Add analysis of LPF, and slip-ring noise
@ -76,6 +76,11 @@ Then, the =f= object can be used to access the filesystem on the target computer
|
|||||||
| rmdir | | |
|
| rmdir | | |
|
||||||
| close | | |
|
| close | | |
|
||||||
|
|
||||||
|
|
||||||
* ELMO
|
* ELMO
|
||||||
tutorials: https://www.elmomc.com/products/application-studio/easii/easii-tutorials/
|
tutorials: https://www.elmomc.com/products/application-studio/easii/easii-tutorials/
|
||||||
|
* Low Pass Filter
|
||||||
|
|
||||||
|
R = 1KOhm
|
||||||
|
C = 1muF
|
||||||
|
|
||||||
|
Fc = 1kHz
|
||||||
|
BIN
slip-ring-test/figs/Glpf_bode.png
Normal file
After Width: | Height: | Size: 64 KiB |
Before Width: | Height: | Size: 47 KiB After Width: | Height: | Size: 55 KiB |
BIN
slip-ring-test/figs/comp_with_without_lpf.png
Normal file
After Width: | Height: | Size: 168 KiB |
BIN
slip-ring-test/figs/lpf.png
Normal file
After Width: | Height: | Size: 4.1 KiB |
Before Width: | Height: | Size: 160 KiB After Width: | Height: | Size: 166 KiB |
Before Width: | Height: | Size: 218 KiB After Width: | Height: | Size: 217 KiB |
Before Width: | Height: | Size: 35 KiB After Width: | Height: | Size: 36 KiB |
Before Width: | Height: | Size: 43 KiB After Width: | Height: | Size: 44 KiB |
BIN
slip-ring-test/figs/sr_lpf_geophone_asd.png
Normal file
After Width: | Height: | Size: 149 KiB |
BIN
slip-ring-test/figs/sr_lpf_geophone_asd_zoom.png
Normal file
After Width: | Height: | Size: 158 KiB |
BIN
slip-ring-test/figs/sr_lpf_geophone_time_off.png
Normal file
After Width: | Height: | Size: 44 KiB |
BIN
slip-ring-test/figs/sr_lpf_geophone_time_on.png
Normal file
After Width: | Height: | Size: 45 KiB |
BIN
slip-ring-test/img/IMG_20190506_160420.jpg
Normal file
After Width: | Height: | Size: 4.2 MiB |
BIN
slip-ring-test/img/IMG_20190506_160438.jpg
Normal file
After Width: | Height: | Size: 3.9 MiB |
@ -25,10 +25,12 @@
|
|||||||
:END:
|
:END:
|
||||||
|
|
||||||
#+begin_src bash :exports none :results none
|
#+begin_src bash :exports none :results none
|
||||||
|
if [ meas_effect_sr.m -nt data/meas_effect_sr.zip ]; then
|
||||||
zip data/meas_effect_sr \
|
zip data/meas_effect_sr \
|
||||||
mat/data_001.mat \
|
mat/data_001.mat \
|
||||||
mat/data_002.mat \
|
mat/data_002.mat \
|
||||||
meas_effect_sr.m
|
meas_effect_sr.m
|
||||||
|
fi
|
||||||
#+end_src
|
#+end_src
|
||||||
|
|
||||||
The data and matlab files are accessible [[file:data/meas_effect_sr.zip][here]].
|
The data and matlab files are accessible [[file:data/meas_effect_sr.zip][here]].
|
||||||
@ -460,18 +462,21 @@ And we plot the ASD of the measured signals (figure [[fig:sr_psd_compare]]);
|
|||||||
zip data/meas_sr_geophone \
|
zip data/meas_sr_geophone \
|
||||||
mat/data_012.mat \
|
mat/data_012.mat \
|
||||||
mat/data_013.mat \
|
mat/data_013.mat \
|
||||||
|
mat/data_016.mat \
|
||||||
|
mat/data_017.mat \
|
||||||
meas_sr_geophone.m
|
meas_sr_geophone.m
|
||||||
#+end_src
|
#+end_src
|
||||||
|
|
||||||
The data and matlab files are accessible [[file:data/meas_sr_geophone.zip][here]].
