jens
2a65062181
- fdet_coarse.m use alternative approach - fdet_wav.m added simple symbol decoding git-svn-id: http://moon:8086/svn/matlab/trunk@28 801c6759-fa7c-4059-a304-17956f83a07c
84 lines
1.9 KiB
Matlab
84 lines
1.9 KiB
Matlab
function fdet_wav(filename, foff, p)
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%
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% Example: fdet_wav('drm-15435-if.wav', -174.65, [700 850 1])
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% Example: ofdm_tx(40, 1)
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% fdet_wav('xv.wav', 0, [700 800 1])
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% or fdet_wav('yv.wav', 0, [700 800 1])
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close all;
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fs = 48000;
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fc = fs/4;
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N = 1024;
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Ng = 256;
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omega_min = p(1)/fs;
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omega_max = p(2)/fs;
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omega_step = p(3)/fs;
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% Generate signal
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[xwav fs nbits] = wavread(filename);
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[len ndim] = size(xwav);
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if (ndim > 1)
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fprintf('Mode: Baseband\n');
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x = xwav(:, 1) + j*xwav(:, 2);
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else
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fprintf('Mode: Passband\n');
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x = xwav.*exp(-j*(2*pi*fc/fs*(0:len-1)'));
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end
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fprintf('Perform frequency correction\n');
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x = x.*exp(j*(2*pi*foff/fs*(0:len-1)'));
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% Remove cyclic prefix
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fprintf('Perform CP calculation\n');
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x0 = x(1:2*(N+Ng));
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x1 = x(N+Ng+1:3*(N+Ng));
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c = xcorr(x0, x1);
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[v, ii] = max(abs(c));
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cp_off = mod(ii, Ng+N)
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% Detect CFO
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fprintf('Perform frequency detection\n');
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[omega, err, dmod, omega_coarse, omega_est, Xm] = fdet(x, N, Ng, cp_off, omega_min, omega_step, omega_max);
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f_coarse = omega_coarse*fs
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f_est = omega_est*fs
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fprintf('Receive Symbols\n');
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K = fix((length(x)-Ng)/(N+Ng));
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for k=10:30
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xp = x((k-1)*(N+Ng)+cp_off+1:k*(N+Ng)+cp_off);
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Xp(:,k) = fft(xp(Ng+1:N+Ng), N);
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end;
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close all;
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plot(abs(c)); grid;
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figure;
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bin = fix(N*750/48000)+1
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plot(real(Xp(bin, :)), imag(Xp(bin, :)), '+'); grid;
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figure;
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plot(0:N-1, abs(Xm)); grid;
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figure;
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subplot(5,1,1)
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plot(1:lge(omega), real(dmod)/N, 1:lge(omega), imag(dmod)/N, 1:lge(omega), abs(dmod)/N); grid; legend('Re', 'Im', 'abs()');
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subplot(5,1,2)
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plot(1:lge(omega), err*fs, '-'); grid; legend('error');
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subplot(5,1,3)
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plot(1:lge(omega), omega*fs); grid; legend('f');
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subplot(5,1,4)
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plot(1:lge(omega), angle(dmod), '-', 1:lge(omega), diff(angle([0 dmod])), 'r-'); grid; legend('phi', 'dphi');
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subplot(5,1,5)
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plot(1:lge(omega), log10(abs(dmod) ./ (1E-6+abs(real(dmod)))), '-'); grid; legend('diff');
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