Pulse oximeter plethysmograph arrangement.

摘要

A pulse oximeter is provided including two light (62, 64) emitting diodes. Each LED is energized by a unique modulation signal. Light produced by the LEDs passes through the tissue of a subject and is detected by a photodiode (60). The photodiode signal is separated by tuned circuits (72, 74) resonant at the two modulation signals frequencies and physiological information signals are recovered from the separated signals by amplitude demodulation (100, 102). The inventive arrangement provides identification of back-to-back coupled LEDs and narrow band filtering for good noise immunity.