|
The data and matlab files are accessible [[file:data/meas_sr_geophone.zip][here]].
|
||||||
|
|
||||||
** Measurement Description
|
** First Measurement without LPF
|
||||||
|
*** Measurement Description
|
||||||
*Goal*:
|
*Goal*:
|
||||||
- Determine if the noise induced by the slip-ring is a limiting factor when measuring the signal coming from a geophone
|
- Determine if the noise induced by the slip-ring is a limiting factor when measuring the signal coming from a geophone
|
||||||
|
|
||||||
*Setup*:
|
*Setup*:
|
||||||
- The geophone is located at the sample location
|
- The geophone is located at the sample location
|
||||||
- The two Voltage amplifiers have the following settings:
|
- The two Voltage amplifiers have the same following settings:
|
||||||
- AC
|
- AC
|
||||||
- 60dB
|
- 60dB
|
||||||
- 1kHz
|
- 1kHz
|
||||||
@ -486,19 +491,19 @@ Second column: Slip-ring measure
|
|||||||
- =data_012=: Slip-Ring OFF
|
- =data_012=: Slip-Ring OFF
|
||||||
- =data_013=: Slip-Ring ON
|
- =data_013=: Slip-Ring ON
|
||||||
|
|
||||||
** Matlab Init :noexport:ignore:
|
*** Matlab Init :noexport:ignore:
|
||||||
#+begin_src matlab :exports none :results silent :noweb yes
|
#+begin_src matlab :exports none :results silent :noweb yes
|
||||||
<<matlab-init>>
|
<<matlab-init>>
|
||||||
#+end_src
|
#+end_src
|
||||||
|
|
||||||
** Load data
|
*** Load data
|
||||||
We load the data of the z axis of two geophones.
|
We load the data of the z axis of two geophones.
|
||||||
#+begin_src matlab :results none
|
#+begin_src matlab :results none
|
||||||
sr_off = load('mat/data_012.mat', 'data'); sr_off = sr_off.data;
|
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;
|
sr_on = load('mat/data_013.mat', 'data'); sr_on = sr_on.data;
|
||||||
#+end_src
|
#+end_src
|
||||||
|
|
||||||
** Time Domain
|
*** 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]]).
|
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
|
#+begin_src matlab :results none :exports none
|
||||||
@ -545,7 +550,7 @@ We compare the signal when the Slip-Ring is OFF (figure [[fig:sr_geophone_time_o
|
|||||||
#+RESULTS: fig:sr_geophone_time_on
|
#+RESULTS: fig:sr_geophone_time_on
|
||||||
[[file:figs/sr_geophone_time_on.png]]
|
[[file:figs/sr_geophone_time_on.png]]
|
||||||
|
|
||||||
** Frequency Domain
|
*** Frequency Domain
|
||||||
We first compute some parameters that will be used for the PSD computation.
|
We first compute some parameters that will be used for the PSD computation.
|
||||||
#+begin_src matlab :results none
|
#+begin_src matlab :results none
|
||||||
dt = sr_off(2, 3)-sr_off(1, 3);
|
dt = sr_off(2, 3)-sr_off(1, 3);
|
||||||
@ -566,7 +571,7 @@ Then we compute the Power Spectral Density using =pwelch= function.
