The electrocardiogram (ECG) signal contains important information that is utilized by physicians for the diagnosis and analysis of heart diseases. Therefore, good quality ECG signal is required. Hilbert-Huang transform (HHT) is a method to analyze non-stationary and non-linear signals. Empirical mode decomposition (EMD) is the core of HHT. EMD breaks down signals into smaller number of components. These components form a complete and nearly orthogonal basis for the original signal. This algorithm is implemented on field-programmable gate array using the process of extrema generation, envelope generation, and stopping criterion.Keywords: Hilbert-Huang transform, Electrocardiogram, Empirical mode decomposition, Field-programmable gate array.
INTRODUCTIONElectrocardiogram (ECG) is the recording of electrical activity of the heart. Fig. 1 shows the normal ECG without any kind of interferences. In clinical practice, ECG is the most commonly used cardiovascular signal because it gives us plenty of diagnostic information. Doctors use ECG to find heart-related problems. ECG from healthy hearts has a characteristic shape. Any damage to heart muscles can change the electrical activity of heart causing change in the characteristic shape of ECG. While recording, ECG contains different types of noises such as power-line interferences, baseline wandering, motion artifacts, electrosurgical noise, and EMG noise which need to be filtered. An ECG contains three main parts: p-wave which denotes atrial depolarization, the QRS complex which denotes ventricular depolarization, and T-wave that represents ventricular repolarization [1]. The most important part in ECG processing is the detection of QRS complex which has an essential role in the diagnosis of heart rhythm irregularities [1,2].Many methods exist to detect QRS complex that are based on standardized filtering and wavelet transform. Each technique has its own advantages and drawbacks. One of the influential signal detection technique considered in literature is adaptive filtering method. One of the most widely used algorithms is least mean square algorithm introduced by Widrow and Hoff in adaptive filtering. It is very simple in structure and is easy to compute [3]. Geophysicist Morlet put forward the concept of wavelet transform in analysis and processing geophysical data in France in 1984. Wavelet transform has the advantage that the windows will adapt, and thus, it is possible to generate an infinite set of possible basis functions [4]. This paper concentrates on the implementation of Empirical mode decomposition (EMD) using field-programmable gate array (FPGA) for denoising of ECG [5,6]. EMD is widely used for non-stationary and non-linear signal analysis procedures. The decomposition method that is used in the EMD algorithm is called shifting process. It has proved versatile in a wide range of applications for signal extraction from nonlinear and non-stationary processes. It is an iterative algorithm which computes the maximum and minimum extreme. Main advantage ...