Heart rate monitors are plagued by noisy sensor data, which makes it difficult for the monitors to output a consistently accurate heart rate reading. To address the issue of noise, some monitors blindly discard sensor data which are too noisy, and stop producing heart rate readings. In some cases, if the monitors do not discard the noisy sensor data, the noisy sensor data can cause irregular heart rate readings. As a result, noisy data can lead to inaccurate heart rate readings or no heart rate readings at all. The present disclosure describes an improved technique for qualifying an input signal, i.e., determining whether a portion of the input signal is likely to result in an accurate heart rate reading, by assessing whether the frequency information of the input signal resembles a heartbeat. The resulting improved heart rate monitor is robust in tracking the heart rate in a noisy environment.
