Processes time series (signal) by complete or partial suppression of some aspect of the signal.
It is often useful to either low-pass filter (smooth) time series in order to reveal low-frequency features and trends, or to high-pass filter (detrend) time series in order to isolate high frequency transients (e.g. storms).
NumXL provides a variety of functions (e.g. Hodrick-Prescot, Baxter-King, etc.) for filtering a time series in order to reveal trends and/or seasonal components in the data.