Removing harmonic power line interference from biopotential signals in low cost acquisition systems

This paper presents a new proposal of a very low cost and highly efficient interference canceller to be applied to biomedical signals. The power line reference is obtained from analog to digital conversion while higher harmonics are mathematically estimated by means of trigonometric relations. These signals are processed by an adaptive algorithm in order to suppress harmonic interference. Biomedical acquisition systems that incorporate a conventional adaptive canceller, whose reference signal is sampled from power line, can be easily modified to improve interference suppression without hardware modifications. Real application examples are supplied in order to demonstrate its usefulness in electroencephalographic, electrocardiographic and auditory evoked potential signals.