The improved pulse oximeter preprocesses the sets of red and infrared signals received from the probe to remove ambient light, to remove noise, and to de-exponeniate the signals. The linearity of the processed red and infrared signals allows the use of statistical techniques such as linear regression...http://www.google.de/patents/US6987994?utm_source=gb-gplus-sharePatent US6987994 - Pulse oximetry SpO2 determination
