Line Frequency Rejection for Biomedical Application

In biomedical measurement systems, periodical disturbances like power line interferences often are a severe limitation. To evaluate small signals under such conditions, a new technique for the compensation of these disturbances has been developed. The operation principle is based on the measurement of some Fourier coefficients of the interference superimposed to the signal to be detected. These measured coefficients are used to synthesize a signal enabling the cancellation of the interference. The major advantages in comparison to usual filtering techniques are 1) the short settling time of the compensation equal to two periods of the interference only, and 2) the absence of signal distortion.