Renamed one folder. Add analysis of vibrations when rotating

slip-ring-electrical-noise/img/.gitignore

@@ -0,0 +1 @@
+*.mp4

slip-ring-electrical-noise/img/nohup.out

@@ -0,0 +1,3 @@
+invalid color string: rgba(50, 48, 47)
+
+(termite:25037): GLib-WARNING **: 14:10:26.520: GChildWatchSource: Exit status of a child process was requested but ECHILD was received by waitpid(). See the documentation of g_child_watch_source_new() for possible causes.

slip-ring-electrical-noise/index.org

@@ -0,0 +1,841 @@
+#+TITLE: Measurements On the Slip-Ring
+#+SETUPFILE: ../config.org
+
+* Effect of the Slip-Ring on the signal
+  :PROPERTIES:
+  :header-args:matlab+: :tangle matlab/meas_slip_ring_geophone.m
+  :header-args:matlab+: :comments org :mkdirp yes
+  :END:
+  <<sec:meas_slip_ring_geophone>>
+
+#+begin_src bash :exports none :results none
+  if [ matlab/meas_slip_ring_geophone.m -nt data/meas_slip_ring_geophone.zip ]; then
+    cp matlab/meas_slip_ring_geophone.m meas_slip_ring_geophone.m;
+    zip data/meas_slip_ring_geophone \
+        mat/data_018.mat \
+        mat/data_019.mat \
+        meas_slip_ring_geophone.m;
+    rm meas_slip_ring_geophone.m;
+  fi
+#+end_src
+
+#+begin_note
+  All the files (data and Matlab scripts) are accessible [[file:data/meas_slip_ring_geophone.zip][here]].
+#+end_note
+
+** Experimental Setup
+Two measurements are made with the control systems of all the stages turned OFF.
+
+One geophone is located on the marble while the other is located at the sample location (figure [[fig:setup_slipring]]).
+
+#+name: fig:setup_slipring
+#+caption: Experimental Setup
+#+attr_html: :width 500px
+[[file:./img/IMG_20190430_112615.jpg]]
+
+The two measurements are:
+| Measurement File | Description                                                      |
+|------------------+------------------------------------------------------------------|
+| =meas_018.mat=   | Signal from the top geophone does not goes through the Slip-ring |
+| =meas_019.mat=   | Signal goes through the Slip-ring (as shown on the figure above) |
+
+Each of the measurement =mat= file contains one =data= array with 3 columns:
+| Column number | Description       |
+|---------------+-------------------|
+|             1 | Geophone - Marble |
+|             2 | Geophone - Sample |
+|             3 | Time              |
+
+** Matlab Init                                              :noexport:ignore:
+#+begin_src matlab :tangle no :exports none :results silent :noweb yes :var current_dir=(file-name-directory buffer-file-name)
+  <<matlab-dir>>
+#+end_src
+
+#+begin_src matlab :exports none :results silent :noweb yes
+  <<matlab-init>>
+#+end_src
+
+** Load data
+We load the data of the z axis of two geophones.
+
+#+begin_src matlab :results none
+  d8 = load('mat/data_018.mat', 'data'); d8 = d8.data;
+  d9 = load('mat/data_019.mat', 'data'); d9 = d9.data;
+#+end_src
+
+** Analysis - Time Domain
+First, we compare the time domain signals for the two experiments (figure [[fig:slipring_time]]).
+
+
+#+begin_src matlab :results none
+  figure;
+  hold on;
+  plot(d9(:, 3), d9(:, 2), 'DisplayName', 'Slip-Ring');
+  plot(d8(:, 3), d8(:, 2), 'DisplayName', 'Wire');
+  hold off;
+  xlabel('Time [s]'); ylabel('Voltage [V]');
+  xlim([0, 50]);
+  legend('location', 'northeast');
+#+end_src
+
+#+NAME: fig:slipring_time
+#+HEADER: :tangle no :exports results :results value raw replace :noweb yes
+#+begin_src matlab :var filepath="figs/slipring_time.pdf" :var figsize="wide-tall" :post pdf2svg(file=*this*, ext="png")
+  <<plt-matlab>>
+#+end_src
+
+#+NAME: fig:slipring_time
+#+CAPTION: Effect of the Slip-Ring on the measured signal - Time domain
+#+RESULTS: fig:slipring_time
+[[file:figs/slipring_time.png]]
+
+** Analysis - Frequency Domain
+We then compute the Power Spectral Density of the two signals and we compare them (figure [[fig:slipring_asd]]).
+#+begin_src matlab :results none
+  dt = d8(2, 3) - d8(1, 3);
+  Fs = 1/dt;
+
+  win = hanning(ceil(1*Fs));
+#+end_src
+
+#+begin_src matlab :results none
+  [pxx8, f] = pwelch(d8(:, 2), win, [], [], Fs);
+  [pxx9, ~] = pwelch(d9(:, 2), win, [], [], Fs);
+#+end_src
+
+#+begin_src matlab :results none
+  figure;
+  hold on;
+  plot(f, sqrt(pxx9), 'DisplayName', 'Slip-Ring');
+  plot(f, sqrt(pxx8), 'DisplayName', 'Wire');
+  hold off;
+  set(gca, 'xscale', 'log');
+  set(gca, 'yscale', 'log');
+  xlabel('Frequency [Hz]'); ylabel('Amplitude Spectral Density $\left[\frac{V}{\sqrt{Hz}}\right]$')
+  xlim([1, 500]);
+  legend('Location', 'southwest');
+#+end_src
+
+#+NAME: fig:slipring_asd
+#+HEADER: :tangle no :exports results :results value raw replace :noweb yes
+#+begin_src matlab :var filepath="figs/slipring_asd.pdf" :var figsize="wide-tall" :post pdf2svg(file=*this*, ext="png")
+  <<plt-matlab>>
+#+end_src
+
+#+NAME: fig:slipring_asd
+#+CAPTION: Effect of the Slip-Ring on the measured signal - Frequency domain
+#+RESULTS: fig:slipring_asd
+[[file:figs/slipring_asd.png]]
+
+** Conclusion
+#+begin_important
+- Connecting the geophone through the Slip-Ring seems to induce a lot of noise.
+#+end_important
+
+#+begin_note
+*Remaining questions to answer*:
+- Why is there a sharp peak at 300Hz?
+- Why the use of the Slip-Ring does induce a noise?
+- Can the capacitive/inductive properties of the wires in the Slip-ring does not play well with the geophone? (resonant RLC circuit)
+#+end_note
+
+* Effect of the rotation of the Slip-Ring
+  :PROPERTIES:
+  :header-args:matlab+: :tangle matlab/meas_effect_sr.m
+  :header-args:matlab+: :comments org :mkdirp yes
+  :END:
+  <<sec:meas_effect_sr>>
+
+#+begin_src bash :exports none :results none
+  if [ matlab/meas_effect_sr.m -nt data/meas_effect_sr.zip ]; then