|
|||||||
[pxsron, ~] = pwelch(sr_on(:, 2), win, [], [], Fs);
|
[pxsron, ~] = pwelch(sr_on(:, 2), win, [], [], Fs);
|
||||||
#+end_src
|
#+end_src
|
||||||
|
|
||||||
Finally, we compare the Amplitude Spectral Density of the signals (figure [[]]);
|
Finally, we compare the Amplitude Spectral Density of the signals (figure [[fig:sr_geophone_asd]]);
|
||||||
|
|
||||||
#+begin_src matlab :results none
|
#+begin_src matlab :results none
|
||||||
figure;
|
figure;
|
||||||
@ -609,10 +614,205 @@ Finally, we compare the Amplitude Spectral Density of the signals (figure [[]]);
|
|||||||
#+RESULTS: fig:sr_geophone_asd_zoom
|
#+RESULTS: fig:sr_geophone_asd_zoom
|
||||||
[[file:figs/sr_geophone_asd_zoom.png]]
|
[[file:figs/sr_geophone_asd_zoom.png]]
|
||||||
|
|
||||||
** Conclusion
|
*** Conclusion
|
||||||
#+begin_important
|
#+begin_important
|
||||||
- When the slip-ring is OFF, it does not add any noise to the measurement
|
- The fact that the Slip-Ring is turned ON adds some noise to the signal.
|
||||||
- When the slip-ring is ON, it adds significant 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 will use a smaller value of the capacitor to have a cut-off frequency at $1kHz$.
|
||||||
#+end_important
|
#+end_important
|
||||||
|
|
||||||
* Measure of the influence of the AC/DC option on the voltage amplifiers
|
* Measure of the influence of the AC/DC option on the voltage amplifiers
|
||||||
@ -681,7 +881,7 @@ The signals are shown on figure [[fig:ac_dc_option_time]].
|
|||||||
plot(meas15(:, 3), meas15(:, 1), 'DisplayName', 'Amp1 - DC');
|
plot(meas15(:, 3), meas15(:, 1), 'DisplayName', 'Amp1 - DC');
|
||||||
plot(meas15(:, 3), meas15(:, 2), 'DisplayName', 'Amp2 - AC');
|
plot(meas15(:, 3), meas15(:, 2), 'DisplayName', 'Amp2 - AC');
|
||||||
hold off;
|
hold off;
|
||||||
legend('Location', 'northeast');
|
legend('Location', 'bestoutside');
|
||||||
xlabel('Time [s]');
|
xlabel('Time [s]');
|
||||||
ylabel('Voltage [V]');
|
ylabel('Voltage [V]');
|
||||||
xlim([0, 100]);
|
xlim([0, 100]);
|
||||||
@ -689,7 +889,7 @@ The signals are shown on figure [[fig:ac_dc_option_time]].
|
|||||||
|
|
||||||
#+NAME: fig:ac_dc_option_time
|
#+NAME: fig:ac_dc_option_time
|
||||||
#+HEADER: :tangle no :exports results :results value raw replace :noweb yes
|
#+HEADER: :tangle no :exports results :results value raw replace :noweb yes
|
||||||
#+begin_src matlab :var filepath="figs/ac_dc_option_time.pdf" :var figsize="wide-normal" :post pdf2svg(file=*this*, ext="png")
|
#+begin_src matlab :var filepath="figs/ac_dc_option_time.pdf" :var figsize="full-normal" :post pdf2svg(file=*this*, ext="png")
|
||||||
<<plt-matlab>>
|
<<plt-matlab>>
|
||||||
#+end_src
|
#+end_src
|
||||||
|
|
||||||
@ -746,5 +946,138 @@ The ASD of the signals are compare on figure [[fig:ac_dc_option_asd]].
|
|||||||
|
|
||||||
** Conclusion
|
** Conclusion
|
||||||
#+begin_important
|
#+begin_important
|
||||||
|
- The voltage amplifiers include some very sharp high pass filters at 1.5Hz (maybe 4th order)
|
||||||
|
- There is a DC offset on the time domain signal because the DC-offset knob was not set to zero
|
||||||
|
|
||||||
|
*Questions*:
|
||||||
|
- What option should be used for the measurements?
