BSL PRO 4 Manual - Biopac

Part C — Analysis Functions 239High Pass FilteringIn the example below, a high pass filter removes the low and middle range data, but allows the high frequencydata to pass through the filter.HighfrequencydataMidfrequencydataHighCutoffHipassFilterLowfrequencydataIncoming dataFiltered dataWhereas the low pass and high pass filters retain data either above or below a given threshold, the next twotypes of filters work with a range, or band, of data.Band pass filterThe band pass filter, allows only the data within the specified range to pass through the filter. A band passfilter is useful when you want to retain only specific waves from an EEG record. For instance, to retain alphawaves, you can set the filter to only pass data between 8 Hz and 13 Hz.HighfrequencydataHighCutoffMidfrequencydataBandPassFilterLowfrequencydataLowCutoffIncoming dataFiltered dataBand stop filterThe band stop filter allows data to pass above and below the specified range. This type of filter is typicallyapplied to remove extraneous 60 Hz or 50 Hz noise from a data record.HighfrequencydataHighCutoffMidfrequencydataBandStopFilterLowfrequencydataLowCutoffIncoming dataFiltered dataBSL PRO Manual