Abstract: A filter for use in filtering noise from cyclical signals having a data component and a noise component in which a predetermined number of the cyclical signals are averaged to produce an average signature signal. The average signature signal is updated each cycle to produce a current updated average signature signal, and the current cyclical signals and the current updated average signals are subtracted from one another to remove the noise component and produce a residual signal which contains the data component. The time frames of the current cyclical signals and the current updated average signals are adjusted to be equal so as to enable point by point subtraction.As an additional feature, the updating of the average pump signature combines a portion of the last average pump signature with a portion of the last residual signal.