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ID Date Author Type Category Subjectdown
  12158   Wed Jun 8 13:50:39 2016 jamieConfigurationCDSSpectracom IRIG-B card installed on fb1

[EDIT: corrected name of installed card]

We just installed a Spectracom TSyc-PCIe timing card on fb1.  The hope is that this will help with the GPS timeing syncronization issues we've been seeing in the new daqd on fb1, hopefully elliminating some of the potential failure channels.

The driver, called "symmetricom" in the advLigoRTS source (name of product from competing vendor), was built/installed (from DCC T1500227):

controls@fb1:~/rtscore/tests/advLigoRTS-40m 0$ cd src/drv/symmetricom/
controls@fb1:~/rtscore/tests/advLigoRTS-40m/src/drv/symmetricom 0$ ls
Makefile  stest.c  symmetricom.c  symmetricom.h
controls@fb1:~/rtscore/tests/advLigoRTS-40m/src/drv/symmetricom 0$ make
make -C /lib/modules/3.2.0-4-amd64/build SUBDIRS=/home/controls/rtscore/tests/advLigoRTS-40m/src/drv/symmetricom modules
make[1]: Entering directory `/usr/src/linux-headers-3.2.0-4-amd64'
  CC [M]  /home/controls/rtscore/tests/advLigoRTS-40m/src/drv/symmetricom/symmetricom.o
/home/controls/rtscore/tests/advLigoRTS-40m/src/drv/symmetricom/symmetricom.c:59:9: warning: initialization from incompatible pointer type [enabled by default]
/home/controls/rtscore/tests/advLigoRTS-40m/src/drv/symmetricom/symmetricom.c:59:9: warning: (near initialization for ‘symmetricom_fops.unlocked_ioctl’) [enabled by default]
/home/controls/rtscore/tests/advLigoRTS-40m/src/drv/symmetricom/symmetricom.c: In function ‘get_cur_time’:
/home/controls/rtscore/tests/advLigoRTS-40m/src/drv/symmetricom/symmetricom.c:89:2: warning: ISO C90 forbids mixed declarations and code [-Wdeclaration-after-statement]
/home/controls/rtscore/tests/advLigoRTS-40m/src/drv/symmetricom/symmetricom.c: In function ‘symmetricom_init’:
/home/controls/rtscore/tests/advLigoRTS-40m/src/drv/symmetricom/symmetricom.c:188:2: warning: ISO C90 forbids mixed declarations and code [-Wdeclaration-after-statement]
/home/controls/rtscore/tests/advLigoRTS-40m/src/drv/symmetricom/symmetricom.c:222:3: warning: label ‘out_remove_proc_entry’ defined but not used [-Wunused-label]
/home/controls/rtscore/tests/advLigoRTS-40m/src/drv/symmetricom/symmetricom.c:158:22: warning: unused variable ‘pci_io_addr’ [-Wunused-variable]
/home/controls/rtscore/tests/advLigoRTS-40m/src/drv/symmetricom/symmetricom.c:156:6: warning: unused variable ‘i’ [-Wunused-variable]
  Building modules, stage 2.
  MODPOST 1 modules
  CC      /home/controls/rtscore/tests/advLigoRTS-40m/src/drv/symmetricom/symmetricom.mod.o
  LD [M]  /home/controls/rtscore/tests/advLigoRTS-40m/src/drv/symmetricom/symmetricom.ko
make[1]: Leaving directory `/usr/src/linux-headers-3.2.0-4-amd64'
controls@fb1:~/rtscore/tests/advLigoRTS-40m/src/drv/symmetricom 0$ sudo make install
#remove all old versions of the driver
find /lib/modules/3.2.0-4-amd64 -name symmetricom.ko -exec rm -f {} \; || true
find /lib/modules/3.2.0-4-amd64 -name symmetricom.ko.gz -exec rm -f {} \; || true
# Install new driver
install -D -m 644 symmetricom.ko /lib/modules/3.2.0-4-amd64/extra/symmetricom.ko
/sbin/depmod -a || true
/sbin/modprobe symmetricom
if [ -e /dev/symmetricom ] ; then \
        rm -f /dev/symmetricom ; \
    fi
mknod /dev/symmetricom c `grep symmetricom /proc/devices|awk '{print $1}'` 0
chown controls /dev/symmetricom
controls@fb1:~/rtscore/tests/advLigoRTS-40m/src/drv/symmetricom 0$ ls /dev/symmetricom
/dev/symmetricom
controls@fb1:~/rtscore/tests/advLigoRTS-40m/src/drv/symmetricom 0$ ls -al /dev/symmetricom
crw-r--r-- 1 controls root 250, 0 Jun  8 13:42 /dev/symmetricom
controls@fb1:~/rtscore/tests/advLigoRTS-40m/src/drv/symmetricom 0$ 
  12161   Thu Jun 9 13:28:07 2016 jamieConfigurationCDSSpectracom IRIG-B card installed on fb1

Something is wrong with the timing we're getting out of the symmetricom driver, associated with the new spectracom card.

controls@fb1:~/rtscore/tests/advLigoRTS-40m/src/drv/symmetricom 127$ lalapps_tconvert 
1149538884
controls@fb1:~/rtscore/tests/advLigoRTS-40m/src/drv/symmetricom 0$ cat /proc/gps 
704637380.00
controls@fb1:~/rtscore/tests/advLigoRTS-40m/src/drv/symmetricom 0$ 

The GPS time is way off, and it's counting up at something like 900 seconds/second.  Something is misconfigured, but I haven't figured out what yet.

The timing distribution module we're using is spitting out what appears to be an IRIG B122 signal (amplitude moduled 1 kHz carrier), which I think is what we expect.  This is being fed into the "AM IRIG input" connector on the card.

Not sure why the driver is spinning so fast, though, with the wrong baseline time.  Reboot of the machine didn't help.

  15615   Tue Oct 6 14:35:16 2020 JordanUpdateVACSpare forepumps

I have placed 3 new in box, IDP 7 forepumps along the x arm of the interferometer. These are to be used as spares for both the 40m and Clean and Bake.

  15168   Tue Jan 28 19:12:30 2020 JonConfigurationPSLSpare channels added to c1psl chassis

After some discussion with Gautam, I decided to build more spare channels into the new c1psl machine. This is anticipation of adding new laser and ISS channels in the near future, to avoid having to disconnect the installed chassis and pull it out of the rack. The spare channels will be wired to DB37M feedthroughs on the front side of the chassis, with enough wire length to be able to pull the breakout boards out of the front to reconfigure their wiring as needed (e.g., split off channels onto a separate connector).

To have enough overhead, this will require installing 1 additional ADC unit (XT1221) and 1 additional DAC (XT1541). We have enough spare BIO channels among the existing units (both sinking and sourcing). This will give us:

  • 13 spare ADC channels
  • 14 spare DAC channels
  • 16 spare sinking BIO channels
  • 12 spare sourcing BIO channels

The updated c1psl chassis wiring assignments are attached. It adds 4 new DB37M connectors for the spare channels (highlighted in yellow) and fixes one typo Jordan found while wiring today. The most current spreadsheet is available here.

  15624   Tue Oct 13 21:22:29 2020 gautamUpdateGeneralSpace cleared in 1Y1 for new FEs

[JV, GV]

We cleared up some space in the 1Y1 electronics rack to install the 3 new FE machines. I removed the current driver and laser from 1Y1, they are now stored in the E10 cabinet. I will upload some photos to gPhotos soon.

  1. I think it's good to have all these FEs in one rack (at least the new ones) - we should then hook it up to an ethernet power source, so that we can remotely power cycle them. I think we have long enough cables to interface to expansion chasses / dolphin switches, but if not, I think it's still a good idea to have these machines in 1Y1 as it is the least sensitive area in terms of immunity to bumping some cable during setup work and disturbing the rest of the IFO.
  2. We found that the rails that the Supermicros shipped with the servers seem to be just a little too narrow - we mounted these in the rack, but had considerable difficulty sliding the server units in. Once they are in, they don't slide smoothly. Is there some special trick to installing these? 
  3. I spent a few minutes trying to get Debian 8 installed on these machines, so that the rest of the setup work could be done remotely - however, there appear to be some firmware issues and so I'm not gonna dive into this.
    • I couldn't find a disk image for Debian 8.5 which is what the KT wikl recommends, so the OS I tried to install was Debian 8.11.
    • The error that comes up is related to a "stalled CPU" - apparently this is related to some graphics driver issue (there's another forum page that suggests upgrading the BIOS, but I don't think that's the problem here).
    • Anyways, this part of the process is only to install some drivers and do the initial setup - these machines will eventually run a diskless boot from the image on FB, so who knows if there will be some other driver issues/hardware-software incompatibilities there 😱 .
    • We should also make an effort to set these machines up with IPMI, but I think we first need to install an OS and a CLI to setup the IPMI. My cursory browsing of the manual suggests that the initial setup maybe can be done without installing an OS, and then subsequent work, including OS install, can be done remotely. If someone reads more in detail and can provide me a step-by-step, I can follow those instructions (if they aren't available to come into the lab). See here for some brief documentation of how to access the IPMI.
  14148   Thu Aug 9 02:12:13 2018 gautamUpdateCOCSouth East or West?

