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  14848   Fri Aug 16 16:40:04 2019 gautamUpdateCDS1Y3 work

[chub, gautam]

Installation: The following equipment were installed in 1Y3, see Attachment #1:

  1. Supermicro server, which is the new c1iscaux machine, with IP Address 192.168.113.83.
  2. 6U Acromag chassis which contains all the ADCs, DACs and BIO units.
  3. 2 Sorensen DC power supplies to provide +24 V DC and +15 V DC to the Acromags.
  4. Fusable DIN rail power blocks were installed on the North side of the 1Y3 rack - I placed 2 banks of 5 connectors each for +15 V DC and +24 V DC.

Removal: The following equipment was removed from 1Y3:

  1. VME crates that were the old c1iscaux and c1iscaux2 machines.
  2. Spare VME crate that used to be c1susaux, which Chub and I brought over to 1Y3 in an attempt to revive the broken c1iscaux2.
  3. Approximately 30 twisted ribbon cables that were going to the cross connects. For now, we have not done a full cleanup and they are just piled along the east arm (see Attachment #2), beware if you are walking there!

Software: 

  1. I connected the c1iscaux machine to the martian network.
  2. Then I edited the relevant files on chiara to free up the IP addresses previously used by c1iscaux (192.168.113.81) and c1iscaux2 (192.168.113.82), and re-assigned the IP address used for c1iscaux to be 192.168.113.83.
  3. I also changed the hostname of the c1iscaux machine (it was temporarily called c1iscaux3 to allow bench testing).
  4. I moved the old /cvs/cds/caltech/target/c1iscaux and /cvs/cds/caltech/target/c1iscaux2 directories to /cvs/cds/caltech/target/preAcromag_oldVME/c1iscaux and /cvs/cds/caltech/target/preAcromag_oldVME/c1iscaux2 respectively.
  5. I moved the temporarily named /cvs/cds/caltech/target/c1iscaux3 directory, from which I was running all the tests, to /cvs/cds/caltech/target/c1iscaux.
  6. I edited all references to c1iscaux3 in the systemd files so that we can run the approriate systemd services.

Next steps: 

  1. We did not get around to running the DB37 cables between the Acromag chassis and the 1Y2 Eurocrates today - this operation itself took the whole day as we also needed to lay out some support struts etc on the rack to support the Sorensens and the Acromag chassis.
  2. Once the Acromags are connected to the Eurocrates, we have to run in-situ tests to make sure the appropriate functionality has been restored.
  3. We must have bumped something in the c1lsc expansion chassis - the CDS FE overview screen is reporting some errors (see Attachment #3). I will fix this.
  4. General tidiness, strain-relief etc.
Quote:

I judge that we are good to go ahead with an install tomorrow.

  4609   Tue May 3 10:59:31 2011 josephbUpdateCDS1Y2 binary output adapter board now powered

I temporarily turned off the power to the 1Y2 rack this morning while wiring in the binary output adapter board power (+/- 15V) into the cross connects.

The board is now powered and we can proceed to testing if can actually control the LSC whitening filters.

  4717   Sat May 14 14:50:21 2011 KojiUpdateLSC1Y2 5V Blown Fuse found -> Fixed

Incidentally, a blown fuse on 5V line at 1Y2 rack was found during the intallation of Sorensens.
The fuse (5A 125V) has been replaced and fixed.

When I plugged the fuse in, I heard some sound like relays were switched. Are there any relays in the LSC rack?

It was a 9th fuse from the top as seen in the picture.

  16453   Mon Nov 8 10:13:52 2021 PacoSummaryBHD1Y1 rack work; Sorensens removed

[Paco, Chub]

Removed all sorensen power supplies from this rack except for 12 VDC one; that one got pushed to the top of the rack and is still powering the cameras.

  16454   Mon Nov 8 13:13:00 2021 KojiSummaryBHD1Y1 rack work; Sorensens removed

Updated the rack layout. Now there is an issue.
We were supposed to have 1U space at the top, but it was occupied by the 12V.
We need to either lower the c1sus2 and IO chassis 1U or move the Sorensen at the bottom.

  16455   Mon Nov 8 15:29:05 2021 PacoSummaryBHD1Y1 rack work; New power for cameras

[Paco, Anchal]

In reference to Koji's concern (see previous elog), we have completely removed sorensen power supplies from 1Y1. We added a 12 Volts / 2 Amps AC-to-DC power supply for the cameras and verified it works. We stripped off all unused hardware from shutters and other power lines in the strips, and saved the relays and fuses.

