filterJ211 is simply a wrapper for the algorithm set forth by SAE-J211 (MAR95) (APPENDIX C);
This standard describes how to calculate the filter coefficients necessary for a BUTTERWORTH 4-POLE PHASELESS DIGITAL FILTER. These coefficients can then be directly applied to an input signal using the standard Matlab |filtfilt| command or with any custom filtering function that requires any number of 2nd-order sections (pole-pairs).
By default, this function will create the coefficients, and (if the Signal Processing Toolbox is installed) filter the input signals.
Meade (2020). Calculate Filter Coefficients for Phaseless, Low Pass, Butterworth Filter (compliant with SAE-J211) (https://www.mathworks.com/matlabcentral/fileexchange/61852-calculate-filter-coefficients-for-phaseless-low-pass-butterworth-filter-compliant-with-sae-j211), MATLAB Central File Exchange. Retrieved .
Included technical documentation.