diff --git a/ofdm/fdet.m b/ofdm/fdet.m
index eacf7b1..eca070d 100644
--- a/ofdm/fdet.m
+++ b/ofdm/fdet.m
@@ -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])
 
-K = fix(length(x)/N);
-
-% Initial guess
-omega_coarse = fdet_coarse(x, N, 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);
@@ -13,11 +10,12 @@ omega_coarse = fdet_coarse(x, N, omega_min, omega_step, omega_max);
 phi_est = 0;
 omega_est = omega_coarse;
 
+off = 0;
 for k=1:K
 	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));
-    dmod(k) = sum(xp.*x_est);
+    dmod(k) = sum(xp(Ng+1:N+Ng).*x_est);
     phi = angle(dmod(k));
     omega_f = phi/N/(2*pi);
     err(k) = omega_f;
diff --git a/ofdm/fdet_eval.m b/ofdm/fdet_eval.m
index fc49e33..37265e2 100644
--- a/ofdm/fdet_eval.m
+++ b/ofdm/fdet_eval.m
@@ -13,7 +13,7 @@ omega_step = p(3)/fs;
 % 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);
 
-[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_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()');
 
 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)
 plot(1:lge(omega), omega*fs); grid; legend('f');
diff --git a/ofdm/fdet_wav.m b/ofdm/fdet_wav.m
index 4447318..eb40e09 100644
--- a/ofdm/fdet_wav.m
+++ b/ofdm/fdet_wav.m
@@ -3,6 +3,7 @@ function fdet_wav(filename, p)
 close all;
 fs = 48000;
 N = 1024;
+Ng = 256;
 
 omega_min = p(1)/fs;
 omega_max = p(2)/fs;
@@ -13,7 +14,7 @@ omega_step = p(3)/fs;
 
 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_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()');
 
 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)
 plot(1:lge(omega), omega*fs); grid; legend('f');