We then mounted SR2, PR3, PR2 Sat Amps, 1Y1 Sat amp adapter, and C1SUS2 AA (2) and AI (3) boards. We made all connections we could make with the cables from the test stand, as well as power connections to an 18 VDC power strip.

  16540   Mon Jan 3 16:46:41 2022 PacoUpdateBHD1Y1 rack work for SR2, PR2, PR3

[Paco, Anchal]

Continued working on 1Y1 rack. Populated the 6 coil drivers, made all connections between sat amp, AA chassis, DAC, and ADC adapters for SR2, PR2, and PR3 suspensions. Powered all boxes and labeled them and cables where needed. Near the end, we had to increase the current limit on the positive rail sorensen (+18 V) from ~ 7 to > 8.0 Amps to feed all the instruments. We also increased the negative (-18 V) current limit proportionally.

We think we are ready for all the new SOS on this side electronics-wise.


Photos: https://photos.app.goo.gl/GviuqLQviSPo1M3G6

  16444   Tue Nov 2 16:42:00 2021 PacoSummaryBHD1Y1 rack work

[paco, ian]

After the new 1Y0 rack was placed near the 1Y1 rack by Chub and Anchal, today we worked on the 1Y1 rack. We removed some rails from spaces ~ 25 - 30. We then drilled a pair of ~ 10-32 thru-holes on some L-shaped bars to help support the c1sus2 machine weight. The hole spacing was set to 60 cm; this number is not a constant across all racks. Then, we mounted c1sus2. While doing this, Paco's knee clicked some of the video MUX box buttons (29 and 8 at least). We then opened the rack's side door to investigate the DC power strips on it before removing stuff. We did power off the DC33 supplies on there. No connections were made to allow us to keep building this rack.

When coming back to the control room, we noticed 3/4 video feed (analog) for the Test masses had gone down... why?


Next steps:

  • Remove sorensen (x5) power supplies from top of 1Y1 .. what are they actually powering???
  • Make more bars to support heavy IO exp and acromag chassis.
  • Make all connections (neat).

Update Tue Nov 2 18:52:39 2021

  • After turning Sorensens back up, the ETM/ITM video feed was restored. I will need to hunt the power lines carefully before removing these.
  16448   Thu Nov 4 15:03:43 2021 KojiSummaryBHD1Y1 rack work

I have visited the binder file for the 40m wiring file in the control room.
The 12V power supply on 1Y1 is for the CCD cameras. So we still want to keep the 12V 0.8A power and the side connections for these. It is not necessary to be Sorensen. Can we replace it with an AC-DC adapter with +12V/1A for example? BTW, the video matrix and quads are AC-powered.

The mysterious thick cables and cross-connects (green wires) on the side panel (labeled AP1/AP2/SP/IMCREFL) are for "EO shutters". It was meant for the protection of the PDs from bright beams.
I don't think they have been used. And we don't need them.

  16440   Fri Oct 29 14:39:37 2021 AnchalSummaryBHD1Y1 cleared. IY3 ready for C1SUS2 I/O and FE.

[Anchal, Paco]

We cleared 1Y1 rack today removing the following items. This stuff is sitting on the floor about 2 meters east of 1Y3 (see attachment 1):

  • A VME crate: We disconnected it's power cords from the side bus.
  • A NI PXIe-1071 crate with some SMA multiplexer units on it.

We also moved the power relay ethernet strip from the middle of the rack to the bottom of the rack clearing the space marked clear in Koji's schematics. See attachment 2.

There was nothing to clear in 1Y3. It is ready for installing c1sus2 I/O chassis and FE once the testing is complete.

We also removed some orphaned hanging SMA RG-405 cables between 1Y3 and 1Y1.

  16539   Mon Jan 3 12:05:08 2022 PacoUpdateBHD1Y0 rack work for LO2 AS1 AS4

[Paco, Anchal]

Continue working on 1Y0. Added coil drivers for LO2, AS1, AS4. Anchal made additional labels for cables and boxes. We lined up all cables, connected the different units and powered them without major events.

  16506   Tue Dec 14 19:29:42 2021 PacoUpdateBHD1Y0 rack work for LO1

[Paco]

Two coil drivers have been installed on 1Y0 (slots 6, 7, for LO1 SOS). All connections have been made from the DAC, AI board, DAC adapter, Coil driver, Sat Amp box. Then no SOS load installed, all return connections have been made from Sat Amp box, ADC adapter, AA board, and to ADC. We will continue this work tomorrow, and try to test everything before closing the loop for LO1 suspension.

