Systems and methods are provided for determining the frequency of a cardiovascular pulse based on a first physiological signal that is continuously available and a second physiological signal that is less available and that is more accurate or otherwise improved relative to the first signal with respect to pulse rate estimation. When the second signal is available it controls the determination of the pulse rate. When the second signal is unavailable, the first signal is used to determine the pulse rate. This can include using the first signal to estimate the pulse rate until the second signal is available, at which point the pulse rate is estimated based on the second physiological signal. Alternatively, the first signal could be used to determine a number of candidate pulse rates, and the second signal could be used to select a pulse rate from the set of candidate pulse rates.