Filtering and filter lag
The advanced filtering options allow you to filter the data in a number of ways. Typically the filtering options will be used to "smooth" the data which removes all the high frequency components of the data. In the example below a low pass Butterworth filter has been applied via the Variable Manager, with a cut off of 5Hz to smooth the longitudinal g force. The black line shows the data with no smoothing, and the red line is with the filter applied.
It is also worth mentioning that the filter is applied forward and backward to the data which removes any time lag (also referred to as phase lag) in the data. If the filter was only applied in the "forward" direction, then not only would the data be smoothed, it would also be delayed by an amount that depended on the filter cut off frequency - an example of this is shown in the data below, which is exactly the same data but only filtered in the forward direction. Please note, that there is no option within the software to turn off the anti-lag function for filters. It is always enabled to give you the most accurate reading possible!