The present invention is directed toward a 
pulse oximetry system for the determination of a physiological parameter capable of removing 
motion artifacts from physiological signals comprises a hardware subsystem and a 
software subsystem. The 
software subsystem is used in conjunction with the hardware subsystem to perform a method for removing a plurality of 
motion artifacts from the photo-plethysmographic data and for obtaining a measure of at least one physiological parameter from the data. The method comprises acquiring the raw photo-plethysmographic data, transforming the data into the 
frequency domain, analyzing the transformed data to locate a series of candidate cardiac spectral peaks (primary plus 
harmonics), reconstructing a photo-plethysmographic 
signal in the 
time domain with only the candidate cardiac spectral peaks (primary plus 
harmonics), computing the second order derivative of the reconstructed photo-plethysmographic 
signal, analyzing the candidate second order derivative photo-plethysmographic 
signal to determine the absence or presence of cardiac physiologic signal characteristics, and finally selecting the best physiologic candidate from the series of potential cardiac spectral peaks (primary plus 
harmonics) based upon a second derivative 
scoring system. This 
scoring system is preferentially based upon second derivative 
processing analysis, but can be equally applied using the first, third, fourth or other similar derivative 
processing analysis.