ID |
Date |
Author |
Type |
Category |
Subject |
10352
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Fri Aug 8 14:27:18 2014 |
Akhil | Update | Computer Scripts / Programs | FOL Scripts |
The scripts written for interfacing the FC with R Pi, building EPICS database, piping data into EPICS channels,PID loop for FOL are contained in :
/opt/rtcds/caltech/c1/scripts/FOL
The instructions to run these codes on R Pi( controls@domenica) will be available on FOL 40m wiki page.
Also instructions regarding EPICS installation on R Pi and building an EPICS SoftIoc to streamline data from hardware devices into channels will be updated shortly.
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10353
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Fri Aug 8 14:42:41 2014 |
Akhil | Update | General | PID loop Design for beat note stabilization |
The attached in a zip file are the Simulink feedback loop models for the FOL for both X and Y ends. The controller PID values are estimated by setting a temperature count reference point to 5344, which corresponds to 100 MHz frequency. The plant transfer function is as calculated in my previous elogs.
We were not able to test the PID loop , with the green laser by PZT actuation because of the misalignment of the arms and non-existence of the beat note since last few days. However, we have a complete idea of the design and PID parameters that will be used for the FOL with infrared laser. So we decided that it would be better to test the loop by temperature actuation after the fiber optics is installed and the coupling of infrared laser into the fiber is complete. As of now, we have planned to place the FOL box inside so that it can be used to obtain the green laser beat note on the StripTool graphs. |
Attachment 1: PID.zip
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306
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Sun Feb 10 20:47:01 2008 |
Alan | Summary | SUS | All watchdogs tripped |
A moderate earthquake occurred at 11:12:06 PM (PST) on Friday, February 8, 2008.
The magnitude 5.1 event occurred 21 km (13 miles) NW of Guadalupe Victoria, Baja California, Mexico.
http://quake.wr.usgs.gov/recenteqs/Quakes/ci14346868.html |
1058
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Mon Oct 20 12:18:38 2008 |
Alan | Update | Computer Scripts / Programs | burtwb missing on Solaris but installed on linux64 |
Quote: | c1lsc stalled this evening, so I powercycled it.
After that, I tried to lock arms to confirm the computer is working.
Then I realized that the restore alignment buttons do not work from any control room computer.
I found that it was because burtwb command was missing. For Solaris, looks like there used to be /cvs/cds/epics/extensions/burtwb but now
there is no /cvs/cds/epics directory. I thought there were directories other than "caltech" in /cvs/cds/, weren't there ?
Right now, there is only /cvs/cds/caltech.
Anyway, I installed burt for 64bit linux computer (under /cvs/cds/caltech/apps/linux64/epics/extensions/).
At this moment the alignment save/restore works on allegra (and probably on rosalba), but not on op440m yet. |
The automatic backup of /cvs/cds (and /frames/minute-trends ) to the LIGO archive in Powell-Booth,
which runs from fb40m using the scripts in /cvs/cds/caltech/scripts/backup ,
stopped when fb40m was rebooted on June 28, 2008,
and the check_backup script I run to send an email when this happens also failed due to a scripting error.
But we still have a backup of /cvs/cds from June 27.
The backup of /cvs/cds (excluding /cvs/cds/caltech and /cvs/cds/tmp)
circa June 27, 2008
has been restored to
/cvs/cds/recover_20081020 .
Please check to see that it has what we need.
Before moving it over to where it belongs,
it would be really nice to figure out what happened...
Meanwhile, I have fixed the check_backup script and restarted the backup, which will run this evening...
but maybe I should wait till the dust settles?
Now is also a good time to think about whether there is anything else besides for
/cvs/cds and /frames/minute-trends that should be backed up regularly.
- Alan |
1060
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Mon Oct 20 16:18:00 2008 |
Alan | Configuration | Computers | /cvs/cds restored |
Quote: | I moved missing files in /cvs/cds restored by Alan and Stuart to the original locations.
I confirmed autoburt runs, and dtt, which had also been having trouble running, runs ok now.
I found an interesting piece of evidence on allegra, our new 64bit linux machine.
In the Trash of controls Desktop on that machine, there is /cvs/cds/vw/ directory.
I remember that when I last time emptied the trash bin on the machine (yesterday), it took somewhat long time.
Too bad that I did not pay attention to what was actually in the Trash, but now I have a feeling that in the Trash were
missing /cvs/cds/* directories.
While emptying the Trash, I encountered several errors saying permission denied or something like that, and skipped those files.
