findHighpassLvl.m

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% BRAVEHEART - Open source software for electrocardiographic and vectorcardiographic analysis
% findHighpassLvl.m -- Find wavelet decomposition level that is just below a frequency cutoff
% Copyright 2016-2025 Hans F. Stabenau and Jonathan W. Waks
% 
% Source code/executables: https://github.com/BIVectors/BRAVEHEART
% Contact: braveheart.ecg@gmail.com
% 
% BRAVEHEART is free software: you can redistribute it and/or modify it under the terms of the GNU 
% General Public License as published by the Free Software Foundation, either version 3 of the License, 
% or (at your option) any later version.
%
% BRAVEHEART is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; 
% without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. 
% See the GNU General Public License for more details.
% 
% You should have received a copy of the GNU General Public License along with this program. 
% If not, see <https://www.gnu.org/licenses/>.
%
% This software is for research purposes only and is not intended to diagnose or treat any disease.
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function n = findHighpassLvl(cut,fs)

% Finds the first wavelet decomposition level BELOW 'cut' Hz given the
% sampling frequency 'fs' Hz

L = 1:1:20;             % Max level 20 - should be more than enough
C = fs./(2.^(L+1));     % Calc freq cutoffs for all levels
ind = find(C < cut);    % Find levels below cutpt

n = ind(1);             % Find first level below cutpt

end