Summary:

For operating the SRC in the "Signal-Recycled" tuning, the SRC macroscopic length needs to be ~4.04m (compared to the current value of ~5.399m), assuming we don't do anything fancy like change the modulation frequencies and not transmit through the IMC. We're putting together a notebook with all the calculations, but today I was thinking about what the signal extraction path should be, specifically which chamber the SRM should be in. Just noting down the thoughts I had here while they're fresh in my head, all this has to be fleshed out, maybe I'm making this out to be more of a problem than it actually is.

Details:

  • For the current modulation frequencies, if we want the reosnance conditions such that the f2 sideband is resonant in the SRC (but not f1, i.e. small Schnupp asymmetry regime) while the carrier is resonant in the arms (required for good sensing of the SRC length), the macroscopic length of the SRC needs to be changed to ~4.04m.
  • Practically, this means that the folded SRC would only have one folding mirror (SR2).
  • There is a shorter SRC length of ~1.something metres which would work, but that would involve changing the relative position between ITMs and BS (currently ~2.3m) so I reject that option for now.
  • So the SR2 would be roughly where it is right now, ~20cm from the BS.
  • The question then becomes, where do we direct the reflection from the SR2? We need an optical path length of ~1.5m from SR2. So options are 
    • ITMY table (East)
    • ITMX table (South)
    • IMC table (West)
  • Moreover, after the SRM, we have to accommodate:
    • Some kind of pickoff for in-air PDs.
    • OFI.
    • OMC MMT.
    • OMC.
  • Some kind of CBA (as of now I think going to the ITMY table is the best option):
Option Advantages Disadvantages
ITMY
  • Easy to direct beam from BS/PRM chamber to the ITMY table (i.e. we don't have to worry too much about avoiding other optics in the path etc).
  • Ease of access to chamber, ease of working in there.
  • ITMY table probably has the most room to work out an OFI + OMC MMT + OMC solution.
  • AS beam extraction to air will be more complicated, possibly have to do it on ITMY optical table.
  • Not sure if the ITMY table can accommodate all of the output optics subsystems I listed above.
  • Routing the LO beam to this table would be tricky I guess.
ITMX
  • Routing the LO beam for homodyne detection is probably easiest in this chamber.
  • Allows for small AoI on folding mirror, reducing the impact of astigmatism.
  • Pain to work in this chamber because of IMC tube.
  • Steering beam from SR2 to ITMX table means threading the needle between PRM and PR3 possibly.
IMC
  • Probably allows the use of (almost) the entire existing OMC chamber for the output optics (OFI, OMC MMT, OMC).
  • IMC table is crowded (2 SOS towers, several steering optics for the input beam, input faraday).
  • Not sure what is the performance of the seismic isolation stacks on these tables vs the larger optical tables.
  • Painful to work in these smaller chambers.
  7751   Tue Nov 27 01:03:42 2012 AyakaUpdateWienerFilteringSound on PSL

 Last Thursday, I put the speaker and my laptop in the PSL table, and make triangular wave sound with the basic frequency of 40Hz, and Gaussian distributed sound.
(I create the sounds from my laptop using the software 'NHC Tone Generator' because I could not find the connector from BNC to speaker plug.)
And I measured the acoustic coupling in MCF signal. The all the 6 microphones were set in PSL table around PMC and PSL output optics. 

The performance of the offline noise cancellation with wiener filter is below.
(The target signal is MCF and the witness signals are 6 microphones.)

  • With Gaussian sound (Sorry for wrong labeling 'XARM' and no calibration)
    gauss_psdcoh_mcf.png
  • With 40Hz Triangular sound (Sorry for no calibration again)
    tri40_psdcoh_mcf.png

I can see some effects on MCF due to the sound on PSL table. Though I can subtract some acoustic signal and there are no coherence between MCF signal and mic signals, still some acoustic noise remains.
This is maybe because of some non-linearity effects or maybe because we have other effective places for acoustic coupling measurement. More investigations are needed.

Also, I compared the wiener filter and the transfer function from microphones signal to MCF signal. They should be the same ideally.
gauss_filters_mcf.pngGauss_estimatefilters_mcf.png

(Left: Wiener filter, Right: Transfer function estimated by the spectrum. They are measured when the Gaussian sound is on.)

These are different especially lower frequencies than 50 Hz. The wiener filter is bigger at lower frequencies. I guess this adds extra noise on the MCF signal. (see the 1st figure.)
The wiener filter can be improved by filterings. But if so, I want to know how can we determine the filters. It is interesting if we have some algorithms to determine the filters and taps and so on.
The more investigations are also needed.

  7760   Wed Nov 28 23:55:13 2012 AyakaUpdateWienerFilteringSound on PSL

 I have been searching for the way we can subtract signal better since I could see the acoustic coupling signal remains in the target signal even though there are no coherence between them.

I changed the training time which is used to decide wiener filter.
I have total 10 minutes data, and the wiener filter was decided using the whole data before.
tri40_psdcoh_mcf_varioust.pnggauss_psdcoh_mcf_varioust.png

(Right: the performance with the data when the triangular sound was created. Left: the performance with the data when the gaussian sound was created.)

I found that the acoustic signal can be fully subtracted above 40 Hz when the training time is short. This means the transfer functions between the acoustic signals and MCF signal change.
However, if the wiener filter is decided with short-time training, the performances at lower frequencies get worse. This is because wiener filter do not have enough low-frequency information.

So, I would like to find the way to combine the short-time training merit and long-time training merit. It should be useful to subtract the broad-band coupling noise.

  16026   Wed Apr 14 13:12:13 2021 AnchalUpdateGeneralSorry, it was me

Sorry about that. It must be me. I'll make sure it doesn't happen again. I was careless to not check back, no further explanation.indecision

  16029   Wed Apr 14 15:30:29 2021 ranaUpdateGeneralSorry, it was me

Maybe tighten the tensioner on the door closer so that it closes by itself even in the low velocity case. Or maybe just use the front door like everyone else?

  341   Tue Feb 26 20:24:04 2008 AndreySummaryTMISorrow
As for that plot of three-dimensional surface, I indeed was wrong with the axis "Q_ETMX-Q_ITMX" (I put there wrong string "Q_ITMX-Q_ETMX"). On Friday plot there were values 10^(-12) on the z-axis, and that should be really meters, but the point that as I realized on Monday, I have never calibrated experimental measurement results from counts to meters , that's why it is this difference between 10^(-6) and 10^(-12). I still did not find the way to compare experim. and theoretical plots, because even if I leave "counts" on both plots, so that I have scale 10^(-6) on both plots, then the change in theoretical plot is just 0.02*10^(-6) for the range of Q-factors change, while the change in experimental measurements is an order of magnitude more 0.4*10^(-6), so the surface for theretical plot would be almost flat in the same axes as experimental results.
  12814   Thu Feb 9 11:22:56 2017 gautamUpdateGeneralSorensens and DIN connections at 1X1

I'd like to fix a few things at 1X1 when we plug in the new amplifier for the 29.5MHz modulation signal. 

  1. Split off separate +24 and ground wires to the green BBPD RF amplifiers and the AOM driver (they are sharing a single fuse at the moment)
  2. Tap a new +24 GND -24V set for the FSS Fast summing box - this is currently running with a bench power supply underneath the PSL table set to +/-18V, but I checked the 7815/7915 datasheets and they accept up to 35V input for a 15V output, so it should be fine to use 24V
  3. Hook up the ZHL-2A for the IMC modulation.

Steve has ordered rolls of pre-twisted wire to run from 1X1 to the PSL table, so that part can be handled later.

But at 1X1, we need to tap new paths from +/- 24V to the DIN connectors. I think it's probably fine to turn off the two Sorensens, do the wiring, and then turn them back on, but is there any procedure for how this should be done? 

  8402   Wed Apr 3 15:00:24 2013 JamieSummaryElectronicsSorensen supplies in LSC rack (1Y2)

I investigated the situation of the two Sorensen supplies in the LSC rack (1Y2).  They are there solely to supply power to the LSC LO RF distribution box.  One is +18 V and the other is +28 V.  All we need to do is make a new longer cable with the appropriate plug on one end (see below), long enough to go from the bottom of the 1Y3 rack to the top of 1Y2, and we could move them over quickly.  Some sort of non-standard circular socket connector is used on the distribution box:

20130403_141842.jpg

It could probably use thicker conduction wire as well.

If someone else makes the cable I'll move everything over.

  224   Thu Jan 3 12:38:49 2008 robBureaucracyTMISore throat

Quote:

I did not feel anything wrong yesterday, but unfortunately I have a very much sore throat today. I need to drink warm milk with honey and rinse my throat often today. So far I do not have other illness symptomes (no fever), so I hope that this small disease will not last for a long time, but I feel that it is better for me to cure my sore throat today at home (and probably it is safer for others in 40-m).

I took yesterday the book "Digital Signal Processing", so I have it for reading at home.

Hope to see you tomorrow.


I've added a new category--TMI--for entries along these lines.
  11990   Mon Feb 15 12:28:03 2016 gautamUpdateGeneralSomething has gone wrong - was there a power outage?