Sometimes, when you move something from NFS mounted directories to the Trash, you get this kind of errors.
So my guess is that someone accidentally (or intentionally) moved /cvs/cds/* except for "caltech" to the Trash of allegra.
And I completely removed them carelessly. |
In the meantime, I have re-started the nightly backup for /frames/minute-trends
but NOT YET for /cvs/cds ,
since I fear that we'll find another problem and will need to go back to the June 27 backup.
Let's wait a few days for the dust to settle,
and if everyone feels confident that /cvs/cds is ok,
I'll restart the backup of that.
How I restored the files, for the record:
Stuart mounted /archive/backup onto an accessible computer (garrak.ligo.caltech.edu ) and I logged on to controls@nodus and ran this command:
/cvs/cds/caltech/scripts/backup/rsync --rsync-path=/usr/bin/rsync --rsh=/usr/bin/ssh --compress --verbose --archive --hard-links --exclude=caltech/ ajw@garrak.ligo.caltech.edu:/backup/40m/cvs /cvs/cds/recover_20081020
I had to type in my GC password, and it ran for ~20 minutes (would have been much longer had I asked for /cvs/cds/caltech as well!).
you can view the backups by logging on to garrak.ligo.caltech.edu with your GC account:
/backup/40m/cvs/cds/
/archive/frames/trend/minute-trend/40m |
1215
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Sun Jan 4 13:17:23 2009 |
Alan | Omnistructure | Computer Scripts / Programs | New 40mWebStatus |
I have set up some code in /cvs/cds/caltech/scripts/webStatus along with a cronjob on controls@nodus to generate a webStatus every half hour, at 40mWebStatus
you are welcome to add/delete lines corresponding to interesting EPICS channels, in the template /cvs/cds/caltech/scripts/webStatus/webStatus_template.html . The 2nd number is the "golden" value of the EPICS channel; it can be edited by hand, or one could copy a "golden" webStatus.html to webStatus_template.html . I think it's probably premature to automate this...
I noticed that Yoichi also has a cron job posting 40m medm screen snapshots. Very nice.
controls@nodus also runs a third cronjob, which checks if the nightly backup fails, and if so, sends an email to me.
I guess we need some kind of "official" crontab file for controls@nodus so that we know how/where to add things. So, I put one in /cvs/cds/caltech/crontab/controls@nodus.crontab |
1216
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Mon Jan 5 11:21:05 2009 |
Alan | Omnistructure | Computer Scripts / Programs | New 40mWebStatus |
Quote: |
I guess we need some kind of "official" crontab file for controls@nodus so that we know how/where to add things. So, I put one in /cvs/cds/caltech/crontab/controls@nodus.crontab |
Alan and I agreed that we should edit the crontab by "crontab -e" command rather than editing the "official" crontab in /cvs/cds/caltech/crontab/.
After confirming that the new crontab works as expected, you are encouraged to make a copy of the new crontab into /cvs/cds/caltech/crontab/ as a backup.
Then do "svn ci" in the directory. |
1372
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Mon Mar 9 10:59:05 2009 |
Alan | Omnistructure | Computers | ssh agent on fb40m restarted for backup |
After the boot-fest, the nightly backup to Powell-Booth failed, and an automatic email got sent to me. I restarted the ssh agent, following the instructions in /cvs/cds/caltech/scripts/backup/000README.txt . |
1564
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Fri May 8 10:05:40 2009 |
Alan | Omnistructure | Computers | Restarted backup since fb40m was rebooted |
Restarted backup since fb40m was rebooted. |
1756
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Thu Jul 16 09:49:52 2009 |
Alan | Update | Computers | fb40m |
Quote: |
The fb40m just went out of order with status indicator number 8
It recovered on its own five minutes later.
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Backup script restarted, backup of trend frames and /cvs/cds is up-to-date.
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1910
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Sat Aug 15 10:36:02 2009 |
Alan | HowTo | Computers | nodus boot procedure |
fb40m was also rebooted. I restarted the ssh-agent for backup of minute-trend and /cvs/cds. |
2445
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Tue Dec 22 13:14:37 2009 |
Alan | Omnistructure | PEM | miracle in the 40m |
Quote: |
We have been waiting for this for 20 some years. Arrowhead water with cooler. AWESOME
THANKS Alan
|
Happy holidays, everyone!
|
3337
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Fri Jul 30 19:20:15 2010 |
Alastair | Configuration | General | Jacket |
Quote: |
Jenne and I need our jackets. We removed them from the Rb clock.