|
||||||
#+end_important
|
#+end_important
|
||||||
|
|
||||||
|
* Measure of the Low Pass Filter
|
||||||
|
** Measurement Description
|
||||||
|
*Goal*:
|
||||||
|
- Measure the Low Pass Filter Transfer Function
|
||||||
|
|
||||||
|
The values of the components are:
|
||||||
|
\begin{aligned}
|
||||||
|
R &= 1k\Omega \\
|
||||||
|
C &= 1\mu F
|
||||||
|
\end{aligned}
|
||||||
|
Which makes a cut-off frequency of $f_c = \frac{1}{RC} = 1000 rad/s = 160Hz$.
|
||||||
|
|
||||||
|
#+NAME: fig:lpf
|
||||||
|
#+HEADER: :headers '("\\usepackage{tikz}" "\\usepackage{import}" "\\import{$HOME/MEGA/These/LaTeX/}{config.tex}")
|
||||||
|
#+HEADER: :imagemagick t :fit yes :iminoptions -scale 100% -density 150 :imoutoptions -quality 100
|
||||||
|
#+HEADER: :results raw replace :buffer no :eval no-export :exports both :mkdirp yes
|
||||||
|
#+HEADER: :output-dir figs
|
||||||
|
#+begin_src latex :file lpf.pdf :post pdf2svg(file=*this*, ext="png") :exports both
|
||||||
|
\begin{tikzpicture}
|
||||||
|
\draw (0,2) node[circ]
|
||||||
|
to [R=\(R\)] ++(2,0)
|
||||||
|
to ++(2,0) node[circ]
|
||||||
|
++(-2,0) node[circ]
|
||||||
|
to [C=\(C\)] ++(0,-2)
|
||||||
|
++(-2,0) node[circ]
|
||||||
|
to ++(2,0) node[circ]
|
||||||
|
to ++(2,0) node[circ];
|
||||||
|
\end{tikzpicture}
|
||||||
|
#+end_src
|
||||||
|
|
||||||
|
#+NAME: fig:lpf
|
||||||
|
#+CAPTION: Schematic of the Low Pass Filter used
|
||||||
|
#+RESULTS: fig:lpf
|
||||||
|
[[file:figs/lpf.png]]
|
||||||
|
|
||||||
|
|
||||||
|
*Setup*:
|
||||||
|
- 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
|
||||||
|
|
||||||
|
*Measurements*:
|
||||||
|
=mat/data_018.mat=:
|
||||||
|
| Column | Signal |
|
||||||
|
|--------+----------------------|
|
||||||
|
| 1 | Amplifier 1 with LPF |
|
||||||
|
| 2 | Amplifier 2 |
|
||||||
|
| 3 | Time |
|
||||||
|
|
||||||
|
** Matlab Init :noexport:ignore:
|
||||||
|
#+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
|
||||||
|
data = load('mat/data_018.mat', 'data'); data = data.data;
|
||||||
|
#+end_src
|
||||||
|
|
||||||
|
** Transfer function of the LPF
|
||||||
|
We compute the transfer function from the signal without the LPF to the signal measured with the LPF.
|
||||||
|
#+begin_src matlab :results none
|
||||||
|
dt = data(2, 3)-data(1, 3);
|
||||||
|
|
||||||
|
Fs = 1/dt; % [Hz]
|
||||||
|
|
||||||
|
win = hanning(ceil(10*Fs));
|
||||||
|
#+end_src
|
||||||
|
|
||||||
|
#+begin_src matlab :results none
|
||||||
|
[Glpf, f] = tfestimate(data(:, 2), data(:, 1), win, [], [], Fs);
|
||||||
|
#+end_src
|
||||||
|
|
||||||
|
We compare this transfer function with a transfer function corresponding to an ideal first order LPF with a cut-off frequency of $1000rad/s$.
|
||||||
|
We obtain the result on figure [[fig:Glpf_bode]].
