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2019-05-02 14:06:23 +02:00
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< / head >
< body >
< div id = "content" >
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< h1 class = "title" > Measurements< / h1 >
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< div id = "table-of-contents" >
< h2 > Table of Contents< / h2 >
< div id = "text-table-of-contents" >
< ul >
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< li > < a href = "#org157e9c7" > 1. Effect of the rotation of the Slip-Ring< / a >
< ul >
< li > < a href = "#orgb6072a4" > 1.1. Measurement Description< / a > < / li >
< li > < a href = "#orgecd569a" > 1.2. Load data< / a > < / li >
< li > < a href = "#org3836a40" > 1.3. Analysis< / a > < / li >
< li > < a href = "#orgc938992" > 1.4. Conclusion< / a > < / li >
< / ul >
< / li >
< li > < a href = "#org64d6a43" > 2. Measure of the noise of the Voltage Amplifier< / a >
< ul >
< li > < a href = "#org3cb5cbc" > 2.1. Measurement Description< / a > < / li >
< li > < a href = "#org9a88df6" > 2.2. Load data< / a > < / li >
< li > < a href = "#org9594967" > 2.3. Time Domain< / a > < / li >
< li > < a href = "#orgb6ac137" > 2.4. Frequency Domain< / a > < / li >
< li > < a href = "#org2bfd545" > 2.5. Conclusion< / a > < / li >
< / ul >
< / li >
< li > < a href = "#orgd197020" > 3. Measure of the noise induced by the Slip-Ring< / a >
< ul >
< li > < a href = "#org6be0417" > 3.1. Measurement Description< / a > < / li >
< li > < a href = "#org894df46" > 3.2. Load data< / a > < / li >
< li > < a href = "#orgfb5cd93" > 3.3. Time Domain< / a > < / li >
< li > < a href = "#orge70b1cd" > 3.4. Frequency Domain< / a > < / li >
< li > < a href = "#org1067ac0" > 3.5. Conclusion< / a > < / li >
< / ul >
< / li >
< li > < a href = "#orga6075e6" > 4. Measure of the noise induced by the slip ring when using a geophone< / a >
< ul >
< li > < a href = "#orga3d1fca" > 4.1. Measurement Description< / a > < / li >
< li > < a href = "#org874ef1d" > 4.2. Load data< / a > < / li >
< li > < a href = "#org3656f2f" > 4.3. Time Domain< / a > < / li >
< li > < a href = "#orgf3c9d01" > 4.4. Frequency Domain< / a > < / li >
< li > < a href = "#orgbee8de0" > 4.5. Conclusion< / a > < / li >
< / ul >
< / li >
< li > < a href = "#org22d6637" > 5. Measure of the influence of the AC/DC option on the voltage amplifiers< / a >
< ul >
< li > < a href = "#org947094c" > 5.1. Measurement Description< / a > < / li >
< li > < a href = "#orgd3f6cb3" > 5.2. Load data< / a > < / li >
< li > < a href = "#org85a856a" > 5.3. Time Domain< / a > < / li >
< li > < a href = "#org18d9eca" > 5.4. Frequency Domain< / a > < / li >
< li > < a href = "#org21d0038" > 5.5. Conclusion< / a > < / li >
< / ul >
< / li >
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< / ul >
< / div >
< / div >
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< div id = "outline-container-org157e9c7" class = "outline-2" >
< h2 id = "org157e9c7" > < span class = "section-number-2" > 1< / span > Effect of the rotation of the Slip-Ring< / h2 >
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< div class = "outline-text-2" id = "text-1" >
< p >
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The data and matlab files are accessible < a href = "data/meas_effect_sr.zip" > here< / a > .
< / p >
< / div >
< div id = "outline-container-orgb6072a4" class = "outline-3" >
< h3 id = "orgb6072a4" > < span class = "section-number-3" > 1.1< / span > Measurement Description< / h3 >
< div class = "outline-text-3" id = "text-1-1" >
< p >
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Random Signal is generated by one DAC of the SpeedGoat.
< / p >
< p >
The signal going out of the DAC is split into two:
< / p >
< ul class = "org-ul" >
< li > one BNC cable is directly connected to one ADC of the SpeedGoat< / li >
< li > 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< / li >
< / ul >
< p >
Two measurements are done.
< / p >
< table border = "2" cellspacing = "0" cellpadding = "6" rules = "groups" frame = "hsides" >
< colgroup >
< col class = "org-left" / >
< col class = "org-left" / >
< / colgroup >
< thead >
< tr >
< th scope = "col" class = "org-left" > Data File< / th >
< th scope = "col" class = "org-left" > Description< / th >
< / tr >
< / thead >
< tbody >
< tr >
< td class = "org-left" > < code > mat/data_001.mat< / code > < / td >
< td class = "org-left" > Slip-ring not turning< / td >
< / tr >
< tr >
< td class = "org-left" > < code > mat/data_002.mat< / code > < / td >
< td class = "org-left" > Slip-ring turning< / td >
< / tr >
< / tbody >
< / table >
< p >
For each measurement, the measured signals are:
< / p >
< table border = "2" cellspacing = "0" cellpadding = "6" rules = "groups" frame = "hsides" >
< colgroup >
< col class = "org-left" / >
< col class = "org-left" / >
< / colgroup >
< thead >
< tr >
< th scope = "col" class = "org-left" > Data File< / th >
< th scope = "col" class = "org-left" > Description< / th >
< / tr >
< / thead >
< tbody >
< tr >
< td class = "org-left" > < code > t< / code > < / td >
< td class = "org-left" > Time vector< / td >
< / tr >
< tr >
< td class = "org-left" > < code > x1< / code > < / td >
< td class = "org-left" > Direct signal< / td >
< / tr >
< tr >
< td class = "org-left" > < code > x2< / code > < / td >
< td class = "org-left" > Signal going through the Slip-Ring< / td >
< / tr >
< / tbody >
< / table >
< p >
The goal is to determine is the signal is altered when the spindle is rotating.
< / p >
< p >
Here, the rotation speed of the Slip-Ring is set to 1rpm.
< / p >
< / div >
< / div >
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< div id = "outline-container-orgecd569a" class = "outline-3" >
< h3 id = "orgecd569a" > < span class = "section-number-3" > 1.2< / span > Load data< / h3 >
< div class = "outline-text-3" id = "text-1-2" >
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< p >
We load the data of the z axis of two geophones.
< / p >
< div class = "org-src-container" >
< pre class = "src src-matlab" > sr_off = load< span class = "org-rainbow-delimiters-depth-1" > (< / span > < span class = "org-string" > 'mat/data_001.mat', 't', 'x1', 'x2'< / span > < span class = "org-rainbow-delimiters-depth-1" > )< / span > ;
sr_on = load< span class = "org-rainbow-delimiters-depth-1" > (< / span > < span class = "org-string" > 'mat/data_002.mat', 't', 'x1', 'x2'< / span > < span class = "org-rainbow-delimiters-depth-1" > )< / span > ;
< / pre >
< / div >
< / div >
< / div >
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< div id = "outline-container-org3836a40" class = "outline-3" >
< h3 id = "org3836a40" > < span class = "section-number-3" > 1.3< / span > Analysis< / h3 >
< div class = "outline-text-3" id = "text-1-3" >
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< p >
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Let's first look at the signal produced by the DAC (figure < a href = "#org9e05a67" > 1< / a > ).
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< / p >
< div class = "org-src-container" >
< pre class = "src src-matlab" > < span class = "org-type" > figure< / span > ;
hold on;
plot< span class = "org-rainbow-delimiters-depth-1" > (< / span > sr_on.t, sr_on.x1< span class = "org-rainbow-delimiters-depth-1" > )< / span > ;
hold off;
xlabel< span class = "org-rainbow-delimiters-depth-1" > (< / span > < span class = "org-string" > 'Time < / span > < span class = "org-string" > < span class = "org-rainbow-delimiters-depth-2" > [< / span > < / span > < span class = "org-string" > s< / span > < span class = "org-string" > < span class = "org-rainbow-delimiters-depth-2" > ]< / span > < / span > < span class = "org-string" > '< / span > < span class = "org-string" > < span class = "org-rainbow-delimiters-depth-1" > )< / span > < / span > < span class = "org-string" > ; ylabel< / span > < span class = "org-string" > < span class = "org-rainbow-delimiters-depth-1" > (< / span > < / span > < span class = "org-string" > 'Voltage < / span > < span class = "org-string" > < span class = "org-rainbow-delimiters-depth-2" > [< / span > < / span > < span class = "org-string" > V< / span > < span class = "org-string" > < span class = "org-rainbow-delimiters-depth-2" > ]< / span > < / span > < span class = "org-string" > '< / span > < span class = "org-rainbow-delimiters-depth-1" > )< / span > ;
xlim< span class = "org-rainbow-delimiters-depth-1" > (< / span > < span class = "org-rainbow-delimiters-depth-2" > [< / span > < span class = "org-highlight-numbers-number" > 0< / span > < span class = "org-highlight-numbers-number" > 10< / span > < span class = "org-rainbow-delimiters-depth-2" > ]< / span > < span class = "org-rainbow-delimiters-depth-1" > )< / span > ;
< / pre >
< / div >
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< div id = "org9e05a67" class = "figure" >
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< p > < img src = "figs/random_signal.png" alt = "random_signal.png" / >
< / p >
< p > < span class = "figure-number" > Figure 1: < / span > Random signal produced by the DAC< / p >
< / div >
< p >
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We now look at the difference between the signal directly measured by the ADC and the signal that goes through the slip-ring (figure < a href = "#orgbaee8bd" > 2< / a > ).