+    cp matlab/meas_effect_sr.m meas_effect_sr.m;
+    zip data/meas_effect_sr \
+        mat/data_001.mat \
+        mat/data_002.mat \
+        meas_effect_sr.m;
+    rm meas_effect_sr.m;
+  fi
+#+end_src
+
+#+begin_note
+  All the files (data and Matlab scripts) are accessible [[file:data/meas_effect_sr.zip][here]].
+#+end_note
+
+** Measurement Description
+Random Signal is generated by one DAC of the SpeedGoat.
+
+The signal going out of the DAC is split into two:
+- one BNC cable is directly connected to one ADC of the SpeedGoat
+- one BNC cable goes two times in the Slip-Ring (from bottom to top and then from top to bottom) and then is connected to one ADC of the SpeedGoat
+
+Two measurements are done.
+| Data File          | Description           |
+|--------------------+-----------------------|
+| =mat/data_001.mat= | Slip-ring not turning |
+| =mat/data_002.mat= | Slip-ring turning     |
+
+For each measurement, the measured signals are:
+| Data File | Description                        |
+|-----------+------------------------------------|
+| =t=       | Time vector                        |
+| =x1=      | Direct signal                      |
+| =x2=      | Signal going through the Slip-Ring |
+
+The goal is to determine is the signal is altered when the spindle is rotating.
+
+Here, the rotation speed of the Slip-Ring is set to 1rpm.
+
+** Matlab Init                                              :noexport:ignore:
+#+begin_src matlab :tangle no :exports none :results silent :noweb yes :var current_dir=(file-name-directory buffer-file-name)
+  <<matlab-dir>>
+#+end_src
+
+#+begin_src matlab :exports none :results silent :noweb yes
+  <<matlab-init>>
+#+end_src
+
+** Load data
+We load the data of the z axis of two geophones.
+#+begin_src matlab :results none
+  sr_off = load('mat/data_001.mat', 't', 'x1', 'x2');
+  sr_on  = load('mat/data_002.mat', 't', 'x1', 'x2');
+#+end_src
+
+** Analysis
+Let's first look at the signal produced by the DAC (figure [[fig:random_signal]]).
+
+#+begin_src matlab :results none
+  figure;
+  hold on;
+  plot(sr_on.t,  sr_on.x1);
+  hold off;
+  xlabel('Time [s]'); ylabel('Voltage [V]');
+  xlim([0 10]);
+#+end_src
+
+#+NAME: fig:random_signal
+#+HEADER: :tangle no :exports results :results value raw replace :noweb yes
+#+begin_src matlab :var filepath="figs/random_signal.pdf" :var figsize="wide-normal" :post pdf2svg(file=*this*, ext="png")
+  <<plt-matlab>>
+#+end_src
+
+#+NAME: fig:random_signal
+#+CAPTION: Random signal produced by the DAC
+#+RESULTS: fig:random_signal
+[[file:figs/random_signal.png]]
+
+We now look at the difference between the signal directly measured by the ADC and the signal that goes through the slip-ring (figure [[fig:slipring_comp_signals]]).
+
+#+begin_src matlab :results none
+  figure;
+  hold on;
+  plot(sr_on.t,  sr_on.x1  -  sr_on.x2,  'DisplayName', 'Slip-Ring - $\omega = 1rpm$');
+  plot(sr_off.t, sr_off.x1 - sr_off.x2,'DisplayName', 'Slip-Ring off');
+  hold off;
+  xlabel('Time [s]'); ylabel('Voltage [V]');
+  xlim([0 10]);
+  legend('Location', 'northeast');
+#+end_src
+
+#+NAME: fig:slipring_comp_signals
+#+HEADER: :tangle no :exports results :results value raw replace :noweb yes
+#+begin_src matlab :var filepath="figs/slipring_comp_signals.pdf" :var figsize="wide-normal" :post pdf2svg(file=*this*, ext="png")
+  <<plt-matlab>>
+#+end_src
+
+#+NAME: fig:slipring_comp_signals
+#+CAPTION: Alteration of the signal when the slip-ring is turning
+#+RESULTS: fig:slipring_comp_signals
+[[file:figs/slipring_comp_signals.png]]
+
+#+begin_src matlab :results none
+  dt = sr_on.t(2) - sr_on.t(1);
+  Fs = 1/dt; % [Hz]
+
+  win = hanning(ceil(1*Fs));
+#+end_src
+
+#+begin_src matlab :results none
+  [pxx_on,  f] = pwelch(sr_on.x1  - sr_on.x2,  win, [], [], Fs);
+  [pxx_off, ~] = pwelch(sr_off.x1 - sr_off.x2, win, [], [], Fs);
+#+end_src
+
+#+begin_src matlab :results none :exports none
+  figure;
+  hold on;
+  plot(f, sqrt(pxx_on), 'DisplayName', 'Slip-Ring - $\omega = 1rpm$');
+  plot(f, sqrt(pxx_off),'DisplayName', 'Slip-Ring off');
+  hold off;
+  set(gca, 'xscale', 'log'); set(gca, 'yscale', 'log');
+  xlabel('Frequency [Hz]'); ylabel('PSD $\left[\frac{V}{\sqrt{Hz}}\right]$');
+  legend('Location', 'northeast');
+  xlim([1, 500]); ylim([1e-5, 1e-3])
+#+end_src
+
+#+NAME: fig:psd_noise
+#+HEADER: :tangle no :exports results :results value raw replace :noweb yes
+#+begin_src matlab :var filepath="figs/psd_noise.pdf" :var figsize="wide-tall" :post pdf2svg(file=*this*, ext="png")
+  <<plt-matlab>>
+#+end_src
+
+#+NAME: fig:psd_noise
+#+CAPTION: ASD of the measured noise
+#+RESULTS: fig:psd_noise
+[[file:figs/psd_noise.png]]
+
+** Conclusion
+#+begin_note
+  *Remaining questions*:
+  - Should the measurement be redone using voltage amplifiers?
+  - Use higher rotation speed and measure for longer periods (to have multiple revolutions) ?
+#+end_note
+
+* Measure of the noise induced by the Slip-Ring
+  :PROPERTIES:
+  :header-args:matlab+: :tangle matlab/meas_slip_ring.m
+  :header-args:matlab+: :comments org :mkdirp yes
+  :END:
+  <<sec:meas_slip_ring>>
+
+#+begin_src bash :exports none :results none
+  if [ matlab/meas_slip_ring.m -nt data/meas_slip_ring.zip ]; then
+    cp matlab/meas_slip_ring.m meas_slip_ring.m;
+    zip data/meas_slip_ring \
+        mat/data_008.mat \
+        mat/data_009.mat \
+        mat/data_010.mat \
+        mat/data_011.mat \
+        meas_slip_ring.m;
+    rm meas_slip_ring.m;
+  fi
+#+end_src
+
+#+begin_note
+  All the files (data and Matlab scripts) are accessible [[file:data/meas_slip_ring.zip][here]].
+#+end_note
+
+** Measurement Description
+*Goal*:
+- Determine the noise induced by the slip-ring
+
+*Setup*:
+- 0V is generated by the DAC of the Speedgoat
+- Using a T, one part goes directly to the ADC
+- The other part goes to the slip-ring 2 times and then to the ADC
+- The parameters of the Voltage Amplifier are: 80dB, AC, 1kHz
+- Every stage of the station is OFF
+
+First column: Direct measure
+Second column: Slip-ring measure
+
+
+*Measurements*:
+- =data_008=: Slip-Ring OFF
+- =data_009=: Slip-Ring ON
+- =data_010=: Slip-Ring ON and omega=6rpm
+- =data_011=: Slip-Ring ON and omega=60rpm
+
+#+name: fig:setup_sr_6rpm
+#+caption: Slip-Ring rotating at 6rpm
+[[file:./img/VID_20190503_160831.gif]]
+
+#+name: fig:setup_sr_60rpm
+#+caption: Slip-Ring rotating at 60rpm
+[[file:./img/VID_20190503_161401.gif]]
+
+** Matlab Init                                              :noexport:ignore:
+#+begin_src matlab :tangle no :exports none :results silent :noweb yes :var current_dir=(file-name-directory buffer-file-name)
+  <<matlab-dir>>
+#+end_src
+
+#+begin_src matlab :exports none :results silent :noweb yes
+  <<matlab-init>>
+#+end_src
+
+** Load data
+We load the data of the z axis of two geophones.
+#+begin_src matlab :results none
+  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;
+#+end_src
+
+** 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]]);
+
+#+begin_src matlab :results none :exports none
+  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');
+#+end_src
+
+#+NAME: fig:sr_direct_time
+#+HEADER: :tangle no :exports results :results value raw replace :noweb yes
+#+begin_src matlab :var filepath="figs/sr_direct_time.pdf" :var figsize="wide-normal" :post pdf2svg(file=*this*, ext="png")
+  <<plt-matlab>>
+#+end_src
+
+#+NAME: fig:sr_direct_time
+#+CAPTION: Direct measurement
+#+RESULTS: fig:sr_direct_time
+[[file:figs/sr_direct_time.png]]
+
+
+#+begin_src matlab :results none :exports none
+  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');
+#+end_src
+
+#+NAME: fig:sr_slipring_time
+#+HEADER: :tangle no :exports results :results value raw replace :noweb yes
+#+begin_src matlab :var filepath="figs/sr_slipring_time.pdf" :var figsize="wide-normal" :post pdf2svg(file=*this*, ext="png")
+  <<plt-matlab>>
+#+end_src
+
+#+NAME: fig:sr_slipring_time
+#+CAPTION: Measurement of the signal going through the Slip-Ring
+#+RESULTS: fig:sr_slipring_time
+[[file:figs/sr_slipring_time.png]]
+
+** Frequency Domain
+We first compute some parameters that will be used for the PSD computation.
+#+begin_src matlab :results none
+  dt = sr_off(2, 3)-sr_off(1, 3);
+
+  Fs = 1/dt; % [Hz]
+
+  win = hanning(ceil(10*Fs));
+#+end_src
+
+Then we compute the Power Spectral Density using =pwelch= function.
+#+begin_src matlab :results none
+  [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);
+#+end_src
+
+And we plot the ASD of the measured signals (figure [[fig:sr_psd_compare]]);
+
+#+begin_src matlab :results none
+  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]);
+#+end_src
+
+#+NAME: fig:sr_psd_compare
+#+HEADER: :tangle no :exports results :results value raw replace :noweb yes
+#+begin_src matlab :var filepath="figs/sr_psd_compare.pdf" :var figsize="full-tall" :post pdf2svg(file=*this*, ext="png")
+  <<plt-matlab>>
+#+end_src
+
+#+NAME: fig:sr_psd_compare
+#+CAPTION: Comparison of the ASD of the measured signals when the slip-ring is ON, OFF and turning
+#+RESULTS: fig:sr_psd_compare
+[[file:figs/sr_psd_compare.png]]
+
+** Conclusion
+#+begin_important
+  *Questions:*
+  - Why is there some sharp peaks? Can this be due to aliasing?
+  - It is possible that the amplifiers were saturating during the measurements => should redo the measurements with a low pass filter before the voltage amplifier
+#+end_important
+
+* Measure of the noise induced by the slip ring when using a geophone
+  :PROPERTIES:
+  :header-args:matlab+: :tangle matlab/meas_sr_geophone.m
+  :header-args:matlab+: :comments org :mkdirp yes
+  :END:
+  <<sec:meas_sr_geophone>>
+
+#+begin_src bash :exports none :results none
+  if [ matlab/meas_sr_geophone.m -nt data/meas_sr_geophone.zip ]; then
+    cp matlab/meas_sr_geophone.m meas_sr_geophone.m;
+    zip data/meas_sr_geophone \
+        mat/data_012.mat \
+        mat/data_013.mat \
+        mat/data_016.mat \
+        mat/data_017.mat \
+        meas_sr_geophone.m;
+    rm meas_sr_geophone.m;
+  fi
+#+end_src
+
+#+begin_note
+  All the files (data and Matlab scripts) are accessible [[file:data/meas_sr_geophone.zip][here]].
+#+end_note
+
+** Matlab Init                                              :noexport:ignore:
+#+begin_src matlab :tangle no :exports none :results silent :noweb yes :var current_dir=(file-name-directory buffer-file-name)
+  <<matlab-dir>>
+#+end_src
+
+#+begin_src matlab :exports none :results silent :noweb yes
+  <<matlab-init>>
+#+end_src
+
+** First Measurement without LPF
+*** Measurement Description
+*Goal*:
+- Determine if the noise induced by the slip-ring is a limiting factor when measuring the signal coming from a geophone
+
+*Setup*:
+- The geophone is located at the sample location
+- The two Voltage amplifiers have the same following settings:
+  - AC
+  - 60dB
+  - 1kHz
+- The signal from the geophone is split into two using a T-BNC:
+  - One part goes directly to the voltage amplifier and then to the ADC.
+  - The other part goes to the slip-ring=>voltage amplifier=>ADC.
+
+First column: Direct measure
+Second column: Slip-ring measure
+
+*Measurements*:
+- =data_012=: Slip-Ring OFF
+- =data_013=: Slip-Ring ON
+
+*** Load data
+We load the data of the z axis of two geophones.
+#+begin_src matlab :results none
+  sr_off = load('mat/data_012.mat', 'data'); sr_off = sr_off.data;
