Abstract: An apparatus for measuring heart rate is provided which comprises a sensor for generating a signal which includes the biopotential signal produced by a heart. This signal is filtered, amplified and digitized. A microcomputer autocorrelates the digitized signal. A plurality of signal indication routines then scan the autocorrelated output for the presence of periodic signals. Each of the signal indication routines uses different search criteria, such as peak and waveform detection, and generates a candidate heart rate. An arbitrator then selects one of the candidate heart rates according to predetermined criteria. These criteria include the value of previously selected heart rates.