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ID Date Author Type Categorydown Subject Text Attachments
  13593   Wed Jan 31 16:29:42 2018 gautamUpdateALSModulation depthsI used the Beat
Mouth to make a quick
 PMCmodDepth.pdfXPDH.pdf 
  13594   Wed Jan 31 16:33:53 2018 gautamUpdateALSALS electronics at LSC rack[steve,
gautam]

We installed some 
  
  13595   Wed Jan 31 22:32:11 2018 gautamUpdateALSALS signal chain + power budgetSummary:

 FiberALS_PowerBudget.pdfpreampProposed.pdf 
  13596   Thu Feb 1 01:24:56 2018 gautamUpdateALSD0902745 revamp underwayI effected the change to the Audio IF preamp
stage on channels 3 and 4 (Xarm and Yarm
respectively) using the resistors Steve ordered
 PSLinterlock.png 
  13597   Thu Feb 1 15:31:12 2018 gautamUpdateALSALS signal chain + power budgetSummary:

A
  
  13599   Fri Feb 2 00:26:34 2018 gautamUpdateALSD0902745 revamp underwayI saw some interesting behaviour of the
Audio IF amplifier stage on the demod board
today, by accident. I was testing the board
  
  13600   Fri Feb 2 13:16:55 2018 gautamUpdateALSALS signals whitening switchingWhile setting up for this measurement,
I noticed something odd with the whitening
switching for the ALS channels. For the usual
 ALS_whitening_switching.pdfALS_whitening_switching_works.pdf 
  13606   Mon Feb 5 14:11:01 2018 gautamUpdateALSHuge harmonics in ALS channelsI've been trying to setup for the THD
measuremetn at the LSC rack for a couple
of days now, but am plagued by a problem
 ALSpowerlineHarmonics.pdf2A1B3AC4-4059-416A-AD88-8AB0431D7A55.jpeg 
  13608   Mon Feb 5 22:57:28 2018 gautamUpdateALSHuge harmonics in ALS channelsDid some quick additional checks to figure
out what's going on here.


The SOS/dewhite board for
  
  13609   Tue Feb 6 11:13:26 2018 gautamUpdateALSPossible source of ground loop identifiedI think I've narrowed down the source
of this ground loop. 
 A68AF89C-E8A9-416D-BBD2-A1AD0A51E0B5.jpeg 
  13612   Tue Feb 6 22:55:51 2018 gautamUpdateALSPossible source of ground loop identified[koji, gautam]

We discussed possible solutions
  
  13613   Wed Feb 7 10:16:26 2018 gautamUpdateALSALS signal chain + power budgetAfter emailing the technical team at Menlo,
I have uploaded the more detailed information
they have given me on our wiki.
  
  13616   Wed Feb 7 15:51:15 2018 gautamUpdateALSD0902745 revamp completeSummary of my tests of the demod boards,
post gain modification:


DC tests (supply voltage,
 6613CD37-5014-44AE-B1FE-6F6A8137DF62.jpeg 
  13621   Thu Feb 8 00:33:20 2018 gautamUpdateALSD990694 characterization / THD measurement planI decided to try doing the THD measurement
with a function generator. Did some quick
trials tonight to verify that the measurement
 D990694THD_trial.pdf 
  13622   Thu Feb 8 01:27:16 2018 KojiUpdateALSD990694 characterization / THD measurement plan>
So my question is - should we just cut the
  
  13623   Thu Feb 8 12:00:09 2018 gautamUpdateALSD990694 is NOT differential receivingCorrecting a mistake   
  13625   Thu Feb 8 13:13:14 2018 gautamUpdateALSD990694 pulled outAfter labeling all cables, I pulled out
one of the D990694s in the LSC rack (the
one used for the ALS X signals, it is Rev-B1,
 IMG_5131.JPGIMG_5133.JPGD990694-B_cuttingPlan.pdf 
  13627   Thu Feb 8 18:10:36 2018 gautamUpdateALSD990694 pulled outThis is proving much more challenging than
I thought - while Cut #1 was easy to identify
and execute, my initial plan for Cut #2 seems
  