+  sr_on  = load('mat/data_013.mat', 'data'); sr_on  = sr_on.data;
+#+end_src
+
+*** Time Domain
+We compare the signal when the Slip-Ring is OFF (figure [[fig:sr_geophone_time_off]]) and when it is ON (figure [[fig:sr_geophone_time_on]]).
+
+#+begin_src matlab :results none :exports none
+  figure;
+  hold on;
+  plot(sr_off(:, 3), sr_off(:, 1), 'DisplayName', 'Direct');
+  plot(sr_off(:, 3), sr_off(:, 2), 'DisplayName', 'Slip-Ring');
+  hold off;
+  legend('Location', 'northeast');
+  xlabel('Time [s]');
+  ylabel('Voltage [V]');
+#+end_src
+
+#+NAME: fig:sr_geophone_time_off
+#+HEADER: :tangle no :exports results :results value raw replace :noweb yes
+#+begin_src matlab :var filepath="figs/sr_geophone_time_off.pdf" :var figsize="wide-normal" :post pdf2svg(file=*this*, ext="png")
+  <<plt-matlab>>
+#+end_src
+
+#+NAME: fig:sr_geophone_time_off
+#+CAPTION: Comparison of the time domain signals when the slip-ring is OFF
+#+RESULTS: fig:sr_geophone_time_off
+[[file:figs/sr_geophone_time_off.png]]
+
+#+begin_src matlab :results none :exports none
+  figure;
+  hold on;
+  plot(sr_on(:, 3),  sr_on(:, 1),  'DisplayName', 'Direct');
+  plot(sr_on(:, 3),  sr_on(:, 2),  'DisplayName', 'Slip-Ring');
+  hold off;
+  legend('Location', 'northeast');
+  xlabel('Time [s]');
+  ylabel('Voltage [V]');
+#+end_src
+
+#+NAME: fig:sr_geophone_time_on
+#+HEADER: :tangle no :exports results :results value raw replace :noweb yes
+#+begin_src matlab :var filepath="figs/sr_geophone_time_on.pdf" :var figsize="wide-normal" :post pdf2svg(file=*this*, ext="png")
+  <<plt-matlab>>
+#+end_src
+
+#+NAME: fig:sr_geophone_time_on
+#+CAPTION: Comparison of the time domain signals when the slip-ring is ON
+#+RESULTS: fig:sr_geophone_time_on
+[[file:figs/sr_geophone_time_on.png]]
+
+*** Frequency Domain
+We first compute some parameters that will be used for the PSD computation.
+#+begin_src matlab :results none
+  dt = sr_off(2, 3)-sr_off(1, 3);
+
+  Fs = 1/dt; % [Hz]
+
+  win = hanning(ceil(10*Fs));
+#+end_src
+
+Then we compute the Power Spectral Density using =pwelch= function.
+#+begin_src matlab :results none
+  % Direct measure
+  [pxdoff, ~] = pwelch(sr_off(:, 1), win, [], [], Fs);
+  [pxdon,  ~] = pwelch(sr_on(:, 1),  win, [], [], Fs);
+
+  % Slip-Ring measure
+  [pxsroff, f] = pwelch(sr_off(:, 2), win, [], [], Fs);
+  [pxsron,  ~] = pwelch(sr_on(:, 2),  win, [], [], Fs);
+#+end_src
+
+Finally, we compare the Amplitude Spectral Density of the signals (figure [[fig:sr_geophone_asd]]);
+
+#+begin_src matlab :results none
+  figure;
+  hold on;
+  plot(f, sqrt(pxdoff), 'DisplayName', 'Direct - OFF');
+  plot(f, sqrt(pxsroff), 'DisplayName', 'Slip-Ring - OFF');
+  plot(f, sqrt(pxdon),  'DisplayName', 'Direct - ON');
+  plot(f, sqrt(pxsron),  'DisplayName', 'Slip-Ring - ON');
+  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]);
+#+end_src
+
+#+NAME: fig:sr_geophone_asd
+#+HEADER: :tangle no :exports results :results value raw replace :noweb yes
+#+begin_src matlab :var filepath="figs/sr_geophone_asd.pdf" :var figsize="full-tall" :post pdf2svg(file=*this*, ext="png")
+  <<plt-matlab>>
+#+end_src
+
+#+NAME: fig:sr_geophone_asd
+#+CAPTION: Comparison of the Amplitude Spectral Sensity
+#+RESULTS: fig:sr_geophone_asd
+[[file:figs/sr_geophone_asd.png]]
+
+#+begin_src matlab :results none :exports none
+  xlim([100, 500]);
+#+end_src
+
+#+NAME: fig:sr_geophone_asd_zoom
+#+HEADER: :tangle no :exports results :results value raw replace :noweb yes
+#+begin_src matlab :var filepath="figs/sr_geophone_asd_zoom.pdf" :var figsize="full-tall" :post pdf2svg(file=*this*, ext="png")
+  <<plt-matlab>>
+#+end_src
+
+#+NAME: fig:sr_geophone_asd_zoom
+#+CAPTION: Comparison of the Amplitude Spectral Sensity - Zoom
+#+RESULTS: fig:sr_geophone_asd_zoom
+[[file:figs/sr_geophone_asd_zoom.png]]
+
+*** Conclusion
+#+begin_important
+  - The fact that the Slip-Ring is turned ON adds some noise to the signal.
+  - The signal going through the Slip-Ring is less noisy than the one going directly to the ADC.
+  - This could be due to less good electromagnetic isolation.
+
+  *Questions*:
+  - Can the sharp peak on figure [[fig:sr_geophone_asd_zoom]] be due to the Aliasing?
+#+end_important
+
+** Measurement using an oscilloscope
+*** Measurement Setup
+Know we are measuring the same signals but using an oscilloscope instead of the Speedgoat ADC.
+
+*** Observations
+Then the Slip-Ring is ON (figure [[fig:oscilloscope_sr_on]]), we observe a signal at 40kHz with a peak-to-peak amplitude of 200mV for the direct measure and 100mV for the signal going through the Slip-Ring.
+
+Then the Slip-Ring is OFF, we don't observe this 40kHz anymore (figure [[fig:oscilloscope_sr_off]]).
+
+#+name: fig:oscilloscope_sr_on
+#+caption: Signals measured by the oscilloscope - Slip-Ring ON - Yellow: Direct measure - Blue: Through Slip-Ring
+#+attr_html: :width 500px
+[[file:./img/IMG_20190506_160420.jpg]]
+
+#+name: fig:oscilloscope_sr_off
+#+caption: Signals measured by the oscilloscope - Slip-Ring OFF - Yellow: Direct measure - Blue: Through Slip-Ring
+#+attr_html: :width 500px
+[[file:./img/IMG_20190506_160438.jpg]]
+
+*** Conclusion
+#+begin_important
+  - By looking at the signals using an oscilloscope, there is a lot of high frequency noise when turning on the Slip-Ring
+  - This can eventually saturate the voltage amplifiers (seen by a led indicating saturation)
+  - The choice is to *add a Low pass filter before the voltage amplifiers* to not saturate them and filter the noise.
+#+end_important
+
+** New measurements with a LPF before the Voltage Amplifiers
+*** Setup description
+A first order low pass filter is added before the Voltage Amplifiers with the following values:
+\begin{aligned}
+  R &= 1k\Omega \\
+  C &= 1\mu F
+\end{aligned}
+
+And we have a cut-off frequency of $f_c = \frac{1}{RC} = 160Hz$.
+
+We are measuring the signal from a geophone put on the marble with and without the added LPF:
+- with the slip ring OFF: =mat/data_016.mat=
+- with the slip ring ON: =mat/data_017.mat=
+
+*** Load data
+We load the data of the z axis of two geophones.
+#+begin_src matlab :results none
+  sr_lpf_off = load('mat/data_016.mat', 'data'); sr_lpf_off = sr_lpf_off.data;
+  sr_lpf_on  = load('mat/data_017.mat', 'data'); sr_lpf_on  = sr_lpf_on.data;
+#+end_src
+
+*** Time Domain
+We compare the signal when the Slip-Ring is OFF (figure [[fig:sr_lpf_geophone_time_off]]) and when it is ON (figure [[fig:sr_lpf_geophone_time_on]]).
+
+#+begin_src matlab :results none :exports none
+  figure;
+  hold on;
+  plot(sr_lpf_off(:, 3), sr_lpf_off(:, 1), 'DisplayName', 'Direct');
+  plot(sr_lpf_off(:, 3), sr_lpf_off(:, 2), 'DisplayName', 'Slip-Ring');
+  hold off;
+  legend('Location', 'northeast');
+  xlabel('Time [s]');
+  ylabel('Voltage [V]');
+#+end_src
+
+#+NAME: fig:sr_lpf_geophone_time_off
+#+HEADER: :tangle no :exports results :results value raw replace :noweb yes
+#+begin_src matlab :var filepath="figs/sr_lpf_geophone_time_off.pdf" :var figsize="wide-normal" :post pdf2svg(file=*this*, ext="png")
+  <<plt-matlab>>
+#+end_src
+
+#+NAME: fig:sr_lpf_geophone_time_off
+#+CAPTION: Comparison of the time domain signals when the slip-ring is OFF
+#+RESULTS: fig:sr_lpf_geophone_time_off
+[[file:figs/sr_lpf_geophone_time_off.png]]
+
+#+begin_src matlab :results none :exports none
+  figure;
+  hold on;
+  plot(sr_lpf_on(:, 3),  sr_lpf_on(:, 1),  'DisplayName', 'Direct');
+  plot(sr_lpf_on(:, 3),  sr_lpf_on(:, 2),  'DisplayName', 'Slip-Ring');
+  hold off;
+  legend('Location', 'northeast');
+  xlabel('Time [s]');
+  ylabel('Voltage [V]');
+#+end_src
+
+#+NAME: fig:sr_lpf_geophone_time_on
+#+HEADER: :tangle no :exports results :results value raw replace :noweb yes
+#+begin_src matlab :var filepath="figs/sr_lpf_geophone_time_on.pdf" :var figsize="wide-normal" :post pdf2svg(file=*this*, ext="png")
+  <<plt-matlab>>
+#+end_src
+
+#+NAME: fig:sr_lpf_geophone_time_on
+#+CAPTION: Comparison of the time domain signals when the slip-ring is ON
+#+RESULTS: fig:sr_lpf_geophone_time_on
+[[file:figs/sr_lpf_geophone_time_on.png]]
+
+*** Frequency Domain
+We first compute some parameters that will be used for the PSD computation.
+#+begin_src matlab :results none
+  dt = sr_lpf_off(2, 3)-sr_lpf_off(1, 3);
+
+  Fs = 1/dt; % [Hz]
+
+  win = hanning(ceil(10*Fs));
+#+end_src
+
+Then we compute the Power Spectral Density using =pwelch= function.
+#+begin_src matlab :results none
+  % Direct measure
+  [pxd_lpf_off, ~] = pwelch(sr_lpf_off(:, 1), win, [], [], Fs);
+  [pxd_lpf_on,  ~] = pwelch(sr_lpf_on(:, 1),  win, [], [], Fs);
+
+  % Slip-Ring measure
+  [pxsr_lpf_off, f] = pwelch(sr_lpf_off(:, 2), win, [], [], Fs);
+  [pxsr_lpf_on,  ~] = pwelch(sr_lpf_on(:, 2),  win, [], [], Fs);
+#+end_src
+
+Finally, we compare the Amplitude Spectral Density of the signals (figure [[fig:sr_lpf_geophone_asd]]);
+
+#+begin_src matlab :results none
+  figure;
+  hold on;
+  plot(f, sqrt(pxd_lpf_off), 'DisplayName', 'Direct - OFF');
+  plot(f, sqrt(pxsr_lpf_off), 'DisplayName', 'Slip-Ring - OFF');
+  plot(f, sqrt(pxd_lpf_on),  'DisplayName', 'Direct - ON');
+  plot(f, sqrt(pxsr_lpf_on),  'DisplayName', 'Slip-Ring - ON');
+  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]);
+#+end_src
+
+#+NAME: fig:sr_lpf_geophone_asd
+#+HEADER: :tangle no :exports results :results value raw replace :noweb yes
+#+begin_src matlab :var filepath="figs/sr_lpf_geophone_asd.pdf" :var figsize="full-tall" :post pdf2svg(file=*this*, ext="png")
+  <<plt-matlab>>
+#+end_src
+
+#+NAME: fig:sr_lpf_geophone_asd
+#+CAPTION: Comparison of the Amplitude Spectral Sensity
+#+RESULTS: fig:sr_lpf_geophone_asd
+[[file:figs/sr_lpf_geophone_asd.png]]
+
+#+begin_src matlab :results none :exports none
+  xlim([100, 500]);
+#+end_src
+
+#+NAME: fig:sr_lpf_geophone_asd_zoom
+#+HEADER: :tangle no :exports results :results value raw replace :noweb yes
+#+begin_src matlab :var filepath="figs/sr_lpf_geophone_asd_zoom.pdf" :var figsize="full-tall" :post pdf2svg(file=*this*, ext="png")
+  <<plt-matlab>>
+#+end_src
+
+#+NAME: fig:sr_lpf_geophone_asd_zoom
+#+CAPTION: Comparison of the Amplitude Spectral Sensity - Zoom
+#+RESULTS: fig:sr_lpf_geophone_asd_zoom
+[[file:figs/sr_lpf_geophone_asd_zoom.png]]
+
+*** Comparison of with and without LPF
+#+begin_src matlab :results none
+  figure;
+  hold on;
+  plot(f, sqrt(pxdon),  'DisplayName', 'Direct - ON');
+  plot(f, sqrt(pxsron),  'DisplayName', 'Slip-Ring - ON');
+  plot(f, sqrt(pxd_lpf_on),  'DisplayName', 'Direct - ON - LPF');
+  plot(f, sqrt(pxsr_lpf_on),  'DisplayName', 'Slip-Ring - ON - LPF');
+  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]);
+#+end_src
+
+#+NAME: fig:comp_with_without_lpf
+#+HEADER: :tangle no :exports results :results value raw replace :noweb yes
+#+begin_src matlab :var filepath="figs/comp_with_without_lpf.pdf" :var figsize="full-tall" :post pdf2svg(file=*this*, ext="png")
+  <<plt-matlab>>
+#+end_src
+
+#+NAME: fig:comp_with_without_lpf
+#+CAPTION: Comparison of the measured signals with and without LPF
+#+RESULTS: fig:comp_with_without_lpf
+[[file:figs/comp_with_without_lpf.png]]
+
+*** Conclusion
+#+begin_important
+  - Using the LPF, we don't have any perturbation coming from the slip-ring when it is on.
+  - However, we should use a smaller value of the capacitor to have a cut-off frequency at $1kHz$.
+#+end_important