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< / p >
< div class = "org-src-container" >
< pre class = "src src-matlab" > < span class = "org-type" > figure< / span > ;
hold on;
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plot< span class = "org-rainbow-delimiters-depth-1" > (< / span > sr_on.t, sr_on.x1 < span class = "org-type" > -< / span > sr_on.x2, < span class = "org-string" > 'DisplayName', '< / span > Slip< span class = "org-type" > -< / span > Ring < span class = "org-type" > -< / span > $< span class = "org-type" > \< / span > omega = < span class = "org-highlight-numbers-number" > 1rpm$< / span > '< span class = "org-rainbow-delimiters-depth-1" > )< / span > ;
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plot< span class = "org-rainbow-delimiters-depth-1" > (< / span > sr_off.t, sr_off.x1 < span class = "org-type" > -< / span > sr_off.x2,< span class = "org-string" > 'DisplayName', 'Slip-Ring off'< / span > < span class = "org-rainbow-delimiters-depth-1" > )< / span > ;
hold off;
xlabel< span class = "org-rainbow-delimiters-depth-1" > (< / span > < span class = "org-string" > 'Time < / span > < span class = "org-string" > < span class = "org-rainbow-delimiters-depth-2" > [< / span > < / span > < span class = "org-string" > s< / span > < span class = "org-string" > < span class = "org-rainbow-delimiters-depth-2" > ]< / span > < / span > < span class = "org-string" > '< / span > < span class = "org-string" > < span class = "org-rainbow-delimiters-depth-1" > )< / span > < / span > < span class = "org-string" > ; ylabel< / span > < span class = "org-string" > < span class = "org-rainbow-delimiters-depth-1" > (< / span > < / span > < span class = "org-string" > 'Voltage < / span > < span class = "org-string" > < span class = "org-rainbow-delimiters-depth-2" > [< / span > < / span > < span class = "org-string" > V< / span > < span class = "org-string" > < span class = "org-rainbow-delimiters-depth-2" > ]< / span > < / span > < span class = "org-string" > '< / span > < span class = "org-rainbow-delimiters-depth-1" > )< / span > ;
xlim< span class = "org-rainbow-delimiters-depth-1" > (< / span > < span class = "org-rainbow-delimiters-depth-2" > [< / span > < span class = "org-highlight-numbers-number" > 0< / span > < span class = "org-highlight-numbers-number" > 10< / span > < span class = "org-rainbow-delimiters-depth-2" > ]< / span > < span class = "org-rainbow-delimiters-depth-1" > )< / span > ;
legend< span class = "org-rainbow-delimiters-depth-1" > (< / span > < span class = "org-string" > 'Location', 'northeast'< / span > < span class = "org-rainbow-delimiters-depth-1" > )< / span > ;
< / pre >
< / div >
2019-05-06 10:28:35 +02:00
< div id = "orgbaee8bd" class = "figure" >
2019-05-02 14:06:23 +02:00
< p > < img src = "figs/slipring_comp_signals.png" alt = "slipring_comp_signals.png" / >
< / p >
< p > < span class = "figure-number" > Figure 2: < / span > Alteration of the signal when the slip-ring is turning< / p >
< / div >
2019-05-03 17:33:15 +02:00
< div class = "org-src-container" >
< pre class = "src src-matlab" > dt = sr_on.t< span class = "org-rainbow-delimiters-depth-1" > (< / span > < span class = "org-highlight-numbers-number" > 2< / span > < span class = "org-rainbow-delimiters-depth-1" > )< / span > < span class = "org-type" > -< / span > sr_on.t< span class = "org-rainbow-delimiters-depth-1" > (< / span > < span class = "org-highlight-numbers-number" > 1< / span > < span class = "org-rainbow-delimiters-depth-1" > )< / span > ;
Fs = < span class = "org-highlight-numbers-number" > 1< / span > < span class = "org-type" > /< / span > dt; < span class = "org-comment" > % [Hz]< / span >
win = hanning< span class = "org-rainbow-delimiters-depth-1" > (< / span > ceil< span class = "org-rainbow-delimiters-depth-2" > (< / span > < span class = "org-highlight-numbers-number" > 1< / span > < span class = "org-type" > *< / span > Fs< span class = "org-rainbow-delimiters-depth-2" > )< / span > < span class = "org-rainbow-delimiters-depth-1" > )< / span > ;
< / pre >
< / div >
< div class = "org-src-container" >
< pre class = "src src-matlab" > < span class = "org-rainbow-delimiters-depth-1" > [< / span > pxx_on, f< span class = "org-rainbow-delimiters-depth-1" > ]< / span > = pwelch< span class = "org-rainbow-delimiters-depth-1" > (< / span > sr_on.x1 < span class = "org-type" > -< / span > sr_on.x2, win, < span class = "org-rainbow-delimiters-depth-2" > []< / span > , < span class = "org-rainbow-delimiters-depth-2" > []< / span > , Fs< span class = "org-rainbow-delimiters-depth-1" > )< / span > ;
< span class = "org-rainbow-delimiters-depth-1" > [< / span > pxx_off, < span class = "org-type" > ~< / span > < span class = "org-rainbow-delimiters-depth-1" > ]< / span > = pwelch< span class = "org-rainbow-delimiters-depth-1" > (< / span > sr_off.x1 < span class = "org-type" > -< / span > sr_off.x2, win, < span class = "org-rainbow-delimiters-depth-2" > []< / span > , < span class = "org-rainbow-delimiters-depth-2" > []< / span > , Fs< span class = "org-rainbow-delimiters-depth-1" > )< / span > ;
< / pre >
< / div >
2019-05-06 10:28:35 +02:00
< div id = "orgd69e796" class = "figure" >
2019-05-03 17:33:15 +02:00
< p > < img src = "figs/psd_noise.png" alt = "psd_noise.png" / >
< / p >
< p > < span class = "figure-number" > Figure 3: < / span > ASD of the measured noise< / p >
< / div >
2019-05-02 14:06:23 +02:00
< / div >
< / div >
2019-05-06 10:28:35 +02:00
< div id = "outline-container-orgc938992" class = "outline-3" >
< h3 id = "orgc938992" > < span class = "section-number-3" > 1.4< / span > Conclusion< / h3 >
< div class = "outline-text-3" id = "text-1-4" >
2019-05-02 14:09:20 +02:00
< div class = "note" >
2019-05-02 14:06:23 +02:00
< p >
< b > Remaining questions< / b > :
< / p >
< ul class = "org-ul" >
< li > Should the measurement be redone using voltage amplifiers?< / li >
< li > Use higher rotation speed and measure for longer periods (to have multiple revolutions) ?< / li >
< / ul >
2019-05-02 14:09:20 +02:00
2019-05-06 10:28:35 +02:00
< / div >
< / div >
< / div >
< / div >
< div id = "outline-container-org64d6a43" class = "outline-2" >
< h2 id = "org64d6a43" > < span class = "section-number-2" > 2< / span > Measure of the noise of the Voltage Amplifier< / h2 >
< div class = "outline-text-2" id = "text-2" >
< p >
The data and matlab files are accessible < a href = "data/meas_volt_amp.zip" > here< / a > .
