174 lines
6.3 KiB
Mathematica
174 lines
6.3 KiB
Mathematica
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function test = fr_test_measure(test)
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%% t = fr_test_measure(t)
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%
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% Measure frequency response from captured frequency sweep created by
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% fr_test_input() that sets most of the input struct fiels. The output
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% is read from file t.fn_out.
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%
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% Input parameters
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% t.f_lo - Measure ripple start frequency
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% t.f_hi - Measure ripple end frequency
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% t.rp_max - Max. ripple +/- dB
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% t.mask_f - Frequencies for mask
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% t.mask_lo - Upper limits of mask
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% t.mask_hi - Lower limits of mask
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%
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% Output parameters
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% t.m - Measured frequency response
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% t.rp - Measured ripple +/- dB
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% t.fr3db_hz - Bandwidth in Hz for -3 dB attenuated response
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% t.fail - Returns zero for passed
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% t.fh - Figure handle
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% t.ph - Plot handle
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%
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% E.g.
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% t.fs=48e3; t.f_max=20e3; t.bits_out=16; t.ch=1; t.nch=2; t=fr_test_input(t);
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% t.fn_out=t.fn_in; t.f_lo=20; t.f_hi=20e3; t.rp_max=[]; t.mask_f=[];
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% t=fr_test_measure(t);
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%
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%%
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% Copyright (c) 2017, Intel Corporation
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% All rights reserved.
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%
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% Redistribution and use in source and binary forms, with or without
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% modification, are permitted provided that the following conditions are met:
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% * Redistributions of source code must retain the above copyright
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% notice, this list of conditions and the following disclaimer.
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% * Redistributions in binary form must reproduce the above copyright
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% notice, this list of conditions and the following disclaimer in the
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% documentation and/or other materials provided with the distribution.
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% * Neither the name of the Intel Corporation nor the
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% names of its contributors may be used to endorse or promote products
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% derived from this software without specific prior written permission.
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%
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% THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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% AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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% IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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% ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
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% LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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% CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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% SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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% INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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% CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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% ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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% POSSIBILITY OF SUCH DAMAGE.
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%
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% Author: Seppo Ingalsuo <seppo.ingalsuo@linux.intel.com>
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%
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%% Reference: AES17 6.2.3 Frequency response
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% http://www.aes.org/publications/standards/
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[x, nx] = load_test_output(test);
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j = 1;
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for channel = test.ch
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if nx == 0
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test.rp(j) = NaN;
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test.fr3db_hz(j) = NaN;
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test.fail = 1;
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return
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end
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%% Find sync
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[d, nt, nt_use, nt_skip] = find_test_signal(x(:,j), test);
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win = hamming(nt_use);
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m0 = zeros(test.nf,1);
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for n=1:test.nf
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fprintf('Measuring %.0f Hz ...\n', test.f(n));
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i1 = d+(n-1)*nt+nt_skip;
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i2 = i1+nt_use-1;
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m0(n) = level_dbfs(x(i1:i2,j).*win) -test.a_db;
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end
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%% Scale 997 Hz point as 0 dB
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df = test.f - test.f_ref;
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[~,i997] = min(abs(df));
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m_offs = m0(i997);
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test.m(:,j) = m0 - m_offs;
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%% Check pass/fail
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idx0 = find(test.f < test.f_hi);
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idx1 = find(test.f(idx0) > test.f_lo);
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range_db = max(test.m(idx1,j))-min(test.m(idx1,j));
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test.rp(j) = range_db/2;
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test.fail = 0;
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if ~isempty(test.rp_max)
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if test.rp > test.rp_max
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fprintf('Failed response +/- %f dBpp (max +/- %f dB)\n', ...
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test.rp, test.rp_max);
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test.fail = 1;
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end
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end
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%% Find frequency response 3 dB 0-X Hz
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idx3 = find(test.m(:,j) > -3);
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test.fr3db_hz(j) = test.f(idx3(end));
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%% Interpolate mask in logaritmic frequencies, check
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if ~isempty(test.mask_f)
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f_log = log(test.f);
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mask_hi = interp1(log(test.mask_f), test.mask_hi(:,j), ...
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f_log, 'linear');
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mask_lo = interp1(log(test.mask_f), test.mask_lo(:,j), ...
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f_log, 'linear');
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over_mask = test.m(:,j)-mask_hi';
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under_mask = mask_lo'-test.m(:,j);
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idx = find(isnan(over_mask) == 0);
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[m_over_mask, io] = max(over_mask(idx));
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idx = find(isnan(under_mask) == 0);
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[m_under_mask, iu] = max(under_mask(idx));
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if m_over_mask > 0
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fprintf('Failed upper response mask around %.0f Hz\n', ...
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test.f(io));
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test.fail = 1;
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end
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if m_under_mask > 0
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fprintf('Failed lower response mask around %.0f Hz\n', ...
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test.f(iu));
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test.fail = 1;
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end
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end
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test.fh(j) = figure('visible', test.visible);
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subplot(1,1,1);
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test.ph(j) = subplot(1,1,1);
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%semilogx(test.f, test.m(:,j));
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plot(test.f, test.m(:,j));
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grid on;
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xlabel('Frequency (Hz)');
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ylabel('Magnitude (dB)');
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if length(test.mask_f) > 0
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hold on;
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plot(test.f, mask_hi, 'r--');
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plot(test.f, mask_lo, 'r--');
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hold off;
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end
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ax = axis();
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axis([ax(1:2) -4 1]);
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if max(max(test.m(idx1,j))-min(test.m(idx1,j))) < 1
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axes('Position', [ 0.2 0.2 0.4 0.2]);
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box on;
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plot(test.f(idx1), test.m(idx1,j));
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if ~isempty(test.rp_max)
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hold on;
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plot([test.f_lo test.f_hi], ...
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[-test.rp_max/2 -test.rp_max/2], 'r--');
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plot([test.f_lo test.f_hi], ...
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[ test.rp_max/2 test.rp_max/2], 'r--');
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hold off;
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end
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grid on;
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axis([0 test.f_hi -0.1 0.1]);
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end
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%% Next channel to measure
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j=j+1;
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end
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end
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