Abstract: A system and method of reducing cross talk in pulse oximetry signals that are attenuated by a patient tissue site are provided. In one embodiment, Red and IR LEDs of a pulse oximeter are separately excited (1010) and the respective Red and IR data vectors output by the detector are measured (1020). The Red and IR data vectors are normalized (1030). Red to IR and IR to Red cross talk vectors are computed (1040). Red and IR demodulation vectors are obtained by subtracting (1050) the respective Red and IR cross talk vectors from the respective normalized Red and IR data vectors. The demodulation vectors are normalized (1060), scaled (1070), and the magnitudes of the Red and IR signal components are obtained by computing (1080) the dot product of the composite signal data vector with the normalized and scaled Red demodulation and IR demodulation vectors, respectively.