ECG Signal Processing Using Digital Signal Processing Techniques - IJSER

9m ago
587.83 KB
5 Pages
Last View : 3m ago
Last Download : 6m ago
Upload by : Bria Koontz

International Journal of Scientific & Engineering Research, Volume 4, Issue 12, December-2013ISSN 2229-55181624ECG Signal Processing Using Digital Signal Processing TechniquesS.Thulasi Prasad (Phd).,Associate Professor.,CVSCE,Tirupati.Email: This work describes theimplementation of wavelet-based de noisingalgorithm on electrocardiogram (ECG)signal and detection of important parametersuch as heart rate, amplitude, timings of theECG, etc. The algorithm is implemented inDSP based starter kit (DSK) with a twoelectrode ECG preamplifier. The signal fromthe ECG preamplifier is acquired throughthe Codec input of the DSP starter kit. Theacquired data is subjected to signalprocessing techniques such as removal ofpower line frequencies and high frequencycomponent removal using wavelet-denoisingtechnique. ECG component analysis such asQRS peak detection, heart rate calculation,etc is performed using nonlinear filtertechnique called first order derivative andmoving average filter. The performance ofthe algorithm is studied in the DSPenvironment as well as MATLABenvironment for comparison. The results ofthis study reveal the potentiality of the DSPsystem for routine clinical use.Dr. S. Varadarajan, comprocessing. In this design, high-speedfloating point digital signal processorTMS320C6711andTLC320AD535dualchannel voice/data codec based DSPstarter kit (DSK) was employed forprocessing the ECG.Electrocardiogram (ECG) signal frequencyrange varies between 0 Hz-300 Hz and mostof the information available in the signal liesin the range 0.5-150 Hz “Ref. [1-4]”.Therefore, the removal of higher frequenciesis necessary to eliminate the unwantedsignals, which reduces only less than 1% ofthe useful information. ECG signalprocessing comprises of two steps viz. (i)preliminary processing and (ii) primaryprocessing. In preliminary processing,artifacts like higher peaks due to electrodemotion and power line interference areremoved through the application of suitablesoftware filters in the DSK system.IJSERIndex Terms: ECG, DSP, Denoising,Wavelet, Heart rate, Power line interference1. IntroductionIn recent years, there has been increasinginterest in the design and implementation ofDSP systems for real time ECG signalIn primary processing, techniques likedenoising, baseline wandering and detectionof P, QRS, and T waveforms are performedthrough the implementation of suitablealgorithms in the DSK system. Foranalyzing the ECG signal in DSK system,the ECG signal is sampled at the frequencyof 1 kHz and the sampled data is stored inDSP buffer for processing. This sampledECG data are subjected to various signalIJSER 2013