< / p >
< / div >
< div id = "outline-container-org3cb5cbc" class = "outline-3" >
< h3 id = "org3cb5cbc" > < span class = "section-number-3" > 2.1< / span > Measurement Description< / h3 >
< div class = "outline-text-3" id = "text-2-1" >
< p >
< b > Goal< / b > :
< / p >
< ul class = "org-ul" >
< li > Determine the Voltage Amplifier noise< / li >
< / ul >
< p >
< b > Setup< / b > :
< / p >
< ul class = "org-ul" >
< li > The two inputs (differential) of the voltage amplifier are shunted with 50Ohms< / li >
< li > The AC/DC option of the Voltage amplifier is on AC< / li >
< li > The low pass filter is set to 1hHz< / li >
< li > We measure the output of the voltage amplifier with a 16bits ADC of the Speedgoat< / li >
< / ul >
< p >
< b > Measurements< / b > :
< / p >
< ul class = "org-ul" >
< li > < code > data_003< / code > : Ampli OFF< / li >
< li > < code > data_004< / code > : Ampli ON set to 20dB< / li >
< li > < code > data_005< / code > : Ampli ON set to 40dB< / li >
< li > < code > data_006< / code > : Ampli ON set to 60dB< / li >
< / ul >
< / div >
< / div >
< div id = "outline-container-org9a88df6" class = "outline-3" >
< h3 id = "org9a88df6" > < span class = "section-number-3" > 2.2< / span > Load data< / h3 >
< div class = "outline-text-3" id = "text-2-2" >
< div class = "org-src-container" >
< pre class = "src src-matlab" > amp_off = load< span class = "org-rainbow-delimiters-depth-1" > (< / span > < span class = "org-string" > 'mat/data_003.mat', 'data'< / span > < span class = "org-rainbow-delimiters-depth-1" > )< / span > ; amp_off = amp_off.data< span class = "org-rainbow-delimiters-depth-1" > (< / span > < span class = "org-type" > :< / span > , < span class = "org-rainbow-delimiters-depth-2" > [< / span > < span class = "org-highlight-numbers-number" > 1< / span > ,< span class = "org-highlight-numbers-number" > 3< / span > < span class = "org-rainbow-delimiters-depth-2" > ]< / span > < span class = "org-rainbow-delimiters-depth-1" > )< / span > ;
amp_20d = load< span class = "org-rainbow-delimiters-depth-1" > (< / span > < span class = "org-string" > 'mat/data_004.mat', 'data'< / span > < span class = "org-rainbow-delimiters-depth-1" > )< / span > ; amp_20d = amp_20d.data< span class = "org-rainbow-delimiters-depth-1" > (< / span > < span class = "org-type" > :< / span > , < span class = "org-rainbow-delimiters-depth-2" > [< / span > < span class = "org-highlight-numbers-number" > 1< / span > ,< span class = "org-highlight-numbers-number" > 3< / span > < span class = "org-rainbow-delimiters-depth-2" > ]< / span > < span class = "org-rainbow-delimiters-depth-1" > )< / span > ;
amp_40d = load< span class = "org-rainbow-delimiters-depth-1" > (< / span > < span class = "org-string" > 'mat/data_005.mat', 'data'< / span > < span class = "org-rainbow-delimiters-depth-1" > )< / span > ; amp_40d = amp_40d.data< span class = "org-rainbow-delimiters-depth-1" > (< / span > < span class = "org-type" > :< / span > , < span class = "org-rainbow-delimiters-depth-2" > [< / span > < span class = "org-highlight-numbers-number" > 1< / span > ,< span class = "org-highlight-numbers-number" > 3< / span > < span class = "org-rainbow-delimiters-depth-2" > ]< / span > < span class = "org-rainbow-delimiters-depth-1" > )< / span > ;
amp_60d = load< span class = "org-rainbow-delimiters-depth-1" > (< / span > < span class = "org-string" > 'mat/data_006.mat', 'data'< / span > < span class = "org-rainbow-delimiters-depth-1" > )< / span > ; amp_60d = amp_60d.data< span class = "org-rainbow-delimiters-depth-1" > (< / span > < span class = "org-type" > :< / span > , < span class = "org-rainbow-delimiters-depth-2" > [< / span > < span class = "org-highlight-numbers-number" > 1< / span > ,< span class = "org-highlight-numbers-number" > 3< / span > < span class = "org-rainbow-delimiters-depth-2" > ]< / span > < span class = "org-rainbow-delimiters-depth-1" > )< / span > ;
< / pre >
< / div >
< / div >
< / div >
< div id = "outline-container-org9594967" class = "outline-3" >
< h3 id = "org9594967" > < span class = "section-number-3" > 2.3< / span > Time Domain< / h3 >
< div class = "outline-text-3" id = "text-2-3" >
< p >
The time domain signals are shown on figure < a href = "#orgcfdcbce" > 4< / a > .
< / p >
< div id = "orgcfdcbce" class = "figure" >
< p > < img src = "figs/ampli_noise_time.png" alt = "ampli_noise_time.png" / >
< / p >
< p > < span class = "figure-number" > Figure 4: < / span > Output of the amplifier< / p >
< / div >
< / div >
< / div >
< div id = "outline-container-orgb6ac137" class = "outline-3" >
< h3 id = "orgb6ac137" > < span class = "section-number-3" > 2.4< / span > Frequency Domain< / h3 >
< div class = "outline-text-3" id = "text-2-4" >
< p >
We first compute some parameters that will be used for the PSD computation.
< / p >
< div class = "org-src-container" >
< pre class = "src src-matlab" > dt = amp_off< span class = "org-rainbow-delimiters-depth-1" > (< / span > < span class = "org-highlight-numbers-number" > 2< / span > , < span class = "org-highlight-numbers-number" > 2< / span > < span class = "org-rainbow-delimiters-depth-1" > )< / span > < span class = "org-type" > -< / span > amp_off< span class = "org-rainbow-delimiters-depth-1" > (< / span > < span class = "org-highlight-numbers-number" > 1< / span > , < span class = "org-highlight-numbers-number" > 2< / span > < span class = "org-rainbow-delimiters-depth-1" > )< / span > ;
Fs = < span class = "org-highlight-numbers-number" > 1< / span > < span class = "org-type" > /< / span > dt; < span class = "org-comment" > % [Hz]< / span >
win = hanning< span class = "org-rainbow-delimiters-depth-1" > (< / span > ceil< span class = "org-rainbow-delimiters-depth-2" > (< / span > < span class = "org-highlight-numbers-number" > 10< / span > < span class = "org-type" > *< / span > Fs< span class = "org-rainbow-delimiters-depth-2" > )< / span > < span class = "org-rainbow-delimiters-depth-1" > )< / span > ;
< / pre >
< / div >
< p >
Then we compute the Power Spectral Density using < code > pwelch< / code > function.
< / p >
< div class = "org-src-container" >
< pre class = "src src-matlab" > < span class = "org-rainbow-delimiters-depth-1" > [< / span > pxoff, f< span class = "org-rainbow-delimiters-depth-1" > ]< / span > = pwelch< span class = "org-rainbow-delimiters-depth-1" > (< / span > amp_off< span class = "org-rainbow-delimiters-depth-2" > (< / span > < span class = "org-type" > :< / span > ,< span class = "org-highlight-numbers-number" > 1< / span > < span class = "org-rainbow-delimiters-depth-2" > )< / span > , win, < span class = "org-rainbow-delimiters-depth-2" > []< / span > , < span class = "org-rainbow-delimiters-depth-2" > []< / span > , Fs< span class = "org-rainbow-delimiters-depth-1" > )< / span > ;
< span class = "org-rainbow-delimiters-depth-1" > [< / span > px20d, < span class = "org-type" > ~< / span > < span class = "org-rainbow-delimiters-depth-1" > ]< / span > = pwelch< span class = "org-rainbow-delimiters-depth-1" > (< / span > amp_20d< span class = "org-rainbow-delimiters-depth-2" > (< / span > < span class = "org-type" > :< / span > ,< span class = "org-highlight-numbers-number" > 1< / span > < span class = "org-rainbow-delimiters-depth-2" > )< / span > , win, < span class = "org-rainbow-delimiters-depth-2" > []< / span > , < span class = "org-rainbow-delimiters-depth-2" > []< / span > , Fs< span class = "org-rainbow-delimiters-depth-1" > )< / span > ;
< span class = "org-rainbow-delimiters-depth-1" > [< / span > px40d, < span class = "org-type" > ~< / span > < span class = "org-rainbow-delimiters-depth-1" > ]< / span > = pwelch< span class = "org-rainbow-delimiters-depth-1" > (< / span > amp_40d< span class = "org-rainbow-delimiters-depth-2" > (< / span > < span class = "org-type" > :< / span > ,< span class = "org-highlight-numbers-number" > 1< / span > < span class = "org-rainbow-delimiters-depth-2" > )< / span > , win, < span class = "org-rainbow-delimiters-depth-2" > []< / span > , < span class = "org-rainbow-delimiters-depth-2" > []< / span > , Fs< span class = "org-rainbow-delimiters-depth-1" > )< / span > ;
< span class = "org-rainbow-delimiters-depth-1" > [< / span > px60d, < span class = "org-type" > ~< / span > < span class = "org-rainbow-delimiters-depth-1" > ]< / span > = pwelch< span class = "org-rainbow-delimiters-depth-1" > (< / span > amp_60d< span class = "org-rainbow-delimiters-depth-2" > (< / span > < span class = "org-type" > :< / span > ,< span class = "org-highlight-numbers-number" > 1< / span > < span class = "org-rainbow-delimiters-depth-2" > )< / span > , win, < span class = "org-rainbow-delimiters-depth-2" > []< / span > , < span class = "org-rainbow-delimiters-depth-2" > []< / span > , Fs< span class = "org-rainbow-delimiters-depth-1" > )< / span > ;
< / pre >
< / div >
< p >
We compute the theoretical ADC noise.