  16463   Tue Nov 9 19:02:47 2021 AnchalSummaryBHD1Y0 Populated and 1Y1,1Y0 powered

[Anchal, Paco]

Today we populated 4 Sat Amp boxes for LO1, Lo2, AS1, and AS4, 2 BO boxes for C1SU2, and 1 Sat Amp Adaptor box, at 1Y0 according the latest rack plan. We also added 2 Sorenson power supplies in 1Y0 at the top slots to power +/- 18V DC strips on both 1Y1 and 1Y0. All wiring has been done for these power connections.

  5993   Thu Nov 24 01:28:09 2011 kiwamuUpdateGeneral1X8 sorensen came back

Quote from #5963

 - One of the Sorensens in 1X8 rack is showing the current limit sign. This is exactly the same situation as we saw before (#5592).

       Currently it's off. It needs an investigation to find who is drawing such a large amount of current.

 The 1X8 Sorensen's issue has been solved somehow.

 To investigate what is going on with the Sorensen in the 1X8 rack, I turned on the Sorensen.
Then this time it didn't show the current limit sign, the voltage went up to 15.0, where it is supposed to be.
Surprisingly this is exactly the same recovery process as we saw before (#5592).
  14592   Fri May 3 12:48:40 2019 gautamUpdateSUS1X4/1X5 cable admin

Chub and I crossed off some of these items today morning. The last bullet was addressed by Jon yesterday. I added a couple of new bullets.

The new power connectors will arrive next week, at which point we will install them. Note that there is no 24V Sorensen available, only 20V.

I am running a test on the 2W Mephisto for which I wanted the diagnostics connector plugged in again and Acromag channels to record them. So we set up the highly non-ideal but temporary set up shown in Attachment #1. This will be cleaned up by Monday evening latest.

update 1630 Monday 5/6: the sketchy PSL acromag setup has been disassembled.

Quote:
 
  • Take photos of the new setup, cabling.
  • Remove the old c1susaux crate from the rack to free up space, possibly put the PSL monitoring acromag chassis there.
  • Test that the OSEM PD whitening switching is working for all 8 vertex optics.(verified as of 5/3/19 5pm)
  • New 15V and 24V power cables with standard LIGO connectors need to be run from the Sorensenn supplies in 1X5. The chassis is currently powered by bench supplies sitting on a cart behind the rack.
  • All 24 new DB-37 signal cables need to be labeled.
  • New 96-pin DIN connectors need to be put on two ribbon cables (1Y5_80 B, 1Y5_81) in the 1X4 rack. We had to break these connectors to remove them from the back of the eurcrates.
  • General cleanup of any cables, etc. left around the rack. We cleaned up most things this evening.
  • Rename the host computer c1susaux2 --> c1susaux, and update the DNS lookup tables on chiara.
  10230   Thu Jul 17 17:08:58 2014 HarryUpdateGeneral1X2 Rack Changes

 Purpose

 

Steve and I moved some things around in the 1X2 rack in order to make room (roughly 6") for the electronics box that will contain rf frequency counters, ADC, and Raspberry Pi's for use in the Frequency Offset Locking apparatus

Picture

1X2Changes.png

Occurrences

First, we killed power by removing the fuse that the boxes we were moving were running through.

Then, we moved the boxes. I dropped//lost a washer. It didn't seem to cause any problems, so no further attempts to locate it were made.

The fuse was reinstalled, and everything was reconnected.

Moving Forward

We are now working on putting together the electronics box, which will contain ADC, and raspberry pi's. The frequency counters will be mounted on the front of the box.

Once complete, it will be installed for use in FOL.

  10233   Thu Jul 17 21:01:28 2014 ManasaUpdateGeneral1X2 Rack Changes

Quote:

 Purpose

 

Steve and I moved some things around in the 1X2 rack in order to make room (roughly 6") for the electronics box that will contain rf frequency counters, ADC, and Raspberry Pi's for use in the Frequency Offset Locking apparatus

Picture

1X2Changes.png

Occurrences

First, we killed power by removing the fuse that the boxes we were moving were running through.

Then, we moved the boxes. I dropped//lost a washer. It didn't seem to cause any problems, so no further attempts to locate it were made.

The fuse was reinstalled, and everything was reconnected.

Moving Forward

We are now working on putting together the electronics box, which will contain ADC, and raspberry pi's. The frequency counters will be mounted on the front of the box.

Once complete, it will be installed for use in FOL.

Additional comments:

This was done based on the earlier proposed setup plan for the frequency counters that will be used to measure the beat note frequencies [Akhil's elog]

I switched off the power supply to the green PDs so that we don't cause any damage while moving the amplifier panel for the beat signals and beatbox. 