International Journal of Scientific & Engineering Research, Volume 4, Issue 12, December-2013ISSN 2229-5518processing algorithms to obtain a noise freeand clear ECG waveform for analysis.2. Hardware DetailsFig. 1, depicts the complete setup for DSPbased ECG system, which comprises of a setof electrodes, ECG pre-amplifier board,TMS320C6711 DSP Starter Kit (DSK) with3.5mm audio jack, and Pentium IV DesktopPC. The DSP based ECG system has beenbuilt around the TMS320C6711 DSK.1625environment (IDE), called Code ComposerStudio (CCS). The CCS is a high-levellanguage, which has built-in FFT, Wavelet,and other functions for signal processingapplications. Also, we can develop our ownfunctions in C for dedicated and novelapplications. The TMS320C6711 DSK has abuilt in CODEC, which has 16-bit register toacquire the ECG signal directly. Theacquired ECG data can be viewed in thedisplay before processing. Here 2048samples can be viewed at a time but the datacan be updated in a circular for real timedisplay of ECG. The DSK can process upto5000 samples at a time, but the display canstore and view only 2048 samples at a timedue to its limitation in video buffer memory.Hence a circular memory technique isemployed in this design to view theprocessed data in a sequential manner.IJSERFig.1 Block Diagram of the DSP Starter Kitbased ECG Analysis Experimental SetupA two-electrode ECG preamplifier “Ref.[5]” is constructed using op-ampsMCP607/OPA2336. A set of standard stickon disposable electrodes are placed in thetwo arms of the subject (patient) picks-upthe ECG signal from the body and the signalis amplified to 1 V level by the ECGpreamplifier circuit. The output of theamplifier is directly connected with theCodec input of the DSK system. The Codecsampled the ECG signal at the sampled of 1kHz. The data is stored in DSK buffermemory for processing.3. Description Of the DSK EnvironmentFor Algorithm DevelopmentFor the development of algorithms in theDSK system, the Texas Instrument DSK isprovided with an integrated developmentFig. 2 is the display of the 2048 raw samplesof a typical ECG signal acquired using thepreamplifier hardware and the DSK system.Here the X-axis represents the samplenumber and the Y-axis represents theamplitude of the signal. This view shows 7QRS peaks and other components of theECG waveforms such as P and T, which areburied in artifacts and noises.Original signalFig. 2 Plot of the actual ECG signal withoutany processingIJSER 2013

International Journal of Scientific & Engineering Research, Volume 4, Issue 12, December-2013ISSN 2229-55184. Implementation Of Wavelet TransformFor DenoisingDenoising is the primary processing toremove all the high frequency as well aspower supply interference from the ECGsignal. Several researches have beenattempting wavelets for denoising ofbiomedical signals “Ref. [6, 7, 8]”. Toestimate the performance of wavelet indenoising, biomedical researchers havemade several attempts employing variouswavelet basis functions like Coiflets, Haar,etc in the “Ref. [9, 10]” The outcome of thisstudy revealed that the performance of theDaubechies (DB4) wavelet basis function indenoising is extremely well and has thebasis function graphically shown in Fig 3.Also, the Daubechies wavelet was chosenfor this work on the basis of the ics of the DB4 basis functionwith the ECG waveform. The denoised ECGsignal using the Daubechies DB4 wavelet isshown in the Fig. 4, which clearly indicatesthat the Daubechies DB4 Wavelet denoisingis an efficient method to completely removeall high frequency as well as power-lineinterferences.1626in the signal. Almost all other unwantedinformations are removed.Fig. 4 Denoising of ECG signal usingDaubechies wavelet5. Analyses Of ECG Waveforms UsingFiltered Derivative Operator And MovingAverage FilterMost of the diseases and complaints arereflected in the waveform intervals,morphology of the waveforms, and theiramplitude values. Most important diagnosticinformation can be obtained by the detectionof QRS complex, calculation of variousintervals and heart rate measurement.Hence, analysis of ECG waveform isperformed mainly on the detection of QRSwaveform “Ref. [11, 12]” and thelocalization of other waveforms (S, T, P)with respective to the QRS complex. In thiswork, the detection of QRS complex isperformed using weighted and squared firstderivative operator (Filtered- Derivative)and Moving Average (MA) filter proposedby Murthy et al “Ref. [13]”. A FilteredDerivative Operator can be represented as,IJSERFig. 3 Daubechies WaveletDaubechies DB4 wavelet has the exactresponse characteristics like the ECG signalexcept the baseline wandering, which hasvery low frequency of the order of 0.05 Hzwhere x(n) is the digitized ECG sample, N isthe width of a window within which firstorder differences are computed, squared,and weighted by the factor (N-i 1). Theweighting factor provides a smoothingIJSER 2013

