nass-micro-station-measurements/slip-ring-test/matlab/meas_slip_ring.m

% Matlab Init                                              :noexport:ignore:

current_dir='/home/thomas/MEGA/These/meas/slip-ring-test/';
%% Clear Workspace and Close figures
clear; close all; clc;

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

% Load data
% We load the data of the z axis of two geophones.

sr_off = load('mat/data_008.mat', 'data'); sr_off = sr_off.data;
sr_on  = load('mat/data_009.mat', 'data'); sr_on  = sr_on.data;
sr_6r  = load('mat/data_010.mat', 'data'); sr_6r  = sr_6r.data;
sr_60r = load('mat/data_011.mat', 'data'); sr_60r = sr_60r.data;

% Time Domain
% We plot the time domain data for the direct measurement (figure [[fig:sr_direct_time]]) and for the signal going through the slip-ring (figure [[fig:sr_slipring_time]]);


figure;
hold on;
plot(sr_60r(:, 3), sr_60r(:, 1), 'DisplayName', '60rpm');
plot(sr_6r(:, 3),  sr_6r(:, 1),  'DisplayName', '6rpm');
plot(sr_on(:, 3),  sr_on(:, 1),  'DisplayName', 'ON');
plot(sr_off(:, 3), sr_off(:, 1), 'DisplayName', 'OFF');
hold off;
xlabel('Time [s]'); ylabel('Voltage [V]');
legend('Location', 'northeast');



% #+NAME: fig:sr_direct_time
% #+CAPTION: Direct measurement
% #+RESULTS: fig:sr_direct_time
% [[file:figs/sr_direct_time.png]]



figure;
hold on;
plot(sr_60r(:, 3), sr_60r(:, 2), 'DisplayName', '60rpm');
plot(sr_6r(:, 3),  sr_6r(:, 2),  'DisplayName', '6rpm');
plot(sr_on(:, 3),  sr_on(:, 2),  'DisplayName', 'ON');
plot(sr_off(:, 3), sr_off(:, 2), 'DisplayName', 'OFF');
hold off;
xlabel('Time [s]'); ylabel('Voltage [V]');
legend('Location', 'northeast');

% Frequency Domain
% We first compute some parameters that will be used for the PSD computation.

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

Fs = 1/dt; % [Hz]

win = hanning(ceil(10*Fs));



% Then we compute the Power Spectral Density using =pwelch= function.

[pxdir, f] = pwelch(sr_off(:, 1), win, [], [], Fs);
[pxoff, ~] = pwelch(sr_off(:, 2), win, [], [], Fs);
[pxon,  ~] = pwelch(sr_on(:, 2),  win, [], [], Fs);
[px6r,  ~] = pwelch(sr_6r(:, 2),  win, [], [], Fs);
[px60r, ~] = pwelch(sr_60r(:, 2), win, [], [], Fs);



% And we plot the ASD of the measured signals (figure [[fig:sr_psd_compare]]);


figure;
hold on;
plot(f, sqrt(pxoff), 'DisplayName', 'OFF');
plot(f, sqrt(pxon),  'DisplayName', 'ON');
plot(f, sqrt(px6r),  'DisplayName', '6rpm');
plot(f, sqrt(px60r), 'DisplayName', '60rpm');
plot(f, sqrt(pxdir), 'k-', 'DisplayName', 'Direct');
hold off;
set(gca, 'xscale', 'log');
set(gca, 'yscale', 'log');
xlabel('Frequency [Hz]'); ylabel('ASD of the measured Voltage $\left[\frac{V}{\sqrt{Hz}}\right]$')
legend('Location', 'northeast');
xlim([0.1, 500]);