I came into the 40m a few minutes ago, and noticed the following (approximately in this order):

  • The striptool plots projected onto the wall were gone, even though the projector seemed to be working fine
  • There was no light at all in the IFO 
  • There was an incessnt beeping noise coming from inside the lab.

To investigate further, I checked today's summary pages, and whatever caused this, happened around 730am today morning (approx 5 hours ago). I also saw that all the watchdogs were tripped, except MC3, BS and SRM. 

I then tracked down the beeping - I believe that it is coming from Megatron.(in fact, it is coming from the Jetstor..) 

I also found that the PSL is OFF, and the Marconi, though ON, has the display parameters set to values that I normally see when it is first turned ON (i.e. the carrier frequency is 1200MHz, the output is -140dBm etc - this is what led me to suspect that somehow the power connection was interrupted? As far as the workstation computers are concerned, I don't think ROSSA was affected, but pianosa is frozen and donatella is at the login screen. The CDS overview MEDM screen refuses to load correctly (though some of the other MEDM screens are working fine). I'm not entirely sure how to go about fixing all of this, so for now, I'm leaving the PSL off and I've shutdown the remaining watchdogs.

It just occurred to me to check the status of the vacuum - the MEDM screen seems to suggest everything is fine (see Attachment #1). I went down to the X end to do a quick check on the status of the turbo pumps and everything looks normal there...

  11991   Mon Feb 15 13:09:33 2016 KojiUpdateGeneralSomething has gone wrong - was there a power outage?

Looks like that's the case. LIGO GC also sent an e-mail that there was a popwer glitch.

  666   Mon Jul 14 10:57:00 2008 KojiFrogsEnvironmentSomeone at 40M sent LHO water of life
Someone at the 40m sent Mike@LHO a pound of peets coffee with the name of Koji Arai.
It was a good surprise! Thanks, we will enjoy it!
I will return to Pasadena next week. See you then.
  14602   Fri May 10 15:18:04 2019 gautamUpdatePSLSome work on/around PSL table
  1. In anticipation of installing the new fan on the PSL, I disconencted the old fan and finally removed the bench power supply from the top shelf.
  2. Moved said bench supply to under the south-west corner of the PSL table.
  3. Installed temporary Acromag crate, now with two ADC cards, under the PSL table and hooked it up to the bench suppy (+15 VDC). Also ran an ethernet cable from 1X3 to the box on over head cable tray and connected it.
  4. Brought other end of 25-pin D-sub cable used to monitor the NPRO diagnostics channels from 1X4/1X5 to the PSL table. Rolled the excess length up and cable tied it, the excess is sitting on top of the PSL enclosure. Key parts of the setup are shown in Attachments #1-3. This is not an ideal setup and is only meant to get us through to the install of the new c1psl/c1ioo Acromag crate.
  5. Edited the modbus config file at /cvs/cds/caltech/target/c1psl2/npro_config.cmd to add Jon's new ADC card to the list.
  6. Edited EPICS database file at /cvs/cds/caltech/target/c1psl2/psl.db to add entries for the C1:PSL-FSS_RMTEMP and C1:PSL-PMC_PMCTRANSPD channels.
  7. Hooked up said channels to the physical ADC inputs via a DB15 cable and breakout board on the PSL table.
    CH0 --- FSS_RMTEMP (Pins 5/18 of the DB25 connector on the interface box to pins 1/9 of the Acromag DB15 connector)
    CH1 --- PMC TRANS (BNC cable from PD to pomona minigrabber to pins 2/10 of the Acromag DB15 connector)
    CH2-6 are unsued currently and are available via the DB15 breakout board shown in Attachment #3. CH7 is not connected at the time of writing
    The pin-out for the temperature sensor interface box may be found here. Restarted the modbus process. The channels are now being recorded, see Attachment #4, although checking the status of the modbus process, I get some error message, not sure what that's about.

So now we can monitor both the temperature of the enclosure (as reported by the sensor on the PSL table) and the NPRO diagnostics channels. The new fan for the controller has not been installed yet, due to us not having a good mounting solution for the new fans, all of which have a bigger footprint than the installed fan. But since the laser isn't running right now, this is probably okay.

modbusPSL.service - ModbusIOC Service via procServ
   Loaded: loaded (/etc/systemd/system/modbusPSL.service; disabled)
   Active:
active (running) since Fri 2019-05-10 13:17:54 PDT; 2h 13min ago
  Process: 8824 ExecStop=/bin/kill -9 ` cat /run/modbusPSL.pid`
(code=exited, status=1/FAILURE)
 Main PID: 8841 (procServ)
   CGroup: /system.slice/modbusPSL.service
           ├─8841 /usr/bin/procServ -f -L /home/controls/modbusPSL.log -p /run/modbusPSL.pid 8009 /cvs/cds/rtapps/epics-3.14.12.2_long/module...
           ├─8842 /cvs/cds/rtapps/epics-3.14.12.2_long/modules/modbus/bin/linux-x86_64/modbusApp /cvs/cds/caltech/target/c1psl2/npro_config.c...
           └─8870 caRepeater

May 10 13:17:54 c1auxex systemd[1]: Started ModbusIOC Service via procServ.

  14604   Sat May 11 11:48:54 2019 JonUpdatePSLSome work on/around PSL table

I took a look at the error being encountered by the modbusPSL service. The problem is that the /run/modbusPSL.pid file is not being generated by procServ, even though the -p flag controlling this is correctly set. I don't know the reason for this, but it was also a problem on c1vac and c1susaux. The solution is to remove the custom kill command (ExecStop=...) and just allow systemd to stop it via its default internal kill method.

modbusPSL.service - ModbusIOC Service via procServ
   Loaded: loaded (/etc/systemd/system/modbusPSL.service; disabled)
   Active:
active (running) since Fri 2019-05-10 13:17:54 PDT; 2h 13min ago
  Process: 8824 ExecStop=/bin/kill -9 ` cat /run/modbusPSL.pid`
(code=exited, status=1/FAILURE)
 Main PID: 8841 (procServ)
   CGroup: /system.slice/modbusPSL.service
           ├─8841 /usr/bin/procServ -f -L /home/controls/modbusPSL.log -p /run/modbusPSL.pid 8009 /cvs/cds/rtapps/epics-3.14.12.2_long/module...
           ├─8842 /cvs/cds/rtapps/epics-3.14.12.2_long/modules/modbus/bin/linux-x86_64/modbusApp /cvs/cds/caltech/target/c1psl2/npro_config.c...
           └─8870 caRepeater

May 10 13:17:54 c1auxex systemd[1]: Started ModbusIOC Service via procServ.

  14152   Fri Aug 10 01:10:56 2018 gautamUpdateLSCSome vertex locking restored

For the first time after the whirlwind vent, I managed to lock the PRMI.

  • First, I did POX/POY locking, dither aligned the arms to maximize TRX and TRY.
  • Next, I misaligned the ETM and tested the Michelson locking
    • Since we've lost ~70% of power on the AS55 PD, I set the whitening gain for AS55 I and Q channels to +6dB (old value was 0dB).
    • worked alright. In this new config, the peak-to-peak Michelson fringe count is ~80 cts, while I reported ~60cts-pp a couple of months ago, so all seems good on that front.
    • But the config script in the IFOconfigure MEDM screen somehow doesn't set the AS55_Q ----> MICH_A element in the LSC input matrix anymore.
    • I edited the .snap file for this configuration to set the relevant matrix element EPICS channel to +1.0.
    • I also edited the overall loop gain for this configuration from +30 to +2 (for bright fringe, use -2 for dark fringe).
  • Feeling adventerous, I decided to try PRMI in the carrier resonant tuning (to be clear, PRCL on REFL11_I, MICH on AS55_Q).
    • Finding the REFL spot on the camera took a while since the PRM has been macroscopically misaligned for the mode-scanning
    • Went out to the table and centered the REFL beam onto REFL11 and REFL55 PDs - didn't need much tweaking, which is a good sign, since we shouldn't have screwed anything up on the symmetric side by any of the vent activities.
    • Restored PRMI locking using the IFOconfigure MEDM screen - lock caught almost immediately.
    • Ran the dither alignment servos for MICH and PRCL - BS needed a bit of encouragement to make the dark spot dark, but POP has been pretty stable over ~15mins.
    • I didn't take any loop transfer functions, to do.

I don't have the energy to make a DRMI attempt tonight - but the signs are encouraging. I'd like to use the IFO in the next few days to try and recover DRMI locking. The main concern is that the optical path on the AS beam has changed by ~0.3m I estimate. So the demod phase for AS55 may need to be adjusted, but the change due to optical path length only should be ~10degrees so the DRMI locking with the old settings should still work. Perhaps we also want to scan the PRC and SRC with the phase information from the Trans/Refl transfer functions as well.


Don't want to jinx it, but the c1lsc FE models have been stable. Tomorrow, I'd like to re-enable c1cal, since it has some useful channels for NBing. Could c1daf/c1oaf which have significant amounts of custom C code be the culprits?

