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ID Date Author Type Category Subjectup
  9535   Tue Jan 7 23:50:27 2014 jamieUpdateCDS/frames space cleared up, daqd stabilized

The wiper script is done and deleted a whole bunch of stuff to clean up some space:

controls@fb ~ 0$ /opt/rtcds/caltech/c1/target/fb/wiper.pl --delete

Tue Jan  7 23:09:21 PST 2014

Directory disk usage:
/frames/trend/minute_raw 385927520k
/frames/trend/second 125729084k
/frames/full 12552144324k
/frames/trend/minute 2311404k
Combined 13066112332k or 12759875m or 12460Gb

/frames size 13460088620k at 97.07%
/frames above keep value of 95.00%
Frame area size is 12401156668k
/frames/full size 12552144324k keep 11781098835k
/frames/trend/second size 125729084k keep 24802313k
/frames/trend/minute size 2311404k keep 620057k
Deleting some full frames to free 771045488k
- /frames/full/10685/C-R-1068567600-16.gwf
- /frames/full/10685/C-R-1068567616-16.gwf
...
controls@fb ~ 0$ df -h /frames
Filesystem            Size  Used Avail Use% Mounted on
/dev/sda1              13T   12T  826G  94% /frames
controls@fb ~ 0$
So it cleaned up 826G of space.  It looks like the fb is stabilized for the moment.  On site folks should confirm...

 

asdfasdfsadf sadf asdf

  9949   Tue May 13 17:45:21 2014 ranaUpdateCDS/frames space cleared up, daqd stabilized

 

 Late last night we were getting some problems with DAQD again. Turned out to be /frames getting full again.

I deleted a bunch of old frame files by hand around 3AM to be able to keep locking quickly and then also ran the wiper script (target/fb/wiper.pl).

controls@pianosa|fb> df -h; date

Filesystem            Size  Used Avail Use% Mounted on

/dev/sda1             440G  9.7G  408G   3% /

none                  7.9G  288K  7.9G   1% /dev

none                  7.9G  464K  7.9G   1% /dev/shm

none                  7.9G  144K  7.9G   1% /var/run

none                  7.9G     0  7.9G   0% /var/lock

none                  7.9G     0  7.9G   0% /lib/init/rw

none                  440G  9.7G  408G   3% /var/lib/ureadahead/debugfs

linux1:/home/cds      1.8T  1.4T  325G  82% /cvs/cds

linux1:/ligo           71G   18G   50G  27% /ligo

linux1:/home/cds/rtcds

                      1.8T  1.4T  325G  82% /opt/rtcds

fb:/frames        13T   12T  559G  96% /frames

linux1:/home/cds/caltech/users

                      1.8T  1.4T  325G  82% /users

Tue May 13 17:35:00 PDT 2014

Looking through the directories by hand it seems that the issue may be due to our FB MXstream instabilities. The wiper looks at the disk usage and tries to delete just enough files to keep us below 95% full for the next 24 hours. If, however, some of the channels are not being written because some front ends are not writing their DAQ channels to frames, then it will misestimate the disk size. In particular, if its currently writing small frames and then we restart the mxstream and the per frame file size goes back up to 80 MB, it can make the disk full.

For now, I have modified the wiper.pl script to try to stay below 93%. As you can see by the above output of 'df', it is already above 96% and it still has files to write until the next run of wiper.pl 7 hours from now at. at 6 AM.

IF we assume that its writing a 75MB file every 16 seconds, then it would write 405 GB of frames every day. There is 559 GB free right now so we are OK for now. With 405 GB of usage per day, we have a lookback of ~12TB/405GB ~ 29 days (ignoring the trend files).

