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git-svn-id: http://moon:8086/svn/matlab/trunk@33 801c6759-fa7c-4059-a304-17956f83a07c
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@@ -0,0 +1,20 @@
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function cfo_coarse_fract_eval(x, cpoff)
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N = 1024;
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Ng = 256;
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L = Ng;
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for d=1:3,
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k = 1;
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Nd = N-2+d;
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for nt=cpoff+1:N+Ng:length(x)-2*N-Ng,
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x1 = x(nt+1:nt+L);
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x2 = x(nt+Nd+1:nt+Nd+L);
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c(k, d) = sum(x1 .* conj(x2));
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k = k + 1;
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end
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end
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domega_f = 1/(2*pi*N) * angle(c)
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figure(1);
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plot(0:length(c)-1, domega_f*48000); grid;
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@@ -0,0 +1,39 @@
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function cfo_fine_eval(f, kn)
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Kdown = 4;
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fs = 48000/Kdown;
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N = 1024/Kdown;
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K = 100;
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n = (0:K*N-1)';
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phi = pi/2;
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x = cos(f/fs*2*pi.*n + phi) + kn*randn(K*N, 1);
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Xlast = [];
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phi_x_ = [];
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phi_z_ = [];
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Zm = ones(N, 1);
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for k=1:K-1,
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xp = x((k-1)*N+1:k*N);
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X = fft(xp);
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if (~isempty(Xlast))
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Z = Xlast .* conj(X);
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[v, bin] = max(abs(Z(1:N/2)));
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phi_x_ = [phi_x_ 0.5*angle(X(bin))/pi/N*fs];
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phi_z_ = [phi_z_ 0.5*angle(Z(bin))/pi/N*fs];
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end
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Xlast = X;
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end
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df = -mean(phi_z_)
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f_est = (bin-1)/N*fs + df
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figure(1)
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plot(abs(Z)); grid;
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figure(2)
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plot(phi_x_); grid; ylabel('phi_x');
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figure(3)
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plot((bin-1)/N*fs - phi_z_); grid; ylabel('d_f');
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@@ -1,33 +0,0 @@
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function cfoml_eval(x)
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N = 1024; % number of subcarriers
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M = 103; % number of subcarriers that carry information
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omega = 2*pi/N; % carrier spacing
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fa = 48000;
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fo = 0.0;
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x = 0.5*exp(i*2*pi.*(0:length(x)-1)'*fo/fa) .* x;
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U = exp(i*omega*(0:N-1)'*(0:N-1));
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W = U(:, 1:M);
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V = U(:, (M+1):N);
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phi = 0;
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dphi = pi/100;
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for j=1:100,
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phik(j) = phi;
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P = calcP(phi, N);
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phi = phi + dphi;
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S(j) = sum(abs(x'*P*U(:, M+1:N)).^2);
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end
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close all;
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plot(phik, real(S)); grid
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function P = calcP(phi, N)
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P = diag(exp(i*(0:N-1)*phi));
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@@ -1,34 +0,0 @@
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function fdet_eval(f_true, phi_true, knoise_dB, p)
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%
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% Example: fdet_eval(1200, pi/4, -10, [1100 1350 1])
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fs = 48000;
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N = 1024;
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K = 40;
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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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x = exp(j*(2*pi*f_true/fs*(0:K*N-1)'+ phi_true)) + sqrt(10^(knoise_dB/10))*randn(K*N,1);
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[omega, err, dmod, omega_coarse, omega_est] = fdet(x, N, 0, 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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error_ppm = 1E6*(1-f_est/f_true)
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close all;
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subplot(4,1,1)
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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(4,1,2)
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plot(1:lge(omega), err*fs, '-'); grid; legend('error');
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subplot(4,1,3)
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plot(1:lge(omega), omega*fs); grid; legend('f');
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subplot(4,1,4)
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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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@@ -1,83 +0,0 @@
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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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@@ -0,0 +1,54 @@
