butterworth (bwfilt)
Filters data forward and backward using a second order Butterworth algorithm.
Syntax
butterworth(vector1, vector2, scalar1, scalar2, [on|off])
Arguments
- vector1
- Time vector of data to analyze (seconds).
- vector2
- The dependent vector of data to analyze.
- scalar 1
- The filter cutoff frequency (Hz).
- scalar 2 (optional)
-
- 0 – use NHTSA algorithm.
- 1 – compensate for ringing at both ends of vector1.
- 2 - compensate for ringing at the beginning of vector1.
- 3 - compensate for ringing at the end of vector1.
- 0|1
- Flag to turn on debug mode and print to the message log (optional).
- 0=off (default)
- 1=on
Example
x = c1.X
y = butterworth(c1.x, c1.y, 60)
Comments
butterworth filters data forward and backward using a second order Butterworth algorithm, producing zero phase shift and -3dB attenuation at the specified cutoff frequency.
When scalar 2 = 1, 2 or 3, the compensation is performed with a reflection method combined with filter initial condition estimates.