Patent ID: 7018338

Claim:
Portable pulse rate detecting device for contact with human body tissue, comprising: a light-emitting source for emitting radiant energy through human body tissue; at least first and second light detectors for detecting intensity of radiant energy after propagation through human body tissue and for providing first and second input signals (y 1 (t), y 2 (t)) as a function of such detected radiant energy; a device for measuring motion of the detecting device with respect to human body tissue and for providing a motion reference signal (a x (t), a y (t), a z (t)) as a function of said motion; processing means for removing, from said first and second input signals (y 1 (t), y 2 (t)), motion-related contributions due to movement of the detecting device with respect to human body tissue and producing first and second enhanced signals, said processing means being arranged to calculate a model of said motion-related contributions based on said motion reference signal (a x (t), a y (t), a z (t)) and to subtract this model from each of said first and second input signals (y 1 (t), y 2 (t)), wherein said processing means is also for removing measurement noise and residual non-modelled contributions from said first and second enhanced signals using a noise reduction algorithm; and means for detecting non-stationary signal segments in said motion reference signal (a x (t), a y (t), a z (t)) and for disabling at least one of said light-emitting source, said light detectors and said processing means when non-stationary signal segments are detected.