Highpass filter an EMG signal
Highpass filter an EMG signal to remove signal artifacts and baseline noise contamination.
an ‘emg’ object.
in case of multi-channel data,
cutoff frequency in Hertz for the highpass filter. See ‘Details’ for recommended values.
a string specifying the name of the variable which will appears on the plots. If empty or not provided is taken from the object given as
This procedure performs a highpass filtering to the EMG signal in order to remove signal artifacts and baseline noise contamination (such as the DC-bias).
There are various recommendations for the value of the cutoff frequency, for example 5Hz (Merletti, 1999) and 10-20Hz (Freriks et.al., 1999).
An ‘emg’ object which contains the filtered EMG.
This procedure only uses a butterworth type filter. In order to apply a different type of filter, please see the documentation of the ‘signal’ package.
J.E. Macias-Diaz, J.A. Guerrero firstname.lastname@example.org
Merletti R. (1999) Standards for Reporting EMG data. Journal of Electromyography and Kinesiology 9(1), III-IV http://www.isek-online.org/standards_emg.html
Freriks B., Stegeman D.F. and Hermens H.J. (1999) European Recommendations Standards for Surface Electromyography for Surface Electromyography, results of the SENIAM project. ISBN: 90-75452-14-4.
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# Load a data.frame with EMG data data(emg95306000) # Coerce a data.frame into an 'emg' object x <- as.emg(emg95306000, samplingrate = 1000, units = "mV") # Filter the fourth channel in x y <- highpass(x, cutoff = 100) # change graphical parameters to show multiple plots op <- par(mfcol = c(2, 2)) # Compute the rectified signals to see the effect of the filter x_rect <- rectification(x) y_rect <- rectification(y) # plot the original channel, the filtered channel and the corresponding # rectified signals plot(x, channel = 1, main = "Original channel") plot(y, main = "Highpass filtered channel") plot(x_rect, main = "Rectified channel") plot(y_rect, main = "Rectified highpass filtered channel") # reset graphical parameters par(op)
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