| Summary: | 碩士 === 龍華科技大學 === 電子工程系碩士班 === 106 === In this thesis, an ECG signal processing system for removing baseline wander 、 electromyography (EMG) interference and heart rate estimation has been implemented via the STM32F429ZI chip which is ARM series chips of STMicroelectronics produced. The ARM processor has operation frequency of up to 180MHz, flash memory size of 2M bytes, SRAM size of 256+4K bytes and is suitable for a large amount of data calculation as well as peripheral interface control. In this work, the sampling rate of ECG is designed as ECG sampling rate is 250 S/sec, data processing takes 1.2 seconds for segment length of 1000 points.
First, moving average filter (MAF) is used to remove the low frequency response in ECG signal resulted from the baseline wanders. For EMG interference, the distorted ECG input signal is taken apart into a number of intrinsic mode functions (IMFs) by the empirical mode decomposition (EMD) method and the sum of high-frequency IMFs can reconstruct the high-frequency IMF integrated waveform (HFIW) from which the EMG components will be extracted. The interfered segments in ECG caused by EMG are detected via digital high-pass filter (DHPF) and the R waves in ECG signal are positioned via a digital low-pass filter (DLPF). Once knowing EMG locating, we take average of the pure ECG in some segment where EMG doesn’t exist and adding it to the EMG-removed segment of ECG signal to rebuild the reconstructed ECG waveform. Then we remove the reconstructed ECG waveform from the high-frequency IMF integrated waveform and the remaining signal is the estimated EMG component. Finally, we can remove it from the original signal to complete EMG filtering. Finally, we estimate the instantaneous heart rate through the relative RR wave interval.
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