A heart rate monitor for calculating heart rate based upon EKG signals. The
monitor preferably utilizes 3 electrodes to pick up EKG signals and a
differential amplifier to cancel common mode signals in the output of the
electrode. An analog bandpass filter comprised of a low pass and high pass
filter in series each with different rolloffs filters out low and high
frequency components. The signals are digitized and digital filtering to
remove power line hum and remnants of low and high frequency noise is
performed. Then the EKG signals are digitally enhanced by differentiating
and squaring the results of the differentiator then being averaged in a
moving average computation so as to generate enhanced digital data. The
enhanced digital data is then processed to learn the EKG characteristics,
and a heart rate arbitrator processes the incoming signals to select out
actual EKG complexes from EMG noise and other noise. The EKG isolation
process is done using rules of reason and the learned characteristics of
the EKG signal.
