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- remove cyclic prefix

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git-svn-id: http://moon:8086/svn/matlab/trunk@21 801c6759-fa7c-4059-a304-17956f83a07c
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jens
2015-04-05 11:05:19 +00:00
parent 7e89f89dd5
commit 7154d5d94e
3 changed files with 10 additions and 11 deletions
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ofdm/fdet.m
+5 -7
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@@ -1,11 +1,8 @@
function [omega, err, dmod, omega_coarse, omega_est] = fdet(x, N, omega_min, omega_step, omega_max) function [omega, err, dmod, omega_coarse, omega_est] = fdet(x, N, Ng, omega_min, omega_step, omega_max)
% %
% Example: fdet_eval(1200, pi/4, -10, [1100 1350 1]) % Example: fdet_eval(1200, pi/4, -10, [1100 1350 1])
K = fix(length(x)/N); K = fix(length(x-Ng)/(N+Ng));
% Initial guess
omega_coarse = fdet_coarse(x, N, omega_min, omega_step, omega_max);
% Initial guess % Initial guess
omega_coarse = fdet_coarse(x, N, omega_min, omega_step, omega_max); omega_coarse = fdet_coarse(x, N, omega_min, omega_step, omega_max);
@@ -13,11 +10,12 @@ omega_coarse = fdet_coarse(x, N, omega_min, omega_step, omega_max);
phi_est = 0; phi_est = 0;
omega_est = omega_coarse; omega_est = omega_coarse;
off = 0;
for k=1:K for k=1:K
omega(k) = omega_est; omega(k) = omega_est;
xp = x((k-1)*N+1:k*N); xp = x((k-1)*(N+Ng)+off+1:k*(N+Ng)+off);
x_est = exp(-j*(2*pi*omega_est*(0:N-1)' + phi_est)); x_est = exp(-j*(2*pi*omega_est*(0:N-1)' + phi_est));
dmod(k) = sum(xp.*x_est); dmod(k) = sum(xp(Ng+1:N+Ng).*x_est);
phi = angle(dmod(k)); phi = angle(dmod(k));
omega_f = phi/N/(2*pi); omega_f = phi/N/(2*pi);
err(k) = omega_f; err(k) = omega_f;
ofdm/fdet_eval.m
+2 -2
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@@ -13,7 +13,7 @@ omega_step = p(3)/fs;
% Generate signal % Generate signal
x = exp(j*(2*pi*f_true/fs*(0:K*N-1)'+ phi_true)) + sqrt(10^(knoise_dB/10))*randn(K*N,1); x = exp(j*(2*pi*f_true/fs*(0:K*N-1)'+ phi_true)) + sqrt(10^(knoise_dB/10))*randn(K*N,1);
[omega, err, dmod, omega_coarse, omega_est] = fdet(x, N, omega_min, omega_step, omega_max); [omega, err, dmod, omega_coarse, omega_est] = fdet(x, N, 0, omega_min, omega_step, omega_max);
f_coarse = omega_coarse*fs f_coarse = omega_coarse*fs
f_est = omega_est*fs f_est = omega_est*fs
@@ -24,7 +24,7 @@ subplot(4,1,1)
plot(1:lge(omega), real(dmod)/N, 1:lge(omega), imag(dmod)/N, 1:lge(omega), abs(dmod)/N); grid; legend('Re', 'Im', 'abs()'); plot(1:lge(omega), real(dmod)/N, 1:lge(omega), imag(dmod)/N, 1:lge(omega), abs(dmod)/N); grid; legend('Re', 'Im', 'abs()');
subplot(4,1,2) subplot(4,1,2)
plot(1:lge(omega), err, '-'); grid; legend('error'); plot(1:lge(omega), err*fs, '-'); grid; legend('error');
subplot(4,1,3) subplot(4,1,3)
plot(1:lge(omega), omega*fs); grid; legend('f'); plot(1:lge(omega), omega*fs); grid; legend('f');
ofdm/fdet_wav.m
+3 -2
View File
@@ -3,6 +3,7 @@ function fdet_wav(filename, p)
close all; close all;
fs = 48000; fs = 48000;
N = 1024; N = 1024;
Ng = 256;
omega_min = p(1)/fs; omega_min = p(1)/fs;
omega_max = p(2)/fs; omega_max = p(2)/fs;
@@ -13,7 +14,7 @@ omega_step = p(3)/fs;
x = xwav(:, 1) + j*xwav(:, 2); x = xwav(:, 1) + j*xwav(:, 2);
[omega, err, dmod, omega_coarse, omega_est] = fdet(x, N, omega_min, omega_step, omega_max); [omega, err, dmod, omega_coarse, omega_est] = fdet(x, N, Ng, omega_min, omega_step, omega_max);
f_coarse = omega_coarse*fs f_coarse = omega_coarse*fs
f_est = omega_est*fs f_est = omega_est*fs
@@ -23,7 +24,7 @@ subplot(4,1,1)
plot(1:lge(omega), real(dmod)/N, 1:lge(omega), imag(dmod)/N, 1:lge(omega), abs(dmod)/N); grid; legend('Re', 'Im', 'abs()'); plot(1:lge(omega), real(dmod)/N, 1:lge(omega), imag(dmod)/N, 1:lge(omega), abs(dmod)/N); grid; legend('Re', 'Im', 'abs()');
subplot(4,1,2) subplot(4,1,2)
plot(1:lge(omega), err, '-'); grid; legend('error'); plot(1:lge(omega), err*fs, '-'); grid; legend('error');
subplot(4,1,3) subplot(4,1,3)
plot(1:lge(omega), omega*fs); grid; legend('f'); plot(1:lge(omega), omega*fs); grid; legend('f');