1. A method for mapping a cardiac chamber, the method comprising: sensing activation signals of intrinsic physiological activity with a plurality of electrodes disposed in or near the cardiac chamber, the activation signals including a near-field activation signal component and a far-field activation signal component, wherein the plurality of electrodes are disposed on a catheter; isolating far-field events in the activation signals; segmenting the activation signals sensed by each electrode; generating a far-field activation template representative of the far-field activation signal component by averaging the far-field events in the segmented activation signals from each electrode; comparing amplitudes among a set of consecutive far-field segmented activation signals corresponding to an electrode of the plurality of electrodes; determining that the consecutive far-field segmented activation signals have inconsistent amplitudes; blanking the electrode in the plurality of electrodes based on determining that the consecutive far-field segmented activation signals have inconsistent amplitudes; and subtracting the far-field activation template from the activation signals at the isolated far-field events to identify the near-field activation signal components in the activation signals.