Method, apparatus, and system, including computer program products, implementing and using techniques for determining a periodic cycle of time series data. A frequency spectrum of the data is provided. The frequency spectrum is processed using at least one of the following steps, resulting in a processed frequency spectrum: filtering the frequency spectrum for reducing noise of the data, truncating the frequency spectrum at low frequencies, and weighting high frequency contributions over low frequency contributions of the frequency spectrum. A periodic cycle is extracted based on the processed frequency spectrum.