tracking notch filter for electrocardiograph measurement

1 >TFig. 14. Comparison between standard and filtered ECG.Results of filtering noise frequency of 60Hz show in Fig.15 to 17. Fig. 16(b) shows that spectral of the filtered ECGsignal at frequency of 60Hz is eliminated when comparingwith Fig. 16(a). The MSE is of 1.44%.1) Ch 1: 500 mV 250 ms(a)(b)Fig. 18. (a) Unfiltered ECG (b) its Spectral.1 >T1 >T1) Ch 1: 500 mV 250 ms(a)(b)Fig. 19. (a) Filtered ECG (b) its Spectral.2 >T1) Ch 1: 500 mV 250 ms2) Ch 2: 500 mV 250 msFig. 15. Upper: ECG combined with noise frequency of 60Hz.Lower: Filtered ECG.(a)(b)Fig. 16. Spectral from analyzing by MATLAB.Fig. 17. Comparison between Standard and Filtered ECG.3.4. Filtering with Real ECG SignalUsing electrode as standard position to measure ECG signal inlead I, such ECG signal is connected to the isolated instrumentamplifier and output signal from one is fed to the designedtracking notch filter. The unfiltered and filtered ECGwaveform is measured and recorded by WAVESTAR program.Fig. 18(a) and (b) show the unfiltered ECG waveform and itsspectral, respectively. Also, Fig. 19(a) and (b) show the filteredECG waveform and its spectral, respectively. Comparing Fig.18 and 19 shows that the designed tracking notch filter canfilter out the noise frequency seeing in both time and frequencydomain.4. ConclusionsFrom frequency response of the designed tracking notchfilter, attenuation at each center frequency is approximately of-35dB to -38dB which is good enough. The difference of thecalculated and measured frequency from frequency synthesizerfor which the multiplication is of 150 times is very close. Theperformance by experiment with the noise frequency addedstandard ECG waveform have shown the filtered ECGwaveform in time domain without noise, frequency domainwithout spectral of noise frequency, and in term of MSE seeingthat it is low enough. Also, the performance of the real ECGsignal has shown the filtered ECG waveform in time domainwithout noise and in frequency domain without spectral ofnoise frequency, only.One of advantage of the designed tracking notch filter is thesmall circuit size when comparing with the closed loop bandstop filter and can use discrete component and passive device.In future, this filter will develop as a single chip.References[1] L. Bustamante and M. A. Soderstrand, “High-RangSwitched Capacitor Tracking,” IEEE InternationalSymposium on Circuits and Systems , vol. 1, pp. 688-691,May, 1999.[2] L. Bustamante, R. H. Strandberg, and M. A. Soderstrand,“Switched-Capacitor Adaptive Sampling Rate Notch Filterfor Enhancement and Elimination of Bandpass Signal,”Proceeding Of the 40 th Midwest Symposium on Circuitsand System, vol. 2, pp. 1354-1357, August, 1997.[3] P. E. McSharry, G. D. Clifford, L. Tarassenko, and L. A.Smith, “A Dynamical Model for Generating SynthesisElectrocardiogram Signals,” IEEE Trans. On BiomedicalEngineering, vol. 50, no. 3, pp. 289-294, March, 2003.190