BSL PRO Software Guide - Biopac

108 Part CFILTEROutputLow PassHigh passBand pass (low+ high)Band PassBand StopBand Stop –Line FreqPerformanceAllows you to specify a frequency cutoff that will “pass” or retain all frequencies below thispoint, while attenuating data with frequencies above the cutoff point.Retains only data with frequencies above the cutoff, and removes data that has a frequencybelow the specified cutoff (opposite of the Low Pass filter).Allows a variable range of data to pass through the filter. For this filter, you need to specify alow frequency cutoff as well as a high frequency cutoff. This defines a range or “band” of datathat will pass through the filter. Frequencies outside this range are attenuated. The Band pass(low + high) is actually a combination of a low pass and a high pass filter, which emulate thebehavior of a band pass filter.This type of filter is best suited for applications where a fairly broad range of data is to bepassed through the filter. For example, this filter can be applied to EEG data in order to retainonly a particular band of data, such as alpha wave activity.Requires only a single frequency setting, which specifies the center frequency of the band to bepassed through the filter. When this type of filter is selected, the “width” of the band isdetermined by the Q setting (previously discussed). Larger Q values result in narrower bandwidths, whereas smaller Q values are associated with a wider band of data that will be passedthrough the filter. This filter has a bandwidth equal to Fo/Q, so the bandwidth of this filtercentered around 50 Hz (with the default Q=5) would be 10 Hz.This type of filter, although functionally equivalent to the band pass (low + high) filter, is mosteffective when passing a single frequency or narrow band of data, and to attenuate data aroundthis center frequency.Defines a range (or band) of data and attenuates data within that band (opposite of the BandPass filter). A center frequency is defined and the Q value determines the width of the band offrequencies that will be attenuated.Defines a band stop at 50 Hz or 60 Hz, based on the line frequency selected during installation.Visit the online support center at www.biopac.com