Low pass filters attenuate the components of a signal above a certain frequency. They are useful for removing higher frequency variation — for instance, from electrical thermal noise or EMG activity that is uninteresting (in context) — from lower frequency signals. For instance, if you have a noisy ECG signal, you can turn on the amplifier's 35 Hz Low Pass filter (a switch on module's front face) to improve the signal quality. You may also perform this filtering in software (“Transform > Digital Filters > IIR > Low Pass…”). The cutoff frequency of the filter provides an indication of which frequencies will have their power levels diminished. Note that some energy at frequencies above the cutoff frequency may remain in the filtered signal.
Page last modified 30Dec2014