Try using it in bright light without the LED Jacopo, Try using it in bright light without the LED. The advantage of this is that it should be less sensitive to movement (when using the LED, the coupling of light into the finger is especially sensitive to movement). The Fourier Transform shows the strongest frequencies in the light signal. The signal changes due to the amount of blood it passes through going from the LED to the camera sensor. The strongest (peak in the Fourier Transform) should be the heart rate as the volume of blood in the finger goes up and down. Any relative movement between the finger and the phone will affect the signal too, so its best to keep it still. Variations in pressure will have a large effect, because the small blood vessels can close easily under pressure. The intensity will go down during the peak (systole) of the cardiac cycle and up during the diastole.
Works ok but i need some explanation on my results perfect. just the flash light is so hot on my Nexus4. But what is the Fourier Transform graph for ? What can I learn from Intensity graph ? And my Hart rate graph ? PS: I also a need a way to store my Heart Rate to compare it...
Excellent! Great explanations!
Fixed bug for devices without flash.