  9955   Thu May 15 01:42:07 2014 ranaUpdateCDS/frames space cleared up, daqd stabilized

 Script seems to be working now:

nodus:~>df -h | grep frames

fb:/frames              13T    12T   931G    93%    /frames

  9042   Tue Aug 20 16:23:41 2013 ranaSummaryGeneral/home/cds nearly full

/home/cds is >98% full - below are some of the usage numbers:

controls@rosalba:/users/OLD 0$ du -h --max-depth=1
42M    ./katrin
1.5M    ./ben
2.4M    ./sanjit
569M    ./waldman
328M    ./sonia
3.6G    ./lsinger
44M    ./dbusby
105M    ./dbarron
21M    ./manuel
709M    ./yaakov
46M    ./rodionov
240M    ./ishwita
2.7G    ./clara
56M    ./gopal
290M    ./mashaB
87M    ./varvella
5.6M    ./Sascha
2.9G    ./ryan
190M    ./nancy
3.5G    ./john
269M    ./elizabeth.davison
165M    ./jweiner
460K    ./mjones
49M    ./stephanie
52M    ./mohana
56M    ./noriyasu
38M    ./mjenson
76M    ./sballmer
224M    ./kirk
812K    ./bonnie
33M    ./janosch
16M    ./kevin
122M    ./dblair
2.6G    ./mirko
389M    ./keenan
195M    ./tf
150M    ./littlezach
193M    ./jmiller
1.8G    ./ting
131M    ./dmalling
842M    ./sharmila
1.4G    ./caryn
12G    ./rward
4.1M    ./jay
443M    ./emintun
184M    ./katharine
76K    ./nick
804K    ./nicole.ing
14M    ./jenny
542M    ./vsanni
45M    ./peter
7.8G    ./miyakawa
4.8M    ./channa
4.0K    ./frank
9.9G    ./razib
35M    ./amin
361M    ./sharon
62M    ./bram
3.9M    ./volodya
7.9M    ./larisa
301M    ./sasha
33M    ./eric.hendries
18M    ./vuk
101M    ./huan
1.8M    ./sonali
453M    ./megan
43M    ./Royal
5.4G    ./ayaka
19M    ./mott
518M    ./justing
501M    ./avi
173M    ./kakeru
3.9G    ./alberto
41M    ./paul.fulda
59M    ./elena
67G    .

controls@rosalba:/opt/rtcds/userapps 0$ du -h --max-depth=1
1.4G    ./tags
13M    ./trunk.bak
40K    ./.svn
3.0G    ./trunk
174M    ./trunk.bak2
4.2G    ./branches
8.7G    .

linux1:cds>nice du -h --max-depth=1
du: `./llo/chans/daq/archive': Permission denied
du: `./llo/chans/daq/old': Permission denied
707M    ./llo
9.7M    ./mit~
752K    ./raidwebFirmware
462M    ./epics
2.1G    ./tmp
1.5G    ./gds
76M    ./project
9.1G    ./ligo
449G    ./rtcds
3.3G    ./apps
20K    ./.kde
512K    ./cdscfg
1.4M    ./.Trash-controls
5.8M    ./scripts
20K    ./.TemporaryItems
964G    ./caltech
71M    ./bin
16K    ./.Trash-1001
4.5G    ./rtapps
564M    ./src
11M    ./vw
3.8M    ./dvSave
460M    ./lho
1.2G    ./data
1.5T    .

  9045   Wed Aug 21 17:42:03 2013 ranaSummaryGeneral/home/cds nearly full

One of the reasons that our disk is getting full is due to the scripts_archive directory. A backup script runs on op340m and makes a tar.bz2 file of the scripts directory and puts it in scripts_archive every morning at 6 AM.

On Oct 7, 2011, Koji fixed this script to point at our new scripts directory instead of the old /cvs/cds/caltech/scripts directory. Since then, however, no one has fixed the exclude file to NOT back up the junk that's in that directory. Its a 1.6 GB directory so its full of it.

I've deleted a bunch of junk from the scripts directory: this directory is for scripts, not for your personal home movies or junk data files. Put those in your USER directory. Put temporary data files in /tmp/. I've also added a few more patterns to the exclude file so that less .mpg, .png, .pdf, .dat, etc get stored every day. The new daily .tar.bz2 file wil be ~25 MB instead of 770 MB.

(also fixed the backup script to use 'env' to setup the perl environment and removed the hard-coded path to tar)

  9147   Fri Sep 20 20:14:52 2013 ranaSummaryGeneral/home/cds nearly full

Quote:

One of the reasons that our disk is getting full is due to the scripts_archive directory. A backup script runs on op340m and makes a tar.bz2 file of the scripts directory and puts it in scripts_archive every morning at 6 AM.