slip-ring-electrical-noise/matlab/meas_effect_sr.m

@@ -0,0 +1,70 @@
+% 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_001.mat', 't', 'x1', 'x2');
+sr_on  = load('mat/data_002.mat', 't', 'x1', 'x2');
+
+% Analysis
+% Let's first look at the signal produced by the DAC (figure [[fig:random_signal]]).
+
+
+figure;
+hold on;
+plot(sr_on.t,  sr_on.x1);
+hold off;
+xlabel('Time [s]'); ylabel('Voltage [V]');
+xlim([0 10]);
+
+
+
+% #+NAME: fig:random_signal
+% #+CAPTION: Random signal produced by the DAC
+% #+RESULTS: fig:random_signal
+% [[file:figs/random_signal.png]]
+
+% We now look at the difference between the signal directly measured by the ADC and the signal that goes through the slip-ring (figure [[fig:slipring_comp_signals]]).
+
+
+figure;
+hold on;
+plot(sr_on.t,  sr_on.x1  -  sr_on.x2,  'DisplayName', 'Slip-Ring - $\omega = 1rpm$');
+plot(sr_off.t, sr_off.x1 - sr_off.x2,'DisplayName', 'Slip-Ring off');
+hold off;
+xlabel('Time [s]'); ylabel('Voltage [V]');
+xlim([0 10]);
+legend('Location', 'northeast');
+
+
+
+% #+NAME: fig:slipring_comp_signals
+% #+CAPTION: Alteration of the signal when the slip-ring is turning
+% #+RESULTS: fig:slipring_comp_signals
+% [[file:figs/slipring_comp_signals.png]]
+
+
+dt = sr_on.t(2) - sr_on.t(1);
+Fs = 1/dt; % [Hz]
+
+win = hanning(ceil(1*Fs));
+
+[pxx_on,  f] = pwelch(sr_on.x1  - sr_on.x2,  win, [], [], Fs);
+[pxx_off, ~] = pwelch(sr_off.x1 - sr_off.x2, win, [], [], Fs);
+
+figure;
+hold on;
+plot(f, sqrt(pxx_on), 'DisplayName', 'Slip-Ring - $\omega = 1rpm$');
+plot(f, sqrt(pxx_off),'DisplayName', 'Slip-Ring off');
+hold off;
+set(gca, 'xscale', 'log'); set(gca, 'yscale', 'log');
+xlabel('Frequency [Hz]'); ylabel('PSD $\left[\frac{V}{\sqrt{Hz}}\right]$');
+legend('Location', 'northeast');
+xlim([1, 500]); ylim([1e-5, 1e-3])

