EMG: Removing DC Bias

Surface EMG signals typically have a frequency content between 50 and 500 Hz. These signals may have a DC bias. It is common to apply a high pass filter with a cutoff frequency of 50 Hz to EMG signals prior to any other processing to remove the DC bias.

Note: Many laboratories assume a frequency content between 20 and 500 Hz

Note: Applying a high pass filter will effectively remove any DC bias in the signal.

! By default, Visual3D uses a second order Butterworth Bidirectional Filter (resulting in a
! fourth order filter) for Lowpass/Highpass filtering.

! High pass filter
Highpass_Filter 
/Signal_Types= ANALOG 
/SIgnal_Names= EMG1+EMG2+EMG3 
/Signal_Folder= ORIGINAL 
! /Result_Suffix= 
! /Result_Folder=PROCESSED 
! /Filter_Class=BUTTERWORTH 
/Frequency_Cutoff= 50 
/Num_Reflected= 0 
/Total_Buffer_Size=100 
/Num_Bidirectional_Passes=1 
;