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High pass filters

High pass filters attenuate the components of a signal below a certain frequency range. They help to remove lower frequency variation — possibly due to signals that are uninteresting in context — from data. For example, you can remove the respiratory component from ECG by running the data through a 1 Hz High Pass filter either in hardware (a setting on the amplifier) or in software (“Transform > Digital Filters > IIR > High Pass…”). The filter will center the signal around the zero line.  The cutoff frequency of the filter provides an indication of what fruequencies are attenuated.  Note that some energy at frequencies lower than the cutoff frequency will remain in the filtered signal.

Page last modified 29Dec2014

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