Oximeter ambient light cancellation

A pulse oximeter method and device, wherein (1) is one a regulation frequency with an annular power line and (50, 60, 100 and 120) are the gap between common multiples claims a notch filter (46), (2) also provides is greater than human body highest pulse rate and is lower than 50, 60 and 100 or the 120Hz any overtone demodulation frequency, to prevent filter to the environment in light, and avoids cleaning or component by a line from the groove filter overtone the moveable demodulation frequency of auditive disorders. Moreover, and measuring part of the length of light wave length is for example power line magnetic-interfering the environment light of any low - frequency auditive disorders, and afterward subtracts the environment light from signal detection mean.