  13628   Fri Feb 9 13:37:44 2018 gautamUpdateALSTHD measurement trialI quickly put together some code that calculates
the THD from CDS data and generates a plot
(see e.g. Attachment #1).
 THD_trial.pdf 
  13635   Fri Feb 16 01:09:55 2018 gautamUpdateALSEX green locking duty cycleI have been puzzled as to why the duty
cycle of the EX
green locks are much
 GreenLock8hrs.png 
  13636   Fri Feb 16 01:34:40 2018 gautamUpdateALSD0902745 in-situ testingHaving implemented the changes to the audio
amplifier stage, I re-installed this unit
at the LSC rack, and did some testing. 
 BeatMouthX_20180216.pdfIMG_5134.JPG 
  13644   Tue Feb 20 23:08:27 2018 gautamUpdateALSD0902745 in-situ testingAttachment #1 shows
the ALS noise measurement today. Main differences
from the spectrum posted last week is that
 BeatMouthX_20180220_diffOut.pdf 
  13648   Thu Feb 22 00:09:11 2018 gautamUpdateALSD0902745 in-situ testingI thought a little bit about the design
of the preamp we want for the demodulated
ALS signals today. The requirements are:
 daughterBoard_TF.pdfdaughterBoard_noise.pdfIMG_6906.JPG 
  13655   Sun Feb 25 00:03:12 2018 gautamUpdateALSDaughter board prototypingUsing one of the prototype  schematic.pdfdaughterBoard_TF.pdfdaughterBoard_noise.pdfTEK00000.PNGdaughterBoard_noise.pdf 
  13657   Mon Feb 26 20:55:56 2018 ranaUpdateALSDaughter board prototypingLooks good.

* for bypass type applications,
you don't have to use Wima caps (which
  
  13658   Tue Feb 27 21:10:45 2018 gautamUpdateALSDaughter board testingI thought a little bit about the next steps
in testing the daughter board. The idea is
to install this into the existing 1U chassis
 IMG_6912.JPGIMG_6913.JPGIMG_6914.JPG 
  13661   Wed Feb 28 19:13:25 2018 gautamUpdateALSADC test for differential receiving in c1lsc[koji,
gautam]

we did a bunch of tests to figure
 c1lsc_ADCtest.png 
  13663   Fri Mar 2 01:45:06 2018 gautamUpdateALSnew look ALS electronicsI spent today making another daughter board
(so that we can use the new scheme for I
and Q for one arm), testing it (i.e. measuring
 IMG_6916.JPG 
  13666   Mon Mar 5 17:27:34 2018 gautamUpdateALSnew look ALS electronics - characterizationI did a quick test of the noise of the
new ALS electronics with the X arm ALS. Attachment
#1 shows the results - but something looks
 BeatMouthX_20180305_diffOut.pdf 
  13668   Thu Mar 8 00:40:25 2018 gautamUpdateALSnew look ALS electronics - characterizationI am almost ready for a digital test of
the new ALS electronics. Today, Koji and
I spent some time tapping new +/-24VDC DIN
 BeatMouthX_20180305_diffOut.pdf 
  13673   Thu Mar 8 19:38:37 2018 gautamUpdateALSdigital unwhitening of daughter boardI made a LISO fit of the measured TF of
the daughter board, so that I can digitally
invert the daughter board whitening. Results
 TFfit.pdf 
  13674   Thu Mar 8 23:50:27 2018 gautamUpdateALSFirst look at new ALS electronics
Locked single arms, dither aligned,
and saved offsets to EPICS (slow) sliders
in anticipation of having to reboot all vertex
 BeatMouth_OOL.pdf 
  13675   Fri Mar 9 01:07:01 2018 gautamUpdateALSFirst look at new ALS electronics[koji,
gautam]
 ALS_vs_POXnoise.pdf 
  13679   Mon Mar 12 22:08:31 2018 gautamUpdateALSNoisy POX[kevin, gautam]

