197 lines
5.7 KiB
Org Mode
197 lines
5.7 KiB
Org Mode
#+TITLE:SpeedGoat
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:DRAWER:
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#+STARTUP: overview
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#+HTML_HEAD: <link rel="stylesheet" type="text/css" href="../css/htmlize.css"/>
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#+HTML_HEAD: <link rel="stylesheet" type="text/css" href="../css/readtheorg.css"/>
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#+HTML_HEAD: <link rel="stylesheet" type="text/css" href="../css/zenburn.css"/>
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#+HTML_HEAD: <script type="text/javascript" src="../js/jquery.min.js"></script>
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#+HTML_HEAD: <script type="text/javascript" src="../js/bootstrap.min.js"></script>
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#+HTML_HEAD: <script type="text/javascript" src="../js/jquery.stickytableheaders.min.js"></script>
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#+HTML_HEAD: <script type="text/javascript" src="../js/readtheorg.js"></script>
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#+PROPERTY: header-args:matlab :session *MATLAB*
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#+PROPERTY: header-args:matlab+ :comments org
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#+PROPERTY: header-args:matlab+ :results output
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#+PROPERTY: header-args:matlab+ :exports both
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#+PROPERTY: header-args:matlab+ :eval no-export
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#+PROPERTY: header-args:matlab+ :output-dir figs
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:END:
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* Setup
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Two L22 geophones are used.
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They are placed on the ID31 granite.
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They are leveled.
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The signals are amplified using voltage amplifier with a gain of 60dB.
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The voltage amplifiers include a low pass filter with a cut-off frequency at 1kHz.
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#+name: fig:figure_name
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#+caption: Setup
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#+attr_html: :width 500px
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[[file:./figs/setup.jpg]]
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#+name: fig:figure_name
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#+caption: Geophones
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#+attr_html: :width 500px
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[[file:./figs/geophones.jpg]]
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* Signal Processing
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** Matlab Init :noexport:ignore:
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#+begin_src matlab :exports none :results silent :noweb yes
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<<matlab-init>>
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#+end_src
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** Load data
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#+begin_src matlab :results none
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load('mat/data_001.mat', 't', 'x1', 'x2');
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dt = t(2) - t(1);
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#+end_src
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** Time Domain Data
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#+begin_src matlab :results none
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figure;
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hold on;
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plot(t, x1);
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plot(t, x2);
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hold off;
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xlabel('Time [s]');
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ylabel('Voltage [V]');
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xlim([t(1), t(end)]);
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#+end_src
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#+NAME: fig:data_time_domain
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#+HEADER: :tangle no :exports results :results value raw replace :noweb yes
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#+begin_src matlab :var filepath="figs/data_time_domain.pdf" :var figsize="wide-normal" :post pdf2svg(file=*this*, ext="png")
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<<plt-matlab>>
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#+end_src
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#+NAME: fig:data_time_domain
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#+CAPTION: Time domain Data
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#+RESULTS: fig:data_time_domain
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[[file:figs/data_time_domain.png]]
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#+begin_src matlab :results none
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figure;
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hold on;
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plot(t, x1);
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plot(t, x2);
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hold off;
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xlabel('Time [s]');
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ylabel('Voltage [V]');
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xlim([0 1]);
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#+end_src
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#+NAME: fig:data_time_domain_zoom
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#+HEADER: :tangle no :exports results :results value raw replace :noweb yes
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#+begin_src matlab :var filepath="figs/data_time_domain_zoom.pdf" :var figsize="wide-normal" :post pdf2svg(file=*this*, ext="png")
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<<plt-matlab>>
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#+end_src
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#+NAME: fig:data_time_domain_zoom
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#+CAPTION: Time domain Data - Zoom
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#+RESULTS: fig:data_time_domain_zoom
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[[file:figs/data_time_domain_zoom.png]]
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** Compute PSD
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#+begin_src matlab :results none
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[pxx1, f1] = pwelch(x1, hanning(ceil(1/dt)), 0, [], 1/dt);
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[pxx2, f2] = pwelch(x2, hanning(ceil(1/dt)), 0, [], 1/dt);
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#+end_src
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** Take into account sensibility of Geophone
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The Geophone used are L22.
