A signal processing method of processing a physiologic signal, such as a Photoplethysmography Signal having at least some cardiac components and/or respirator components in the physiologic signal, the processing including the steps of: Identifying a potential cardiac and or respiratory components of a physiologic signal wherein the potential cardiac and or respiratory components have a series of peaks and valleys; Calculating a comparison of the durations of a peak to valley sub-component and a valley to peak sub component of the potential cardiac and or respiratory components; and Utilizing the calculated comparison to evaluate the potential cardiac and or respiratory components.