mirror of https://github.com/thesofproject/sof.git
71 lines
2.6 KiB
Matlab
71 lines
2.6 KiB
Matlab
function [b, a] = stdnotch_get(fn, fs)
|
|
|
|
%% [b, a] = stdnotch_get(fn, fs)
|
|
%
|
|
% Input
|
|
% fn - notch frequency
|
|
% fs - sample rate
|
|
%
|
|
% Output
|
|
% b - coefficients for filter zeros
|
|
% a - coefficients for filter poles
|
|
%
|
|
|
|
%%
|
|
% Copyright (c) 2017, Intel Corporation
|
|
% All rights reserved.
|
|
%
|
|
% Redistribution and use in source and binary forms, with or without
|
|
% modification, are permitted provided that the following conditions are met:
|
|
% * Redistributions of source code must retain the above copyright
|
|
% notice, this list of conditions and the following disclaimer.
|
|
% * Redistributions in binary form must reproduce the above copyright
|
|
% notice, this list of conditions and the following disclaimer in the
|
|
% documentation and/or other materials provided with the distribution.
|
|
% * Neither the name of the Intel Corporation nor the
|
|
% names of its contributors may be used to endorse or promote products
|
|
% derived from this software without specific prior written permission.
|
|
%
|
|
% THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
|
|
% AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
|
% IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
|
% ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
|
|
% LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
|
|
% CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
|
|
% SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
|
|
% INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
|
|
% CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
|
|
% ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
|
|
% POSSIBILITY OF SUCH DAMAGE.
|
|
%
|
|
% Author: Seppo Ingalsuo <seppo.ingalsuo@linux.intel.com>
|
|
%
|
|
|
|
target_q = 2.1;
|
|
bw = (2*fn/fs)/target_q;
|
|
if exist(fullfile('iirnotch.m'),'file') == 2
|
|
[b, a] = iirnotch(2*fn/fs, bw);
|
|
else
|
|
[b, a] = pei_tseng_notch(2*fn/fs, bw);
|
|
end
|
|
if 0
|
|
%% In AES17 5.2.8 standard notch must have Q 1.2-3.0
|
|
% Quality factor is ratio of of center frequency to
|
|
% differenence between -3 dB frequencies.
|
|
figure;
|
|
f = linspace(0.2*fn, min(2*fn,fs/2), 5000);
|
|
h = freqz(b, a, f, fs);
|
|
m = 20*log10(abs(h));
|
|
plot(f, m); grid on;
|
|
idx = find(m < -3);
|
|
f1 = f(idx(1));
|
|
f2 = f(idx(end));
|
|
q = fn/(f2-f1);
|
|
if (q < 1.2) || (q > 3.0)
|
|
fprintf('Required Q value failed, Q = %5.2f\n', q);
|
|
else
|
|
fprintf('Q = %5.2f\n', q);
|
|
end
|
|
end
|
|
end
|