Enhancement of surface His activity with adaptive filtering

Adaptive filtering is used to enhance His activity in individual beats in signals acquired from the surface of the body. Signals are high-pass filtered to remove T-waves. Common mode signals are reduced with a separate continuous adaptive filter specifically for this purpose. Random noise is reduced with a time-sequenced adaptive filter with parameter updating both on the preceding and current beat. To reduce effects of parameter biasing, an average of filter parameters is computed during periods of no activity in each beat and subtracted from all parameters