Thanks for making them warm. Probably a Scotland sweater would fit.
|
Thanks for the loan guys. I do have a lot of warm weather clothing at home that is not so necessary in the California climate. I will find some suitable attire for the Rb clocks there. |
3368
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Thu Aug 5 16:18:37 2010 |
Alastair | Update | General | clocks still not locked fully - hut removed |
The rubidium clocks are still not quite locked together, though it is clear that the beat frequency has dropped a lot since yesterday.
I checked on the clocks and the 1pps sync light is on. The clocks are really hot again though despite the gap left at the bottom of the igloo. The side of the clocks were hot enough to not be touchable.
I made the executive decision that I would remove the hut just now. We can let the clocks lock together and then put the hut back on just before measuring. This way the hut will isolate from temperature fluctuations during the measurement but it won't be running at the hotter equilibrium temperature. I hope that the temperature won't change too much during the measurement if we put the hut back on.
RA: Attachment deleted because it was in Postscript format. Also not allowed here are the Stone Tablet and Cave Painting formats. |
3433
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Wed Aug 18 12:02:29 2010 |
Alastair | Configuration | Computers | elog had crashed again... |
...I restarted it. |
3441
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Thu Aug 19 09:52:51 2010 |
Alastair | Update | Computers | Elog down |
I restarted it using start-elog-nodus and this worked out fine - even though I did it from Pete's on my phone ;-) |
3442
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Thu Aug 19 11:38:48 2010 |
Alastair | Update | Computers | ATF wiki |
The ATF wiki page doesn't seem to be working any more. Does anyone know where this is held so we can try to get it back online? Thanks  |
3443
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Thu Aug 19 12:06:07 2010 |
Alastair | Update | Computers | ATF wiki |
Quote: |
The ATF wiki page doesn't seem to be working any more. Does anyone know where this is held so we can try to get it back online? Thanks 
|
I phoned Phil Ehrens and found out that all these wikis have been moved to a new wiki site
The ATF wiki can now be found here
I have updated the link from the 40m wiki to reflect this |
3452
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Fri Aug 20 20:36:05 2010 |
Alastair | Update | General | Elog |
Elog was down, I restarted it. |
3461
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Tue Aug 24 06:34:01 2010 |
Alastair | Update | General | Elog... |
...was down. Have restarted it. |
3475
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Fri Aug 27 07:21:13 2010 |
Alastair | Update | General | elog... |
was down. I restarted the version in the 2.7.5 folder. It went down again almost immediately but stayed up after the second restart. |
4563
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Mon Apr 25 11:23:41 2011 |
Alastair | Bureaucracy | Computers | wiki? |
40m wiki seems to have been down for quite a while now but I can't see any info in the elog about it. Is there some ongoing problem?

|
4566
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Mon Apr 25 12:55:35 2011 |
Alastair | Bureaucracy | Computers | wiki? |
Quote: |
Quote: |
40m wiki seems to have been down for quite a while now but I can't see any info in the elog about it. Is there some ongoing problem?
|
There was an email from Dave Barker about this. They had to reorganize the DNS at LHO. The URL that should be used is: http://blue.ligo-wa.caltech.edu:8000/40m
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Thanks Jamie, I've updated the links from the ATF wiki to reflect this. |
4897
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Tue Jun 28 11:25:56 2011 |
Alastair | Bureaucracy | Computers | restarted elog |
The manual instructions on the 40m wiki for restarting wouldn't work. I killed the process okay, but then I got an error saying it "couldn't bind to port 8080, please try again using -p to select port". The automated script worked though. |
8382
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Mon Apr 1 16:16:16 2013 |
Albert | Update | optical tables | Optical Table Toolboxes Update |
A heavy duty plastic box is the likeliest candidate for the optical table toolbox. It measures 5 9/16 in. x 11 5/8 in. x 4 5/8 in. and fits all the tools comfortably. ( http://www.mcmaster.com/#plastic-bin-boxes/=m4yh4m , under Heavy Duty Plastic Bin Boxes)
The list of tools has been updated to include a pen and a wire cutter as well as everything previously stated.
In addition, Steve has recommended that boxes should be secured to the walls or surfaces near the optical tables as opposed to the optical tables themselves, as to keep the tables from wobbling when tools are being exchanged.