|
||||||
|
#+begin_src matlab :results none
|
||||||
|
Gth = 1/(1+s/1000)
|
||||||
|
#+end_src
|
||||||
|
|
||||||
|
#+begin_src matlab :results none
|
||||||
|
figure;
|
||||||
|
ax1 = subplot(2, 1, 1);
|
||||||
|
hold on;
|
||||||
|
plot(f, abs(Glpf));
|
||||||
|
plot(f, abs(squeeze(freqresp(Gth, f, 'Hz'))));
|
||||||
|
hold off;
|
||||||
|
set(gca, 'xscale', 'log'); set(gca, 'yscale', 'log');
|
||||||
|
set(gca, 'XTickLabel',[]);
|
||||||
|
ylabel('Magnitude');
|
||||||
|
|
||||||
|
ax2 = subplot(2, 1, 2);
|
||||||
|
hold on;
|
||||||
|
plot(f, mod(180+180/pi*phase(Glpf), 360)-180);
|
||||||
|
plot(f, 180/pi*unwrap(angle(squeeze(freqresp(Gth, f, 'Hz')))));
|
||||||
|
hold off;
|
||||||
|
set(gca, 'xscale', 'log');
|
||||||
|
ylim([-180, 180]);
|
||||||
|
yticks([-180, -90, 0, 90, 180]);
|
||||||
|
xlabel('Frequency [Hz]'); ylabel('Phase');
|
||||||
|
|
||||||
|
linkaxes([ax1,ax2],'x');
|
||||||
|
xlim([1, 500]);
|
||||||
|
#+end_src
|
||||||
|
|
||||||
|
#+NAME: fig:Glpf_bode
|
||||||
|
#+HEADER: :tangle no :exports results :results value raw replace :noweb yes
|
||||||
|
#+begin_src matlab :var filepath="figs/Glpf_bode.pdf" :var figsize="full-tall" :post pdf2svg(file=*this*, ext="png")
|
||||||
|
<<plt-matlab>>
|
||||||
|
#+end_src
|
||||||
|
|
||||||
|
#+NAME: fig:Glpf_bode
|
||||||
|
#+CAPTION: Bode Diagram of the measured Low Pass filter and the theoritical one
|
||||||
|
#+RESULTS: fig:Glpf_bode
|
||||||
|
[[file:figs/Glpf_bode.png]]
|
||||||
|
** Conclusion
|
||||||
|
#+begin_important
|
||||||
|
As we want to measure things up to $500Hz$, we chose to change the value of the capacitor to obtain a cut-off frequency of $1kHz$.
|
||||||
|
#+end_important
|
||||||
|
|
||||||
|
** TODO Low Pass Filter with a cut-off frequency of 1kHz
|
||||||
|
This time, the value are
|
||||||
|
\begin{aligned}
|
||||||
|
R &= 1k\Omega \\
|
||||||
|
C &= 150nF
|
||||||
|
\end{aligned}
|
||||||
|
|
||||||
|
Which makes a low pass filter with a cut-off frequency of $f_c = 1060Hz$.
|
||||||
|
71
slip-ring-test/meas_effect_sr.m
Normal file
@ -0,0 +1,71 @@
|
|||||||
|
% Matlab Init :noexport:ignore:
|
||||||
|
|
||||||
|
clear; close all; clc;
|
||||||
|
|
||||||
|
%% Intialize Laplace variable
|
||||||
|
s = zpk('s');
|
||||||
|
|
||||||
|
%% Initialize ans with org-babel
|
||||||
|
ans = 0;
|
||||||
|
|
||||||
|
% 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])
|
66
slip-ring-test/meas_noise_ac_dc.m
Normal file
@ -0,0 +1,66 @@
|
|||||||
|
% Matlab Init :noexport:ignore:
|
||||||
|
|
||||||
|
clear; close all; clc;
|
||||||
|
|
||||||
|
%% Intialize Laplace variable
|
||||||
|
s = zpk('s');
|
||||||
|
|
||||||
|
%% Initialize ans with org-babel
|
||||||
|
ans = 0;
|
||||||
|
|
||||||
|
% Load data
|
||||||
|
% We load the data of the z axis of two geophones.
