A computer-implemented method of processing cardiac information, comprising: receiving an activation waveform comprising a set of activation waveform data; receiving a set of window parameters comprising a range of window size; determining a set of confidence values, each confidence value corresponding to a window size, by iterating through a plurality of window sizes in the range of window size; for each of the plurality of window sizes, selecting a position of a central window, the central window having the each of the plurality of window sizes; calculating a set of backward correlations, each of the set of backward correlations being a correlation of the activation waveform in the central window and the activation waveform in a backward shifted window, the backward shifted window being the central window shifted backward, calculating a set of forward correlations, each of the set of forward correlations being a correlation of the activation waveform in the central window and the activation waveform in a forward shifted window, the forward shifted window being the central window shifted forward; determining a backward confidence value based on the set of backward correlations, the set of confidence values comprising the backward confidence value; and determining a forward confidence value based on the set of forward correlations, the set of confidence values comprising the forward confidence value; comparing the set of confidence values to select a designated confidence value and a selected window size corresponding to the designated confidence value; and determining a local cycle length based on the selected window size. receiving an activation waveform comprising a set of activation waveform data; receiving a set of window parameters comprising a range of window size; determining a set of confidence values, each confidence value corresponding to a window size, by iterating through a plurality of window sizes in the range of window size; for each of the plurality of window sizes, selecting a position of a central window, the central window having the each of the plurality of window sizes; calculating a set of backward correlations, each of the set of backward correlations being a correlation of the activation waveform in the central window and the activation waveform in a backward shifted window, the backward shifted window being the central window shifted backward, calculating a set of forward correlations, each of the set of forward correlations being a correlation of the activation waveform in the central window and the activation waveform in a forward shifted window, the forward shifted window being the central window shifted forward; determining a backward confidence value based on the set of backward correlations, the set of confidence values comprising the backward confidence value; and determining a forward confidence value based on the set of forward correlations, the set of confidence values comprising the forward confidence value; selecting a position of a central window, the central window having the each of the plurality of window sizes; calculating a set of backward correlations, each of the set of backward correlations being a correlation of the activation waveform in the central window and the activation waveform in a backward shifted window, the backward shifted window being the central window shifted backward, calculating a set of forward correlations, each of the set of forward correlations being a correlation of the activation waveform in the central window and the activation waveform in a forward shifted window, the forward shifted window being the central window shifted forward; determining a backward confidence value based on the set of backward correlations, the set of confidence values comprising the backward confidence value; and determining a forward confidence value based on the set of forward correlations, the set of confidence values comprising the forward confidence value; comparing the set of confidence values to select a designated confidence value and a selected window size corresponding to the designated confidence value; and determining a local cycle length based on the selected window size.