A diagram of tentative box placements will go out soon. |
8384
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Mon Apr 1 16:35:42 2013 |
Albert | Update | optical tables | Optical Table Toolboxes Update |
Quote: |
A heavy duty plastic box is the likeliest candidate for the optical table toolbox. It measures 5 9/16 in. x 11 5/8 in. x 4 5/8 in. and fits all the tools comfortably. ( http://www.mcmaster.com/#plastic-bin-boxes/=m4yh4m , under Heavy Duty Plastic Bin Boxes)
The list of tools has been updated to include a pen and a wire cutter as well as everything previously stated.
In addition, Steve has recommended that boxes should be secured to the walls or surfaces near the optical tables as opposed to the optical tables themselves, as to keep the tables from wobbling when tools are being exchanged.
A diagram of tentative box placements will go out soon.
|
I also took every allen key I can find so they can be sorted. They will be back in the appropriate drawer locations soon. |
8408
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Wed Apr 3 19:01:06 2013 |
Albert | Update | optical tables | Optical Table Toolboxes Update |
Quote: |
Quote: |
A heavy duty plastic box is the likeliest candidate for the optical table toolbox. It measures 5 9/16 in. x 11 5/8 in. x 4 5/8 in. and fits all the tools comfortably. ( http://www.mcmaster.com/#plastic-bin-boxes/=m4yh4m , under Heavy Duty Plastic Bin Boxes)
The list of tools has been updated to include a pen and a wire cutter as well as everything previously stated.
In addition, Steve has recommended that boxes should be secured to the walls or surfaces near the optical tables as opposed to the optical tables themselves, as to keep the tables from wobbling when tools are being exchanged.
A diagram of tentative box placements will go out soon.
|
No, the small boxes must be attached to the optical tables. They won't be heavy enough to change the table tilt.
Also, all tools must be color coded according to the optical table using the 3M Vinyl table color code:
http://www.3m.com/product/images/Vinyl-Electrical-Color-Tape-300.jpg
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Ok.
So the new tentative plan on the boxes is to bolt them (magnetic strips were proposed but overruled on the grounds that they're not strong enough to withstand being knocked down by accidents).
The boxes are going to be a mix of the Thorlabs Benchtop Organizer (http://www.thorlabs.com/thorProduct.cfm?partNumber=BT17) and the original box. The box will have a region covered in mesh, so tools can be placed and held there. The box will also have a spacer at the bottom, with another mesh right above it, lined up. However, this double-mesh will only cover half of the box. The other half of the box will be compartmentalized to hold things such as screws, connectors, etc. I will talk to Steve about building the boxes.
Also, using nail-polish to coat the Allen wrenches is not going to work. Nail polish does not stick easily enough. The tentative new plan is oil paint, but this is to be reviewed.
Finally, the diagram with the placement of the boxes relative to the optical tables has been put on paper, but needs to be computerized so it's easier to read. This will be done as soon as possible. |
8445
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Thu Apr 11 16:29:23 2013 |
Albert | Update | optical tables | Optical Table Toolboxes Update |
Quote: |
There are some tips for how to appy nail polish on YouTube from MKNails and MissJenFABULOUS. Their tips on how to prepare the site for a strong bonding strength are probably helpful for our gold/nickel coated tools. For chrome tools we may need to abrade the surface with a stone or fine sandpaper for it to take the layer better. IF the YouTube videos don't do it for you, then I suggest contacting Tom Evans at LLO to find out what kind of nail polish he uses.
|
This is the tentative box placement per optical table. The toolboxes are going to be color-coded by a combination of two colors (the order won't matter). The side of each toolbox will have a little panel to let you know which box corresponds to which set of colors.
On the diagram, the set of colors is simply the color of the box border and the color of the text.
If anyone has a problem with any of the colors or the box placement let me know before they are installed and become an annoyance:

Box Placements:
ETMY: Box will be attached to the underside of the table by magnets. The box will be on the north side of the optical table.
POY: Box will be attached to the side of the optical table by magnets. The box will be on the west side of the optical table.
BSPRM: Box will be attached to the side of the optical table by magnets. The box will be on the west side of the optical table.
AS: Box will be attached to the side of the optical table by magnets. The box will be on the north side of the optical table.
PSL1: Box will be inside the optical table, in the northeast corner.
PSL2: Box will be inside the optical table, in the southwest corner.
POX: Box will be attached to the side of the optical table by magnets. The box will be on the south side of the optical table.
MC2: Box will be attached to the side of the optical table by magnets. The box will be on the south side of the optical table.
ETMX: Box will be attached to the side of the optical table by magnets. The box will be on the east side of the optical table. |
8457
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Mon Apr 15 17:44:28 2013 |
Albert | Update | optical tables | Optical Table Toolboxes Update |
I decided to go see what the electrical tape looks like on the other tools.