On Oct 7, 2011, Koji fixed this script to point at our new scripts directory instead of the old /cvs/cds/caltech/scripts directory. Since then, however, no one has fixed the exclude file to NOT back up the junk that's in that directory. Its a 1.6 GB directory so its full of it.

I've deleted a bunch of junk from the scripts directory: this directory is for scripts, not for your personal home movies or junk data files. Put those in your USER directory. Put temporary data files in /tmp/. I've also added a few more patterns to the exclude file so that less .mpg, .png, .pdf, .dat, etc get stored every day. The new daily .tar.bz2 file wil be ~25 MB instead of 770 MB.

(also fixed the backup script to use 'env' to setup the perl environment and removed the hard-coded path to tar)

 OUr disk was getting full again. Turned out my "fix" to 25 MB was only a fix to 250 MB. Since we were getting disk full warnings on our Ubuntu workstations, I deleted some COMSOL.dmg files from users/zach/ and then started deleting every other tarball from the scripts_archive directory. ~221 GB are now free. Still need to fix the exclude file for scripts better.

  11986   Thu Feb 11 14:28:50 2016 SteveUpdateTreasure091415 declared

   Beautifully Done

   Chirp

  what is next?

Atm 3, Ron Drever could not celebrate with us because of health issues.

 

  6496   Fri Apr 6 15:06:05 2012 DenUpdateIOO1 Hz resonance

I think we can try to damp 1 Hz resonance more. In September it was not seen because of the digital noise. After we've figured it out, 1 Hz resonance began to be more clear (blue line).

psd_mcl.jpg

Now applying oaf we reduce the effect of the stack and the 1 Hz resonance is even more clear:

mcl.jpg

 

  7234   Mon Aug 20 13:02:57 2012 DenUpdateAdaptive Filtering1 Hz resonance

Static filter was adjusted to filter 1 Hz resonance in MCL and it could do it. Stack is not great in this experiment due to the phase mismatch. I'll fix it.

1hz.png

  8008   Wed Feb 6 14:51:25 2013 JenneUpdateElectronics1 power supply replaced!

Quote:

Currently, DC power for amplifiers ZHL-1000LN+ is supplied by Aligent E3620A.
I tried to use power supply from the side of 1X1 rack, but fuse plug(Phoenix Contact ST-SI-UK-4) showed red LED, so I couldn't use it.

 Yuta, Jenne

We fixed things so that we are now using regular fused rack power for these amplifiers.  The fuse no longer had a red LED, but it measured open when we checked the resistance.  Although, somehow (magic?) 13.73V were getting to the other side of the fuse. 

Anyhow, replacing the fuse with a new one fixed the problem right up.

  3171   Wed Jul 7 19:41:27 2010 JenneUpdateSUS1.5 more ECD sets suspended for tip tilts

[Jenne, Kyung Ha]

We made some good progress on suspending the Tip Tilt ECDs today.  We finished one whole set, plus another half.  The half is because one of the screw holes on the lower right ECD somehow got cross threaded.  The ECD and screws in question were separately wrapped in foil to mark them as iffy.  We'll redo that second half tomorrow.  This makes a total of 2.5 (including yesterday's work) ECD backplanes suspended.  The only thing left for these ones is to trim up the excess wire.

We also (with Koji) took a look at the jig used for suspending the mirror holder.  It looks like it was designed for so many Tip Tilt generations ago as to be basically useless for the 40m TTs.  The only really useful thing we'll get out of it is the distance between the suspension block and the mirror holder clamps.  Other than that we'll have to make do by holding the mirror and block at the correct distance apart, utilizing a ruler, calipers, or similar.  Rana pointed out that we should slightly bend the blade springs up a bit, so that when they are holding the load of the mirror holder, they sit flat. 

Attached below are 2 different pictures of one of the ECD backplane sets that has been suspended.  One with black background to illustrate the general structure, and one with foil background to emphasize the wires.