  10234   Thu Jul 17 22:08:14 2014 KojiUpdateGeneral1X2 Rack Changes

It sounds like the work was done carefully. Even so, Jenne or Manasa have to run the ALS (X and Y) to check if they are still functional.

  7433   Mon Sep 24 17:03:39 2012 JenneUpdatePEM1X1 rack power

Quote:

I've installed Guralp readout box back and it turned out that it does not work with voltage provided from the rack (+13.76 0 -14.94).  +/-12 voltage regulators inside the box convert it to -0.9 0 -12. I've connected the box to +/-15 DC voltage supply to measure seismic motion at the ETMY table. Readout box works fine with +/- 15.

 I'm not sure what the problem is here.  Den and I looked at it for a few minutes, before I went back to helping with putting doors on.  The Sorensons are not supplying the rack power for 1X1.  There are some flat cables which go from the fuses on the side of the rack up to the cable tray, and go elsewhere.  Den is going to continue looking into this, but I think it's a moderately high priority, since lots of things should be getting served by that same power.

  15669   Tue Nov 10 12:41:23 2020 gautamUpdateIOO1W > IMC

Looking back through the elog, 1mtorr is the pressure at which it is deemed safe to send the full power beam into the IMC. After replacing the HR mirror in the MCREFL path with a 10% reflective BS, I just cranked the power back up. IMC is locked. With the increased exposure on the MC2T camera, lots of new scattered light has become visible.

  2804   Sat Apr 17 18:30:12 2010 ZachUpdateGreen Locking1W NPRO output profile

NOTE: This measurement is wrong and only remains for documentation purposes.

Koji asked me to take a profile of the output of the 1W NPRO that will be used for green locking. I used the razor-scan method, plotting the voltage output of a PD vs the position of the razor across the beam, both vertically and horizontally. This was done at 6 points along the beam path out of the laser box.

I determined the beam spot size at each point by doing a least-squares fit on the plots above in Matlab (using w as one of the fitting parameters) to the cumulative distribution functions (error functions) they should approximate.

I then did another least-squares fit, fitting the above "measured" beam profiles to the gaussian form for w vs z. Below is a summary.

It seems reasonable, though I know that M2 < 1 is fishy, as it implies less divergence than ideal for that waist size. Also, like Koji feared, the waist is inside the box and thus the scan is almost entirely in the linear regime.

profile_fit_4_17_10.png

  2807   Mon Apr 19 11:31:04 2010 AidanUpdateGreen Locking1W NPRO output profile

Quote:

 Koji asked me to take a profile of the output of the 1W NPRO that will be used for green locking. I used the razor-scan method, plotting the voltage output of a PD vs the position of the razor across the beam, both vertically and horizontally. This was done at 6 points along the beam path out of the laser box.

I determined the beam spot size at each point by doing a least-squares fit on the plots above in Matlab (using w as one of the fitting parameters) to the cumulative distribution functions (error functions) they should approximate.

I then did another least-squares fit, fitting the above "measured" beam profiles to the gaussian form for w vs z. Below is a summary.

It seems reasonable, though I know that M2 < 1 is fishy, as it implies less divergence than ideal for that waist size. Also, like Koji feared, the waist is inside the box and thus the scan is almost entirely in the linear regime.

profile_fit_4_17_10.png

There is a clearly a difference in the divergence angle of the x and y beams - maybe 10-20%. Since the measurements are outside the Rayleigh range and approximately in the linear regime, the slope of the divergence in this plot should be inversely proportional to the waists - meaning the x- and y- waist sizes should differ by about 10-20%. You should check your fitting program for the waist.

 

  2818   Tue Apr 20 13:02:14 2010 ZachUpdateGreen Locking1W NPRO output profile

EDIT: I used an IFIT (inverse fast idiot transform) to change the x-axis of the plot from Hz to m. I think xlabel('Frequency [Hz]') is in my muscle memory now..

I have redone the beam fit, this time omitting the M2, which I believe was superfluous. I have made the requested changes to the plot, save for the error analysis, which I am still trying to work out (the function I used for the least squares fit does not work out standard error in fit parameters). I will figure out a way to do this and amend the plot to have error bars.

 
profile_fit_4_19_10.png
  2819   Tue Apr 20 13:37:36 2010 JenneUpdateGreen Locking1W NPRO output profile

Quote:

I have redone the beam fit, this time omitting the M2, which I believe was superfluous. I have made the requested changes to the plot, save for the error analysis, which I am still trying to work out (the function I used for the least squares fit does not work out standard error in fit parameters). I will figure out a way to do this and amend the plot to have error bars.

 
profile_fit_4_19_10.png

 Are you sure about your x-axis label? 

