- fdet.m pass Xm

- 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

ofdm/fdet.m

@@ -1,10 +1,10 @@
-function [omega, err, dmod, omega_coarse, omega_est] = fdet(x, N, Ng, off, omega_min, omega_step, omega_max)
+function [omega, err, dmod, omega_coarse, omega_est, Xm] = fdet(x, N, Ng, off, omega_min, omega_step, omega_max)
 %
 
 K = fix((length(x)-Ng)/(N+Ng));
 
 % Initial guess
-omega_coarse = fdet_coarse(x, N, omega_min, omega_step, omega_max);
+[omega_coarse, Xm] = fdet_coarse(x, N, Ng, omega_min, omega_step, omega_max);
 
 phi_est = 0;
 omega_est = omega_coarse;

ofdm/fdet_coarse.m

@@ -1,4 +1,22 @@
-function omega_coarse = fdet_coarse(x, N, omega_min, omega_step, omega_max)
+function [omega_coarse, Xm] = fdet_coarse(x, N, Ng, omega_min, omega_step, omega_max)
+
+Xm = zeros(N,1);
+
+if 0
+    
+K = fix((length(x))/(N+Ng));
+
+for k=1:K,
+    xp = x((k-1)*(N+Ng)+1:k*(N+Ng));
+    Xm = 0.5*Xm + fft(xp(Ng+1:N+Ng), N);
+end
+
+Nmax = ceil(omega_max*N)+1
+[v, ii] = max(abs(Xm(1:Nmax)))
+
+omega_coarse = (ii-1)/N;
+
+else
     
 omega_range = (omega_min:omega_step:omega_max);
 
@@ -9,3 +27,4 @@ end;
 [v maxk] = max(abs(dmod));
 omega_coarse = omega_range(maxk);
 
+end

ofdm/fdet_wav.m

@@ -42,16 +42,30 @@ cp_off = mod(ii, Ng+N)
 
 % Detect CFO
 fprintf('Perform frequency detection\n');
-[omega, err, dmod, omega_coarse, omega_est] = fdet(x, N, Ng, cp_off, omega_min, omega_step, omega_max);
+[omega, err, dmod, omega_coarse, omega_est, Xm] = fdet(x, N, Ng, cp_off, omega_min, omega_step, omega_max);
 
 f_coarse = omega_coarse*fs
 f_est = omega_est*fs
 
+fprintf('Receive Symbols\n');
+K = fix((length(x)-Ng)/(N+Ng));
+for k=10:30
+    xp = x((k-1)*(N+Ng)+cp_off+1:k*(N+Ng)+cp_off);
+    Xp(:,k) = fft(xp(Ng+1:N+Ng), N);
+end;
+
 close all;
 
 plot(abs(c)); grid;
 figure;
 
+bin = fix(N*750/48000)+1
+plot(real(Xp(bin, :)), imag(Xp(bin, :)), '+'); grid;
+
+figure;
+plot(0:N-1, abs(Xm)); grid;
+
+figure;
 subplot(5,1,1)
 plot(1:lge(omega), real(dmod)/N, 1:lge(omega), imag(dmod)/N, 1:lge(omega), abs(dmod)/N); grid; legend('Re', 'Im', 'abs()');
 
@@ -65,4 +79,5 @@ subplot(5,1,4)
 plot(1:lge(omega), angle(dmod), '-', 1:lge(omega), diff(angle([0 dmod])), 'r-'); grid; legend('phi', 'dphi');
 
 subplot(5,1,5)
-plot(1:lge(omega), abs(dmod)/N - real(dmod)/N, '-'); grid; legend('diff');
+plot(1:lge(omega), log10(abs(dmod) ./ (1E-6+abs(real(dmod)))), '-'); grid; legend('diff');
+