diff --git a/sim_fft-adev/ad_cov.m b/sim_fft-adev/ad_cov.m
new file mode 100644
index 0000000..b53ef0a
--- /dev/null
+++ b/sim_fft-adev/ad_cov.m
@@ -0,0 +1,38 @@
+clear all
+close all
+clc
+
+N = 1e5;
+Ts = 1;
+
+dc.rate = Ts;
+d1.rate = Ts;
+d2.rate = Ts;
+dd.rate = Ts;
+
+r = 10;
+
+com = noise(N, 1, 'brown');
+n1 = r.*noise(N, 1, 'brown');
+n2 = r.*noise(N, 1, 'brown');
+
+dc.freq = com;
+d1.freq = com.+n1;
+d2.freq = com.+n2;
+dd.freq = d1.freq;
+dd.freq2 = d2.freq;
+
+[ad_dc, S, err_dc, tau_dc] = allan(dc,2.^[0:20],'dc',0);
+[ad_d1, S, err_d1, tau_d1] = allan(d1,2.^[0:20],'d1',0);
+[ad_d2, S, err_d2, tau_d2] = allan(d2,2.^[0:20],'d2',0);
+[ad_dd, S, err_dd, tau_dd] = allan_cov(dd,2.^[0:20],'dd',0);
+
+figure
+hold on
+loglogerr(tau_dc, ad_dc, err_dc, 'mo')
+loglogerr(tau_d1, ad_d1, err_d1, 'b')
+loglogerr(tau_d2, ad_d2, err_d2, 'r')
+loglogerr(tau_dd, ad_dd, err_dd, 'k')
+grid on
+
+ad_dd./ad_dc
diff --git a/sim_fft-adev/adev_averaging.m b/sim_fft-adev/adev_averaging.m
new file mode 100644
index 0000000..3594bff
--- /dev/null
+++ b/sim_fft-adev/adev_averaging.m
@@ -0,0 +1,36 @@
+clc
+close all
+clear all
+
+Ts = 0.2;
+N = 1e6;
+D = 5;
+
+data_raw.rate = 1/Ts;
+data_raw.freq = 1/2.*noise(N, 1, 'white') + 1.*noise(N, 1, 'pink') + 1.*noise(N, 1, 'brown') + 0e-8.*[0:N-1]';
+t_raw = [0:length(data_raw.freq)-1];
+[ad_raw, S, err_raw, tau_raw] = allan(data_raw, 2.^[0:20].*Ts, 'raw',0);
+
+data_avg.rate = 1/(Ts*D);
+data_avg.freq = mean(reshape(data_raw.freq', [D, N/D]))';
+t_avg = D.*[1:length(data_avg.freq)];
+[ad_avg, S, err_avg, tau_avg] = allan(data_avg, 2.^[0:20].*Ts*D, 'avg',0);
+
+data_decim.rate = 1/(Ts*D);
+data_decim.freq = reshape(data_raw.freq', [D, N/D])(1,:)';
+t_decim = D.*[0:length(data_decim.freq)-1];
+[ad_decim, S, err_decim, tau_decim] = allan(data_decim, 2.^[0:20].*Ts*D, 'decim',0);
+
+figure
+hold on
+loglogerr(tau_raw, ad_raw, err_raw, 'b')
+loglogerr(tau_decim, ad_decim, err_decim, 'm')
+loglogerr(tau_avg, ad_avg, err_avg, 'r')
+grid on
+
+figure
+hold on
+plot(t_raw, data_raw.freq, 'b')
+plot(t_decim, data_decim.freq, 'm')
+plot(t_avg, data_avg.freq, 'r')
+grid on
diff --git a/sim_fft-adev/adev_tf.m b/sim_fft-adev/adev_tf.m
new file mode 100644
index 0000000..0884e19
--- /dev/null
+++ b/sim_fft-adev/adev_tf.m
@@ -0,0 +1,62 @@
+clc
+close all
+clear all
+
+%%
+
+N = 1e5;
+G = tf(1, [1e3,1]);
+
+%%
+
+data_white.rate = 1;
+data_white.freq = noise(N, 1, 'white');
+[ad_white, S, err_white, tau] = allan(data_white, 2.^[0:20], 'white noise',0);
+
+data_white_f.rate = 1;
+data_white_f.freq = lsim(G, data_white.freq, 1:length(data_white.freq));
+[ad_white_f, S, err_white_f, tau] = allan(data_white_f, 2.^[0:20], 'white noise filtered',0);
+
