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Fri Oct 4 13:41:44 2019, anchal, Notes, FSS, FSS Plant Model  
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Fri Oct 4 14:56:42 2019, Ian MacMillan, Notes, FSS, FSS Plant Model
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Tue Oct 8 10:41:43 2019, anchal, Notes, FSS, FSS Plant Model
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Mon Oct 14 12:54:41 2019, anchal, Notes, FSS, FSS Plant Model v2  
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Tue Oct 22 13:07:45 2019, Ian MacMillan, Notes, FSS, FSS Plant Model v2  
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Thu Oct 24 11:42:06 2019, Ian MacMillan, Notes, FSS, FSS Plant Model v2
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Tue Dec 3 17:27:54 2019, Ian MacMillan, Notes, FSS, FSS Plant Model v2 
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Mon Dec 9 18:08:13 2019, Ian MacMillan, Notes, FSS, FSS Plant Model v2 
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Tue Dec 10 11:57:58 2019, Ian MacMillan, Notes, FSS, FSS Plant Model v2
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Thu Dec 12 11:54:11 2019, Ian MacMillan, Notes, FSS, FSS Plant Model v2   
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Thu Dec 12 19:05:33 2019, rana, Notes, FSS, FSS Plant Model v2
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Mon Dec 16 09:43:56 2019, Ian MacMillan, Notes, FSS, FSS Plant Model v2  
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Tue Jan 14 13:30:39 2020, Ian MacMillan, Notes, FSS, FSS Plant Model v2  
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Tue Jan 14 13:32:16 2020, Ian MacMillan, Notes, FSS, FSS Plant Model v2  
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Tue Jan 28 13:27:25 2020, Ian MacMillan, Notes, FSS, FSS Plant Model v2  
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Mon Feb 10 12:46:17 2020, Ian MacMillan, Notes, FSS, FSS Plant Model v2
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Fri Feb 14 16:46:47 2020, Ian MacMillan, Notes, FSS, FSS Plant Model v2 
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Tue Feb 18 15:42:46 2020, Ian MacMillan, Notes, FSS, FSS Plant Model v2  
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Tue Mar 3 17:13:04 2020, Ian MacMillan, Notes, FSS, FSS Plant Model v2    
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Wed Mar 11 15:40:50 2020, Ian MacMillan, Notes, FSS, FSS Plant Model v2 
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Thu Mar 12 16:21:49 2020, Ian MacMillan, Notes, FSS, FSS Plant Model v2 
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Thu Mar 12 17:18:51 2020, rana, Notes, FSS, FSS Plant Model v2
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Message ID: 2550
Entry time: Tue Mar 3 17:13:04 2020
In reply to: 2541
Reply to this: 2554
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Author: |
Ian MacMillan |
Type: |
Notes |
Category: |
FSS |
Subject: |
FSS Plant Model v2 |
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Anchal and I connected the circuit to the EOM and PZT in a closed loop (LIGO-D040105). We looked at the output as seen in the Oscilloscope data and it does not look like the sinusoid that I was expecting. It looks like the sum of a square wave and a misshapen sinusoid. I think that there is some sort of reflection of the signal that is causing this but I don't know where. When we took the spectrum of that data and we saw a large peak at around 2kHz and then harmonics of the signal. (Note there are two spectrums both with the same data just one is on a log-log scale)
We also measured the open-loop transfer function of the circuit and the results are given below. The unity gain frequency is 1240 Hz. This is different from the 2688 Hz that is the location of the first peak in the spectrum. We had thought that maybe these harmonics were a result of the UGF but they don't occur at the same frequency.
We will try to figure out why we have harmonics and what we can do to prevent them. We really have no idea what they are. |
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