slip-ring-electrical-noise/matlab/meas_slip_ring.m

@@ -0,0 +1,87 @@
+% 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]);

slip-ring-electrical-noise/matlab/meas_slip_ring_geophone.m

@@ -0,0 +1,57 @@
+% Matlab Init                                              :noexport:ignore:
+
+current_dir='/home/thomas/MEGA/These/meas/slip-ring-test/';
+%% Go to current Directory
+cd(current_dir);
+
+%% Initialize ans with org-babel
+ans = 0;
+
+%% 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.
+
+
+d8 = load('mat/data_018.mat', 'data'); d8 = d8.data;
+d9 = load('mat/data_019.mat', 'data'); d9 = d9.data;
+
+% Analysis - Time Domain
+% First, we compare the time domain signals for the two experiments (figure [[fig:slipring_time]]).
+
+
+
+figure;
+hold on;
+plot(d9(:, 3), d9(:, 2), 'DisplayName', 'Slip-Ring');
+plot(d8(:, 3), d8(:, 2), 'DisplayName', 'Wire');
+hold off;
+xlabel('Time [s]'); ylabel('Voltage [V]');
+xlim([0, 50]);
+legend('location', 'northeast');
+
+% Analysis - Frequency Domain
+% We then compute the Power Spectral Density of the two signals and we compare them (figure [[fig:slipring_asd]]).
+
+dt = d8(2, 3) - d8(1, 3);
+Fs = 1/dt;
+
+win = hanning(ceil(1*Fs));
+
+[pxx8, f] = pwelch(d8(:, 2), win, [], [], Fs);
+[pxx9, ~] = pwelch(d9(:, 2), win, [], [], Fs);
+
+figure;
+hold on;
+plot(f, sqrt(pxx9), 'DisplayName', 'Slip-Ring');
+plot(f, sqrt(pxx8), 'DisplayName', 'Wire');
+hold off;
+set(gca, 'xscale', 'log');
+set(gca, 'yscale', 'log');
+xlabel('Frequency [Hz]'); ylabel('Amplitude Spectral Density $\left[\frac{V}{\sqrt{Hz}}\right]$')
+xlim([1, 500]);
+legend('Location', 'southwest');

slip-ring-electrical-noise/matlab/meas_sr_geophone.m

@@ -0,0 +1,193 @@
+% 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_012.mat', 'data'); sr_off = sr_off.data;
+sr_on  = load('mat/data_013.mat', 'data'); sr_on  = sr_on.data;
+
+% Time Domain
+% We compare the signal when the Slip-Ring is OFF (figure [[fig:sr_geophone_time_off]]) and when it is ON (figure [[fig:sr_geophone_time_on]]).
+
+
+figure;
+hold on;
+plot(sr_off(:, 3), sr_off(:, 1), 'DisplayName', 'Direct');
+plot(sr_off(:, 3), sr_off(:, 2), 'DisplayName', 'Slip-Ring');
+hold off;
+legend('Location', 'northeast');
+xlabel('Time [s]');
+ylabel('Voltage [V]');
+
+
+
+% #+NAME: fig:sr_geophone_time_off
+% #+CAPTION: Comparison of the time domain signals when the slip-ring is OFF
+% #+RESULTS: fig:sr_geophone_time_off
+% [[file:figs/sr_geophone_time_off.png]]
+
+
+figure;
+hold on;
+plot(sr_on(:, 3),  sr_on(:, 1),  'DisplayName', 'Direct');
+plot(sr_on(:, 3),  sr_on(:, 2),  'DisplayName', 'Slip-Ring');
+hold off;
+legend('Location', 'northeast');
+xlabel('Time [s]');
+ylabel('Voltage [V]');
+
+% 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.
+
+% Direct measure
+[pxdoff, ~] = pwelch(sr_off(:, 1), win, [], [], Fs);
+[pxdon,  ~] = pwelch(sr_on(:, 1),  win, [], [], Fs);
+
+% Slip-Ring measure
+[pxsroff, f] = pwelch(sr_off(:, 2), win, [], [], Fs);
+[pxsron,  ~] = pwelch(sr_on(:, 2),  win, [], [], Fs);
+
+
+
+% Finally, we compare the Amplitude Spectral Density of the signals (figure [[fig:sr_geophone_asd]]);
+
+
+figure;
+hold on;
+plot(f, sqrt(pxdoff), 'DisplayName', 'Direct - OFF');
+plot(f, sqrt(pxsroff), 'DisplayName', 'Slip-Ring - OFF');
+plot(f, sqrt(pxdon),  'DisplayName', 'Direct - ON');
+plot(f, sqrt(pxsron),  'DisplayName', 'Slip-Ring - ON');
+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]);
+
+
+
+% #+NAME: fig:sr_geophone_asd
+% #+CAPTION: Comparison of the Amplitude Spectral Sensity
+% #+RESULTS: fig:sr_geophone_asd
+% [[file:figs/sr_geophone_asd.png]]
+
+
+xlim([100, 500]);
+
+% Load data
+% We load the data of the z axis of two geophones.
+
+sr_lpf_off = load('mat/data_016.mat', 'data'); sr_lpf_off = sr_lpf_off.data;
+sr_lpf_on  = load('mat/data_017.mat', 'data'); sr_lpf_on  = sr_lpf_on.data;
+
+% Time Domain
+% We compare the signal when the Slip-Ring is OFF (figure [[fig:sr_lpf_geophone_time_off]]) and when it is ON (figure [[fig:sr_lpf_geophone_time_on]]).
+
+
+figure;
+hold on;
+plot(sr_lpf_off(:, 3), sr_lpf_off(:, 1), 'DisplayName', 'Direct');
+plot(sr_lpf_off(:, 3), sr_lpf_off(:, 2), 'DisplayName', 'Slip-Ring');
+hold off;
+legend('Location', 'northeast');
+xlabel('Time [s]');
+ylabel('Voltage [V]');
+
+
+
+% #+NAME: fig:sr_lpf_geophone_time_off
+% #+CAPTION: Comparison of the time domain signals when the slip-ring is OFF
+% #+RESULTS: fig:sr_lpf_geophone_time_off
+% [[file:figs/sr_lpf_geophone_time_off.png]]
+
+
+figure;
+hold on;
+plot(sr_lpf_on(:, 3),  sr_lpf_on(:, 1),  'DisplayName', 'Direct');
+plot(sr_lpf_on(:, 3),  sr_lpf_on(:, 2),  'DisplayName', 'Slip-Ring');
+hold off;
+legend('Location', 'northeast');
+xlabel('Time [s]');
+ylabel('Voltage [V]');
+
+% Frequency Domain
+% We first compute some parameters that will be used for the PSD computation.
+
+dt = sr_lpf_off(2, 3)-sr_lpf_off(1, 3);
+
+Fs = 1/dt; % [Hz]
+
+win = hanning(ceil(10*Fs));
+
+
+
+% Then we compute the Power Spectral Density using =pwelch= function.
+
+% Direct measure
+[pxd_lpf_off, ~] = pwelch(sr_lpf_off(:, 1), win, [], [], Fs);
+[pxd_lpf_on,  ~] = pwelch(sr_lpf_on(:, 1),  win, [], [], Fs);
+
+% Slip-Ring measure
+[pxsr_lpf_off, f] = pwelch(sr_lpf_off(:, 2), win, [], [], Fs);
+[pxsr_lpf_on,  ~] = pwelch(sr_lpf_on(:, 2),  win, [], [], Fs);
+
+
+
+% Finally, we compare the Amplitude Spectral Density of the signals (figure [[fig:sr_lpf_geophone_asd]]);
+
+
+figure;
+hold on;
+plot(f, sqrt(pxd_lpf_off), 'DisplayName', 'Direct - OFF');
+plot(f, sqrt(pxsr_lpf_off), 'DisplayName', 'Slip-Ring - OFF');
+plot(f, sqrt(pxd_lpf_on),  'DisplayName', 'Direct - ON');
+plot(f, sqrt(pxsr_lpf_on),  'DisplayName', 'Slip-Ring - ON');
+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]);
+
+
+
+% #+NAME: fig:sr_lpf_geophone_asd
+% #+CAPTION: Comparison of the Amplitude Spectral Sensity
+% #+RESULTS: fig:sr_lpf_geophone_asd
+% [[file:figs/sr_lpf_geophone_asd.png]]
+
+
+xlim([100, 500]);
+
+% Comparison of with and without LPF
+
+figure;
+hold on;
+plot(f, sqrt(pxdon),  'DisplayName', 'Direct - ON');
+plot(f, sqrt(pxsron),  'DisplayName', 'Slip-Ring - ON');
+plot(f, sqrt(pxd_lpf_on),  'DisplayName', 'Direct - ON - LPF');
+plot(f, sqrt(pxsr_lpf_on),  'DisplayName', 'Slip-Ring - ON - LPF');
+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]);