  5914   Wed Nov 16 17:29:46 2011 kiwamuUpdateGreen LockingSome updates on the Y end green PDH
Quote from #5894

 (Things to be done)

   [DONE]   1.1 Measurement of the arm fluctuation => to allow re-designing the servo shape
   [DONE]   1.2 temporary SR560 servo
   [ONGOING]1.3 Sanity checks on the modulation depth, reflectivity, PD dark noise and etc.,
   [DONE]  1.4 Make the servo more robust
   [DONE]  1.5 Some modifications on the medm screens
   [NOTYET]   1.6 Activation of the temperature feedback through the realtime digital control

Some updates on the Y end green PDH lock

(Measurement of the Y arm fluctuation)

In order to design the PDH box's servo shape we wanted to measure the Y arm fluctuation.
Here is the spectrum taken by looking at the control signal before the laser PZT.
 
 Yarm_fluctuation.png
 The scale of the Y axis is calibrated by using the PZT response of 5 MHz/V.
Above 10 Hz the spectrum shows 1/f noise which I believe the laser frequency noise.
 

(Temporary servo setup)

 We have found that the servo shape was not enough (#5890) to well-suppress the fluctuation shown above.
 Since the Newfocus fast servo box only makes 1/f shape, the error signal wasn't suppressed within the linear range.
So I have added an SR560 in the other input of the Newfocus servo box to make the filter shape 1/f^2.
Then the lock became more solid and the reflected DC light in time series is now much flat if the alignments are good.
I will post the servo shape and diagram later.

(Sanity checks)

 I looked at the reflected DC light when the laser was kept locked.
The reflectivity of the Y arm cavity went down to about 30% and this is good because it is supposed to be 27.5% when it is locked according the spec.
This means the mode-matching is not so bad.
  4834   Fri Jun 17 23:20:05 2011 KojiUpdateLSCSome updates of the LSC screen

Some updates of the LSC screen

- Signal amplitude monitor for the PD signals (--> glows red for more than 1000)

- Kissel Buttons for the main matrices

- Trigger display at the output of the DOF filters

- Signal amplitude monitor for the SUS LSC output (--> glows red for more than 10000)

 

ADC Over flow monitor is showing some unknown numbers (as ADCs are handled by IOPs).
I asked Joe for the investigation (and consideration for the policies)

  14324   Thu Nov 29 17:46:43 2018 gautamUpdateGeneralSome to-dos

[koji, gautam, jon, steve]

  • We suspect analog voltage from N2 pressure gauge is connected to interfacing Omega controller with the 'wrong' polarity (i.e pressure is rising over ~4 days and then rapidly falling instead of the other way around). This should be fixed.
  • N2 check script logic doesn't seem robust. Indeed, it has not been sending out warning emails (threshold is set to 60 psi, it has certainly gone below this threshold even with the "wrong" polarity pressure gauge hookup). Probably the 40m list is rejecting the email because controls isn't a part of the 40m group.
  • Old frames have to be re-integrated from JETSTOR to the new FB in order to have long timescale lookback.
  • N2 cylinder pressure gauges (at the cylinder end) need a power supply - @ Steve, has this been purchased? If not, perhaps @ Chub can order it.
  • MEDM vacuum screen should be updated to have gate valves be a different color to the spring-loaded valves. Manual valve between TP1 and V1 should also be added.
  • P2, P3 and P4 aren't returning sensible values (they should all be reading ~760torr as is P1). @ Steve, any idea if these gauges are broken?
  • Hornet gauges (CC and Pirani) should be hooked up to the new vacuum system.
  • add slow channels of   foreline pressures of TP2 & 3   and    C1:Vac-IG1_status_pressure
  15418   Fri Jun 19 16:30:09 2020 gautamUpdateASCSome thoughts about ASC

Summary:

In ELOG 15368, I had claimed that the POP QPD based feedback servo actuating on the PRM stabilized the lock. I now believe this scheme of sensing using the POP QPD and feeding back to the PRM is not a good topology for stabilizing the PRC angular motion.

Details:

  • I was never able to get a measurement of the OLTF of this loop that made sense 
    • the loop was initally commissioned with the PRMI locked on the carrier, and the settings hence inferred to give a ~5 Hz UGF loop were used in the PRFPMI lock.
    • In the PRFPMI configuration, however, the loop gain seemed way too low when I measured using the usual IN1/IN2 method.
    • So it is critical for the lock stability that the angular feedforward works well, which it kind of does now (not that I have changed anything, but the glitches in the seismometer have not resurfaced recently).
    • Hopefully, this becomes less of an issue once we replace the TTs with SOS and OSEM based damping.
  • To get some more insight, I did some finesse modeling
    • Attachment #1 shows the sensing response at the QPDs we have available currently (POP and TR). 
    • I included the telescopes (propagation distances, in-air lenses) to these QPDs as best as I could.
    • A simplified model (3 mirror coupled cavity) is used, so there isn't really a common/differential mode in this picture, but we still get some insight I think.
    • Specifically, once the full lock is realized, the PRC optic motion isn't sensed well with our QPDs, and so it was some fluke that turning on these PRC angular feedback loops worked. 
    • Attachment #2 shows the same info as Attachment #1, but with the pendulum transfer functions (and radiation pressure effects) included. The SOS suspensions are modelled as f0=0.7/0.8 Hz (for P/Y), Q=5, while the tip-tilts have f0~5 Hz, Q~10. The high frequency phase is 0 degrees and not 180 as expected because of the pendulum complex pole pair because of the way the quantity is computed in Finesse.
  • The current scheme I use is:
    • DC couple the ITM oplevs, using their individual Oplev QPDs.
    • Use the TR QPDs, mixed to actuate on the ETMs in a common/differential way.
    • I think the system is under-determined with the sensors we currently have - we wan't to sense the 10 angular modes - PIT and YAW for the PRC, Csoft, Chard, Dsoft and Dhard (using the terminology from Kate's thesis), but we only have 6 sensors of the same field (POP, TRX and TRY QPDs, PIT and YAW from each).
    • So we need more sensors?
  • One thing that can easily be improved I think is to make the ASS system work at high power. 
    • think this should be as simple as scaling the gain for the loops to work for the high power.
    • Then we can counteract the input pointing drift at least.
    • But the ITM Oplev DC coupling would need to be turned OFF and then ON again, I'm not sure if this will introduce some transient that will destroy the lock...

I would also like to bring up the topic of implementing some WFS for the interferometer fields again, there doesn't seem to be any mention of this in the procurement/planning for the BHD. It is not obvious to me yet that we need WFS and not just DC QPDs from a noise point of view, but at least we should discuss this.

  15682   Wed Nov 18 22:49:06 2020 gautamUpdateASCSome thoughts about AS WFS electronics

Where do we want to install the interface and readout electronics for the AS port WFS? Options are:

  • 1Y1 / 1Y3  (i.e. adjacent to the LSC rack) - advantage is that 55 MHz RF signal is readily available for demodulation. But space is limited (1Y2, where the RF signal is, is too full so at the very least, we'd have to run a short cable to an adjacent rack), and we'd have a whole bunch of IPC channels between c1lsc and c1ioo models.
  • 1X1/1X2. There's much more space and we can directly digitize into the c1ioo model, but we'd have to route the 55 MHz signal back to this rack (kind of lame since the signal generation is happening here). I'm leaning towards this option though - thinking we can just open up the freq generation box and take a pickoff of the 55 MHz signal...

There isn't much difference in terms of cable length that will be required - I believe the AS WFS is going to go on the AP table even in the new optical layout and not on the ITMY in-air oplev table? 

The project requires a large number of new electronics modules. Here is a short update and some questions I had:

  1. WFS head and housing. Need to finalize the RF transimpedance gain (i.e. the LC resonant part), and also decide which notches we want to stuff. Rich's advise was to not stuff any more than is absolutely necessary, so perhaps we can have at first just the 2f notch and add others as we deem necessary once we look at the spectrum with the interferometer locked. Need to also figure out a neat connector solution to get the signals from the SMP connectors on the circuit board to the housing - I'm thinking of using Front-Panel-Express to design a little patch board that we can use for this purpose, I'll post a more detailed note about the design once I have it.
  2. WFS interface board + soft-start board (the latter provides a smooth ramp up of the PD bias voltage). These go in a chassis, the assembly is almost complete, just waiting on the soft-start board from JLCPCB. One question is how to power this board - Sorensens or linear? If we choose to install in 1X1/1X2, I guess Sorensen is the only option, unless we have a couple of linear power supplies lying around spare.
  3. Demod board (quad chassis). Assembly is almost complete, need to install the 4 way RF splitter, some insulating shoulder washers. (to ensure the RF ground is isolated from the chassis), and better nuts for the D-sub connectors. A related question is how we want to supply the electrical LO signal for demodulation. The "nominal" level each demod board wants is 10 dBm. This signal will be sourced inside the chassis from a 4-way RF splitter (~7 dB insertion loss). So we'd need 17dBm going into the splitter. This is a little too high for a compact amplifier like the ZHL-500-HLN to drive (1dB compression point is 16 dBm), and the signal level available at the LSC rack is only ~2 dBm. So do we want a beefy amplifier outside the chassis amplifying the signal to this level? Or do we want to use the ZHL-500-HLN, and amplify the signal to, say 13 dBm, and drive each board with ~6 dBm LO? The Peregrine mixer on these boards (PE4140) are supposed to be pretty forgiving in terms of the LO level they want... In either case, I think we should avoid having an amplifier also inside the chassis, it is rather full in there with 4 demod boards, regulator board, all the cabling, and an RF splitter. It may be that heat dissipation becomes an issue if we stick an RF amplifier in there too...
  4. Whitening chassis. Waiting for front panels to arrive, PCBs and interface board are in hand, stuffed and ready to go. A question here is how we want to control the whitening - it's going to be rather difficult to have fast switchable whitening. I think we can just fix the whitening state. Another option would be to control the whitening using Acromag BIO channels.
  5. AI chassis - will go between whitening and ADC.
  6. Large number of cables to interconnect all the above pieces. I've asked Chub to order the usual "Deluxe" shielded Dsub cables, and we will get some long SMA-SMA cables to transmit the RF signals from head to demod board from Pasternack (or similar), do we need to use Heliax or the Times Microwave alternative for this purpose? What about the LO signal? Do we want to use any special cable to route it from the LSC rack to the IOO rack, if we end up going that way? 