These are the tools I felt were necessary to label with tape: (the others don't seem to be terribly important in terms of not interchanging between boxes)

On another note I'm not sure why electrical tape can't be used on the Allen Wrenches too.
I also plan on ordering smaller flash lights for each table (this one is bulky and unwieldy), and filling in the gaps of the Allen Wrench sets as soon as I get the go-ahead. |
8502
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Mon Apr 29 08:17:40 2013 |
Albert | Update | optical tables | Optical Table Toolboxes Update |
Quote: |
I decided to go see what the electrical tape looks like on the other tools.
These are the tools I felt were necessary to label with tape: (the others don't seem to be terribly important in terms of not interchanging between boxes)

On another note I'm not sure why electrical tape can't be used on the Allen Wrenches too.
I also plan on ordering smaller flash lights for each table (this one is bulky and unwieldy), and filling in the gaps of the Allen Wrench sets as soon as I get the go-ahead.
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8505
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Mon Apr 29 15:53:49 2013 |
Albert | Update | optical tables | Optical Table Boxes |
Quote: |
Albert, our new undergrad work force received 40m specific- basic safety training last week. Please read and sign 40m procedures booklet.
|
These are the tentative box placements. Roughly. I don't actually have the box finalized yet, but the box should be around that size.
AS1
BSPRM
ETMX
ETMY
MC2
POX
POY
How do I perspective ._. |
8342
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Mon Mar 25 18:58:09 2013 |
Albert Yang | Update | optical tables | Optical Table Toolboxes |
For those of you who spend annoying amounts of time looking for tools, fear no more. Toolboxes for each optical table are coming!
They will probably have:
IR Viewer (a few optical tables will have IR viewers, these specific tables will be labeled in the diagram coming out later)
IR Card
Ball screw drivers (3/16 in.) 6-8 in. handle
SMA Wrench
Allen Keys
Flashlight
Various Connectors (I'll find out what's needed at some point)
Zip Ties
Small flat screwdrivers (for adjusting camera gains)
Please suggest what else may be needed in these boxes.
The boxes will be held to the side of the tables, either by magnets or screws. A diagram of where they will be placed on each optical table in order to minimize obstruction of walkways will be distributed soon. Any objections can then be noted. |
131
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Wed Nov 28 16:18:15 2007 |
Alberto | Metaphysics | Environment | so clean you can eat on it |
I tidied up the desks in the lab, brought the Spectrum Analyzers back to the Salumeria (you don't want to know about that), sorted a lot of stuff and boxed up what I didn't know (you can find it in a couple of carton boxes on the table).
The blackmail with the pie might not work next time.
Please, preserve the common sort.
Alberto |
Attachment 1: DSC_0180.JPG
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Attachment 2: DSC_0181.JPG
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142
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Thu Nov 29 18:10:13 2007 |
Alberto | HowTo | Computer Scripts / Programs | GPIB Scripts |
I've spent a lot of time trying to configurate the GPIB-USB interface for the HP4195. After installing 1) the Agilent libraries, 2) the drivers, 3) the matlab Instrument Toolbox, 4) Jamie script, 5) Alice's script the computer can see the HP but still they can't 'talk' to each other.
I give up. I asked Alice Wang how she managed to get data. I'm not sure she used the GPIB interace. Rob said she might have used the old fashion floppy disks that we can't read anymore here.
I would really appreciate any suggestion by anyone who happened to have the same problems. |
246
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Thu Jan 17 18:22:14 2008 |
Alberto | Update | Electronics | RF Monitor Band-pass Filter |
After we finalized the schematic for the RF monitor board based on buffered LC resonators, on Richard Abbott's suggestion to avoid the complication brought in by the fast op-amps, we gave another chance to the a passive configuration of the band-pass filter based on a Chebyshev topology. Rich and Ben gave me an old but very powerful software tool to design that kind of filters and showed me the way to circumvent many hassles in making RF test boards.
I made a test circuit for the 166MHz line (see attached schematic), using tunable inductors. The TF are also attached.
We get more than 20 dB of isolation after 33MHz (with a loss of only few dB at the resonance - it could be less), which is enough for all the other frequencies (33,133,199 MHz) but we would like more for the 166. We are going to add one or two extra orders to the filter.
We also have to understand the spike at about 320Mhz and eventually somehow get rid of it.