we tested my noisy POX hypothesis
tonight. By locking the single arm with POX,
 NoisyPOX_20180312.pdf 
  13680   Mon Mar 12 23:57:31 2018 gautamUpdateALSNoisy POX[kevin,
gautam]
 NoisyPOXandPOY_20180312.pdfnoisyPOX_Jan2018.pdf 
  13688   Mon Mar 19 15:02:29 2018 gautamUpdateALSNoisy MC sensingThe working hypothesis, since the excess
noise in single arm locks is coherent between
both arms, the excess sensing noise is frequency
  
  13749   Thu Apr 12 18:12:49 2018 gautamUpdateALSNPRO channels hijackedSummary:


Today,
the measured IR ALS noise for the X arm was
dramatically improved. The main change was
 IR_ALS_20180412.pdfBeatMouthDrift.pngETMX_20180416.jpg 
  13751   Fri Apr 13 11:02:41 2018 gautamUpdateALSEX fiber polarization driftAttachment #1  EX_pol_drift.png 
  13752   Fri Apr 13 16:59:12 2018 gautamUpdateALSEX green mode-matchingTHIS CALCULATION   
  13753   Fri Apr 13 17:56:26 2018 gautamUpdateALSFibers switched outI swapped the EX fiber for the PSL fiber
in the polarization monitoring setup. There
is a lot more power in this fiber, and one
  
  13754   Sat Apr 14 14:42:09 2018 gautamUpdateALSFibers switched outIt looks like the drift in polarization
content in the PSL pickoff is actually much
higher than that in the EX pickoff. Note
 PSLdrift.png 
  13757   Tue Apr 17 14:08:29 2018 gautamUpdateALSFibers switched outA follow-up on the discussion from today's
lunch meeting - Rana pointed out that rotation
of the fiber in the mount by ~5degrees cannot
 PSL_fluctuations.png 
  13773   Fri Apr 20 00:26:34 2018 gautamUpdateALSFibers switched outSummary:

  
  13779   Sat Apr 21 20:25:12 2018 gautamUpdateALSPSL fiber pickoff statusSeems like there is still a bit of variation
in the power in the two polarizations, though
it is much smaller now, at the ~5% level
 PSL-beatMouthPickoff.png 
  13784   Tue Apr 24 11:31:59 2018 gautamConfigurationALSProposed changes to EX fiber couplingMotivation:
I want to make another measurement of the
 EX_fiber_MM.pdfEX_fiber_changes.png 
  13786   Tue Apr 24 18:54:15 2018 gautamConfigurationALSProposed changes to EX fiber couplingI started working on the EX table. Work
is ongoing so I will finish this up later
in the evening, but in case anyone is wondering
  
  13789   Wed Apr 25 19:09:37 2018 gautamConfigurationALSNew look EX Fiber couplingSummary:

I implemented most of the things
outlined in my previous elog.
 EX_fiber_MM.pdfIMG_6977.JPGIMG_6972.JPGIMG_6974.JPGIMG_6976.JPG 
  13791   Thu Apr 26 11:24:50 2018 gautamConfigurationALSNew look EX Fiber coupling - pol stabilityHere is a first look at the overnight stability.
For the temperature, I used the calibration
I found in the old psl database file, seems
 polStab.pdf 
  13792   Thu Apr 26 18:58:21 2018 BruceConfigurationALSNew look EX Fiber coupling - pol stability    
  13796   Fri Apr 27 01:36:02 2018 gautamConfigurationALSIR ALS noise performanceSummary:

My goal was to do some further
characterization of the IR ALS system tonight.
 2018_04_BeatMouth_POX.pdf2018_04_BeatMouth.pdfALSSpecgram.pdfALS_ASD.pdfALSstab.pdf 
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