TECHNIQUES FOR DETECTING HEART PULSES AND REDUCING POWER CONSUMPTION IN SENSORS

摘要

Low power techniques for sensing cardiac pulses in a signal from a sensor
(101) are provided. A pulse detection block (102) senses the sensor signal and
determines its signal-to-noise ratio. After comparing the signal-to-noise
ratio to a threshold, the drive current of light emitting elements in the
sensor is dynamically adjusted to reduce power consumption while maintaining
the signal-to-noise ratio at an adequate level. The signal component of the
sensor signal can be measured by identifying systolic transitions. The
systolic transitions are detected using a maximum and minimum derivative
averaging scheme. The moving minimum (301) and the moving maximum (304) are
compared to the scaled sum (312, 313) of the moving minimum and moving maximum
to identify the systolic transitions. Once the signal component has been
identified, the signal component is compared to a noise component to calculate
the signal-to-noise ratio.