  2821   Tue Apr 20 19:37:02 2010 KojiUpdateGreen Locking1W NPRO output profile

Beautiful fitting.

Quote:

EDIT: I used an IFIT (inverse fast idiot transform) to change the x-axis of the plot from Hz to m. I think xlabel('Frequency [Hz]') is in my muscle memory now..

I have redone the beam fit, this time omitting the M2, which I believe was superfluous. I have made the requested changes to the plot, save for the error analysis, which I am still trying to work out (the function I used for the least squares fit does not work out standard error in fit parameters). I will figure out a way to do this and amend the plot to have error bars.

 
profile_fit_4_19_10.png

 

  12070   Mon Apr 11 17:03:41 2016 SteveUpdateCalibration-Repair1W Innolight repair completed

The laser is back. Test report is in the 40m wiki as New Pump Diode Mephisto 1000

It will go on the PSL table.

  12040   Mon Mar 21 14:29:32 2016 SteveUpdateCalibration-Repair1W Innolight laser repair diagnoses

 

Quote:
Quote:

After adjusting the alignment of the two beams onto the PD, I managed to recover a stronger beatnote of ~ -10dBm. I managed to take some measurements with the PLL locked, and will put up a more detailed post later in the evening. I turned the IMC autolocker off, turned the 11MHz Marconi output off, and closed the PSL shutter for the duration of my work, but have reverted these to their nominal state now. The are a few extra cables running from the PSL table to the area near the IOO rack where I was doing the measurements from, I've left these as is for now in case I need to take some more data later in the evening...I

Innolight 1W 1064nm, sn 1634 was purchased in 9-18-2006 at CIT. It came to the 40m around 2010

It's diodes should be replaced, based on it's age and performance.

RIN and noise eater bad. I will get a quote on this job.

The Innolight Manual frequency noise plot is the same as Lightwave' elog 11956

Diagnoses from Glasglow:

“So far we have analyzed the laser. The pump diode is degraded. Next we would replace it with a new diode. We would realign the diode output beam into the laser crystal. We check all the relevant laser parameters over the whole tuning range. Parameters include single direction operation of the ring resonator, single frequency operation, beam profile and others. If one of them is out of spec, then we would take actions accordingly. We would also monitor the output power stability over one night. Then we repackage and ship the laser.”

  3751   Thu Oct 21 10:44:56 2010 steveMetaphysicsTreasure1987 supernova tapes plus....?

I'm cleaning out to make room for our new optical cabinet. Are we keeping these? There are  ~20  pieces of 10" od 1" wide tapes and large number of cassettes.

AJW,  Zucker,  Stuart A and Koji were notified in this matter.

Alan suggested to save data of Bruce Allen paper of observation of binary neutron stars in the 40m on 1994 November 14-20 and save back up tapes of his period in the 40m.

Mike: reels are not readable any more, it is time to let go

  16155   Mon May 24 08:38:26 2021 ChubUpdateElectronics18-bit AI, 16-bit AI and 16-bit AA

- High priority units: 2x 18AI / 1x 16AI / 3x 16AA

All six are reworked and on the electronics workbench. The rest should be ready by the end of the week.

Chub

  11772   Tue Nov 17 14:31:25 2015 ericqUpdateCDS16Hz frame writing temporarily disabled

To test the effect on EPICS latency, I've restarted daqd with modified ini files which disable all frame writing of 16Hz channels. 

This happened at GPS:1131835955 aka Nov 17 2015 22:52:18 UTC

Last night, I started running a script written by Dave Barker that monitors a specified EPICS channel (in this case C1:IOO-MC_TRANS_SUM), to look for seconds in which it does not update the expected number of times. This is still running, so I will be able to compare the rate of EPICS slowdowns before and after this change. 

I will revert back to the nominal state of things in a few hours, or until someone asks me to. 

  11777   Tue Nov 17 20:57:43 2015 ericqUpdateCDS16Hz frame writing running again

Back to nominal FB configuration at 1131857782, aka Nov 18 2015 04:56:05 UTC.

Weirdly, during this time, the script watching MC_TRANS_SUM from pianosa saw tons of freezes, but another instance  watching LSC-TRY_OUT16 on optimus saw no freezes. 

  1534   Thu Apr 30 05:49:06 2009 YoichiUpdateLocking166MHz LO phase changed
In order to optimize the REFL_2I demod phase, I changed the delay line setting for the 166MHz LO.
Right now, the delay is not yet optimal.
Since the AS166 shares the same LO, the digital demodulation phase of the AS166 had to be changed too.
The DD demod phases and the DD hand off script were also tweaked to improve the resonant condition of the central part.
Now we have more 166MHz coming out of the AS port and the SPOB is larger (more 33MHz resonant in PRC).