+%%
+
+data_pink.rate = 1;
+data_pink.freq = noise(N, 1, 'pink');
+[ad_pink, S, err_pink, tau] = allan(data_pink, 2.^[0:20], 'pink noise',0);
+
+data_pink_f.rate = 1;
+data_pink_f.freq = lsim(G, data_pink.freq, 1:length(data_pink.freq));
+[ad_pink_f, S, err_pink_f, tau] = allan(data_pink_f, 2.^[0:20], 'pink noise filtered',0);
+
+%%
+
+data_brown.rate = 1;
+data_brown.freq = noise(N, 1, 'brown');
+[ad_brown, S, err_brown, tau] = allan(data_brown, 2.^[0:20], 'brown noise',0);
+
+data_brown_f.rate = 1;
+data_brown_f.freq = lsim(G, data_brown.freq, 1:length(data_brown.freq));
+[ad_brown_f, S, err_brown_f, tau] = allan(data_brown_f, 2.^[0:20], 'brown noise filtered',0);
+
+%%
+
+data_red.rate = 1;
+data_red.freq = noise(N, 1, 'red');
+[ad_red, S, err_red, tau] = allan(data_red, 2.^[0:20], 'red noise',0);
+
+data_red_f.rate = 1;
+data_red_f.freq = lsim(G, data_red.freq, 1:length(data_red.freq));
+[ad_red_f, S, err_red_f, tau] = allan(data_red_f, 2.^[0:20], 'red noise filtered',0);
+
+%%
+
+figure
+hold on
+loglogerr(tau, ad_white, err_white, 'b')
+loglogerr(tau, ad_white_f, err_white_f, 'r')
+loglogerr(tau, ad_pink, err_pink, 'b-o')
+loglogerr(tau, ad_pink_f, err_pink_f, 'r-o')
+loglogerr(tau, ad_brown, err_brown, 'b-d')
+loglogerr(tau, ad_brown_f, err_brown_f, 'r-d')
+loglogerr(tau, ad_red, err_red, 'b-*')
+loglogerr(tau, ad_red_f, err_red_f, 'r-*')
+grid on
diff --git a/sim_fft-adev/psd_tf.m b/sim_fft-adev/psd_tf.m
new file mode 100644
index 0000000..91ab2c6
--- /dev/null
+++ b/sim_fft-adev/psd_tf.m
@@ -0,0 +1,38 @@
+clc
+close all
+clear all
+
+%%
+N = 1e7;
+Fs = 1000;
+%%
+
+data_white.rate = Fs;
+data_white.freq = noise(N, 1, 'white');
+[ad_white, S, err_white, tau] = allan(data_white, 2.^[0:nextpow2(length(data_white.freq))]./Fs, 'white noise',0);
+[p_white, f_white] = pwelch(data_white.freq, [], [], [], data_white.rate, 'onesided');
+
+data_pink.rate = Fs;
+data_pink.freq = noise(N, 1, 'pink');
+[ad_pink, S, err_pink, tau] = allan(data_pink, 2.^[0:nextpow2(length(data_pink.freq))]./Fs, 'pink noise',0);
+[p_pink, f_pink] = pwelch(data_pink.freq, [], [], [], data_pink.rate, 'onesided');
+
+
+data_brown.rate = Fs;
+data_brown.freq = noise(N, 1, 'brown');
+[ad_brown, S, err_brown, tau] = allan(data_brown, 2.^[0:nextpow2(length(data_brown.freq))]./Fs, 'brown noise',0);
+[p_brown, f_brown] = pwelch(data_brown.freq, [], [], [], data_brown.rate, 'onesided');
+
+figure
+hold on
+loglogerr(tau, ad_white, err_white, 'b')
+loglogerr(tau, ad_pink, err_pink, 'm')
+loglogerr(tau, ad_brown, err_brown, 'k')
+grid on
+
+figure
+hold on
+semilogx(f_white, 10*log10(p_white), 'b')
+semilogx(f_pink, 10*log10(p_pink), 'm')
+semilogx(f_brown, 10*log10(p_brown), 'k')
+grid on