Example of autocorrelation sequence with search window for maxima. In this example, the autocorrelation sequence contains some spurious peaks. Ad1 and Ad2 peaks are indicated. The search window is shifted over the whole sequence (solid line: window in the position corresponding to Ad1 peak).
Tura et al. Journal of NeuroEngineering and Rehabilitation 2012 9:11 doi:10.1186/1743-0003-9-11