Since REFL166 and AS166 demodulation phases are not yet optimized, the cm_step script won't work at this moment.
  1536   Fri May 1 01:32:43 2009 YoichiUpdateLocking166MHz LO phase adjustment
I continued to adjust the REFL_2I demodulation phase.
I first optimized the demod phase for SRCL in the DRMI configuration (the error signals were DDs).
Then I restored the full IFO and offset locked it.
Before handing the DARM to RF, I adjusted the 166MHz delay line to maximize the SRCL signal at REFL_2I.
I did this before the DARM RF hand off because changing the delay line setting also changes the AS166 demodulation phase.
After this, I adjusted the digital phase shifter for AS166 to maximize the DARM signal for this port.

I also adjusted the digital demodulation phase of PD11 (REFL_2I) because the optimal demodulation phase for the initial lock acquisition is somewhat (15deg)
different from the optimal demodulation phase for the SRCL when the central part is locked with the DD signals.
This happens because the resonant condition of the central part (lock points of the recycling cavities) changes when the error signals are switched to the DD signals,
due to the offset in the DD signals. This is not good and should be fixed by the optimization of the DD demodulation phases.

Finally, I reduced the CARM offset to zero and tweaked the delay line a bit to maximize the arm power.

Right now, the locking script runs fine until the end.
At the end of the script, I was able to engage the boost on the CM board.
  1537   Fri May 1 10:04:10 2009 robUpdateLocking166MHz LO phase adjustment

Quote:
I continued to adjust the REFL_2I demodulation phase.
I first optimized the demod phase for SRCL in the DRMI configuration (the error signals were DDs).
Then I restored the full IFO and offset locked it.
Before handing the DARM to RF, I adjusted the 166MHz delay line to maximize the SRCL signal at REFL_2I.
I did this before the DARM RF hand off because changing the delay line setting also changes the AS166 demodulation phase.
After this, I adjusted the digital phase shifter for AS166 to maximize the DARM signal for this port.

I also adjusted the digital demodulation phase of PD11 (REFL_2I) because the optimal demodulation phase for the initial lock acquisition is somewhat (15deg)
different from the optimal demodulation phase for the SRCL when the central part is locked with the DD signals.
This happens because the resonant condition of the central part (lock points of the recycling cavities) changes when the error signals are switched to the DD signals,
due to the offset in the DD signals. This is not good and should be fixed by the optimization of the DD demodulation phases.

Finally, I reduced the CARM offset to zero and tweaked the delay line a bit to maximize the arm power.

Right now, the locking script runs fine until the end.
At the end of the script, I was able to engage the boost on the CM board.



Awesome. Up next: dewhitening.
  2552   Thu Jan 28 09:17:32 2010 AlbertoUpdateLSC166 Modulation turned off

I temporarily turned off the 166 modulation.

  2545   Mon Jan 25 16:30:37 2010 AlbertoUpdateABSL166 MHz sideband turned off

I turned off the modulation at 166MHZ becasue I don't need it if I'm only locking the PRC.

It was introducing extra amplitude modulations of the beam which interfered with the AbsL's PLL photodiode.

I'm going to turn it back on later on.

  2546   Mon Jan 25 16:46:33 2010 AlbertoUpdateABSL166 MHz sideband turned off

Quote:

I turned off the modulation at 166MHZ becasue I don't need it if I'm only locking the PRC.

It was introducing extra amplitude modulations of the beam which interfered with the AbsL's PLL photodiode.

I'm going to turn it back on later on.

 I turned back on the 166MHz modulation just a bit. I set the slider at 4.156.

When it was totally off the MZ seemd quite unhappy.

  2547   Tue Jan 26 03:28:56 2010 ranaUpdateABSL166 MHz sideband turned off

 

 You can turn the 166 off if you want. MZ is unhappy after its turned off, but that's just the thermal transient from removing the RF heat. After a several minutes, the heat goes away and the MZ can be relocked.

One of these days we should evaluate the beam distortion we get in EOMs because of the RF heat induced dn/dT. Beam steering, beam size, etc.

  2389   Thu Dec 10 17:05:21 2009 AlbertoConfigurationLSC166 MHz LO SMA-to-Heliax connection repaired

I replaced the SMA end connector for the 166 MHZ Local Oscillator signal that goes to the back of the flange in the 1Y2 rack. The connector had got damaged after it twisted when I was tigheting the N connector of the Heliax cable on the front panel.

