1. A physiological signal processing method for an ambulatory monitoring system, comprising the steps of: comparing by the ambulatory monitoring system peak width properties of physiological signals with distinguishing peak width properties of good, noisy and weak signals; classifying by the ambulatory monitoring system at least one of the physiological signals as noisy based on at least one of the comparisons; and processing by the ambulatory monitoring system the at least one physiological signal in accordance with the classification, wherein the physiological signal is classified as noisy based at least in part on a determination that a central peak of the physiological signal has a width above a central peak width threshold, and wherein a noisy signal notification is generated and outputted in response to classifying the physiological signal as noisy.