function fdet_eval(f_true, knoise_dB)

fs = 48000;
N = 1024;

phi_true = 1;

x_true = exp(j*(2*pi*f_true/fs*(0:N-1)'+phi_true)) + sqrt(10^(knoise_dB/10))*randn(N,1);

% Initial guess
X = fft(x_true, N);
[v maxk] = max(abs(X));
f_est = (maxk-1)*fs/N
phi_est = angle(x_true(1));
mu = 1.0;

for k=1:500
    x_est = exp(-j*(2*pi*f_est/fs*(0:N-1)'+phi_est));
    dmod(k) = sum(x_true.*x_est);
    err(k) = sign(imag(dmod(k)))*(1-real(dmod(k)/abs(dmod(k))))^.5;
    f_est = f_est + mu*err(k);
	f(k) = f_est;
end;

f_true = f_true
f_est = f_est

close all;
subplot(3,1,1)
plot(1:lge(f), 1-real(dmod)./abs(dmod), 1:lge(f), imag(dmod)./abs(dmod)); grid;

subplot(3,1,2)
plot(1:lge(f), err, '-*'); grid;

subplot(3,1,3)
plot(1:lge(f), f); grid;