Portable digital heart rate meter/stethoscope

摘要

Electrical signals corresponding to heart sounds detected by a pulse/sound transducer are filtered in a narrow bandpass filter whose pass band is centered on a characteristic heart sound frequency of 33 Hz. The filter improves signal-to-noise ratio and enables the transducer to be used over a patient's clothing. The unfiltered signal is amplified and fed to binaural leads to provide the function of an electronic stethoscope. In addition, the filtered signal is converted into pulses in response to which a count corresponding to the detected heart rate is established in a counter and displayed as a digital heart rate indication.