Design Of Non-reconfigurable Portable ECG Signal Acquisition System Based On Random Demodulation

With the rapid development of intelligent medicine and mobile terminals,the appearance of 24-hour uninterrupted monitoring portable ECG signal acquisition equipment improves the traditional equipment in real-time and flexibility greatly.However,such portable devices are generally bulky,Lack of endurance by the impact of battery capacity.At present,low-power design is the key to portable ECG testing equipment.This paper intends to collect,process and transmit ECG signals in the compressed domain based on the well-known compressed sensing theory.To reduce the power consumption of portable ECG signal acquisition devices by reducing the processing rate of the system.Compressed sensing is one of the most famous innovations in the field of information in recent years.It collects and processes the signal at a rate much lower than Nyquist bandwidth of the signal based on the sparsity or compressibility of the signal,the ultimate purpose is to acquire the information carried by the signal.This paper first study the basic characteristics of ECG signal and do comparative analysis about sparse characteristics of the ECG signal in the wavelet domain and the frequency domain.After this,we discuss the low rate acquisition and processing of ECG signals based on random demodulation.Specific work is as follows:(1)Since random demodulation is based on the frequency domain sparsity of the signal,but it is just asymptotically sparse in the frequency domain while it performs a good sparsity in wavelet domain.In order to avoid the error brought by the use of traditional reconstruction method and thus affect the ECG signal characteristics extraction.In this paper,a wavelet coefficient reconstruction method based on partial Fourier coefficients is designed,these wavelet coefficient can be used for ECG signal characteristics extraction.(2)Built a complete hardware and software testing system,it includes ECG signal acquisition front-end,random demodulation module,control module and the host computer processing module.The random demodulation circuit based on the switch is designed after the analysis of the principle of random demodulation.The proposed algorithm is achieved by the MATLAB and used for the process of compressed values.Finally,the experimental results show that the test system in a certain compression ratio,after compression acquisition processing,the proposed detection algorithm in this paper can do more accurate extraction of the R wave.