jens
579c1544b1
git-svn-id: http://moon:8086/svn/matlab/trunk@157 801c6759-fa7c-4059-a304-17956f83a07c
28 lines
572 B
Matlab
Executable File
28 lines
572 B
Matlab
Executable File
function downconvert()
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omega_lp = 0.48;
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N_lp = 101;
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N = 10000;
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w = 2*pi;
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n = (0:N-1);
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rf = 0.4*cos(0.25*w*n);
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lo_r = cos(0.25*w*n);
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lo_i = -sin(0.25*w*n);
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w_lp = FIRCalcLowpass(omega_lp, N_lp);
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im = 2*rf .*lo_r + i*2*rf.*lo_i;
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im_f = filter(w_lp, 1, real(im)) + i*filter(w_lp, 1, imag(im));
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subplot(2, 1, 1)
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plot(n, rf, '-*'); grid;
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axis ([0 N-1 -1 1]);
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subplot(2, 1, 2)
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plot(n, real(im_f), '-*', n, imag(im_f), '-*'); grid;
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axis ([0 N-1 -1 1]);
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wavwrite(rf, 48000, 16, 'ddc_rf.wav');
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wavwrite(im, 48000, 16, 'ddc_im.wav');
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wavwrite(im_f, 48000, 16, 'ddc_imf.wav');
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