Approximately half of the assembly of the various electronics is now complete. The basic electrical testing of the interface chassis and demod chassis are also done (i.e. they get power, the LEDs light up, and are stable for a few minutes). Detailed noise and TF characterization will have to be done.

  15690   Wed Nov 25 18:30:23 2020 gautamUpdateASCSome thoughts about AS WFS electronics

An 8 channel whitening chassis was prepared and tested. I measured:

  1. TF from input to output - there are 7 switchable stages (3 dB, 6 dB, 12 dB and 24 dB flat whitening gain, and 3 stages of 15:150 Hz z:p whitening). I enabled one at a time and measured the TF. 
  2. Noise with input terminated.

In summary,

  1. All the TFs look good (I will post the plots later), except that the 3rd stage of whitening on both boards don't show the expected transfer function. The fact that it's there on both boards makes me suspect that the switching isn't happening correctly (I'm using a little breakout board). I'm inclined to not debug this because it's unlikely we will ever use 3 stages of 15:150 whitening for the AS WFS. 
  2. The noise measurement displayed huge (x1000 above the surrounding broadband noise floor) 60 Hz harmonics out to several kHz. My hypothesis is that this has to do with some bad grounding. I found that the circuit ground is shorted to the chassis via the shell of the 9pin and 15pin Dsub connectors (but the two D37 connector shields are isolated). This seems very wierd, idk what to make of this. Is this expected? Looking at the schematic, it would appear that the shields of the connectors are shorted to ground which seems like a bad idea. afaik, we are using the same connectors as on the chassis at the sites - is this a problem there too? Any thoughts
Quote:

Whitening chassis. Waiting for front panels to arrive, PCBs and interface board are in hand, stuffed and ready to go. A question here is how we want to control the whitening - it's going to be rather difficult to have fast switchable whitening. I think we can just fix the whitening state. Another option would be to control the whitening using Acromag BIO channels.

  2310   Fri Nov 20 17:44:38 2009 JenneUpdateAdaptive FilteringSome svn shenanigans

[Sanjit, Jenne]

Sanjit and I are trying to put names to some signals which exist in SimuLink land, but which don't (yet) exist in EPICS land.  The deelio is that for each of the chosen SEIS signals in the ASS_TOP_PEM screen, the signal is split.  One part of the signal is used to decide how the adaptive filter should look, and the other part is actually used when doing the on-line subtraction.  Previously only the part of the signal which is used to decide on the Adaptive Filter could be seen on the screens, and had names. 

Before touching anything on the Simulink ASS.mdl, I did an svn check in, which put things at revision 36639. 

To try to make the desired signals exist, I put cdsFilt boxes (to create filter modules for each of these signals), and gave each of them a name (kind of like the Neverending Story....once they have a name, they'll exist).  My new names are C1:ASS-TOP_PEM_#_APPLY, which correspond to the previously-existing C1:ASS-TOP_PEM_#_ADPT (these are the ones that are along the top of the ASS_TOP_PEM matrix screen).  This version of the simulink model was checked in, and the svn is now at revision 36640.

We then did some "make clean", "make ass" and "make install-ass" action, and burt restored c1assepics, but nothing seems to be happening.  The screen doesn't have white boxes all over the place, and we didn't get any errors when we did the makes, and I'm sure we burt restored correctly (made sure the ASS GDS screen had a 1 in the lower left box etc), but all the values on the screen are still zero.  

When we ran the ass front end in terminal on the c1ass machine, we did see an error: "Invalid chan num found 2 = 30624" "DAQ init failed -- exiting".  I think this means that we need to have told some file somewhere that I was going to be adding 8 new channels. (maybe an .ini file?) Hopefully the Joe & Peter team can help us out with this, since they've been doing this kind of thing for the new system.

Moral of the story is, the new (non-working) simulink file has been svn checked in as revision 36640, and we're reverting to revision 36639, which was before I touched anything today.

  11212   Fri Apr 10 03:44:51 2015 JenneUpdateLSCSome small progress, may have DAC problem?

Small steps tonight, but all in the forward direction.

On one of my better locks, I saw a kind of weird phenomenon with the PRMI sideband powers versus the carrier powers:

For the last 100 seconds of this plot, I'm all 1f.  Alignment is being handled mostly by Q's DC coupled ITM oplevs, and the transmission QPD ASC loops, although I was trying to adjust the offsets in the ASC loops to improve transmission for a bit.

At the very end, the last 10 seconds or so, the POP110 power goes down, and sits at about half it's maximum value.  POP22 isn't quite as bad, in that it still touches the max, but the RIN is about 50%.  The carrier DC signals (TRX, TRY, POPDC) don't see this huge jump.  I don't think I was touching anything the last few tens of seconds.  I'm not sure yet how I can so significantly lose sideband power, without losing a similar amount of carrier power. 

The ring-ups at about -70sec in the CARM and DARM outs are the bounce mode. 

I tried looking at 2D histograms of different combinations of channels, for the time around -30 seconds where things looked pretty clean.  It looks like the offsets that Q put in last night (+1 for MICH_B and -3 for PRCL_B) are still about right.  The PRCL_IN1 and MICH_IN1 were centered around zero at the maximum power points.  CARM and DARM had small offsets, which I put into the DARM_B and CARM_B filter banks (0.0066 for DARM_B, and 0.027 for CARM_B), although these are small enough that I don't know that they really do anything.


As a break from locking for a little while, I tried to see if I could get the TT3 and TT4 DAC channels to work for me.  I had hoped it would be a quick and easy task, but I'm not seeing signal out.  Since it wasn't working, I decided to go back to locking for the night, and look into the DAC in the daytime.  I want to use one channel as the IN2 input of the CM board, and another as the external modulation input to the Marconi for transfer functions, so I need them to work. 

As a side note on the input to the Marconi situation, it occurred to me that instead of laying a new cable, I can borrow the POP55 heliax.  We don't have a POP55 diode right now, and the other end comes out across the hall from the Marconi, so it would be pretty easy to have a medium-length cable go from ITMX table to the Marconi.  Objections to this? 

  11213   Fri Apr 10 12:09:19 2015 ericqUpdateLSCSome small progress, may have DAC problem?
Quote:

At the very end, the last 10 seconds or so, the POP110 power goes down, and sits at about half it's maximum value.  POP22 isn't quite as bad, in that it still touches the max, but the RIN is about 50%.  The carrier DC signals (TRX, TRY, POPDC) don't see this huge jump.  I don't think I was touching anything the last few tens of seconds.  I'm not sure yet how I can so significantly lose sideband power, without losing a similar amount of carrier power. 

I saw this same kind of behavior in my locklosses on Wednesday night; we should check out the 165 data, and see if the 3f PRCL error signal shows some drift away from zero.

Also, it's odd that CARM_IN1 and REFL11_I_ERR have different low frequency behavior in the plot you posted. I guess they have some difference in demodulation phase.  REFL11_I's bump at -40sec coincides with the dip in arm power and a rise in REFLDC, but ASDC seems pretty smooth, so maybe it is a real CARM fluctuation.

I set the REFL11 analog demodulation angle (via cable length) about a year ago (ELOG 9850), with some assumption about PRCL having the same demod angle as CARM, but this was probably set with the arms misaligned. We should recheck this; maybe we're coupling some other junk into CARM. 

  15195   Fri Feb 7 02:24:24 2020 gautamUpdateLSCSome short notes

[koji, gautam] 

Plots + interpretation tomorrow.

  • CM_Slow path can be used to stabilize the arm powers somewhat but the AO crossover remains out of reach.
  • The REFL11 (=CARM_B) path offset has to be manually determined - we found that it can change by ~20% depending on the alignment, which maybe isn't surprising given that the mode shapes seen at POP, REFL and AS look like Rorschach inkblots.
  • We saw TRX/TRY regularly hit ~150, and at times even 200 (= recycling gain of ~10). Though any conclusive statement about the PRG can only be made once the lock is stabilized.
  • I was able to take a few CARM loop TFs with an SR785 hooked up at 1Y2. Despite ramping up the AO gain, we saw no effect at high frequencies in the TF shape (the phase bubble continued to roll off at ~100 Hz and there was no visible phase lead even as the AO gain was increased). It has to be estimated what the expected crossover gain is from the experiment with the high BW POY locking (taking into account the net difference in optical gain between POY for single arm and REFL for the full IFO).
  • The fact that I was able to hold the high BW POY lock makes me think that the IMC servo board's IN2 input (and indeed the rest of the IMC locking loop) is functioning as expected. But maybe this board will benefit from a detailed checkout like Koji did for the CM board.