< / p >
< div class = "org-src-container" >
< pre class = "src src-matlab" > q = < span class = "org-highlight-numbers-number" > 20< / span > < span class = "org-type" > /< / span > < span class = "org-highlight-numbers-number" > 2< / span > < span class = "org-type" > ^< / span > < span class = "org-highlight-numbers-number" > 16< / span > ; < span class = "org-comment" > % quantization< / span >
Sq = q< span class = "org-type" > ^< / span > < span class = "org-highlight-numbers-number" > 2< / span > < span class = "org-type" > /< / span > < span class = "org-highlight-numbers-number" > 12< / span > < span class = "org-type" > /< / span > < span class = "org-highlight-numbers-number" > 1000< / span > ; < span class = "org-comment" > % PSD of the ADC noise< / span >
< / pre >
< / div >
< p >
Finally, the ASD is shown on figure < a href = "#orgf5bb8f5" > 5< / a > .
< / p >
< div id = "orgf5bb8f5" class = "figure" >
< p > < img src = "figs/ampli_noise_psd.png" alt = "ampli_noise_psd.png" / >
< / p >
< p > < span class = "figure-number" > Figure 5: < / span > Amplitude Spectral Density of the measured voltage at the output of the voltage amplifier< / p >
< / div >
< / div >
< / div >
< div id = "outline-container-org2bfd545" class = "outline-3" >
< h3 id = "org2bfd545" > < span class = "section-number-3" > 2.5< / span > Conclusion< / h3 >
< div class = "outline-text-3" id = "text-2-5" >
< div class = "important" >
< p >
Noise induced by the voltage amplifiers is not a limiting factor.
< / p >
< / div >
< / div >
< / div >
< / div >
< div id = "outline-container-orgd197020" class = "outline-2" >
< h2 id = "orgd197020" > < span class = "section-number-2" > 3< / span > Measure of the noise induced by the Slip-Ring< / h2 >
< div class = "outline-text-2" id = "text-3" >
< p >
The data and matlab files are accessible < a href = "data/meas_slip_ring.zip" > here< / a > .
< / p >
< / div >
< div id = "outline-container-org6be0417" class = "outline-3" >
< h3 id = "org6be0417" > < span class = "section-number-3" > 3.1< / span > Measurement Description< / h3 >
< div class = "outline-text-3" id = "text-3-1" >
< p >
< b > Goal< / b > :
< / p >
< ul class = "org-ul" >
< li > Determine the noise induced by the slip-ring< / li >
< / ul >
< p >
< b > Setup< / b > :
< / p >
< ul class = "org-ul" >
< li > 0V is generated by the DAC of the Speedgoat< / li >
< li > Using a T, one part goes directly to the ADC< / li >
< li > The other part goes to the slip-ring 2 times and then to the ADC< / li >
< li > The parameters of the Voltage Amplifier are: 80dB, AC, 1kHz< / li >
< li > Every stage of the station is OFF< / li >
< / ul >
< p >
First column: Direct measure
Second column: Slip-ring measure
< / p >
< p >
< b > Measurements< / b > :
< / p >
< ul class = "org-ul" >
< li > < code > data_008< / code > : Slip-Ring OFF< / li >
< li > < code > data_009< / code > : Slip-Ring ON< / li >
< li > < code > data_010< / code > : Slip-Ring ON and omega=6rpm< / li >
< li > < code > data_011< / code > : Slip-Ring ON and omega=60rpm< / li >
< / ul >
< / div >
< / div >
< div id = "outline-container-org894df46" class = "outline-3" >
< h3 id = "org894df46" > < span class = "section-number-3" > 3.2< / span > Load data< / h3 >
< div class = "outline-text-3" id = "text-3-2" >
< p >
We load the data of the z axis of two geophones.
< / p >
< div class = "org-src-container" >
< pre class = "src src-matlab" > sr_off = load< span class = "org-rainbow-delimiters-depth-1" > (< / span > < span class = "org-string" > 'mat/data_008.mat', 'data'< / span > < span class = "org-rainbow-delimiters-depth-1" > )< / span > ; sr_off = sr_off.data;
sr_on = load< span class = "org-rainbow-delimiters-depth-1" > (< / span > 'mat< span class = "org-type" > /< / span > data_009.mat', < span class = "org-string" > 'data'< / span > < span class = "org-rainbow-delimiters-depth-1" > )< / span > ; sr_on = sr_on.data;
sr_6r = load< span class = "org-rainbow-delimiters-depth-1" > (< / span > < span class = "org-string" > 'mat/data_010.mat', 'data'< / span > < span class = "org-rainbow-delimiters-depth-1" > )< / span > ; sr_6r = sr_6r.data;
sr_60r = load< span class = "org-rainbow-delimiters-depth-1" > (< / span > < span class = "org-string" > 'mat/data_011.mat', 'data'< / span > < span class = "org-rainbow-delimiters-depth-1" > )< / span > ; sr_60r = sr_60r.data;
< / pre >
< / div >
< / div >
< / div >
< div id = "outline-container-orgfb5cd93" class = "outline-3" >
< h3 id = "orgfb5cd93" > < span class = "section-number-3" > 3.3< / span > Time Domain< / h3 >
< div class = "outline-text-3" id = "text-3-3" >
< p >
We plot the time domain data for the direct measurement (figure < a href = "#orgcff48af" > 6< / a > ) and for the signal going through the slip-ring (figure < a href = "#orgfbc52db" > 7< / a > );
< / p >
< div id = "orgcff48af" class = "figure" >
< p > < img src = "figs/sr_direct_time.png" alt = "sr_direct_time.png" / >
< / p >
< p > < span class = "figure-number" > Figure 6: < / span > Direct measurement< / p >
< / div >
< div id = "orgfbc52db" class = "figure" >
< p > < img src = "figs/sr_slipring_time.png" alt = "sr_slipring_time.png" / >
< / p >
< p > < span class = "figure-number" > Figure 7: < / span > Measurement of the signal going through the Slip-Ring< / p >
< / div >
< / div >
< / div >
< div id = "outline-container-orge70b1cd" class = "outline-3" >
< h3 id = "orge70b1cd" > < span class = "section-number-3" > 3.4< / span > Frequency Domain< / h3 >
< div class = "outline-text-3" id = "text-3-4" >
< p >
We first compute some parameters that will be used for the PSD computation.
< / p >
< div class = "org-src-container" >
< pre class = "src src-matlab" > dt = sr_off< span class = "org-rainbow-delimiters-depth-1" > (< / span > < span class = "org-highlight-numbers-number" > 2< / span > , < span class = "org-highlight-numbers-number" > 3< / span > < span class = "org-rainbow-delimiters-depth-1" > )< / span > < span class = "org-type" > -< / span > sr_off< span class = "org-rainbow-delimiters-depth-1" > (< / span > < span class = "org-highlight-numbers-number" > 1< / span > , < span class = "org-highlight-numbers-number" > 3< / span > < span class = "org-rainbow-delimiters-depth-1" > )< / span > ;
Fs = < span class = "org-highlight-numbers-number" > 1< / span > < span class = "org-type" > /< / span > dt; < span class = "org-comment" > % [Hz]< / span >
win = hanning< span class = "org-rainbow-delimiters-depth-1" > (< / span > ceil< span class = "org-rainbow-delimiters-depth-2" > (< / span > < span class = "org-highlight-numbers-number" > 10< / span > < span class = "org-type" > *< / span > Fs< span class = "org-rainbow-delimiters-depth-2" > )< / span > < span class = "org-rainbow-delimiters-depth-1" > )< / span > ;
< / pre >
< / div >
< p >
Then we compute the Power Spectral Density using < code > pwelch< / code > function.