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function [n, Nd, valid, Zf] = timing_coarse(x, N, Ng, L, Zi)
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if (~isfield(Zi, 'valid'))
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Zi = struct('valid', 1, 'n', 0, 'xp', [], 'p', 1.0);
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end
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Zf = Zi;
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Zf.xp = [Zf.xp' x']';
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n = Zf.n;
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Nd = N;
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valid = 0;
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if (length(Zf.xp) < 3*N+Ng)
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return
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end
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RCWIN_ROLLOFF = 0.125;
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[rcwin Nt wng] = txwin_eval(N, Ng, RCWIN_ROLLOFF);
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% RC Windowing at TX
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% Calculate merged CP'
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% -----------------------------------------------
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% | CP | : : | CP | : : | CP |
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% ----------------------------------------------------> nt
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% x0 x1 x2
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%
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% CP' = x0 * (1-w) + x2 * w
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k = 1;
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for nt=N+Ng:N+Ng+N-2,
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for d=1:3,
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Nd = N-2+d;
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x0 = Zf.xp(nt-Nd+1:nt-Nd+L);
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x1 = Zf.xp(nt+1:nt+L);
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x2 = Zf.xp(nt+Nd+1:nt+Nd+L);
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xcps = x0 .* (1-wng') + x2 .* (wng');
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n = 0.5*(abs(x1).^2 + abs(xcps).^2);
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c(k, d) = sum(abs(x1 .* conj(xcps)) - 1.0*n);
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end
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k = k + 1;
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end
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[v1, n1] = max(c);
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[v2, n2] = max(v1);
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Nd = N-2+n2;
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n = mod(n1(n2)-1, N+Ng);
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Zf.xp = Zf.xp(N+Ng+1:length(Zf.xp));
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Zf.n = n;
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valid = 1;
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if (0)
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plot(d); grid;
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pause(0.01);
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end
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@@ -0,0 +1,38 @@
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function timing_coarse_eval(x)
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N = 1024;
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Ng = 256;
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L = Ng;
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RCWIN_ROLLOFF = 0.125;
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[rcwin Nt wng] = txwin_eval(N, Ng, RCWIN_ROLLOFF);
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% RC Windowing at TX
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% Calculate merged CP'
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% -----------------------------------------------
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% | CP | : : | CP | : : | CP |
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% ----------------------------------------------------> nt
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% x0 x1 x2
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%
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% CP' = x0 * (1-w) + x2 * w
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k = 1;
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for nt=N+Ng:8*(N+Ng),
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for d=1:3,
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Nd = N-2+d;
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x0 = x(nt-Nd+1:nt-Nd+L);
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x1 = x(nt+1:nt+L);
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x2 = x(nt+Nd+1:nt+Nd+L);
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xcps = x0 .* (1-wng') + x2 .* (wng');
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n = 0.5*(abs(x1).^2 + abs(xcps).^2);
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c(k, d) = sum(abs(x1 .* conj(xcps)) - 1.0*n);
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end
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k = k + 1;
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end
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[v1, n1] = max(c);
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[v2, n2] = max(v1);
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n = mod(n1(n2)-1, N+Ng)
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figure(1);
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plot(0:length(c)-1, 1-abs(c)); grid;
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@@ -0,0 +1,23 @@
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function [kc, valid, Zf] = frame_timing(Z, bins_timing_pilots, sym_per_frame, Zi)
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N = length(Z);
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if (~isfield(Zi, 'valid'))
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Zi = struct('valid', 1, 'Zk', []);
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end
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if 1
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valid = 0;
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kc = 0;
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if ~isempty(Zi.Zk)
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Xk = Z .* conj(Zi.Zk);
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if 0
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plot(0:length(Xk)-1, abs(Xk), '-*'); grid;
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pause (0.01);
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end
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valid = 1;
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kc = mean(abs(Xk));
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end
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Zi.Zk = Z;
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end
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Zf = Zi;
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