jens
988b2ed138
git-svn-id: http://moon:8086/svn/vhdl/trunk@146 cc03376c-175c-47c8-b038-4cd826a8556b
59 lines
1.6 KiB
Matlab
59 lines
1.6 KiB
Matlab
% Read data
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function tb_mix_results()
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fa = 100.0;
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f = TEXTREAD('freq.txt')*1E-6
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I_in = TEXTREAD('i_in.txt')';
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I_out = TEXTREAD('i_out.txt')';
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N= length(I_out);
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N_fft = N
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N_fft2 = N_fft/2;
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fft_y2 = 2/N_fft*abs(fft(I_out(1:N_fft).*hann(N_fft)'));
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[i, v] = get_maxpur(fft_y2, fa, f);
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max_spur_freq = (i*fa/N_fft);
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max_spur_value = 20*log10(v);
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fft_y3 = 2/N_fft*abs(fft(I_in(1:N_fft).*hann(N_fft)'));
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[i, v] = get_maxpur(fft_y3, fa, f);
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max_ditherd_spur_freq = (i*fa/N_fft);
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max_ditherd_spur_value = 20*log10(v);
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% Output
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close all;
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subplot(2,1,1)
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plot(fa/N_fft*(0:N_fft2),20*log10(fft_y2(1:N_fft2+1)), '-', fa/N_fft*(0:N_fft2), max_spur_value*ones(1,N_fft2+1), 'r-', [max_spur_freq], [max_spur_value], 'ro'); grid;
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spur_legend = sprintf('Max. spur %.1fdB at %.3fMHz', max_spur_value, max_spur_freq);
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legend('With dithering', spur_legend);
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legend('No dithering', spur_legend);
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title('Table');
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ylabel('dB');
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xlabel('f/MHz');
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axis([0 fa/2 -140 0]);
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subplot(2,1,2)
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plot(fa/N_fft*(0:N_fft2),20*log10(fft_y3(1:N_fft2+1)), '-', fa/N_fft*(0:N_fft2), max_ditherd_spur_value*ones(1,N_fft2+1), 'r-', [max_ditherd_spur_freq], [max_ditherd_spur_value], 'ro'); grid;
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spur_legend = sprintf('Max. spur %.1fdB at %.3fMHz', max_ditherd_spur_value, max_ditherd_spur_freq);
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legend('With dithering', spur_legend);
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title('Table');
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ylabel('dB');
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xlabel('f/MHz');
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axis([0 fa/2 -140 0]);
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function [max_i, max_v] = get_maxpur(spec, fa, f)
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max_v = 0;
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max_i = 0;
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for ii=1:fix(length(spec)/2+1),
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fi = ii*fa/length(spec);
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dfi = fi - f;
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if abs(dfi) > 0.005*f
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if spec(ii) > max_v
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max_v = spec(ii);
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max_i = ii-1;
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end
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end;
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end;
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