  2384   Thu Dec 10 13:10:25 2009 AlbertoConfigurationLSC166 LO Disconnected

I temporarily disconnected the Heliax cable that brings the 166MHz LO to the LSC rack.

I'm doing a couple of measurement and I'll put it back in as soon as I'm done.

  2393   Thu Dec 10 18:31:44 2009 AlbertoConfigurationLSC166 LO Disconnected

Quote:

I temporarily disconnected the Heliax cable that brings the 166MHz LO to the LSC rack.

I'm doing a couple of measurement and I'll put it back in as soon as I'm done.

 These are the losses I measured on a RG-174 cable for the two frequencies that we're planning to use in the Upgrade:

@11MHz Loss=0.22dBm/meter

@55MHz Loss=0.41dBm/meter

(The cable was 2.07m long. The input signal was +10dBm and the output voltages at the oscilloscope where: Vpk-pk(11MHz)=1.90V, Vpk-pk(11MHz)=1.82V )

  2395   Fri Dec 11 09:30:09 2009 KojiConfigurationLSC166 LO Disconnected

They must not be dBm, must be dB

Quote:

Quote:

I temporarily disconnected the Heliax cable that brings the 166MHz LO to the LSC rack.

I'm doing a couple of measurement and I'll put it back in as soon as I'm done.

 These are the losses I measured on a RG-174 cable for the two frequencies that we're planning to use in the Upgrade:

@11MHz Loss=0.22dBm/meter

@55MHz Loss=0.41dBm/meter

(The cable was 2.07m long. The input signal was +10dBm and the output voltages at the oscilloscope where: Vpk-pk(11MHz)=1.90V, Vpk-pk(11MHz)=1.82V )

 

  2396   Fri Dec 11 11:42:26 2009 AlbertoConfigurationLSC166 LO Disconnected

Quote:

They must not be dBm, must be dB

Quote:

Quote:

I temporarily disconnected the Heliax cable that brings the 166MHz LO to the LSC rack.

I'm doing a couple of measurement and I'll put it back in as soon as I'm done.

 These are the losses I measured on a RG-174 cable for the two frequencies that we're planning to use in the Upgrade:

@11MHz Loss=0.22dBm/meter

@55MHz Loss=0.41dBm/meter

(The cable was 2.07m long. The input signal was +10dBm and the output voltages at the oscilloscope where: Vpk-pk(11MHz)=1.90V, Vpk-pk(11MHz)=1.82V )

 

I apologize for the lack of correctness on the units in yesterday's elog entry, but I wasn't very sharp last night.

I repeated the measurement today, this time also making sure that I had a 50ohm input impedance set in the scope. These the results for the losses.

RG-174 Cable 0.053 dB/m @ 11MHz  0.155 dB/m @ 55 MHz

 I also measured the losses in the Heliax cable going from the 166 MHz LO to the LSC rack:

166MHz LO Heliax 0.378 dB @ 11MHz  1.084 dB @ 55 MHz

 

  2398   Fri Dec 11 14:12:32 2009 ranaConfigurationLSC166 LO Disconnected

 

 Seems like very strange cable loss numbers. The Heliax is lossier than the RG-174? I wonder how these compare with the specs in the cable catalog?

  2402   Fri Dec 11 19:51:13 2009 AlbertoConfigurationLSC166 LO Disconnected

Quote:

 

 Seems like very strange cable loss numbers. The Heliax is lossier than the RG-174? I wonder how these compare with the specs in the cable catalog?

In my last entry there was a typo for the measurement of the Heliax at 55 MHz. I corrected it. It was 1.084 dB instead of 1.084 dB/m.
For the Heliax I don't have the measurement of the loss per meter since I don't know the cable actual length.
 
Except for that, I checked the values I found on the Internet.
My measurements for the RG-174 seem comparable to the loss specified in the catalog (here): 6.6dB in 100ft @ 55 MHz, that is 0.22 dB/m, that compare with 0.155 dB/m that I measured.

I did the measurement on a 4.33 meter long cable with SMA connectors at the ends.

  12948   Wed Apr 19 15:46:24 2017 gautamUpdateGeneral1611/1811 inventory check

I looked through the lab area to do a fast photodiode inventory check, as we may need to buy some for the higher order mode spectroscopy SURF project. I looked on the following optical tables: ETMY, ITMY, BS, AS, PSL, SP, ITMX, Jenne laser table, and ETMX, as well as the photodiode cabinet, and could only find two 1611s. Here is a summary of the inventory: 

  • Power supply 0901: 2x in photodiode cabinet (E6 along the Y arm), 1x on Jenne laser table
  • Newfocus 1611 S/N 7284-WX, labelled "REF DET" on ITMY optical table, currently unused
  • Newfocus 1611 S/N 57109 on Jenne laser table

I have not yet checked if these photodiodes are in working order.

