nass-micro-station-measurements/ground-motion/matlab/ground_meas_id31.m

%% Clear Workspace and Close figures
clear; close all; clc;

%% Intialize Laplace variable
s = zpk('s');

% Load data

data = load('mat/data_028.mat', 'data'); data = data.data;

% Time domain plots

figure;
hold on;
plot(data(:, 3), data(:, 1));
hold off;
xlabel('Time [s]'); ylabel('Voltage [V]');
xlim([0, 100]);

% Computation of the ASD of the measured voltage

dt = data(2, 3) - data(1, 3);

Fs = 1/dt;
win = hanning(ceil(10*Fs));

[px_dc, f] = pwelch(data(:, 1), win, [], [], Fs);

figure;
hold on;
plot(f, sqrt(px_dc));
hold off;
set(gca, 'xscale', 'log');
set(gca, 'yscale', 'log');
xlabel('Frequency [Hz]'); ylabel('Amplitude Spectral Density $\left[\frac{V}{\sqrt{Hz}}\right]$')
xlim([0.1, 500]);

% Scaling to take into account the sensibility of the geophone and the voltage amplifier
% The Geophone used are L22. Their sensibility is shown on figure [[fig:geophone_sensibility]].


S0 = 88; % Sensitivity [V/(m/s)]
f0 = 2; % Cut-off frequency [Hz]

S = S0*(s/2/pi/f0)/(1+s/2/pi/f0);

figure;
bodeFig({S}, logspace(-1, 2, 1000));
ylabel('Amplitude $\left[\frac{V}{m/s}\right]$')



% #+NAME: fig:geophone_sensibility
% #+CAPTION: Sensibility of the Geophone
% #+RESULTS: fig:geophone_sensibility
% [[file:figs/geophone_sensibility.png]]

% We also take into account the gain of the electronics which is here set to be $60dB$.


G0_db = 60; % [dB]

G0 = 10^(G0_db/20); % [abs]



% We divide the ASD measured (in $\text{V}/\sqrt{\text{Hz}}$) by the gain of the voltage amplifier to obtain the ASD of the voltage across the geophone.
% We further divide the result by the sensibility of the Geophone to obtain the ASD of the velocity in $m/s/\sqrt{Hz}$.


scaling = 1./squeeze(abs(freqresp(G0*S, f, 'Hz')));

% Computation of the ASD of the velocity
% The ASD of the measured velocity is shown on figure [[fig:ground_motion_id31_asd_velocity]].


figure;
hold on;
plot(f, sqrt(px_dc).*scaling);
hold off;
set(gca, 'xscale', 'log');
set(gca, 'yscale', 'log');
xlabel('Frequency [Hz]'); ylabel('ASD of the measured Velocity $\left[\frac{m/s}{\sqrt{Hz}}\right]$')
xlim([0.1, 500]);



% #+NAME: fig:ground_motion_id31_asd_velocity
% #+CAPTION: Amplitude Spectral Density of the Velocity
% #+RESULTS: fig:ground_motion_id31_asd_velocity
% [[file:figs/ground_motion_id31_asd_velocity.png]]

% We also plot the ASD in displacement (figure [[fig:ground_motion_id31_asd_displacement]]);


figure;
hold on;
plot(f, (sqrt(px_dc).*scaling)./(2*pi*f));
hold off;
set(gca, 'xscale', 'log'); set(gca, 'yscale', 'log');
xlabel('Frequency [Hz]'); ylabel('ASD of the displacement $\left[\frac{m}{\sqrt{Hz}}\right]$')
xlim([0.1, 500]);



% #+NAME: fig:ground_motion_id31_asd_displacement
% #+CAPTION: Amplitude Spectral Density of the Displacement
% #+RESULTS: fig:ground_motion_id31_asd_displacement
% [[file:figs/ground_motion_id31_asd_displacement.png]]
% And also in $\frac{{\mu u}^2}{Hz}$ (figure [[fig:ground_motion_id31_psd_displacement]]).

figure;
hold on;
plot(f, ((sqrt(px_dc).*scaling)./(2*pi*f).*1e6).^2);
hold off;
set(gca, 'xscale', 'log');
set(gca, 'yscale', 'log');
xlabel('Frequency [Hz]'); ylabel('PSD of the measured displacement $\left[\frac{{ \mu m }^2}{Hz}\right]$')
xlim([0.1, 500]);

% Load the measurement data
% First we load the measurement data.
% Here we have one measurement of the floor motion made at the ESRF in 2018, and one measurement made at CERN.

id09 = load('./mat/id09_floor_september2018.mat');
cern = load('./mat/ground_motion_dist.mat');

% Compute PSD of the measurements
% We compute the Power Spectral Densities of the measurements.

Fs_id09 = 1/(id09.time3(2)-id09.time3(1));
win_id09 = hanning(ceil(10*Fs_id09));
[id09_pxx, id09_f] = pwelch(1e-6*id09.x_y_z(:, 3), win_id09, [], [], Fs_id09);

Fs_cern = 1/(cern.gm.time(2)-cern.gm.time(1));
win_cern = hanning(ceil(10*Fs_cern));
[cern_pxx, cern_f] = pwelch(cern.gm.signal, win_cern, [], [], Fs_cern);

% Compare PSD of Cern, ID09 and ID31
% And we compare all the measurements (figure [[fig:ground_motion_compare]]).


figure;
hold on;
plot(id09_f, id09_pxx, 'DisplayName', 'ID09');
plot(cern_f, cern_pxx, 'DisplayName', 'CERN');
plot(f, ((sqrt(px_dc).*scaling)./(2*pi*f)).^2, 'k', 'DisplayName', 'ID31');
hold off;
set(gca, 'XScale', 'log'); set(gca, 'YScale', 'log');
xlabel('Frequency [Hz]'); ylabel('PSD [$m^2/Hz$]');
legend('Location', 'northeast');
xlim([0.1, 500]);