  9482   Tue Dec 17 20:59:23 2013 JenneUpdateLSC1/sqrt(TR) signals added to frames

I noticed that we have not been saving the 1/sqrt(TRX) and 1/sqrt(TRY) data, so I modified the c1lsc model and added them to the DAQ channels block.  I restarted the c1lsc model, and the _DQ channels are now archived.

  1640   Mon Jun 1 19:19:26 2009 ranaUpdatePSL1000 days of hour-trend
  9253   Fri Oct 18 08:12:08 2013 SteveUpdatePEM1000 days trends
  12949   Fri Apr 21 13:59:47 2017 Eric GustafsonSummary 1064 nm Semiconductor Laser Fiber Distribution System and Mirror Tomography

1064 nm Semiconductor Laser Fiber Distribution System and Mirror Tomography

Below threshold these Semiconductor Fabry-Perot lasers have an axial mode structure with a spacing of about a THz. As you turn up the current to above threshold the first mode to oscillate saturates the gain down on all the modes and only it oscillates.  The laser I have here in my office (a backup for the one you have at the 40 meter) has a wavelength of 1064.9 nm at 70 Degrees C.  We should be able to temperature tune it down to 1064.3 nm although this could be a bit tedious the first time we do it. The specifications claim a "spectrum width" of 1.097 nm which I believe is the temperature tuning range.  I don’t know what the line width is but it will be single frequency and we shouldn’t have mode hoping problems.  So we should be able to use it in the “Mirror Tomography” experiment.  You might want to use some sort of polarization diversity to avoid the problems of fiber polarization drift.

There have been 2 student projects on using the fiber distributed PD frequency response at1064 nm laser.

“Automated Photodiode Frequency Response Measurement System,” Alexander Cole - T1300618

“Final Report: Automated Photodiode Frequency Response Measurement System for Caltech 40m lab,” Nichin Sreekantaswamy - P140021

I’ll look up a few more references and add include them in the next elog.

Eric

 

  2653   Wed Mar 3 18:32:25 2010 AlbertoUpdate40m Upgrading11 MHz RFPD elctronics
** Please add LISO file w/ component values.
 
I designed the circuit for one of the 11 MHz photodiodes that we're going to install in the 40m Upgrade.

This is a simple representation of the schematic:

          gnd
#          |
#          Cw2
#          |
#          n23
#          |
#          Lw2
#          |
#           n22
#          |
#          Rw2                
#                 |                   |\            
#           n2- - - C2 - n3 -  - -  - |  \          
#            |    |      |   |        |4106>-- n5 - Rs -- no
# iinput    Rd   L1     L2 R24    n6- |  /     |           |
#      nin - |    |      |   |    |   |/       |         Rload    
#           Cd   n7     R22 gnd   |            |           |          
#            |    |      |        | - - - R8 - -          gnd              
#           gnd  R1     gnd      R7 
#                 |               |
#         gnd               gnd
#                 
#
#

I chose the values of the components in a realistic way, that is using part available from Coilcraft or Digikey.

Using LISO I simulated the Tranfer Function and the noise of the circuit.

I'm attaching the results.

I'll post the 55MHz rfpd later.

  2655   Thu Mar 4 08:43:35 2010 AlbertoUpdate40m Upgrading11 MHz RFPD elctronics

Quote:
** Please add LISO file w/ component values.

oops, forgotten the third attachment...

here it is

  7515   Wed Oct 10 02:15:14 2012 ranaUpdateLSC11 MHz reconnected to EOM

 Absolutely hokey. What are our requirements for this RFPD? What are the power levels and SNR that we want (I seem to remember that its for 22 as well as 110 MHz)? Perhaps we can test an aLIGO one if Rich has one sitting around, or if the aLIGO idea is to use a broadband PD I guess we can just keep using what we have.

  845   Mon Aug 18 09:19:55 2008 steveSummaryVAC11 days at atm
It took 11 days to fix earth quake triggered sus problems of ITMX, SRM and PRM
Only ITMX north and BSC north vac doors were removed.

The PRM sus had to be removed form the vac envelope for "hip replacement"-new wire stand off was
epoxied in place.
Note: the PRM has no guide rod on the other side

ITMX, SRM and BS osems were optimized in place.
No crosscoupling optimization was performed.
Beam block was removed from ITMXC, it was too close to the main beam.