< / p >
< div class = "org-src-container" >
< pre class = "src src-matlab" > < span class = "org-rainbow-delimiters-depth-1" > [< / span > pxdir, f< span class = "org-rainbow-delimiters-depth-1" > ]< / span > = pwelch< span class = "org-rainbow-delimiters-depth-1" > (< / span > sr_off< span class = "org-rainbow-delimiters-depth-2" > (< / span > < span class = "org-type" > :< / span > , < span class = "org-highlight-numbers-number" > 1< / span > < span class = "org-rainbow-delimiters-depth-2" > )< / span > , win, < span class = "org-rainbow-delimiters-depth-2" > []< / span > , < span class = "org-rainbow-delimiters-depth-2" > []< / span > , Fs< span class = "org-rainbow-delimiters-depth-1" > )< / span > ;
< span class = "org-rainbow-delimiters-depth-1" > [< / span > pxoff, < span class = "org-type" > ~< / span > < span class = "org-rainbow-delimiters-depth-1" > ]< / span > = pwelch< span class = "org-rainbow-delimiters-depth-1" > (< / span > sr_off< span class = "org-rainbow-delimiters-depth-2" > (< / span > < span class = "org-type" > :< / span > , < span class = "org-highlight-numbers-number" > 2< / span > < span class = "org-rainbow-delimiters-depth-2" > )< / span > , win, < span class = "org-rainbow-delimiters-depth-2" > []< / span > , < span class = "org-rainbow-delimiters-depth-2" > []< / span > , Fs< span class = "org-rainbow-delimiters-depth-1" > )< / span > ;
< span class = "org-rainbow-delimiters-depth-1" > [< / span > pxon, < span class = "org-type" > ~< / span > < span class = "org-rainbow-delimiters-depth-1" > ]< / span > = pwelch< span class = "org-rainbow-delimiters-depth-1" > (< / span > sr_on< span class = "org-rainbow-delimiters-depth-2" > (< / span > < span class = "org-type" > :< / span > , < span class = "org-highlight-numbers-number" > 2< / span > < span class = "org-rainbow-delimiters-depth-2" > )< / span > , win, < span class = "org-rainbow-delimiters-depth-2" > []< / span > , < span class = "org-rainbow-delimiters-depth-2" > []< / span > , Fs< span class = "org-rainbow-delimiters-depth-1" > )< / span > ;
< span class = "org-rainbow-delimiters-depth-1" > [< / span > px6r, < span class = "org-type" > ~< / span > < span class = "org-rainbow-delimiters-depth-1" > ]< / span > = pwelch< span class = "org-rainbow-delimiters-depth-1" > (< / span > sr_6r< span class = "org-rainbow-delimiters-depth-2" > (< / span > < span class = "org-type" > :< / span > , < span class = "org-highlight-numbers-number" > 2< / span > < span class = "org-rainbow-delimiters-depth-2" > )< / span > , win, < span class = "org-rainbow-delimiters-depth-2" > []< / span > , < span class = "org-rainbow-delimiters-depth-2" > []< / span > , Fs< span class = "org-rainbow-delimiters-depth-1" > )< / span > ;
< span class = "org-rainbow-delimiters-depth-1" > [< / span > px60r, < span class = "org-type" > ~< / span > < span class = "org-rainbow-delimiters-depth-1" > ]< / span > = pwelch< span class = "org-rainbow-delimiters-depth-1" > (< / span > sr_60r< span class = "org-rainbow-delimiters-depth-2" > (< / span > < span class = "org-type" > :< / span > , < span class = "org-highlight-numbers-number" > 2< / span > < span class = "org-rainbow-delimiters-depth-2" > )< / span > , win, < span class = "org-rainbow-delimiters-depth-2" > []< / span > , < span class = "org-rainbow-delimiters-depth-2" > []< / span > , Fs< span class = "org-rainbow-delimiters-depth-1" > )< / span > ;
< / pre >
< / div >
< p >
And we plot the ASD of the measured signals (figure < a href = "#org16c9932" > 8< / a > );
< / p >
< div class = "org-src-container" >
< pre class = "src src-matlab" > < span class = "org-type" > figure< / span > ;
hold on;
plot< span class = "org-rainbow-delimiters-depth-1" > (< / span > f, sqrt< span class = "org-rainbow-delimiters-depth-2" > (< / span > pxoff< span class = "org-rainbow-delimiters-depth-2" > )< / span > , < span class = "org-string" > 'DisplayName', 'OFF'< / span > < span class = "org-rainbow-delimiters-depth-1" > )< / span > ;
plot< span class = "org-rainbow-delimiters-depth-1" > (< / span > f, sqrt< span class = "org-rainbow-delimiters-depth-2" > (< / span > pxon< span class = "org-rainbow-delimiters-depth-2" > )< / span > , < span class = "org-string" > 'DisplayName', 'ON'< / span > < span class = "org-rainbow-delimiters-depth-1" > )< / span > ;
plot< span class = "org-rainbow-delimiters-depth-1" > (< / span > f, sqrt< span class = "org-rainbow-delimiters-depth-2" > (< / span > px6r< span class = "org-rainbow-delimiters-depth-2" > )< / span > , 'DisplayName', '< span class = "org-highlight-numbers-number" > 6rpm< / span > '< span class = "org-rainbow-delimiters-depth-1" > )< / span > ;
plot< span class = "org-rainbow-delimiters-depth-1" > (< / span > f, sqrt< span class = "org-rainbow-delimiters-depth-2" > (< / span > px60r< span class = "org-rainbow-delimiters-depth-2" > )< / span > , 'DisplayName', '< span class = "org-highlight-numbers-number" > 60rpm< / span > '< span class = "org-rainbow-delimiters-depth-1" > )< / span > ;
plot< span class = "org-rainbow-delimiters-depth-1" > (< / span > f, sqrt< span class = "org-rainbow-delimiters-depth-2" > (< / span > pxdir< span class = "org-rainbow-delimiters-depth-2" > )< / span > , < span class = "org-string" > 'k-', 'DisplayName', 'Direct'< / span > < span class = "org-rainbow-delimiters-depth-1" > )< / span > ;
hold off;
< span class = "org-type" > set< / span > < span class = "org-rainbow-delimiters-depth-1" > (< / span > < span class = "org-variable-name" > gca< / span > , < span class = "org-string" > 'xscale', 'log'< / span > < span class = "org-rainbow-delimiters-depth-1" > )< / span > ;
< span class = "org-type" > set< / span > < span class = "org-rainbow-delimiters-depth-1" > (< / span > < span class = "org-variable-name" > gca< / span > , < span class = "org-string" > 'yscale', 'log'< / span > < span class = "org-rainbow-delimiters-depth-1" > )< / span > ;
xlabel< span class = "org-rainbow-delimiters-depth-1" > (< / span > < span class = "org-string" > 'Frequency < / span > < span class = "org-string" > < span class = "org-rainbow-delimiters-depth-2" > [< / span > < / span > < span class = "org-string" > Hz< / span > < span class = "org-string" > < span class = "org-rainbow-delimiters-depth-2" > ]< / span > < / span > < span class = "org-string" > '< / span > < span class = "org-string" > < span class = "org-rainbow-delimiters-depth-1" > )< / span > < / span > < span class = "org-string" > ; ylabel< / span > < span class = "org-string" > < span class = "org-rainbow-delimiters-depth-1" > (< / span > < / span > < span class = "org-string" > '< / span > ASD of the measured Voltage $< span class = "org-type" > \< / span > left< span class = "org-rainbow-delimiters-depth-2" > [< / span > < span class = "org-type" > \< / span > frac< span class = "org-rainbow-delimiters-depth-3" > {< / span > V< span class = "org-rainbow-delimiters-depth-3" > }{< / span > < span class = "org-type" > \< / span > sqrt< span class = "org-rainbow-delimiters-depth-4" > {< / span > Hz< span class = "org-rainbow-delimiters-depth-4" > }< / span > < span class = "org-rainbow-delimiters-depth-3" > }< / span > < span class = "org-type" > \< / span > right< span class = "org-rainbow-delimiters-depth-2" > ]< / span > $'< span class = "org-rainbow-delimiters-depth-1" > )< / span >
legend< span class = "org-rainbow-delimiters-depth-1" > (< / span > < span class = "org-string" > 'Location', 'northeast'< / span > < span class = "org-rainbow-delimiters-depth-1" > )< / span > ;
xlim< span class = "org-rainbow-delimiters-depth-1" > (< / span > < span class = "org-rainbow-delimiters-depth-2" > [< / span > < span class = "org-highlight-numbers-number" > 0< / span > .< span class = "org-highlight-numbers-number" > 1< / span > , < span class = "org-highlight-numbers-number" > 500< / span > < span class = "org-rainbow-delimiters-depth-2" > ]< / span > < span class = "org-rainbow-delimiters-depth-1" > )< / span > ;
< / pre >
< / div >
< div id = "org16c9932" class = "figure" >
< p > < img src = "figs/sr_psd_compare.png" alt = "sr_psd_compare.png" / >
< / p >
< p > < span class = "figure-number" > Figure 8: < / span > Comparison of the ASD of the measured signals when the slip-ring is ON, OFF and turning< / p >
< / div >
< / div >
< / div >
< div id = "outline-container-org1067ac0" class = "outline-3" >
< h3 id = "org1067ac0" > < span class = "section-number-3" > 3.5< / span > Conclusion< / h3 >
< div class = "outline-text-3" id = "text-3-5" >
< div class = "important" >
< p >
< / p >
< / div >
< / div >
< / div >
< / div >
< div id = "outline-container-orga6075e6" class = "outline-2" >
< h2 id = "orga6075e6" > < span class = "section-number-2" > 4< / span > Measure of the noise induced by the slip ring when using a geophone< / h2 >
< div class = "outline-text-2" id = "text-4" >
< p >
The data and matlab files are accessible < a href = "data/meas_sr_geophone.zip" > here< / a > .