International Journal of Scientific & Engineering Research, Volume 4, Issue 12, December-2013ISSN 2229-5518effect. Further smoothing was performed bythe moving average filter defined by thefollowing equation.This algorithm provides a single peak foreach QRS complex and suppresses the othercomponents in the ECG such as P, T, etc.Fig. 5 shows the QRS peak detection afterapplying the Filtered Derivative Operatorand Moving Average Filter. Here the QRSdetection is achieved by applying athreshold and finding out the number ofpeaks that cross the threshold value, fortypercentage of the maximum amplitude of thesignal is chosen as threshold value for thedetection of QRS peaks.1627Using the above relationship, the heart ratecalculated for normal case as 73 beats perminute (bpm) for the R-R interval of 825 msec, which is well agreed with thecommercial machine readings. The samemethodology was employed forotherimportant interval calculation by fixingdifferent threshold for identifying the othercomponents of the ECG such as P, T, etc.Important intervals and durations of thewaveforms are found after identifying andlocating the P, QRS and T waves.6. Calculation EfficiencyFig. 6 shows the timing diagram of theprocessor in terms of the execution cycle.The total processing time becomesT t T proc N Tist . (3)IJSERIn this process, the position of each QRS hasbeen identified and from the QRS values,the R-R interval is measured by calculatingthe number of samples between adjacent Rpeaks multiplied with the sampling time.Fig. 6 Processor efficiency AnalysisWhere N is the number of interruptions thatoccur in Tt, given by,N T t / T T t T sam . (4)Therefore,T t (1- fsam T ist ) T proc . (5)Fig. 5 Application of first-Derivative andMoving AverageFrom the Fig 5, the time duration calculatedbetween the adjacent R peaks as 825 m sec.From the R-R interval, the heart rate iscalculated using the formulaHeart Rate (1/RR interval in sec.) * 607. ConclusionIn this work, the power of the memory onchip DSP was realized by implementing thevarious signal processing algorithms forECG signal processing and analysis. Novelsignal processing techniques such asDaubechies Wavelet and Filtered-Derivativeoperator are tested for ECG denoising andQRS peak detection respectively. De-IJSER 2013

International Journal of Scientific & Engineering Research, Volume 4, Issue 12, December-2013ISSN 2229-5518noising comparison between Coif3 and db4was also made and achieved the promisingresult with db4 wavelet.The wavelet approach is more convenientthan the conventional filtering techniques,which highlights the details of the ECGsignalwithoptimaltime-frequencyresolution. The result of this study revealsthat the DSP system paves way toimplement highly complex mathematicaltechniques such as Wavelet Transform andaveraging techniques for real time signalprocessing and analysis of the ECG signalthrough structured algorithms for routineclinical use.Proceedings of the IEEE Volume 84, Issue4, Apr 1996 Page(s): 626 – 638[7]. Bahoura M., Hassani M., Hubin M,“DSP implementation of wavelet transformfor real time ECG wave forms detection andheart rate analysis”, Computer Methods andPrograms in Biomedicine, No. 52, 35 – 44,1997.[8]. Behzad Mozaffary, Mohammad A.Tinati, ECG Baseline Wander Eliminationusing Wavelet Packets, Transactions onEngineering, Computing and TechnologyV3 Dec 2004 ISSN 1305-5313[9]. Fatimah Ibrahim, Noor Azuan AbuOsman, Juliana Usman and Nahrizul AdibKadri, Performance Evaluation of CoifmanWavelet for ECG Signal Denoising, IFMBEProceedings, vol 15, pp 419-422, 2007[10]. D.Nedumaran, S.Stalin and D.Balasubramaniam, Application of m signal, Proceedings ofthe National Conference on BioInstrumentation (BINCON-2005), RoyalInstitute of Technology and Science, 19th &20th March 2005, pp.31-34.[11]. Aldroubi, M.A. Unser, Wavelets inMedicine and Biology, CRC Press, BocaRaton FL, USA, 1996, 616 pages.[12]. Ivaylo I Christov, Real timeelectrocardiogram QRS detection usingcombined adaptive threshold, BiomedicalEngineering On Line 2004, 3:28[13]. Murthy ISN and Rangaraj MR, NewConcepts for PVC detection, IEEETransactions on Biomedical Engineering,26(7): 409-416, 1979.IJSERReferences[1]. Rangaraj M. Rangayyan. Bio-MedicalSignal Analysis, Wiley-Interscience (IEEEpress), 2002.[2]. Hamilton PS, Tompkins WJ,“Quantitative investigation of QRS detectionrules using the MITBIH arrhythmiadatabase”,IEEETransactionsonBiomedical Engineering 1996, BME-33:1157-1187[3]. Joseph D. Bronzing, The BiomedicalEngineering Handbook, Published by CRCPress, 2000[4]. Ivaylo I Christov, Real timeelectrocardiogram QRS detection usingcombined adaptive threshold, BioMedicalEngineering Online 2004, 3:28[5]. D. Dobrev, Technical Note: Twoelectrodelowsupplyvoltageelectrocardiogram signal amplifier, Med.Biol. Eng. Comput., 2004, 42, 272-276.[6]. Unser, M.; Aldroubi, A. A review ofwavelets in biomedical applications,1628IJSER 2013