|
||||||
|
|
||||||
|
meas14 = load('mat/data_014.mat', 'data'); meas14 = meas14.data;
|
||||||
|
meas15 = load('mat/data_015.mat', 'data'); meas15 = meas15.data;
|
||||||
|
|
||||||
|
% Time Domain
|
||||||
|
% The signals are shown on figure [[fig:ac_dc_option_time]].
|
||||||
|
|
||||||
|
figure;
|
||||||
|
hold on;
|
||||||
|
plot(meas14(:, 3), meas14(:, 1), 'DisplayName', 'Amp1 - AC');
|
||||||
|
plot(meas14(:, 3), meas14(:, 2), 'DisplayName', 'Amp2 - DC');
|
||||||
|
plot(meas15(:, 3), meas15(:, 1), 'DisplayName', 'Amp1 - DC');
|
||||||
|
plot(meas15(:, 3), meas15(:, 2), 'DisplayName', 'Amp2 - AC');
|
||||||
|
hold off;
|
||||||
|
legend('Location', 'bestoutside');
|
||||||
|
xlabel('Time [s]');
|
||||||
|
ylabel('Voltage [V]');
|
||||||
|
xlim([0, 100]);
|
||||||
|
|
||||||
|
% Frequency Domain
|
||||||
|
% We first compute some parameters that will be used for the PSD computation.
|
||||||
|
|
||||||
|
dt = meas14(2, 3)-meas14(1, 3);
|
||||||
|
|
||||||
|
Fs = 1/dt; % [Hz]
|
||||||
|
|
||||||
|
win = hanning(ceil(10*Fs));
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
% Then we compute the Power Spectral Density using =pwelch= function.
|
||||||
|
|
||||||
|
[pxamp1ac, f] = pwelch(meas14(:, 1), win, [], [], Fs);
|
||||||
|
[pxamp2dc, ~] = pwelch(meas14(:, 2), win, [], [], Fs);
|
||||||
|
|
||||||
|
[pxamp1dc, ~] = pwelch(meas15(:, 1), win, [], [], Fs);
|
||||||
|
[pxamp2ac, ~] = pwelch(meas15(:, 2), win, [], [], Fs);
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
% The ASD of the signals are compare on figure [[fig:ac_dc_option_asd]].
|
||||||
|
|
||||||
|
figure;
|
||||||
|
hold on;
|
||||||
|
plot(f, sqrt(pxamp1ac), 'DisplayName', 'Amp1 - AC');
|
||||||
|
plot(f, sqrt(pxamp2dc), 'DisplayName', 'Amp2 - DC');
|
||||||
|
plot(f, sqrt(pxamp1dc), 'DisplayName', 'Amp1 - DC');
|
||||||
|
plot(f, sqrt(pxamp2ac), 'DisplayName', 'Amp2 - AC');
|
||||||
|
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]);
|
88
slip-ring-test/meas_slip_ring.m
Normal file
@ -0,0 +1,88 @@
|
|||||||
|
% Matlab Init :noexport:ignore:
|
||||||
|
|
||||||
|
clear; close all; clc;
|
||||||
|
|
||||||
|
%% Intialize Laplace variable
|
||||||
|
s = zpk('s');
|
||||||
|
|
||||||
|
%% Initialize ans with org-babel
|
||||||
|
ans = 0;
|
||||||
|
|
||||||
|
% 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]);
|
194
slip-ring-test/meas_sr_geophone.m
Normal file
@ -0,0 +1,194 @@
|
|||||||
|
% Matlab Init :noexport:ignore:
|
||||||
|
|
||||||
|
clear; close all; clc;
|
||||||
|
|
||||||
|
%% Intialize Laplace variable
|
||||||
|
s = zpk('s');
|
||||||
|
|
||||||
|
%% Initialize ans with org-babel
|
||||||
|
ans = 0;
|
||||||
|
|
||||||
|
% 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]);
|
74
slip-ring-test/meas_volt_amp.m
Normal file
@ -0,0 +1,74 @@
|
|||||||
|
% Matlab Init :noexport:ignore:
|
||||||
|
|
||||||
|
clear; close all; clc;
|
||||||
|
|
||||||
|
%% Intialize Laplace variable
|
||||||
|
s = zpk('s');
|
||||||
|
|
||||||
|
%% Initialize ans with org-babel
|
||||||
|
ans = 0;
|
||||||
|
|
||||||
|
% Load data
|
||||||
|
|
||||||
|
amp_off = load('mat/data_003.mat', 'data'); amp_off = amp_off.data(:, [1,3]);
|
||||||
|
amp_20d = load('mat/data_004.mat', 'data'); amp_20d = amp_20d.data(:, [1,3]);
|
||||||
|
amp_40d = load('mat/data_005.mat', 'data'); amp_40d = amp_40d.data(:, [1,3]);
|
||||||
|
amp_60d = load('mat/data_006.mat', 'data'); amp_60d = amp_60d.data(:, [1,3]);
|
||||||
|
|
||||||
|
% Time Domain
|
||||||
|
% The time domain signals are shown on figure [[fig:ampli_noise_time]].