Alberto |
Attachment 1: RF166Mhz.png
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Attachment 2: Chebyshevb.png
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Attachment 3: Chebyshev2b.png
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248
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Fri Jan 18 11:53:50 2008 |
Alberto | Update | Electronics | RF Monitor Band-pass Filter |
The response is asymmetric and on the left side of the peak, we have at least 33dB within 33Mhz, which is enough for all the frequencies. We probably don't need an higher order filter but just low pass filters in series.
The spike at 320MHz doesn't depend on the circuit board. It's either the cables, their connection, or the splitters.
Note that the frequency of this test circuit has still to be tuned exactly at 166MHz (now it's 149).
Alberto
Quote: | After we finalized the schematic for the RF monitor board based on buffered LC resonators, on Richard Abbott's suggestion to avoid the complication brought in by the fast op-amps, we gave another chance to the a passive configuration of the band-pass filter based on a Chebyshev topology. Rich and Ben gave me an old but very powerful software tool to design that kind of filters and showed me the way to circumvent many hassles in making RF test boards.
I made a test circuit for the 166MHz line (see attached schematic), using tunable inductors. The TF are also attached.
We get more than 20 dB of isolation after 33MHz (with a loss of only few dB at the resonance - it could be less), which is enough for all the other frequencies (33,133,199 MHz) but we would like more for the 166. We are going to add one or two extra orders to the filter.
We also have to understand the spike at about 320Mhz and eventually somehow get rid of it.
Alberto |
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Attachment 1: Chebyshevb.png
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268
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Fri Jan 25 15:53:59 2008 |
Alberto | Update | Electronics | 40 dB from the 3rd order Chebyschev |
I managed to tune the 7 knobs in the 3rd order Chebyshev bandpass filter obtaining the tranfer function attached to this entry. We have now 40 dB of attenuation between 166 Mhz and 133 and 199. With this tuning the insertion loss is rather high. We need a better one.
Alberto |
Attachment 1: 166MhzElog.png
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285
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Wed Jan 30 11:49:30 2008 |
Alberto | Summary | Electronics | RF monitor's filters final schematics and transfer functions |
These are the final schematics for the 6th order Chebyshev filters of the RF monitor board. I'm also attaching the TF as I measured. The tuning is probably not optimal, less insertion noise could be achieved. |
Attachment 1: 33Melog30Jan08.png
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Attachment 2: 133Melog30Jan08.png
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Attachment 3: 166Melog30Jan08.png
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Attachment 4: 199Melog30Jan08.png
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Attachment 5: 33elog30Jan08.png
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Attachment 6: 133elog30Jan08.png
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Attachment 7: 166elog30Jan08.png
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Attachment 8: 199elog30Jan08.png
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314
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Wed Feb 13 11:41:00 2008 |
Alberto | Update | Electronics | Some characterization of the RF Monitor Box (StocMon) |
I'm attaching a table with some measurements and the power spectrum from the pd to help evaluate the numbers.
The box output ranges from 0.5V to 2.1V. The coefficient between power and voltage is negative so higher voltage means lower power.
The red numbers are the outputs from each channel at their resonant frequencies. As one can see these are not very well centered on the dynamic range of the power detectors.
The cross coupling seems to be not a problem.
Even if the 166 filter, which handles the smallest of the frequencies and is also the most lossy (for construction reason), mounts a preamplifier, the output is still rather small. this explain also the high bias due to the noise amplification at the maximum power (13dB). A better insertion loss either remaking the filter or re-tuning that one would simplify many problems, i.e. there is not much room in the metal pomona box to fit the amplifier. I might want to consider, after everything else is ready and if I have time before leaving next week, to work on a new 166 filter. |
Attachment 1: CircuitCharacterization.png
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Attachment 2: alberto.spectrum3.png
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321
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Mon Feb 18 12:04:39 2008 |
Alberto | Update | Electronics | RF Monitor (StocMon) |
I put the amplifiers next to the monitor on the PSL table, layed the power and the RF SMA cables out to the rack. I'm powering the box and the amplifiers with the power supply, waiting for someone to show me tomorrow how to connect it to the Sorensen (Steve, Ben?).
I'm ready to hook up the channels into EPICS. |
Attachment 1: DSC_0443.JPG
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331
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Fri Feb 22 08:29:07 2008 |
Alberto | Update | Electronics | RF Monitor (StocMon) |
Quote: | I put the amplifiers next to the monitor on the PSL table, layed the power and the RF SMA cables out to the rack. I'm powering the box and the amplifiers with the power supply, waiting for someone to show me tomorrow how to connect it to the Sorensen (Steve, Ben?).
