ECG DENOISING TECHNIQUES :A SURVEY
Abstract: This paper describes about different techniques for ECG denoising.ECG signal gives information about the electrical activities of the heart. ECG signal is corrupted by presence of different noises like power line interference, channel noise, baseline wander, electromyogram (EMG) Noise, electrode contact noise, and motion artifacts that may lead to wrong interpretation in diagnosis. Efficient denoising techniques are required for the accurate diagnosis of cardiac problems.
Keywords:
Electrocardiogram ,Denoising, Emperical mode decomposition ,Discrete wavelet transform.
1.INTRODUCTION
Signal processing plays a significant role in biomedical engineering and diagnostics. For efficient diagnosis of various…show more content… An ECG signal represents the cardiac activity of the human heart recorded by placing electrodes on the skin and is used by the physicians for clinical diagnosis of cardiac abnormalities. The ECG signal is a representation of electrical activity generated by rhythmic contractions of the heart and it can be measured by placing electrodes on the body’s surface. An electrode lead, or patch, is placed on both arm and leg and six leads are placed across the chest wall. The signals generated at the electrodes are recorded.[1]
Fig.1 depicts an normal ECG signal. Each ECG signal of normal heart .It consists of six continuous electromagnetic peaks ,ie, PQRST and U. The P wave reflects the activation of the right and left atria. The QRS complex shows depolarization of the right and left ventricles. The T wave, which is generated after QRS complex shows ventricular activation [3]. On the reading of
ECG the atrial repolarization is not recorded. The electrocardiogram can also be used to measure the rate and rhythm of the heartbeat, as well as provides the evidence of blood flow to the heart muscle. The ECG signal will be corrupted due to the presence of different types of artifacts…show more content… Section III explains about different denoising techniques .
Section IV concludes the work.
II.Noises in ECG Signal:
Different type of noises which contaminate ECG signals are Power line interference,
Electrode contact noise, Motion artifacts, Muscle contraction, Base line wander, Instrumentation noise generated by electronic devices and Electrosurgical noise [2].
a.Power line interference:
Power line interference consists of 60/50 Hz pickup and harmonics and the amplitude is
50% of peak-to-peak ECG amplitude. Some of the common causes of the 50 Hz interferences are
1.stray effect of the alternating current fields due to loops in the cables
2.improper grounding of ECG machine or disconnected electrode on the patients body
3. Electromagnetic interference from the power lines
4. Electrical equipments such as air conditioner, elevators and X-ray units draw heavy power line current,which induce 50 Hz signals in the input circuits of the ECG machine.
Fig 2:60 Hz power line interference
b. Electrode contact noise:
The connection between patient and measuring system is interrupted for a short duration due to improper contact of the electrodes which creates electrode contact noise which is