< / p >
< / div >
< div id = "outline-container-orga3d1fca" class = "outline-3" >
< h3 id = "orga3d1fca" > < span class = "section-number-3" > 4.1< / span > Measurement Description< / h3 >
< div class = "outline-text-3" id = "text-4-1" >
< p >
< b > Goal< / b > :
< / p >
< ul class = "org-ul" >
< li > Determine if the noise induced by the slip-ring is a limiting factor when measuring the signal coming from a geophone< / li >
< / ul >
< p >
< b > Setup< / b > :
< / p >
< ul class = "org-ul" >
< li > The geophone is located at the sample location< / li >
< li > The two Voltage amplifiers have the following settings:
< ul class = "org-ul" >
< li > AC< / li >
< li > 60dB< / li >
< li > 1kHz< / li >
< / ul > < / li >
< li > The signal from the geophone is split into two using a T-BNC:
< ul class = "org-ul" >
< li > One part goes directly to the voltage amplifier and then to the ADC.< / li >
< li > The other part goes to the slip-ring=> voltage amplifier=> ADC.< / li >
< / ul > < / li >
< / ul >
< p >
First column: Direct measure
Second column: Slip-ring measure
< / p >
< p >
< b > Measurements< / b > :
< / p >
< ul class = "org-ul" >
< li > < code > data_012< / code > : Slip-Ring OFF< / li >
< li > < code > data_013< / code > : Slip-Ring ON< / li >
< / ul >
< / div >
< / div >
< div id = "outline-container-org874ef1d" class = "outline-3" >
< h3 id = "org874ef1d" > < span class = "section-number-3" > 4.2< / span > Load data< / h3 >
< div class = "outline-text-3" id = "text-4-2" >
< p >
We load the data of the z axis of two geophones.
< / p >
< div class = "org-src-container" >
< pre class = "src src-matlab" > sr_off = load< span class = "org-rainbow-delimiters-depth-1" > (< / span > < span class = "org-string" > 'mat/data_012.mat', 'data'< / span > < span class = "org-rainbow-delimiters-depth-1" > )< / span > ; sr_off = sr_off.data;
sr_on = load< span class = "org-rainbow-delimiters-depth-1" > (< / span > < span class = "org-string" > 'mat/data_013.mat', 'data'< / span > < span class = "org-rainbow-delimiters-depth-1" > )< / span > ; sr_on = sr_on.data;
< / pre >
< / div >
< / div >
< / div >
< div id = "outline-container-org3656f2f" class = "outline-3" >
< h3 id = "org3656f2f" > < span class = "section-number-3" > 4.3< / span > Time Domain< / h3 >
< div class = "outline-text-3" id = "text-4-3" >
< p >
We compare the signal when the Slip-Ring is OFF (figure < a href = "#orge33756c" > 9< / a > ) and when it is ON (figure < a href = "#orgb36b65d" > 10< / a > ).
< / p >
< div id = "orge33756c" class = "figure" >
< p > < img src = "figs/sr_geophone_time_off.png" alt = "sr_geophone_time_off.png" / >
< / p >
< p > < span class = "figure-number" > Figure 9: < / span > Comparison of the time domain signals when the slip-ring is OFF< / p >
< / div >
< div id = "orgb36b65d" class = "figure" >
< p > < img src = "figs/sr_geophone_time_on.png" alt = "sr_geophone_time_on.png" / >
< / p >
< p > < span class = "figure-number" > Figure 10: < / span > Comparison of the time domain signals when the slip-ring is ON< / p >
< / div >
< / div >
< / div >
< div id = "outline-container-orgf3c9d01" class = "outline-3" >
< h3 id = "orgf3c9d01" > < span class = "section-number-3" > 4.4< / span > Frequency Domain< / h3 >
< div class = "outline-text-3" id = "text-4-4" >
< p >
We first compute some parameters that will be used for the PSD computation.
< / p >
< div class = "org-src-container" >
< pre class = "src src-matlab" > dt = sr_off< span class = "org-rainbow-delimiters-depth-1" > (< / span > < span class = "org-highlight-numbers-number" > 2< / span > , < span class = "org-highlight-numbers-number" > 3< / span > < span class = "org-rainbow-delimiters-depth-1" > )< / span > < span class = "org-type" > -< / span > sr_off< span class = "org-rainbow-delimiters-depth-1" > (< / span > < span class = "org-highlight-numbers-number" > 1< / span > , < span class = "org-highlight-numbers-number" > 3< / span > < span class = "org-rainbow-delimiters-depth-1" > )< / span > ;
Fs = < span class = "org-highlight-numbers-number" > 1< / span > < span class = "org-type" > /< / span > dt; < span class = "org-comment" > % [Hz]< / span >
win = hanning< span class = "org-rainbow-delimiters-depth-1" > (< / span > ceil< span class = "org-rainbow-delimiters-depth-2" > (< / span > < span class = "org-highlight-numbers-number" > 10< / span > < span class = "org-type" > *< / span > Fs< span class = "org-rainbow-delimiters-depth-2" > )< / span > < span class = "org-rainbow-delimiters-depth-1" > )< / span > ;
< / pre >
< / div >
< p >
Then we compute the Power Spectral Density using < code > pwelch< / code > function.