POX pick off mirror and mount will be replaced next vent.

Vac viewports were inspected from the inside.
  7360   Fri Sep 7 12:28:09 2012 KojiUpdateLSC11&55MHz modulations turned off

11MHz modulation source was turned off (disabled) at Marconi at 12:00.

  9072   Tue Aug 27 18:21:35 2013 JenneConfigurationElectronics110 MHz LO options

As I see it, we have a few options for getting the 110 MHz LO to both the POP110 and AS110 demod boards.  

The current situation is described by Kiwamu in elog 5746.  The 55 MHz signal comes into the box, and is split 4 ways, with each path having 19.7 dBm.  One of these 4 is for 110.  It has a 2dB attenuator (giving us ~17.7 dBm), and then it goes to an MK-2 frequency multiplier.  I'm a little lost on why we're giving the MK-2 17 dBm, since it says that it can handle an input power between 1 - 15 dBm.  It has ~16 dB conversion loss, so the 110 output of the distribution board has (according to the drawing) 1.9 dBm.  The demod boards have a 10 dB attenuator as the first element on the LO path, so we're giving the ERA-5 -8 dBm. 

We can either amplify the 110 leaving the distribution box, split it, and then attenuate it to the appropriate level for the demod boards, or we can change the attenuators on the POP110 and AS110 demod boards. 

Since we seem to be over driving the 2x frequency multiplier, I think I should change the 2dB attenuator to a 5dB attenuator, so we're giving the 2x multiplier ~15 dBm.  The conversion loss of ~16 dB means we'll have -1 dBm of 110 MHz.  I want to amplify that by ~10 dB, to give 9 dBm.  Attenuate by 5 dB to get to 4 dBm, then split into 2, giving me 2 110 MHz spigots, each of ~1 dBm.  Since the demod boards expect between 0-2 dBm for the LO's, this should be just fine.

Thoughts, before I start scrounging parts, and pulling the RF distribution box?

  9073   Tue Aug 27 18:58:52 2013 KojiConfigurationElectronics110 MHz LO options

- Do we have an appropriate amplifier?

- True challenge could be to find a feedthrough for the new port. (or to find a space for the amplifier in the box)

- PDXXX channels is on the DC whitening filter module. There could be some modification on this module (like diabling the whitening gain selector).

- We don't have AS11 and AS165, and so far it is unlikely to use AS11. i.e. The feedthrough, the slot on the crate, the whitening, and the channels can be trasnsition from 11 to 110.

Quote:

I want to amplify that by ~10 dB, to give 9 dBm.  Attenuate by 5 dB to get to 4 dBm, then split into 2, giving me 2 110 MHz spigots, each of ~1 dBm. 

Thoughts, before I start scrounging parts, and pulling the RF distribution box?

 

  11230   Tue Apr 21 11:55:05 2015 SteveUpdateOptical Levers1103P noise measurement

Manasa and Steve,

Is this what you want?  Dashed lines are dark.

BS and PRM oplevs are blocked for this measurement. I will restore to normal operation at 4pm today.
 

  11231   Tue Apr 21 15:03:27 2015 ranaUpdateOptical Levers1103P noise measurement

It doesn't work with the lens in there, but it seems pretty close. Please leave it as is and I'll play with it after 5 today.

  11232   Tue Apr 21 21:46:34 2015 ranaUpdateOptical Levers1103P noise measurement

To test what the inherent angular noise of the HeNe 1103P laser is, we're testing it on a table pointing into the BS OL QPD with only a few steering mirrors.

From the setup that I found today, I've removed the lens nearest to the laser (which was used for the BS and PRM) as well as the ND filter (what was this for?) and the lens placed just before the BS QPD.

With the ND filter removed, the quadrant signals are now ~15000 if we misalign it and ~9000 each with the beam centered.

In order to calibrate the OLPIT_IN1 and OLYAW_IN1 signals into mm of beam motion, I misaligned the mirror just before the QPD. The knobs on there actuate the 100 TPI screws and the knurling on the knob itself has 10 ridges, so that's 36 deg per bump.

