A physiological measurement system is disclosed which can take a pulse oximetry signal such as a photoplethysmogram from a patient and then analyse the signal to measure physiological parameters including respiration, pulse, oxygen saturation and movement. The system comprises a pulse oximeter which includes a light emitting device and a photodetector attachable to a subject to obtain a pulse oximetry signal analogue to digital converter means arranged to convert said pulse oximetry signal into a digital pulse oximetry signal signal processing means suitable to receive said digital pulse oximetry signal and arranged to decompose that signal by wavelet transform means feature extraction means arranged to derive physiological information from the decomposed signal an analyser component arranged to collect information from the feature extraction means and data output means arranged in communication with the analyser component.