I'm ready to hook up the channels into EPICS. |
Me and Ben Abbot were plugging the cables that power that RF Monitor box into the PSL rack when inadvertently we made some arcs spark between the pins on the back of one of the ADC. Somehow that made the laser shut down although the MOPA stayed on. We also notice some smell of burn.
Later on, after several failed attempts, Rob, Ben and Steve could restart the laser. It took some times because the written procedure to start the chiller is not very precise. |
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Fri Feb 22 08:33:18 2008 |
Alberto | Update | Electronics | RF Monitor (StocMon) |
Quote: | I put the amplifiers next to the monitor on the PSL table, layed the power and the RF SMA cables out to the rack. I'm powering the box and the amplifiers with the power supply, waiting for someone to show me tomorrow how to connect it to the Sorensen (Steve, Ben?).
I'm ready to hook up the channels into EPICS. |
With Ben, we hooked up the RF Monitor box into the PSL rack and created 4 EPICS channels for the outputs:
C1:IOO_RF_STOC_MON_33
C1:IOO_RF_STOC_MON_133
C1:IOO_RF_STOC_MON_166
C1:IOO_RF_STOC_MON_199
The power cable bringing +15V to the preamplifier on the PSL table should be replaced eventually. |
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Thu Jun 19 15:52:06 2008 |
Alberto | Configuration | Computers | Measure of the current absorbed by the new Megatron Computer |
Together with Rich Abbot, sam Abbot and I measured the current absorbed by the new Megatron computer that we installed yesterday in the 1Y3 rack. The computer alone absorbs 8.1A at the startup and then goes down to 5.9A at regime. The rest of the rack took 5.2A without the computer so the all rack needs 13.3 at the startup and the 11.1A.
We also measured the current for the 1Y6 rack where an other similar Sun machine has been installed as temporary frame builder and we get 6.5A.
Alberto, Rich and Sam Abbot |
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Mon Jun 23 21:51:19 2008 |
Alberto | Update | General | Arm Cavity Length Measurement |
We measured the arm cavity lengths sweeping the ETM mirror position and looking at the reflected demodulated output. We excited the mirror by a sine wave of 0.2 Hz and amplitude of 30000 counts. From the time series of the occurrences of the resonances of the sidebands and of the carrier we evaluated the free spectral range of the cavities and thus the lengths. The details of the procedure are explained in the attached document. As discussed in it, for each cavity we obtain two possible values of the length depending on which of the sideband resonances is that corresponding to the upper sideband and which corresponds to the lower one instead. The numbers are:
Lx=(38.30 +/- 0.08)m / (38.45 +/- 0.08)m
Ly=(38.16 +/- 0.08)m / (38.70 +/- 0.08)m
Since the difference between the two possibilities is quite large, we should be able to decide which one is correct by somehow measuring directly the cavity length. We want to try it tomorrow by a tape meter.
Alberto and Koji |
Attachment 1: 40mLengthMeasure.pdf
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Wed Jul 2 06:46:05 2008 |
Alberto | Configuration | General | NPRO on to warm up |
This morning I turned on the NPRO on the AP table so that it can warm up for a few hours before I start using it today.
The flipping mirror is down so no beam is injected in to the IFO.
Alberto |
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Wed Jul 2 19:15:52 2008 |
Alberto | Update | General | Status of the alignment of the NPRO beam for the Absolute Length Measurement |
Today I've tried to bring the frequency of the NPRO laser close enough to that of the IFO beam so that the beat between the two beams can be at a detectable frequency for the photodiode. The way I've been changing the frequency is by the NPRO's temperature control on its driver.
Looking at the signal from the AS OSA should enable us to monitor the direction in which the frequency is changing. Every time the resonances of the IFO beam and of the NPRO beam overlap, we know that the frequencies of the two beams are some FSR of the OSA away from each other. At the overlapping of the resonances, if the difference of frequency is within the detectable range of the photodiode, we should see a peak in the network/spectrum analyzer.
This way turned out not very easy in practice because from the AS OSA one can hardly distinguish the resonances of the primary beam from those of the secondary beam. The cause is mainly the flashing of the IFO beam at the AS port which produces a pattern of resonances of different amplitude. Also for some reason, triggering the output signal from the OSA at the oscilloscope doesn't work very well.