Pit Knob (deg) OLPIT Yaw Knob (deg) OLYAW
0 29 0 -36
45 13 36 -16
90 -16 72 19
135 -39 108 36
       

PIT cal ~ 1.55 (knob deg / count) -->> 10 microns / count --->>> 10 urad / count

YAW cal ~ 1 (knob deg / count)  -->> 6.5 microns / count --->>> 6.5 urad / count

Distance from the 45 deg turning mirror to the QPD silicon surface is 23 cm. Distance between knob tip and fixed pivot point is ~4 cm. 1 knob turn = 0.01" = 0.254 mm = 0.254/40 radians of mirror angle.

So 360 deg of knob gives 2*0.254/40 = 0.012 radians of beam angle = 0.012 * 230 mm ~2.3 mm of beam spot motion. Or 6.4 microns of translation / deg of knob.

The distance from the face of the laser to the QPD is 96 cm.


The punchline is that the laser shows a level of noise which has a similar shape to what's seen at LLO, but 10x lower.

The noise at 0.05 - 0.2 Hz is ~2-3x worse than the PR3 at LLO. Not sure if this is inherent to the HeNe or the wind in our setup.

  6590   Mon Apr 30 22:58:57 2012 JenneUpdateElectronics11MHz Marconi set to default after power outage

After a power outage, a Marconi comes back to it's defaults.  It needed to be reset to the values in elog 5530.  I'm putting a label on the Marconi so we don't have to look it up next time.

Before fixing the Marconi, POY11, AS11 and AS55 all looked like noise, no real signals, even though the arm is flashing.  Now they all look PDH-y, so things are better.

  2656   Thu Mar 4 19:53:56 2010 AlbertoUpdate40m Upgrading11MHz PD designed adjusted for diode's resistance; 55 MHz RFPD designed
After reading this study done at LIGO MIT in 1998 I understood why it is difficult to define an effective impedance for a photodiode.

I read a few datasheets of the C30642GH photodiode that we're going to use for the 11 and 55 MHz. Considering the  values listed for the resistance and the capacitance in what they define "typical conditions" (that is, specific values of bias voltage and DC photocurrent) I fixed Rd=25Ohms and Cd=175pF.

Then I picked the tunable components in the circuit so that we could adjust for the variability of those parameters.

Finally with LISO I simulated transfer functions and noise curves for both the 11 and the 55MHz photodiodes.

I'm attaching the results and the LISO source files.

 

  2657   Thu Mar 4 22:07:21 2010 ranaUpdate40m Upgrading11MHz PD not yet designed

Use 10 Ohms for the resistance - I have never seen a diode with 25 Ohms.

p.s. PDFs can be joined together using the joinPDF command or a few command line options of 'gs'.

  4533   Fri Apr 15 15:15:08 2011 kiwamuUpdateLSC11MHz demod board : 90 degree splitter

[Rana, Koji, Kiwamu]

 Moreover the amplitude of the I and Q signals are highly unbalanced, depending on the LO power again.

This implies the coil for a 90 degree splitting won't work at 11 MHz since the coil is home made and used to be designed for a specific frequency (i.g. 24.5 MHz).

We decided to use a Mini circuit 90 deg splitter instead. Steve will order few of them soon and we will test it out.

Quote:

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

It is now under investigation.

 

  4537   Sat Apr 16 02:00:14 2011 ranaUpdateLSC11MHz demod board : 90 degree splitter

One way to avoid some of the bad stuff in there is to take the 1 dBm input and amplify it to ~21 dBm before splitting and sending in to the Level 17 mixers.

One way to do this is by using the A3CP6025 from Teledyne-Cougar. Its an SMA connectorized amp which can put out 25 dBm and has a gain of 24 dB. We can just glue it onto the demod boards. Then we can remove the ERA-5 amplifiers and just use the broadband splitter as Kiwamu mentioned.

  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.

  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.

  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.

  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.

 

 

  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.

 

  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.

  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.

  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.

  2552   Thu Jan 28 09:17:32 2010 AlbertoUpdateLSC166 Modulation turned off

I temporarily turned off the 166 modulation.

  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.
  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.
  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. 

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