|
||||||
|
|
||||||
|
|
||||||
|
figure;
|
||||||
|
hold on;
|
||||||
|
plot(amp_off(:, 2), amp_off(:, 1), 'DisplayName', 'OFF');
|
||||||
|
plot(amp_20d(:, 2), amp_20d(:, 1), 'DisplayName', '20dB');
|
||||||
|
plot(amp_40d(:, 2), amp_40d(:, 1), 'DisplayName', '40dB');
|
||||||
|
plot(amp_60d(:, 2), amp_60d(:, 1), 'DisplayName', '60dB');
|
||||||
|
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 = amp_off(2, 2)-amp_off(1, 2);
|
||||||
|
|
||||||
|
Fs = 1/dt; % [Hz]
|
||||||
|
|
||||||
|
win = hanning(ceil(10*Fs));
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
% Then we compute the Power Spectral Density using =pwelch= function.
|
||||||
|
|
||||||
|
[pxoff, f] = pwelch(amp_off(:,1), win, [], [], Fs);
|
||||||
|
[px20d, ~] = pwelch(amp_20d(:,1), win, [], [], Fs);
|
||||||
|
[px40d, ~] = pwelch(amp_40d(:,1), win, [], [], Fs);
|
||||||
|
[px60d, ~] = pwelch(amp_60d(:,1), win, [], [], Fs);
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
% We compute the theoretical ADC noise.
|
||||||
|
|
||||||
|
q = 20/2^16; % quantization
|
||||||
|
Sq = q^2/12/1000; % PSD of the ADC noise
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
% Finally, the ASD is shown on figure [[fig:ampli_noise_psd]].
|
||||||
|
|
||||||
|
figure;
|
||||||
|
hold on;
|
||||||
|
plot(f, sqrt(pxoff), 'DisplayName', 'OFF');
|
||||||
|
plot(f, sqrt(px20d), 'DisplayName', '20dB');
|
||||||
|
plot(f, sqrt(px40d), 'DisplayName', '40dB');
|
||||||
|
plot(f, sqrt(px60d), 'DisplayName', '60dB');
|
||||||
|
plot([0.1, 500], [sqrt(Sq), sqrt(Sq)], 'k--');
|
||||||
|
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]);
|
@ -68,7 +68,6 @@ Second column: DC
|
|||||||
|
|
||||||
- meas14: col-1 = amp1+AC. col-2 = amp2+DC.
|
- meas14: col-1 = amp1+AC. col-2 = amp2+DC.
|
||||||
- meas15: col-1 = amp1+DC. col-2 = amp2+AC.
|
- meas15: col-1 = amp1+DC. col-2 = amp2+AC.
|
||||||
|
|
||||||
* Measurement of the LPF
|
* Measurement of the LPF
|
||||||
We are measuring the signal from from Geophone with a BNC T
|
We are measuring the signal from from Geophone with a BNC T
|
||||||
On part goes to column 1 through the LPF
|
On part goes to column 1 through the LPF
|
||||||
|