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ISBN 978-952-5726-09-1 (Print)<br />
Proceedings of the Second International Symposium on Networking and Network Security (ISNNS ’10)<br />
Jinggangshan, P. R. China, 2-4, April. 2010, pp. 246-249<br />
ECG Pattern Recognition Based on Wavelet<br />
Transform and BP Neural Network<br />
Shanxiao Yang, and Guangying Yang<br />
School of Physical & Electronics Engineering, Taizhou University, Taizhou, China<br />
ysxtzc@126.com<br />
Abstract—This paper introduces the Electrocardiogram<br />
(ECG) pattern recognition method based on wavelet<br />
transform and standard BP neural network classifier.<br />
Experiment analyzes wavelet transform of ECG to extract<br />
the maximum wavelet coefficients of multi-scale firstly. We<br />
then input them to BP classify for different kinds ECG. The<br />
experimental result shows that the standard BP neural<br />
network classifier’s overall pattern recognition rate is well.<br />
The ECG in this paper was from MIT-BIH. Experimental<br />
result shows that feature vector extracted by the wavelet<br />
transform can characterize ECG patterns, and BP neural<br />
network classifier has a stronger ECG recognition effect.<br />
Index Terms—Electrocardiogram (ECG); Pattern<br />
Recognition; BP neural network; Wavelet Transform;<br />
MIT-BIH<br />
I. INTRODUCTION<br />
Since 1903 the Electrocardiogram(ECG) was<br />
introduced to clinical medicine, the techniques have been<br />
developed rapidly in the record, processing and diagnosis<br />
of the ECG whether it is in the biomedical area or in<br />
engineering and we accumulate considerable experience.<br />
ECG plays an important role in the clinical diagnosis of<br />
the heart disease. It provides an objective indicator for<br />
correct analysis, diagnosis, treatment and care of the heart<br />
disease. Because of its important social value and<br />
economic value, it has a very wide range of applications<br />
in the modern medicine. ECG is still a major research<br />
subject in the biomedical engineering [1].<br />
ECG is the recording of the electrical activity of the<br />
heart, and has become one of the most important tools in<br />
the diagnosis of heart diseases [2]. ECG signal is shaped<br />
by P wave, QRS complex, and T wave. In the normal<br />
ECG beat, the main parameters including shape, duration,<br />
R-R interval and relationship between P wave, QRS<br />
complex, and T wave components are inspected. Any<br />
change in these parameters indicates an illness of the<br />
heart.<br />
The study of ECG recognition has an important<br />
significance in understanding human hear in the role of<br />
human intelligence. Although many efforts have been<br />
taken recently to recognize ECG using different methods,<br />
current recognition systems are not yet advanced enough<br />
to be used in realistic applications.<br />
This work is supported by education department Program of Zhejiang<br />
Province in University (2010).<br />
II.<br />
THE SOURCE OF THE ECG<br />
A. Data Acquisition from the Acquisition Card<br />
Human ECG is a non-linear, non-stationary, weak<br />
signal and low signal to noise ratio. The voltage of the<br />
conventional ECG is just mv level and its frequency is<br />
0.05-100HZ.<br />
Due to equipment, human factors, the acquisition of<br />
ECG accompany with interference. Common ECG<br />
interference has three types 1Electrocardiogram (ECG)<br />
interference. It is caused by human activities and muscle<br />
tension. Its frequency is 5-2000HZ. ECG has wide<br />
spectrum and often mixed with the ECG’s spectrum. So it<br />
is difficult to use the general filtering to separate them. 2<br />
The frequency interference of the power-line. It is fixed<br />
frequency interference. It is form of 50HZ and its<br />
harmonic components. It is caused by the space<br />
electromagnetic interference to human body from powersupply<br />
network and its equipment .In essence, the<br />
alternating current are non-stationary random process in<br />
the frequency and amplitude with a slow fluctuation. 3<br />
Baseline drift. It is caused by the low-frequency<br />
interference, such as the movement of the measuring<br />
electric class, respiratory of the human. Its general<br />
frequency is less than 1HZ [3]. Therefore, the collected<br />
ECG is often accompanied with the above noise.<br />
B. Recognition Methods --BP neural network<br />
BP neural network is fully named as the Back-<br />
Propagation Network, that is, back-propagation network.<br />
It is a forward multi-layer network, which uses the error<br />
back-propagation algorithm to train the network. BP<br />
algorithm [4,5] was proposed by Rumelhart et al in 1986,<br />
and since then, due to simple structure, multi-adjustable<br />
parameters, much training algorithm and good<br />
operational performance, BP neural network got a wide<br />
range of practical application.<br />
The network structure of the three-layer BP neural<br />
network is shown in Figure 1, from which we can see that,<br />
BP neural network contains an input layer, a middle layer<br />
(hidden layer) and an output layer. There is a full<br />
connectivity between the upper and lower layers and no<br />
connections between neurons in each layer. For the input<br />
signal, it needs to spread towards to hidden layer nodes<br />
and transformed by the function, then transmit the input<br />
signal of hidden layer nodes to the output layer nodes.<br />
Usually, the transfer function of BP neural network is<br />
Sigmoid Type differentiable function, which can achieve<br />
arbitrary non-linear mapping between the input and<br />
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