diff --git a/ground-motion/data/ground_meas_id31.zip b/ground-motion/data/ground_meas_id31.zip
index ad8f547..cf6ac2e 100644
Binary files a/ground-motion/data/ground_meas_id31.zip and b/ground-motion/data/ground_meas_id31.zip differ
diff --git a/ground-motion/matlab/ground_meas_id31.m b/ground-motion/matlab/ground_meas_id31.m
index 87cd5b2..e39fa04 100644
--- a/ground-motion/matlab/ground_meas_id31.m
+++ b/ground-motion/matlab/ground_meas_id31.m
@@ -8,7 +8,7 @@ s = zpk('s');
 
 data = load('mat/data_028.mat', 'data'); data = data.data;
 
-% Time domain plots
+% Time domain plots of the measured voltage
 
 figure;
 hold on;
@@ -82,6 +82,35 @@ psd_gv = px_dc./abs(squeeze(freqresp(G0*S, f, 'Hz'))).^2;
 
 psd_gm = psd_gv./(2*pi*f).^2;
 
+% Time domain plots of the ground motion
+% We can inverse the dynamics of the geophone to convert the measured voltage into the estimated ground motion.
+
+
+est_vel = lsim(inv(G0*S)*(s/2/pi)/(1+s/2/pi), data(:, 1), data(:, 3)); % Estimated velocity above 1Hz
+est_vel = est_vel - mean(est_vel(data(:,3)>10)); % The mean value of the velocity if removed
+est_dis = lsim(1/(1+s/2/pi), est_vel, data(:, 3)); % The velocity is integrated above 1Hz
+
+figure;
+hold on;
+plot(data(:, 3), est_vel);
+hold off;
+xlabel('Time [s]'); ylabel('Velocity [m/s]');
+xlim([10, 100]);
+
+
+
+% #+NAME: fig:time_domain_velocity
+% #+CAPTION: Time domain velocity ([[./figs/time_domain_velocity.png][png]], [[./figs/time_domain_velocity.pdf][pdf]])
+% [[file:figs/time_domain_velocity.png]]
+
+
+figure;
+hold on;
+plot(data(:, 3), est_dis);
+hold off;
+xlabel('Time [s]'); ylabel('Displacement [m]');
+xlim([10, 100]);
+
 % Computation of the ASD of the velocity and displacement
 % The ASD of the measured velocity is shown on figure [[fig:ground_motion_id31_asd_velocity]].
 
@@ -135,7 +164,7 @@ xlim([0.1, 500]); ylim([1e-13, 1e3]);
 % Save
 % We save the PSD of the ground motion for further analysis.
 
-save('./mat/psd_gm', 'f', 'psd_gm');
+save('./mat/psd_gm.mat', 'f', 'psd_gm', 'psd_gv');
 
 % Load the measurement data
 % First we load the measurement data.