1. A pressure sore detection system for detecting pressure sores in human tissue comprising: a signal generator for generating a digital modulation signal representing a code sequence; an optical illumination source coupled to said signal generator for receiving said digital modulation signal and for transmitting a modulated optical signal along an optical transmission path to said human tissue in response to said digital modulation signal; a detector optically coupled to said human tissue for receiving said modulated optical signal after transmitting to said human tissue; and a processor coupled to said detector for deriving a temporal transfer characteristic for said optical signal received by said detector.