slip-ring-electrical-noise/readme.org

@@ -0,0 +1,90 @@
+* DONE Measure of the noise of the Voltage Amplifier
+  CLOSED: [2019-05-06 lun. 09:00]
+- The two inputs (differential) of the voltage amplifier are shunted with 50Ohms
+- The AC/DC option of the Voltage amplifier is on AC
+- The low pass filter is set to 1hHz
+
+Measure: Second Column
+
+meas3: Ampli OFF
+meas4: Ampli ON 20dB
+meas5: Ampli ON 40dB
+meas6: Ampli ON 60dB
+meas7: Ampli ON 80dB
+
+* DONE Measure of the noise induced by the Slip-Ring
+  CLOSED: [2019-05-06 lun. 09:28]
+Setup:
+- 0V is generated by the DAC of the Speedgoat
+- Using a T, one part goes to ADC
+- the other part goes to the slip-ring 2 times and then to the ADC
+- Gain of the Voltage Amplifier: 80dB, AC, 1kHz
+- Everything is OFF
+
+We had some diffuculties to not have a lot of noise on the measurement.
+
+First column: Direct measure
+Second column: Slip-ring measure
+
+Measurements:
+- meas8: Slip-Ring OFF
+- meas9: Slip-Ring ON
+- meas10: Slip-Ring ON and omega=6rpm
+- meas11: Slip-Ring ON and omega=60rpm
+
+* DONE Measure of the noise induced by the slip ring when using a geophone
+  CLOSED: [2019-05-06 lun. 09:28]
+The geophone is located at the sample location
+The two Voltage amplifiers have the following settings:
+- AC
+- 60dB
+- 1kHz
+
+The signal from the geophone is split into two using a T-BNC.
+On part goes directly to the voltage amplifier and then to the ADC.
+The other part goes to the slip-ring=>voltage amplifier=>ADC.
+
+The other two cables that go through the slip ring have 50Ohms resistors at one end, the other end is open circuit.
+
+
+First column: Direct measure
+Second column: Slip-ring measure
+
+- meas12: Slip-Ring OFF
+- meas13: Slip-Ring ON
+
+Redone the measurements with 1kHz additional low pass filter:
+- meas16: Slip-Ring OFF
+- meas17: Slip-Ring ON
+
+* DONE Measure of the influence of the AC/DC option on the voltage amplifiers
+  CLOSED: [2019-05-06 lun. 09:28]
+One geophone is located on the marble.
+It's signal goes to two voltage amplifiers with a gain of 60dB.
+On voltage amplifier is on the AC option, the other on the DC option.
+
+First column: AC
+Second column: DC
+
+- meas14: col-1 = amp1+AC. col-2 = amp2+DC.
+- meas15: col-1 = amp1+DC. col-2 = amp2+AC.
+
+* Measurement of the LPF
+
+We are measuring the signal from from Geophone with a BNC T
+On part goes to column 1 through the LPF
+The other part goes to column 2 without the LPF
+- meas18
+
+New measurement with C = 150nF => fc = 1kHz
+Voltage Ampli: 60dB, DC, 1kHz
+- meas19
+
+* Measure of the noise induced by the Slip-Ring - BIS
+Same as before but with a LPF
+
+Measurements:
+- meas20: Slip-Ring OFF
+- meas21: Slip-Ring ON
+- meas22: Slip-Ring ON and omega=6rpm
+- meas23: Slip-Ring ON and omega=60rpm