However, even if we didn't have these problems, I think that the two beams are not very well aligned, at least not anymore. I'm attaching some pictures from the AS port. The bright spot on the left is the NPRO beam and the one in the center which flashes is the IFO beam. We probably need some more work in the alignment of the NRPO beam. |
Attachment 1: DSC_0156.JPG
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Attachment 2: DSC_0158.JPG
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Thu Jul 3 18:48:09 2008 |
Alberto | Update | General | Beats of the two lasers in the absolute length measurement observed |
I adjusted the alignment of the flipper mirror as suggested by Koji making the two beam spots match. I also aligned all the IFO mirrors (ITMs, PRM, SRM, ETMs) to have more power for the IFO signal at the AS port. When I did that I could see the beats at the AS OSA. Then I explored the range of temperature of the NPRO from 35deg (C) to 51.2807deg and at that point I could observe a peak corresponding to the beat at about 10MHz on the network analyzer. The peak tends to drift because the laser takes probably a longer time to actually thermalize and it moves very rapidly changing the temperature of the laser. |
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Mon Jul 7 11:22:02 2008 |
Alberto | Update | General | Beats of the two lasers in the absolute length measurement observed |
I didn't post a screenshot from the RF SA because I had troubles with the interface with the computer (unfortunately the network SA cannot export the data either).
There is problem with the PLL circuit. The signal, beside the beat, also contains peaks at 33, 66 and 99 MHz, so we should think about filtering those out.
Quote: | Great! Conguraturation! I wish if I could see it! It's nice if you can put the photo or anything of the RF spectrum analyzer.
Next step:
o You can try to maximize the beat amplitude by the tuning of the Injection steering mirrors.
o At the south end of the SP table, I prepared a frequency mixer. You can put the beat signal into the RF input, and an oscillator (which you can bring from somewhere) to the LO input in order to obtain the error signal of the PLL. Put the IF output of the mixer in a SR560, and please try to lock it by a simple 6db/oct (1st order) LPF of the SR560. For the actuator you can use the fast-pzt input of the NPRO.
Quote: | Then I explored the range of temperature of the NPRO from 35deg (C) to 51.2807deg and at that point I could observe a peak corresponding to the beat at about 10MHz on the network analyzer. |
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Mon Jul 7 19:15:38 2008 |
Alberto | Update | General | Optics alignement on the ABS length experiment |
Today I started setting up the PLL instruments to lock the frequency of the NPRO beam to the IFO beam. with no need of a new alignment after the weekend I was able to see the beat again, although this time I found at a different temperature of the NPRO laser of about 54 degrees (vs 51 of the last time).
I've got the Marconi as local oscillator (LO), the mixer Koji suggetsed, the SR560 and a 5 MHz low pass filter to cut the 33, 66 and 99 MHz present in the output signal from the PD. The filter worked well and I was able to single out only the beat resonance from the power spectrum.
In the attempt to enhance the amplitude of the beat, as Koji suggested, I tried to work on the alignment of the steering mirrors. While I was doing that, for some reason the pre-modecleaner lost the alignment and I had to ask John to help me lock it again. during the process I lost the old alignment but at the end I got a new one, apparently (from the camera) even better than the other. Although after that the beats were gone. Actually after the lock-in of the PMC the IFO beam didn't look as good as before, so it might be also for that reason.
I'll try again tomorrow, after that probably tonight Rob is going to reset the alignments of the interferometers. |
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Thu Jul 10 19:12:07 2008 |
Alberto | Update | General | abs cavity length measurement experiment |
Yesterday morning, when I started, I found the IFO beam on a different position and the beam spot at the AS port looked very deformed. The overlapping with the secondary beam was not good enough to observe the beats anymore. Restoring the alignments of the interferometers did not work because, as John found out later, some of the photodiodes had offsets and gain which made the restore script ineffective. After resetting the parameters, we had to align every mirror of the interferometers and save the configuration twice. The second times was because on the first time the alignment had been done with the illuminators on. To avoid that in the future, John wrote an alarm to warn about the status of the lights.
After that we fixed the IFO beam, I had to realign the optics in the table to match the secondary beam to the IFO beam. I got the two beam overlapping and, even though the NPRO spot looked distorted, I could observe again some signal of the beat. To do that it was also necessary to have all the interferometer mirrors aligned so that we had more power from the ifo beam although it also made the spot flash. Ideally, to avoid the flashing (which we would also impede the PLL to work) we should work with the interferometer locked. Since that doesn't seem actually possible, we should just keep one of the ITM aligned and improve the beam matching so that we can observe the beats even with less power.
Today I spent the day trying to improve the alignement of the optics to observe the beats with only the ITM aligned, resetting the alignment of both beams with the ireses, with the Farady and all the rest. It was a rather long and tiring process but I think I'm close to the target and maybe tomorrow. |