Electromyogram (EMGdi) is used in various circumstances such as diagnostic and prosthesis control. Howevever, recorded EMGdi signals are always contaminated by electrocardiogram (ECG). Cancellation of the ECG contamination, expecially in real-time, is not a simple operation because the spectra of EMG and ECG overlap. In this project, we propose a hardware implementation to validate a EMGdi real-time filtering technique that will be integrated to a wireless esophageal catheter which records EMGdi and Pdi.
EMGdi recording system:
The acquisition of EMGdi with the EMGdi recording system (figure 1) can be summarized as follows: a 2 mm diameter catheter is inserted through the esophagus down to the stomach. Five EMG platinum ring electrodes with an inter-electrode distance of 1.5 cm and a wide of 2 mm are fixed in this catheter. The low amplitude EMG signals acquired by the ring electrodes were first amplified and conditioned by an external card. Then the EMG signal was digitalized by a 16 bits analog to digital converter (ADC). Finally, the EMGdi samples were processed by two microcontrollers which form frames and sent them through a Bluetooth link to a PC host for recording.
The implemented hybrid technique:
The hybrid technique (figure 2) combines a spike-clipping algorithm and a high-pass Butterworth filter. The spike clipping algorithm is based on an adaptive threshold which depends on the values of a number of previous points and a gain fixed by the user.