Getting closer... To facilitate this work, I made some convenience scripts that can be run from the CM MEDM screen.

  5439   Fri Sep 16 17:46:13 2011 kiwamuUpdateSUSSome screens fixed

The bad medm screens have been fixed. There are no blank fields and all the links are correct.

Quote from #5409

I've found that a few of the screens still have Whited-Out fields due to naming changes (OL SUM and ALS-> TM OFFSET). I attach a screen shot of it.

The OL screens have the wrong SUM names and the IFO ALIGN screen is pointing to the wrong SUS screens.

 

  5466   Mon Sep 19 17:45:39 2011 ranaUpdateSUSSome screens fixed

Quote:

Kiwamu:       The bad medm screens have been fixed. There are no blank fields and all the links are correct.

Quote from #5409

I've found that a few of the screens still have Whited-Out fields due to naming changes (OL SUM and ALS-> TM OFFSET). I attach a screen shot of it.

The OL screens have the wrong SUM names and the IFO ALIGN screen is pointing to the wrong SUS screens.

 

 Really? I found this one with ~15 seconds of clicking around.

Untitled.png

  5409   Wed Sep 14 20:30:36 2011 ranaUpdateSUSSome screens are still bad

I've found that a few of the screens still have Whited-Out fields due to naming changes (OL SUM and ALS-> TM OFFSET). I attach a screen shot of it.

The OL screens have the wrong SUM names and the IFO ALIGN screen is pointing to the wrong SUS screens.

Untitled.png

  9827   Thu Apr 17 17:27:32 2014 ericqUpdateLSCSome reference Plots

Jenne made some suggestions for some plots that would be useful on our CARM offset reduction adventures, so I made some with my MIST model. 

First, here's a plot showing the transfer function of CARM to TRX, with logarithmically spaced offsets out to 3nm. While not a control signal, it shows us where the optical plant resonance stuff is happening. The peaks in this TF correspond to peaks in REFL11, REFL55, AS11, etc., as in the close-to-resonance TFs in ELOG 9785

carm2TRX.pdf

[more to come, had a MATLAB issue]

 

  2103   Fri Oct 16 12:40:59 2009 KojiConfigurationGeneralSome questions

Some questions came arise to me:

A. How the green injection system should be? How the handing off between 532 and 1064 should be?

This is not new, though. It would be worth reminding.

B. Do we still need PMC if we use 2W innolight?

Innolight has low intensity noise at the detection freq. Also the spacial mode is clean.

C. Do we still need frequency prestabilization by RC?

Is the stabilization of the laser freq by the MC not enough?
What is the relationship with the green?

  3985   Wed Nov 24 18:11:26 2010 JenneUpdatePEMSome progress on getting PEM channels

I have made a little bit of progress on the PEM channels.  I have begun writing up detailed instructions in the DAQ Wiki page on how to add a channel to the new DAQ system.  I have followed those instructions thus far, and can see my channels in the .ini file (and in the daqconfig gui thing), but I don't have any channels in Dataviewer or DTT. 

There are some tricky "gotchas" involved in creating new models and channels.  Some examples include:  No use of the characters "DUMMY" in any channel name.  The makefile is specifically hardcoded to fail if that string of characters is used.  Also, you must have at least 2 filter banks in every model.  Why? No one knows.  You just do.  The model won't compile unless you have 2 or more filter banks. 

My efforts today included ~3 reboots of the frame builder, and ~2 reboots of c1sus.  When Kiwamu and I rebooted c1sus, we burt restored to some time in the last 24 hrs.  Some of the SUS filters on some of the optics were not set correctly (things like the bounce roll filter), so we turned all of them on, and reset all of the input and output matricies to be the correct combination of +1 and -1's to make Pit, Pos and Yaw.  The tuning seems to happen now-a-days in the gains for each DOF, and the gains were set correctly by the burt restore for every optic except PRM.  We made some educated guesses for what the gains should be based on the other optics, and PRM is damping pretty well (these guesses included reducing the SIDE gain by ~10 from the BS SIDE value, since the analog gain of the PRM SIDE sensor is much higher than others).  We'll have to fine tune these gains using some Yuta-developed method soon.  Or find a burt snapshot that had some non-unity values in there.

  2001   Fri Sep 25 16:10:17 2009 JenneUpdateAdaptive FilteringSome progress on OAF, but more still to be done

[Jenne, Sanjit]

It seems now that we are able to get the OAF system to do a pretty good job of approximating the MC_L signal, but we can't get it to actually do any subtracting.  I think that we're not correctly setting the phase delay between the witness and the MC_L channels or something (I'm not sure though why we get a good filter match if the delay is set incorrectly, but we do get a good filter match for very different delay settings: 1, 5, 100, 1000 all seem to do equally well at adjusting the filter to match MC_L). 

The Matt Evans document in elog 395 suggests measuring the phase at the Nyquist frequency, and calculating the appropriate delay from that.  The sticking point with this is that we can't get test points for any channel which starts with C1:ASS.  I've emailed Alex to see what he can do about this.  Elog 1982 has a few words about how we're perhaps using a different awgtpman on the ass machine than we used to, which may be part of the problem. 

The golden plan, which in my head will work perfectly, is as follows: Alex will fix the testpoint problem, then Sanjit and I will be able to measure the phase between our OAF signal and the incoming MC_L signal, we will be able to match them as prescribed in the Matt Evans document, and then suddenly the Adaptive Filtering system will do some actual subtracting!

The plot below shows the Reference MC_L without any OAF system (black), the output of the OAF (green), and the 'reduced' MC_L (red).  As you can see, the green trace is doing a pretty good job of matching the black one, but the red trace isn't getting reduced at all.

  15273   Fri Mar 13 00:32:38 2020 gautamUpdateLSCSome progress

Finally, some RF only CARM, see Attachment #1. During this time, DARM was also on a blend of IR and ALS control, but I couldn't turn the ALS path off in ~4-5 attempts tonight (mostly me pressing a wrong button). Attachment #2 shows the CARM OLTF, with ~2kHz UGF - for now, I didn't bother turning any boosts on. PRCL and MICH are still on 3f signals.

The recycling gain is ~7-8 (so losses >200ppm), but there may be some offset in some loop. I'll look at REFL DC tomorrow.

Can we please make an effort to keep the IFO in this state for the next week or two
- it really helped tonight I didn't have to spend 2 hours fixing some random stuff and could focus on the task at hand.

  15953   Mon Mar 22 16:29:17 2021 gautamUpdateASCSome prep for AS WFS commissioning
  1. Added rough cts2mW calibration filters to the quadrants, see Attachment #1. The number I used is:
              0.85 A/W         *       500 V/A            *          10 V/V                              *         1638.4 cts/V
    (InGaAs responsivity)     (RF transimpedance)  (IQ demod conversion gain)      (ADC calibration)
  2. Recovered FPMI locking. Once the arms are locked on POX / POY, I lock MICH using AS55_Q as a sensor and BS as an actuator with ~80 Hz UGF.
  3. Phased the digital demod phases such that while driving a sine wave in ETMX PIT, I saw it show up only in the "I" quadrant signals, see Attachment #2.

The idea is to use the FPMI config, which is more easily accessed than the PRFPMI, to set up some tests, measure some TFs etc, before trying to commission the more complicated optomechanical system.

  2534   Wed Jan 20 20:11:56 2010 AlbertoUpdateABSLSome preliminary results from measuring PRC's transmissivity for an amplitude modulated beam
Here I'm posting a plot showing a set of measurements that I made in the past few days to determine the absolute length of the PRC cavity.
As in my other AbsL measurements, I inject an auxiliary laser beam into the cavity and look at the transmission. In the PRC case, the beam is injected through the dark port and I look at a pick-off of the REFL beam. The aux laser is phase locked to the PSL beam and I control the differential frequency between the two. The PSL and the aux beam interfere and beat at their differential frequency.
 
The attached plot shows the transmitted power as a function of the beat frequency.
 
Fitting the data with the model would let me determine the cavity length. 
By now I can estimate the length of the PRC at about 2.257m, but it's still a rather approximate value.
I can't provide accurate error bars yet. I need to optimize the measurements to get a more precise value.
 
I will go more through the details of the measurement technique and of the fitting function as soon as I have more definitive results.
 
The data points shown here were taken at different times and not always in optimal alignment condition of the PRC. 
To get a good fit of the data I should have fewer frequency segments, taken in a shorter period of time, and in which the power circulating inside of the cavity (ie SPOB) fluctuates as little as possible.
 
For what regards the time needed for a measurements, I already significantly sped up the measurements (i.e. optimizing the scanning and acquisition GPIB scripts, and fixing a couple of problems with the PDH box used in the PLL), and finally now I can scan several tens of MHz in few minutes.
About the frequency segments, so far they have been determined by two factors
1) Tthe frequency generator in the PLL: the Marconi works as a continuous wave generator only in limited ranges. Switching from one to another brakes the wave in a way that causes the PLL to lose lock.
2) Getting below 18 MHz a series of other beats appear on the PLL photodiode and make the PLL lose lock.
 