< / p >
< div class = "org-src-container" >
< pre class = "src src-matlab" > < span class = "org-comment" > % Direct measure< / span >
< span class = "org-rainbow-delimiters-depth-1" > [< / span > pxdoff, < span class = "org-type" > ~< / span > < span class = "org-rainbow-delimiters-depth-1" > ]< / span > = pwelch< span class = "org-rainbow-delimiters-depth-1" > (< / span > sr_off< span class = "org-rainbow-delimiters-depth-2" > (< / span > < span class = "org-type" > :< / span > , < span class = "org-highlight-numbers-number" > 1< / span > < span class = "org-rainbow-delimiters-depth-2" > )< / span > , win, < span class = "org-rainbow-delimiters-depth-2" > []< / span > , < span class = "org-rainbow-delimiters-depth-2" > []< / span > , Fs< span class = "org-rainbow-delimiters-depth-1" > )< / span > ;
< span class = "org-rainbow-delimiters-depth-1" > [< / span > pxdon, < span class = "org-type" > ~< / span > < span class = "org-rainbow-delimiters-depth-1" > ]< / span > = pwelch< span class = "org-rainbow-delimiters-depth-1" > (< / span > sr_on< span class = "org-rainbow-delimiters-depth-2" > (< / span > < span class = "org-type" > :< / span > , < span class = "org-highlight-numbers-number" > 1< / span > < span class = "org-rainbow-delimiters-depth-2" > )< / span > , win, < span class = "org-rainbow-delimiters-depth-2" > []< / span > , < span class = "org-rainbow-delimiters-depth-2" > []< / span > , Fs< span class = "org-rainbow-delimiters-depth-1" > )< / span > ;
< span class = "org-comment" > % Slip-Ring measure< / span >
< span class = "org-rainbow-delimiters-depth-1" > [< / span > pxsroff, f< span class = "org-rainbow-delimiters-depth-1" > ]< / span > = pwelch< span class = "org-rainbow-delimiters-depth-1" > (< / span > sr_off< span class = "org-rainbow-delimiters-depth-2" > (< / span > < span class = "org-type" > :< / span > , < span class = "org-highlight-numbers-number" > 2< / span > < span class = "org-rainbow-delimiters-depth-2" > )< / span > , win, < span class = "org-rainbow-delimiters-depth-2" > []< / span > , < span class = "org-rainbow-delimiters-depth-2" > []< / span > , Fs< span class = "org-rainbow-delimiters-depth-1" > )< / span > ;
< span class = "org-rainbow-delimiters-depth-1" > [< / span > pxsron, < span class = "org-type" > ~< / span > < span class = "org-rainbow-delimiters-depth-1" > ]< / span > = pwelch< span class = "org-rainbow-delimiters-depth-1" > (< / span > sr_on< span class = "org-rainbow-delimiters-depth-2" > (< / span > < span class = "org-type" > :< / span > , < span class = "org-highlight-numbers-number" > 2< / span > < span class = "org-rainbow-delimiters-depth-2" > )< / span > , win, < span class = "org-rainbow-delimiters-depth-2" > []< / span > , < span class = "org-rainbow-delimiters-depth-2" > []< / span > , Fs< span class = "org-rainbow-delimiters-depth-1" > )< / span > ;
< / pre >
< / div >
< p >
Finally, we compare the Amplitude Spectral Density of the signals (figure [[]]);
< / p >
< div class = "org-src-container" >
< pre class = "src src-matlab" > < span class = "org-type" > figure< / span > ;
hold on;
plot< span class = "org-rainbow-delimiters-depth-1" > (< / span > f, sqrt< span class = "org-rainbow-delimiters-depth-2" > (< / span > pxdoff< span class = "org-rainbow-delimiters-depth-2" > )< / span > , < span class = "org-string" > 'DisplayName', 'Direct - OFF'< / span > < span class = "org-rainbow-delimiters-depth-1" > )< / span > ;
plot< span class = "org-rainbow-delimiters-depth-1" > (< / span > f, sqrt< span class = "org-rainbow-delimiters-depth-2" > (< / span > pxsroff< span class = "org-rainbow-delimiters-depth-2" > )< / span > , < span class = "org-string" > 'DisplayName', 'Slip-Ring - OFF'< / span > < span class = "org-rainbow-delimiters-depth-1" > )< / span > ;
plot< span class = "org-rainbow-delimiters-depth-1" > (< / span > f, sqrt< span class = "org-rainbow-delimiters-depth-2" > (< / span > pxdon< span class = "org-rainbow-delimiters-depth-2" > )< / span > , < span class = "org-string" > 'DisplayName', 'Direct - ON'< / span > < span class = "org-rainbow-delimiters-depth-1" > )< / span > ;
plot< span class = "org-rainbow-delimiters-depth-1" > (< / span > f, sqrt< span class = "org-rainbow-delimiters-depth-2" > (< / span > pxsron< span class = "org-rainbow-delimiters-depth-2" > )< / span > , < span class = "org-string" > 'DisplayName', 'Slip-Ring - ON'< / span > < span class = "org-rainbow-delimiters-depth-1" > )< / span > ;
hold off;
< span class = "org-type" > set< / span > < span class = "org-rainbow-delimiters-depth-1" > (< / span > < span class = "org-variable-name" > gca< / span > , < span class = "org-string" > 'xscale', 'log'< / span > < span class = "org-rainbow-delimiters-depth-1" > )< / span > ;
< span class = "org-type" > set< / span > < span class = "org-rainbow-delimiters-depth-1" > (< / span > < span class = "org-variable-name" > gca< / span > , < span class = "org-string" > 'yscale', 'log'< / span > < span class = "org-rainbow-delimiters-depth-1" > )< / span > ;
xlabel< span class = "org-rainbow-delimiters-depth-1" > (< / span > < span class = "org-string" > 'Frequency < / span > < span class = "org-string" > < span class = "org-rainbow-delimiters-depth-2" > [< / span > < / span > < span class = "org-string" > Hz< / span > < span class = "org-string" > < span class = "org-rainbow-delimiters-depth-2" > ]< / span > < / span > < span class = "org-string" > '< / span > < span class = "org-string" > < span class = "org-rainbow-delimiters-depth-1" > )< / span > < / span > < span class = "org-string" > ; ylabel< / span > < span class = "org-string" > < span class = "org-rainbow-delimiters-depth-1" > (< / span > < / span > < span class = "org-string" > '< / span > ASD of the measured Voltage $< span class = "org-type" > \< / span > left< span class = "org-rainbow-delimiters-depth-2" > [< / span > < span class = "org-type" > \< / span > frac< span class = "org-rainbow-delimiters-depth-3" > {< / span > V< span class = "org-rainbow-delimiters-depth-3" > }{< / span > < span class = "org-type" > \< / span > sqrt< span class = "org-rainbow-delimiters-depth-4" > {< / span > Hz< span class = "org-rainbow-delimiters-depth-4" > }< / span > < span class = "org-rainbow-delimiters-depth-3" > }< / span > < span class = "org-type" > \< / span > right< span class = "org-rainbow-delimiters-depth-2" > ]< / span > $'< span class = "org-rainbow-delimiters-depth-1" > )< / span >
legend< span class = "org-rainbow-delimiters-depth-1" > (< / span > < span class = "org-string" > 'Location', 'northeast'< / span > < span class = "org-rainbow-delimiters-depth-1" > )< / span > ;
xlim< span class = "org-rainbow-delimiters-depth-1" > (< / span > < span class = "org-rainbow-delimiters-depth-2" > [< / span > < span class = "org-highlight-numbers-number" > 0< / span > .< span class = "org-highlight-numbers-number" > 1< / span > , < span class = "org-highlight-numbers-number" > 500< / span > < span class = "org-rainbow-delimiters-depth-2" > ]< / span > < span class = "org-rainbow-delimiters-depth-1" > )< / span > ;
< / pre >
< / div >
< div id = "org574455b" class = "figure" >
< p > < img src = "figs/sr_geophone_asd.png" alt = "sr_geophone_asd.png" / >
< / p >
< p > < span class = "figure-number" > Figure 11: < / span > Comparison of the Amplitude Spectral Sensity< / p >
< / div >
< div id = "org7c2558c" class = "figure" >
< p > < img src = "figs/sr_geophone_asd_zoom.png" alt = "sr_geophone_asd_zoom.png" / >
< / p >
< p > < span class = "figure-number" > Figure 12: < / span > Comparison of the Amplitude Spectral Sensity - Zoom< / p >
< / div >
< / div >
< / div >
< div id = "outline-container-orgbee8de0" class = "outline-3" >
< h3 id = "orgbee8de0" > < span class = "section-number-3" > 4.5< / span > Conclusion< / h3 >
< div class = "outline-text-3" id = "text-4-5" >
< div class = "important" >
< ul class = "org-ul" >
< li > When the slip-ring is OFF, it does not add any noise to the measurement< / li >
< li > When the slip-ring is ON, it adds significant noise to the signal< / li >
< / ul >
< / div >
< / div >
< / div >
< / div >
< div id = "outline-container-org22d6637" class = "outline-2" >
< h2 id = "org22d6637" > < span class = "section-number-2" > 5< / span > Measure of the influence of the AC/DC option on the voltage amplifiers< / h2 >
< div class = "outline-text-2" id = "text-5" >
< p >
The data and matlab files are accessible < a href = "data/meas_noise_ac_dc.zip" > here< / a > .
< / p >
< / div >
< div id = "outline-container-org947094c" class = "outline-3" >
< h3 id = "org947094c" > < span class = "section-number-3" > 5.1< / span > Measurement Description< / h3 >
< div class = "outline-text-3" id = "text-5-1" >
< p >
< b > Goal< / b > :
< / p >
< ul class = "org-ul" >
< li > Measure the influence of the high-pass filter option of the voltage amplifiers< / li >
< / ul >
< p >
< b > Setup< / b > :
< / p >
< ul class = "org-ul" >
< li > One geophone is located on the marble.< / li >
< li > It's signal goes to two voltage amplifiers with a gain of 60dB.< / li >
< li > One voltage amplifier is on the AC option, the other is on the DC option.< / li >
< / ul >
< p >
< b > Measurements< / b > :
First measurement (< code > mat/data_014.mat< / code > file):
< / p >
< table border = "2" cellspacing = "0" cellpadding = "6" rules = "groups" frame = "hsides" >
< colgroup >
< col class = "org-right" / >
< col class = "org-left" / >
< / colgroup >
< thead >
< tr >
< th scope = "col" class = "org-right" > Column< / th >
< th scope = "col" class = "org-left" > Signal< / th >
< / tr >
< / thead >
< tbody >
< tr >
< td class = "org-right" > 1< / td >
< td class = "org-left" > Amplifier 1 with AC option< / td >
< / tr >
< tr >
< td class = "org-right" > 2< / td >
< td class = "org-left" > Amplifier 2 with DC option< / td >
< / tr >
< tr >
< td class = "org-right" > 3< / td >
< td class = "org-left" > Time< / td >
< / tr >
< / tbody >
< / table >
< p >
Second measurement (< code > mat/data_015.mat< / code > file):
< / p >
< table border = "2" cellspacing = "0" cellpadding = "6" rules = "groups" frame = "hsides" >
< colgroup >
< col class = "org-right" / >
< col class = "org-left" / >
< / colgroup >
< thead >
< tr >
< th scope = "col" class = "org-right" > Column< / th >
< th scope = "col" class = "org-left" > Signal< / th >
< / tr >
< / thead >
< tbody >
< tr >
< td class = "org-right" > 1< / td >
< td class = "org-left" > Amplifier 1 with DC option< / td >
< / tr >
< tr >
< td class = "org-right" > 2< / td >
< td class = "org-left" > Amplifier 2 with AC option< / td >
< / tr >
< tr >
< td class = "org-right" > 3< / td >
< td class = "org-left" > Time< / td >
< / tr >
< / tbody >
< / table >
< / div >
< / div >
< div id = "outline-container-orgd3f6cb3" class = "outline-3" >
< h3 id = "orgd3f6cb3" > < span class = "section-number-3" > 5.2< / span > Load data< / h3 >
< div class = "outline-text-3" id = "text-5-2" >
< p >
We load the data of the z axis of two geophones.
