A method and system for measuring oxygen levels and various blood constituents utilizing a sensor having one or more light sources, and one or more light detectors is disclosed. The system is capable of using data collected by the one or more detectors from a non-monochromatic light source to provide accurate information during motion events occurring with an extremity the sensor. The system is also capable of detecting and providing an alert if the sensor is not properly placed on a patient or becomes disengaged therefrom.