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#+begin_src matlab :results none
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S0 = 88; % Sensitivity [V/(m/s)]
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f0 = 2; % Cut-off frequnecy [Hz]
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S = (s/2/pi/f0)/(1+s/2/pi/f0);
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#+end_src
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#+begin_src matlab :results none
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figure;
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bodeFig({S});
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ylabel('Amplitude [V/(m/s)]')
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#+end_src
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#+NAME: fig:geophone_sensibility
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#+HEADER: :tangle no :exports results :results value raw replace :noweb yes
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#+begin_src matlab :var filepath="figs/geophone_sensibility.pdf" :var figsize="wide-normal" :post pdf2svg(file=*this*, ext="png")
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<<plt-matlab>>
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#+end_src
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#+NAME: fig:geophone_sensibility
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#+CAPTION: Sensibility of the Geophone
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#+RESULTS: fig:geophone_sensibility
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[[file:figs/geophone_sensibility.png]]
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We take into account the gain of the electronics.
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The cut-off frequency is set at 1kHz.
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- [ ] Check what is the order of the filter
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- [ ] Maybe I should not use this filter as there is no high frequencies anyway?
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#+begin_src matlab :results none
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G0 = 60; % [dB]
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G = G0/(1+s/2/pi/1000);
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#+end_src
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#+begin_src matlab :results none
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figure;
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hold on;
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plot(f1, sqrt(pxx1)./squeeze(abs(freqresp(G, f1, 'Hz')))./squeeze(abs(freqresp(S, f1, 'Hz'))));
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plot(f2, sqrt(pxx2)./squeeze(abs(freqresp(G, f2, 'Hz')))./squeeze(abs(freqresp(S, f2, 'Hz'))));
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hold off;
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set(gca, 'xscale', 'log');
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set(gca, 'yscale', 'log');
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xlabel('Frequency [Hz]'); ylabel('PSD [m/s/sqrt(Hz)]')
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xlim([2, 500]);
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#+end_src
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#+NAME: fig:psd_velocity
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#+HEADER: :tangle no :exports results :results value raw replace :noweb yes
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#+begin_src matlab :var filepath="figs/psd_velocity.pdf" :var figsize="full-tall" :post pdf2svg(file=*this*, ext="png")
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<<plt-matlab>>
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#+end_src
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#+NAME: fig:psd_velocity
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#+CAPTION: Spectral density of the velocity
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#+RESULTS: fig:psd_velocity
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[[file:figs/psd_velocity.png]]
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** Transfer function between the two geophones
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#+begin_src matlab :results none
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[T12, f12] = tfestimate(x1, x2, hanning(ceil(length(x1)/100)), [], [], 1/dt);
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#+end_src
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#+begin_src matlab :results none
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figure;
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ax1 = subplot(2, 1, 1);
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plot(f12, abs(T12));
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set(gca, 'xscale', 'log'); set(gca, 'yscale', 'log');
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set(gca, 'XTickLabel',[]);
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ylabel('Magnitude');
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ax2 = subplot(2, 1, 2);
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plot(f12, mod(180+180/pi*phase(T12), 360)-180);
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set(gca, 'xscale', 'log');
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ylim([-180, 180]);
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yticks([-180, -90, 0, 90, 180]);
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xlabel('Frequency [Hz]'); ylabel('Phase');
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linkaxes([ax1,ax2],'x');
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xlim([1, 500]);
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#+end_src
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#+NAME: fig:tf_geophones
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#+HEADER: :tangle no :exports results :results value raw replace :noweb yes
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#+begin_src matlab :var filepath="figs/tf_geophones.pdf" :var figsize="full-tall" :post pdf2svg(file=*this*, ext="png")
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<<plt-matlab>>
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#+end_src
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#+NAME: fig:tf_geophones
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#+CAPTION: Estimated transfer function between the two geophones
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#+RESULTS: fig:tf_geophones
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[[file:figs/tf_geophones.png]]
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