 

  4351   Thu Feb 24 17:42:00 2011 AidanUpdateGreen Locking15% of end laser sideband power transmitted through cavity

I did a quick calculation to determine the amount of sideband transmission through the FP cavity.

The modulation frequency of the end PDH is 216kHz. The FSR of the cavity is about 3.9MHz. So the sidebands pick up about 0.17 radians extra phase on one round trip in the cavity compared to the carrier.

The ITM reflectance is r_ITM^2 = 98.5% of power, the ETM reflection is r_ETM^2 = 95%.

So the percentage of sideband power reflected from the cavity is R_SB = r_ITM*r_ETM*(exp(i*0.17) - 1)^2 / (1 - r_ETM*r_ITM exp(i*0.17) )^2 = 0.85 = 85%

So about 15% of the sideband power is transmitted through the cavity. The ratio of the sideband and carrier amplitudes at the ETM is 0.05

So, on the vertex PD, the power of the 80MHz +/-200kHz sidebands should be around sqrt(0.15)*0.05 = 0.02 = 2% of the 80MHz beatnote.

Once we get the green and IR locked to the arm again, we're going to look for the sidebands around the beatnote.

 

 

  9618   Mon Feb 10 18:03:41 2014 jamieUpdateCDS12 core c1sus replacement

I have configured one of the spare Supermicro X8DTU-F chassis as a dual-CPU, 12-core CDS front end machine.  This is meant to be a replacement for c1sus.  The extra cores are so we can split up c1rfm and reduce the over-cycle problems we've been seeing related to RFM IPC delays.

I pulled the machine fresh out of the box, and installed the second CPU and additional memory that Steve purchased.  The machine seems to be working fine.  After assigning it a temporary IP address, I can boot it from the front-end boot server on the martian network.  It comes up cleanly with both CPUs recognized, and /proc/cpustat showing all 12 cores, and free showing 12 GB memory.

The plan is:

  1. pull the old c1sus machine from the rack
  2. pull OneStop, Dolphin, RFM cards from c1sus chassis
  3. installed OneStop, Dolphin, RFM cards into new c1sus
  4. install new c1sus back in rack
  5. power everything on and have it start back up with no problems

Obviously the when of all this needs to be done when it won't interfere with locking work.  fwiw, I am around tomorrow (Tuesday, 2/11), but will likely be leaving for LHO on Wednesday.

  7513   Tue Oct 9 23:12:56 2012 JenneUpdateLSC11MHz reconnected to EOM

Riju hasn't been in the lab in a long time to do any measurements, so I put the signals back to how they should be. 

I turned off / confirmed off the things which were sending signal to the EOM:  the network analyzer, the RF generator box, and the Marconi which supplies the 11MHz. 

I removed the cavity scanning cable, and terminated it, and put the regular 11MHz cable back on the splitter.

I then turned on the RF gen box and the Marconi.  The Marconi had been off, so we were not getting any 11MHz or 55MHz out of the RF gen. box.  This is why I couldn't lock any cavities last night (duh). 

On to locking!

----------------- In other news,

While swapping out the EOM cable, I noticed that the DC power supply sitting under the POX table was supplying a weird value, 17 point something volts.  I checked on the table to remind myself why that power supply is there...it's powering an RF amplifier right after the commercial PD that is acting as POP22.  The amplifier wants +15 and GND, so I reset the power supply to 15V.  We should add this to the list of things to fix, because it's dumb.  Either we need to put in the real POP22 (long term goal), or we need to get this guy some rack power, and do the same for any amplifiers for the Beat setup.  It's a little hoakey to have power supplies littering the lab.

  4530   Fri Apr 15 12:17:39 2011 kiwamuUpdateLSC11MHz demod board : funny I-Q phase

During checking the 11MHz demod boards I found that the I-Q relative phase showed funny LO power dependence.

It is now under investigation.

relativephase.png

 In the plot above the green curve represents the I-Q phase of a 11MHz demod board (see here).

It showed a strong dependence on the LO power and it changes from -60 deg to -130 deg as the LO power changes.

This is not a good situation because any power modulation on the LO will cause a phase jitter.

For a comparison I also took I-Q relative phase of a 33MHz demod board, which hasn't been modified recently.

 It shows a nice flat curve up to 5 dBm although it looks like my rough measurement adds a systematic error of about -5 deg.

 

 - to do -

* check RF power in every point of LO path on the circuit

* check if there is saturation by looking at wave forms.

ELOG V3.1.3-