention relates to a filtering unit (100) for compensating baseline drift in electrocardiographic real-time applications, which comprises a finite impulse response filter unit (106) configured to generate and provide a filtered digital electrocardiographic signal, and having an impulse response h[n] consisting of a finite sequence of between 900 and 160000 consecutive Kronecker delta pulses δ[n]. The impulse response is formed by at least three consecutive sets of consecutive scaled Kronecker delta pulses, all scaled Kronecker delta pulses within a respective set having a respective constant amplitude, wherein a modulus of the sum of the amplitudes of every Kronecker delta pulse pulses is smaller than 0.1. A number of the scaled Kronecker delta pulses of at least one of the sets of Kronecker delta pulses is equal to or higher than a minimum number of samples resulting from multiplying the sampling frequency by a time span of 10-2 seconds.