< / p >
< div class = "org-src-container" >
< pre class = "src src-matlab" > meas14 = load< span class = "org-rainbow-delimiters-depth-1" > (< / span > < span class = "org-string" > 'mat/data_014.mat', 'data'< / span > < span class = "org-rainbow-delimiters-depth-1" > )< / span > ; meas14 = meas14.data;
meas15 = load< span class = "org-rainbow-delimiters-depth-1" > (< / span > < span class = "org-string" > 'mat/data_015.mat', 'data'< / span > < span class = "org-rainbow-delimiters-depth-1" > )< / span > ; meas15 = meas15.data;
< / pre >
< / div >
< / div >
< / div >
< div id = "outline-container-org85a856a" class = "outline-3" >
< h3 id = "org85a856a" > < span class = "section-number-3" > 5.3< / span > Time Domain< / h3 >
< div class = "outline-text-3" id = "text-5-3" >
< p >
The signals are shown on figure < a href = "#org5f9a2bc" > 13< / a > .
< / p >
< div id = "org5f9a2bc" class = "figure" >
< p > < img src = "figs/ac_dc_option_time.png" alt = "ac_dc_option_time.png" / >
< / p >
< p > < span class = "figure-number" > Figure 13: < / span > Comparison of the signals going through the Voltage amplifiers< / p >
< / div >
< / div >
< / div >
< div id = "outline-container-org18d9eca" class = "outline-3" >
< h3 id = "org18d9eca" > < span class = "section-number-3" > 5.4< / span > Frequency Domain< / h3 >
< div class = "outline-text-3" id = "text-5-4" >
< p >
We first compute some parameters that will be used for the PSD computation.
< / p >
< div class = "org-src-container" >
< pre class = "src src-matlab" > dt = meas14< span class = "org-rainbow-delimiters-depth-1" > (< / span > < span class = "org-highlight-numbers-number" > 2< / span > , < span class = "org-highlight-numbers-number" > 3< / span > < span class = "org-rainbow-delimiters-depth-1" > )< / span > < span class = "org-type" > -< / span > meas14< span class = "org-rainbow-delimiters-depth-1" > (< / span > < span class = "org-highlight-numbers-number" > 1< / span > , < span class = "org-highlight-numbers-number" > 3< / span > < span class = "org-rainbow-delimiters-depth-1" > )< / span > ;
Fs = < span class = "org-highlight-numbers-number" > 1< / span > < span class = "org-type" > /< / span > dt; < span class = "org-comment" > % [Hz]< / span >
win = hanning< span class = "org-rainbow-delimiters-depth-1" > (< / span > ceil< span class = "org-rainbow-delimiters-depth-2" > (< / span > < span class = "org-highlight-numbers-number" > 10< / span > < span class = "org-type" > *< / span > Fs< span class = "org-rainbow-delimiters-depth-2" > )< / span > < span class = "org-rainbow-delimiters-depth-1" > )< / span > ;
< / pre >
< / div >
< p >
Then we compute the Power Spectral Density using < code > pwelch< / code > function.
< / p >
< div class = "org-src-container" >
< pre class = "src src-matlab" > < span class = "org-rainbow-delimiters-depth-1" > [< / span > pxamp1ac, f< span class = "org-rainbow-delimiters-depth-1" > ]< / span > = pwelch< span class = "org-rainbow-delimiters-depth-1" > (< / span > meas14< span class = "org-rainbow-delimiters-depth-2" > (< / span > < span class = "org-type" > :< / span > , < span class = "org-highlight-numbers-number" > 1< / span > < span class = "org-rainbow-delimiters-depth-2" > )< / span > , win, < span class = "org-rainbow-delimiters-depth-2" > []< / span > , < span class = "org-rainbow-delimiters-depth-2" > []< / span > , Fs< span class = "org-rainbow-delimiters-depth-1" > )< / span > ;
< span class = "org-rainbow-delimiters-depth-1" > [< / span > pxamp2dc, < span class = "org-type" > ~< / span > < span class = "org-rainbow-delimiters-depth-1" > ]< / span > = pwelch< span class = "org-rainbow-delimiters-depth-1" > (< / span > meas14< span class = "org-rainbow-delimiters-depth-2" > (< / span > < span class = "org-type" > :< / span > , < span class = "org-highlight-numbers-number" > 2< / span > < span class = "org-rainbow-delimiters-depth-2" > )< / span > , win, < span class = "org-rainbow-delimiters-depth-2" > []< / span > , < span class = "org-rainbow-delimiters-depth-2" > []< / span > , Fs< span class = "org-rainbow-delimiters-depth-1" > )< / span > ;
< span class = "org-rainbow-delimiters-depth-1" > [< / span > pxamp1dc, < span class = "org-type" > ~< / span > < span class = "org-rainbow-delimiters-depth-1" > ]< / span > = pwelch< span class = "org-rainbow-delimiters-depth-1" > (< / span > meas15< span class = "org-rainbow-delimiters-depth-2" > (< / span > < span class = "org-type" > :< / span > , < span class = "org-highlight-numbers-number" > 1< / span > < span class = "org-rainbow-delimiters-depth-2" > )< / span > , win, < span class = "org-rainbow-delimiters-depth-2" > []< / span > , < span class = "org-rainbow-delimiters-depth-2" > []< / span > , Fs< span class = "org-rainbow-delimiters-depth-1" > )< / span > ;
< span class = "org-rainbow-delimiters-depth-1" > [< / span > pxamp2ac, < span class = "org-type" > ~< / span > < span class = "org-rainbow-delimiters-depth-1" > ]< / span > = pwelch< span class = "org-rainbow-delimiters-depth-1" > (< / span > meas15< span class = "org-rainbow-delimiters-depth-2" > (< / span > < span class = "org-type" > :< / span > , < span class = "org-highlight-numbers-number" > 2< / span > < span class = "org-rainbow-delimiters-depth-2" > )< / span > , win, < span class = "org-rainbow-delimiters-depth-2" > []< / span > , < span class = "org-rainbow-delimiters-depth-2" > []< / span > , Fs< span class = "org-rainbow-delimiters-depth-1" > )< / span > ;
< / pre >
< / div >
< p >
The ASD of the signals are compare on figure < a href = "#org86218d3" > 14< / a > .
< / p >
< div id = "org86218d3" class = "figure" >
< p > < img src = "figs/ac_dc_option_asd.png" alt = "ac_dc_option_asd.png" / >
< / p >
< p > < span class = "figure-number" > Figure 14: < / span > Amplitude Spectral Density of the measured signals< / p >
< / div >
< / div >
< / div >
< div id = "outline-container-org21d0038" class = "outline-3" >
< h3 id = "org21d0038" > < span class = "section-number-3" > 5.5< / span > Conclusion< / h3 >
< div class = "outline-text-3" id = "text-5-5" >
< div class = "important" >
< p >
< / p >
< / div >
2019-05-02 14:09:20 +02:00
< / div >
2019-05-02 14:06:23 +02:00
< / div >
< / div >
< / div >
< div id = "postamble" class = "status" >
< p class = "author" > Author: Thomas Dehaeze< / p >
2019-05-06 10:28:35 +02:00
< p class = "date" > Created: 2019-05-06 lun. 10:28< / p >
2019-05-02 14:06:23 +02:00
< p class = "validation" > < a href = "http://validator.w3.org/check?uri=referer" > Validate< / a > < / p >
< / div >
< / body >
< / html >
