Patent ID: 8496595

Claim:
A method for determining a pulse of a person with a pulse measuring device wherein the pulse measuring device comprises a first light source adapted to generate light waves having a first wavelength, a second light source adapted to generate light waves having a second wavelength, and a photodetector disposed to sense light reflected by skin tissue and blood vessels and operably connected to provide measurement signals to a microcontroller unit, wherein the first and second wavelengths are different and determined so that the light waves with the first wavelength are sensitive to a pulse beat and to a movement of the person, and so that the light waves with the second wavelength are sensitive to movement, wherein the method comprises the steps of: (a)—generating light waves with the first wavelength by the first light source and generating light waves with the second wavelength by the second light source, and transmitting both light waves in a direction of the skin of the person; (b)—detecting, using the photodetector, light waves of the first and second wavelengths reflected by the skin tissue and blood vessels and providing measurement signals to the microcontroller unit; (c)—calculating, using the microcontroller unit, at least one non-coherent power spectrum on the basis of a spectral coherence function γ, wherein the spectral coherence function γ accounts for the dependence between the measurement signals relating to the first wavelength and to the second wavelength by the formula S NC =(1−γ 2 )· S AA , where S AA is the average Fourier power spectrum of the measurement signals relating to the first wavelength of the sensed light waves and where γ 2 is between 0 and 1; and (d)—determining the pulse of the person by the non-coherent power spectrum.