Array processing technique for the acquisition of surface EMG signals

The estimation and detection of surface EMG signals provides us with more detailed information on the functional state of a muscle, when measurement applied with smaller pickup areas. In fact the signal to noise ratio (SNR) of the observed EMG activity is proportional to the area of the pickup electrodes, and depends on the type of the muscle. The activity of small muscles is more difficult to sensed with small electrodes, that is why large surface electrodes are used, and in this case more physiological information lost. The estimation and detection of these signals can aid in the diagnosis of many pathological conditions after extracting some physiological parameters (e.g. median frequency). The relevance of these parameters estimated from the surface EMG signals, depends largely on the SNR. Our method is to use an array of small surface electrodes to capture the surface EMG activity. Two processing techniques based on the orthogonal projection principle were employed to enhance the SNR, one of them can be applied in real time processing.