DSP systems for real time ECG signal processing. In this design, high-speed floating point digital signal processor TMS320C6711 and TLC320AD535 dualchannel voice/data codec based DSP starter kit (DSK) was employed for processing the ECG. Electrocardiogram (ECG) signal frequency range varies between 0 Hz300 Hz and most -

Related Documents:

signal affected by electrode motion artifact is shown in (Figure 5) below. Figure 5: ECG affected by electrode motion artifacts [2] 2. Techniques to Remove Artifacts from ECG Signal In this section, various signal processing methods for removing the artifacts from ECG signal have been described. These methods are simple yet effective. The .

Real-time Heart Monitoring and ECG Signal Processing Fatima Bamarouf, Claire Crandell, and Shannon Tsuyuki Advisors: Drs. Yufeng Lu and Jose Sanchez . Design must include real-time ECG signal processing, on-board signal processing computations, and battery-powered functionality 44 . Summary and Conclusions

some time due to some electrical issue there may be chances of generation of some wrong information of ECG signal which is really too dangerous for the patient. So there is a need for some effective filtering applications which will filter the output of ECG signal and generate the real ECG signal which will help for human health diagnosigation.

by the AD8232 sensor and Arduino UNO act as the analogue to digital converter (ADC). LabVIEW is used for the monitoring and stored the data of ECG signal. Keywords: ECG, LabVIEW, Arduino, Electrodes, ECG Signal Processing I. INTRODUCTION An electrocardiogram is a test that checks how your heart is

most of the digital signal processing concepts have benn well developed for a long time, digital signal processing is still a relatively new methodology. Many digital signal processing concepts were derived from the analog signal processing field, so you will find a lot o f similarities between the digital and analog signal processing.

Electrocardiography (ECG) Handout Thanks to everyone who has looked at the EmergencyPedia page since we started in April 2013. Since the start we've been keen to include a FOAM ECG page to share our ECG collection and ideas. We have started by presenting an ECG checklist, OSCE station and more than 20 original ECG cases on this page (see below).

learning algorithms are the optimum choice. After reviewing the literature carefully, we have chosen adaptive filters as a potential candidate for the processing of ECG signal because of its flexibility to adapt to the changes in the signal. As ECG is a non-linear

Samy T. (Purdue) Rough Paths 1 Aarhus 2016 12 / 16. Study of equations driven by fBm Basicproperties: 1 Momentsofthesolution 2 Continuityw.r.tinitialcondition,noise Moreadvancednaturalproblems: 1 Densityestimates, Hu-Nualart Lotsofpeople 2 Numericalschemes, Neuenkirch-T,Friz-Riedel 3 Invariantmeasures,ergodicity, Hairer-Pillai,Deya-Panloup-T 4 Statisticalestimation(H,coeff. V j .