For the first problem, I'm thinking of using two Marconis and to mix their signals. I would keep one at 300MHz and I would scan the other from 300MHz to 500MHz. In fat, in that frequency range the Marconi has not discontinuity.
 
To try to avoid the other beats at low frequency, I'm not entirely sure about what to do yet. 
 
To be continued...
  2536   Thu Jan 21 10:31:13 2010 KojiUpdateABSLSome preliminary results from measuring PRC's transmissivity for an amplitude modulated beam

Nice and interesting plot.

I suppose slight decrease of the Schnupp asymmetry (in your model) adjusts the discrepancy in the high freq region.
At the same time, it will make the resonance narrower. So you need to put some loss at the recombination (=on the BS)?

...of course these depends on the flatness of the calibration.

  14917   Mon Sep 30 17:04:30 2019 gautamUpdateCDSSome path changes

I made some model changes to c1lsc. To propagate the changes, I tried the usual rtcds make sequence. But I got an error about the model file not being in the path. This is down to my re-organization of the paths to cleanly get everything under git version control. So I had to run the following path modification. Where is this variable set and how can I add the new paths to it? The model compilation, installation and restart all went smooth after I made this change. 

For smooth reboot of the models, I used the reboot script. I had to restart the daqd processes on FB, but now all the CDS indicator lights are green.

export RCG_LIB_PATH=/opt/rtcds/userapps/release/isc/c1/models/isc/:/opt/rtcds/userapps/release/isc/c1/models/cds/:/opt/rtcds/userapps/release/isc/c1/models/sus/:$RCG_LIB_PATH
Quote:

I commenced the procedure of the migration, starting with making a tagged commit of the current running simulink models. A local backup was also made, plus we have the usual chiara-based backup so I think we're in good hands.

  15564   Tue Sep 8 11:49:04 2020 gautamUpdateCDSSome path changes

I edited /diskless/root.jessie/home/controls/.bashrc so that I don't have to keep doing this every time I do a model recompile.

Quote:

Where is this variable set and how can I add the new paths to it? 

export RCG_LIB_PATH=/opt/rtcds/userapps/release/isc/c1/models/isc/:/opt/rtcds/userapps/release/isc/c1/models/cds/:/opt/rtcds/userapps/release/isc/c1/models/sus/:$RCG_LIB_PAT
  10727   Tue Nov 18 22:34:28 2014 JenneUpdateLSCSome other plots from PRFPMI

Quote:

I was able to hold the PRMI on REFL33I&Q, and have ALS CARM and DARM at zero CARM offset.  The arm would "buzz" through the resonance regularly.  I use the word buzz because that's kind of what it sounded like.  This is the noise of the ALS system.

Here is a plot of when the arm powers went pretty high from last night.  CARM and DARM were on ALS comm and diff, PRMI was on REFL33 I&Q.  I set the CARM offset so that I was getting some full arm resonances, and it goes back and forth over the resonance.

The Y axes aren't perfect when I zoom, but the maximum TRX value was 98 in this plot, while the max TRY value was 107. 

MICH_OUT was hitting its digital rails sometimes, and also it looks like PRCL and MICH occasionally lost lock for very brief periods of time. 

Glitch-like events in PRCL_OUT are at the edges of these mini-locklosses. I don't know why POPDC has glitch-y things, but we should see if that's real.

TRXmax98_TRYmax107_CARMdarmOnALS_0carmOffset.png

Okay, I've zoomed in a bit, and have found that, interestingly, I see that both POP22 and POP110 decrease, then increase, then decrease again as we pass through full resonance.  This happens in enough places that I'm pretty sure we're not just going back and forth on one side of the resonance, but that we're actually passing through it.  Q pointed out that maybe our demod phase angle is rotating, so I've made some zoom-in plots to see that that's not a significant effect.  I plot the I and Q phases individually, as well as the total=sqrt(I**2 + Q**2), along with TRY (since the increases and decreases are common to both arms, as seen in the plot above).

For POP 22:

Zoom_with_POP22.png

For POP 110:

Zoom_with_POP110.png

I also plot the MICH and PRCL error signals along with TRY and POP22 total.  You can see that both MICH and PRCL were triggered off about 0.1msec after POP22 total this it's first super low point.  Then, as soon as POP22 becomes large enough, they're triggered back on, which happens about 1.5msec later. (The triggering was actually on POP22I, not POP22tot, but the shapes are the same, and I didn't want to overcrowd my plots).

Zoom_with_ErrSigs.png

I am not sure if we consistently lose sideband signal in the PRC more on one side of the CARM resonance than the other, but at least POP22 and POP110 are both lower on the farther side of this particular peak.  I want to think about this more in relation to the simulations that we've done.  One of the more recent things that I see from Q is from September:  elog 10502, although this is looking specifically at the REFL signals at 3f, not the 2f circulating PRCL power as a function of CARM offset.

  15553   Wed Sep 2 00:49:47 2020 gautamUpdateBHDSome notes about homodyne phase

Summary:

Using a heterodyne measurement setup to track both quadratures, I estimated the relative phase fluctuation between the LO field and the interferometer output field. It may be that a single PZT to control the homodyne phase provides insufficient actuation range. I'll also need to think about a good sensing scheme for controlling the homodyne phase, given that it goes through ~3 fringes/sec - I didn't have any success with the double demodulation scheme in my (admittedly limited) trials.

For everything in this elog, the system under study was a simple Michelson (PRM, SRM and ETMs misaligned) locked on the dark fringe.

Details:

​This work was mainly motivated by my observation of rapid fringing on the BHD photodiodes with MICH locked on the dark fringe. The seismic-y appearance of these fringes reminded me that there are two tip-tilt suspensions (SR2, SR3), one SOS (SRM) + various steering optics on seismic stacks (6+ steering mirrors) between the dark port of the beamsplitter and the AS table, where the BHD readout resides. These suspensions modulate the phase of the output field of course. So even though the Michelson phase is tightly controlled by our LSC feedback loop, the field seen by the homodyne readout has additional phase noise due to these optics (this will be a problem for in vacuum BHD too, the question is whether we have sufficient actuator range to compensate).

To get a feel for how much relative phase noise there is between the LO field and the interferometer output field (this is the metric of interest), I decided to set up a heterodyne readout so that I can simultaneously monitor two orthogonal quadratures.

  • The idea is that with the Michelson locked, there is no DC carrier field from the interferometer.
  • The field incident on the DCPD from the interferometer should be dominated by the 55 MHz sideband transmitted to the dark port given the Schnupp asymmetry. 
  • The LO field is picked off before any RF sidebands are added to it (the PMC modulation sideband should be suppressed by the cavity transmission).
  • Therefore, the LO field should be dominantly at the carrier frequency.
  • By placing a broadband RFPD (PDA10CF) in place of one of the DCPDs, I can demodulate the optical beat between this 55 MHz sideband, which shares the same output path to the location of the DCPD as the audio-frequency sidebands on the carrier from the dark Michelson, to estimate the relative phase noise between the LO and IFO output fields.
  • The point is that with the heterodyne readout, I can track the fringe wrapping, which is not an option for the BHD readout with two DCPDs, and uncontrolled LO phase.

Attachment #1 shows the detailed measurement setup. I hijacked the ADC channels normally used by the DCPDs (along with the front-end whitening) to record these time-series.

Attachments #2, #3 shows the results in the time domain. The demodulated signal isn't very strong despite my pre-amplification of the PDA10CF output by a ZFL-500-HLN, but I think for the purposes of this measurement, there is sufficient SNR.

This would suggest that there are pretty huge (~200um) relative phase excursions between the LO and IFO fields. I suppose, over minutes, it is reasonable that the fiber length changes by 100um or so? If true, we'd need some actuator that has much more range to control the homodyne phasethan the single PZT we have available right now. Maybe some kind of thermal actuator on the fiber length? If there is some pre-packaged product available, that'd be best, making one from scratch may be a whole project in itself. Attachment #3 is just a zoomed-in version of the time series, showing the fringing more clearly.

Attachment #4 has the same information as Attachment #2, except it is in the frequency domain. The FFT length was 30 seconds. The features between ~1-3 Hz support my hypothesis that the SR2/SR3 suspensions are a dominant source of relative phase noise between LO and IFO fields at those frequencies. I guess we could infer something about the acoustic pickup in the fibers from the other peaks.

  14012   Sun Jun 24 20:02:07 2018 gautamUpdateSUSSome notes about coil driver noise

Summary:

For a series resistance of 4.5 kohm, we are suffering from the noise-gain amplified voltage noise of the Op27 (2*3.2nV/rtHz), and the Johnson noise of the two 1 kohm input and feedback resistances. As a result, the current noise is ~2.7 pA/rtHz, instead of the 1.9 pA/rtHz we expect from just the Johnson noise of the series resistance. For the present EX coil driver configuration of 2.25 kohm, the Op27 voltage noise is actually the dominant noise source. Since we are modeling small amounts (<1dB) of measurable squeezing, such factors are important I think. 

Details:

[Attachment #1] --- Sketch of the fast signal path in the coil driver board, with resistors labelled as in the following LISO model plots. Note that as long as the resistance of the coil itself << the series resistance of the coil driver fast and slow paths, we can just add their individual current noise contributions, hence why I have chosen to model only this section of the overall network.

[Attachment #2] --- Noise breakdown per LISO model with top 5 noises for choice of Rseries = 2.25 kohm. The Johnson noise contributions of Rin and Rf exactly overlap, making the color of the resulting line a bit confusing, due to the unfortunate order of the matplotlib default color cycler. I don't want to make a custom plot, so I am leaving it like this.

[Attachment #3] --- Noise breakdown per LISO model with top 5 noises for choice of Rseries = 4.5 kohm. Same comments about color of trace representing Johnson noise of Rin and Rf. 

Possible mitigation strategies:

  1. Use an OpAmp with lower voltage noise. I will look up some candidates. LT1028/LT1128? LISO library warns of a 400 kHz noise peak though...
  2. Use lower Rin and Rf. The values of these are set by the current driving capability of the immediately preceeding stage, which is the output OpAmp of the De-Whitening board, which I believe is a TLE2027. These can source/sink 50 mA according to the datasheet . So for +/-10V, we could go to 400 ohm Ri and Rf, source/sink a maximum of 25mA, and reduce the Johnson noise contribution by 40%.

Other comments/remarks:

I've chosen to ignore the noise contribution of the high current buffer IC that is inside the feedback loop. Actually, it may be interesting to compare the noise measurements (on the electronics bench) of the circuit as drawn in Attachment #1, without and with the high current buffer, to see if there is any difference.

This study also informs about what level of electronics noise is tolerable from the De-Whitening stage (aim for ~factor of 5 below the Rseries Johnson noise).

Finally, in doing this model, I understand that the observation the voltage noise of the coil driver apparently decreased after increasing the series resistance, as reported in my previous elog. This is due to the network formed by the fast and slow paths (during the measurement, the series resistance in the slow path makes a voltage divider to ground), and is consistent with LISO modeling. If we really want to measure the noise of the fast path alone, we will have to isolate it by removing the series resistance of the slow bias path.


Comment about LISO breakdown plots: for the OpAmp noises, the index "0" corresponds to the Voltage noise, "1" and "2" correspond to the current noise from the "+" and "-" inputs of the OpAmp respectively. In future plots, I'll re-parse these...


Quote:

I will upload more details + photos + data + schematic + LISO model breakdown tomorrow to a DCC page

 

  15458   Tue Jul 7 14:06:10 2020 gautamUpdateASCSome more thoughts about ASC

Summary:

I want to be able to run the dither alignment servo with the PRFPMI locked - I've been thinking about what the scheme should be, and I list here some questions I had while thinking about this.

Details:

  1. ITM Oplev DC coupling
    • In the current scheme, I DC couple the ITM Oplev servos after the arms have been aligned to maximize POX/POY transmission.
    • However, looking back at data from when the CARM offset is reduced (e.g. Attachment #1), it looks like the ITMs are being torqued quite a bit during this process (ITMX PIT changes by ~20urad, ITMY YAW by ~10urad in this particular lock attempt). 
    • So the spots are not actually being centered on the test-masses? I guess the spot position on ITMX isn't actually controlled because we have only one actuator (BS) for the XARM beam axis. Is it unexpected that ITMY gets torqued so much? 
    • It is unclear what would happen if the ITM Oplev servos are not DC coupled. I wonder if I'd still be able to reach the high circulating powers and then rely solely on the TR QPDs for the arm cavity angular control.
    • Another possibility is to offload the DC part of the control signal to the optic's slow bias voltage slider, and then turn off the DC coupling. After that, the dither alignment can optimize the cavity alignment.
  2. Dither alignment at high circulating power
    • think that the system should work with the same settings as for the POX/POY locking, with the following changes:
      • Scale the overall loop gain by the arm transmission.
      • Change LSC2ASS matrix element from XARM/YARM ---> DARM.
        Does this sound right?
    • In light of the above, I was thinking that we should introduce a gain scaling field in the c1ass RTCDS model (like we have for the LSC power normalization matrix). Is it worth to go through the somewhat invasive process of model recompilation etc?
    • With the PRFPMI locked, I am wondering if I can simultaneously run the dither alignment loops for all the DoFs. Probably not, especially for MICH, since the actuator is the BS, which is also the actuator for the XARM loop?
  5961   Sat Nov 19 15:58:04 2011 MirkoUpdateIOOSome more looks into OSEM noise

[Den, Mirko]

We looked some more into the the OSEM signals and their coherence to the seismometer signals.

We were able to verify that the coherence OSEM sensor <-> seismometer signal goes down with increasing the OSEM gain. This seems to indicate that the OSEM FB add noise to the distance mirror <-> frame. We injected some noise into the OSEMs to see how the coherence behaves.

MC2 SUSPOS, 0.1Hz - 0.8Hz, 3mins each

Inj. amplitude   Time(UTC) Note

-                     21:35          Free swinging
-                     21:42          Big LF OSEM gain
-                     21:48          Small LF OSEM gain
150                     21:56          -"-
300                     22:00          -"-
900                     22:05          -"-

Free swinging:

FreeSwinging.png

High OSEM gain:


LocalDampingOn.pdf

Low OSEM gain:

LowOsemGain.pdf

LowOsemGainInj150.pdf

Low_LF_OSEM_Gain_Inj300.fig

LowOsemGainInj900.pdf

 

We left the filters that lower the OSEM gain below 0.3Hz on.

  4314   Thu Feb 17 13:20:06 2011 SureshUpdateVIDEOSome more labels

[Larisa, Kiwamu, Steve and Suresh]

 

  We continued the labeling of video cables. All exiting cables which are going to be used used in the new scheme have been labeled.

We also labeled the cables running from the video mux to the TV monitors in the computer room. Some of these will be removed or reallocated.

We will continue next Wednesday (after the meeting) and will lay cables that are most urgently required. 

 i

  16395   Tue Oct 12 17:10:56 2021 AnchalSummaryCDSSome more information

Chris pointed out some information displaying scripts, that show if the DAQ network is working or not. I thought it would be nice to log this information here as well.

controls@fb1:/opt/mx/bin 0$ ./mx_info
MX Version: 1.2.16
MX Build: controls@fb1:/opt/src/mx-1.2.16 Mon Aug 14 11:06:09 PDT 2017
1 Myrinet board installed.
The MX driver is configured to support a maximum of:
    8 endpoints per NIC, 1024 NICs on the network, 32 NICs per host
===================================================================
Instance #0:  364.4 MHz LANai, PCI-E x8, 2 MB SRAM, on NUMA node 0
    Status:        Running, P0: Link Up
    Network:    Ethernet 10G

    MAC Address:    00:60:dd:45:37:86
    Product code:    10G-PCIE-8B-S
    Part number:    09-04228
    Serial number:    423340
    Mapper:        00:60:dd:45:37:86, version = 0x00000000, configured
    Mapped hosts:    3

                                                        ROUTE COUNT
INDEX    MAC ADDRESS     HOST NAME                        P0
-----    -----------     ---------                        ---
   0) 00:60:dd:45:37:86 fb1:0                             1,0
   1) 00:25:90:05:ab:47 c1bhd:0                           1,0
   2) 00:25:90:06:69:c3 c1sus2:0                          1,0

 

controls@c1bhd:~ 1$ /opt/open-mx/bin/omx_info
Open-MX version 1.5.4
 build: root@fb1:/opt/src/open-mx-1.5.4 Tue Aug 15 23:48:03 UTC 2017

Found 1 boards (32 max) supporting 32 endpoints each:
 c1bhd:0 (board #0 name eth1 addr 00:25:90:05:ab:47)
   managed by driver 'igb'

Peer table is ready, mapper is 00:60:dd:45:37:86
================================================
  0) 00:25:90:05:ab:47 c1bhd:0
  1) 00:60:dd:45:37:86 fb1:0
  2) 00:25:90:06:69:c3 c1sus2:0

 

controls@c1sus2:~ 0$ /opt/open-mx/bin/omx_info
Open-MX version 1.5.4
 build: root@fb1:/opt/src/open-mx-1.5.4 Tue Aug 15 23:48:03 UTC 2017

Found 1 boards (32 max) supporting 32 endpoints each:
 c1sus2:0 (board #0 name eth1 addr 00:25:90:06:69:c3)
   managed by driver 'igb'

Peer table is ready, mapper is 00:60:dd:45:37:86
================================================
  0) 00:25:90:06:69:c3 c1sus2:0
  1) 00:60:dd:45:37:86 fb1:0
  2) 00:25:90:05:ab:47 c1bhd:0

These outputs prove that the framebuilder and the FEs are able to see each other in teh DAQ network.


Further, the error that we see when IOP model is started which crashes the mx_stream service on the FE machines (see 40m/16391) :

isendxxx failed with status Remote Endpoint Unreachable

This has been seen earlier when Jamie was troubleshooting the current fb1 in martian network in 40m/11655 in Oct, 2015. Unfortunately, I could not find what Jamie did over a year to fix this issue.

ELOG V3.1.3-