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  2570   Thu Feb 4 12:29:04 2010 josephbUpdateComputersMartian IP switch over notes

What is the change:

We will be moving the 131.215.113.XXX ip addresses of the martian network over to a 192.168.XXX.YYY scheme.

What will users notice:

Computer names (i.e. linux1, scipe25/c1dcuepics) will not change.  The domain name martian, will not change (i.e. linux1.martian.).  What will change is the underlying IP address associated with the host names.  Linux1 will no longer be 131.215.113.20 but something like 192.168.0.20.  If everything is done properly, that should be it.  There should be no impact or need to change anything in EPICS for example.  However, if there are custom scripts with hard coded IP addresses rather than hostnames, those would need to be updated, if they exist.

What needs to be done:

Each computer and router will need to either be accessed remotely, or directly, and the configuration files controlling the IP address (and/or dns lookup locations) be modified.  Then it needs to be rebooted so the configuration changes take effect. I'll be making an updated list of computers this week (tracked down via their physical ethernet cables), and next week, probably on Thursday, and then we simply go down the list one by one.

LINUX

For a linux machine, this means checking the /etc/hosts file and making sure it doesn't have old information.  It should look like:

127.0.0.1               localhost.localdomain localhost
::1             localhost6.localdomain6 localhost6

Then change the /etc/sysconfig/network-scripts/ifcfg-eth0 file (or ethX file depending on the ethernet card in question).  The IPADDR, NETWORK, and GATEWAY lines will need to be changed.  You can change the hostname (although I don't plan on it) by modifying the /etc/sysconfig/network file.

The /etc/resolv.conf file will need to be updated with the new DNS server location (i.e. 131.215.113.20 to 192.168.0.20 for example).

SOLARIS

Simlarly to linux, the /etc/hosts file will need to be updated and/or simplified.  The /etc/defaultrouter file will need to be updated to the new router ip.  /etc/defaultdomain will need to be updated.  The /etc/resolv.conf will need to be updated with the new dns server.

vxWorks

Looking at the vxWorks machines, the command bootChange can be used to view or edit the IP configuration.

The following is an example from c1iscey.

-> bootChange

'.' = clear field;  '-' = go to previous field;  ^D = quit

boot device          : eeE0
processor number     : 0
host name            : linux1
file name            : /cvs/cds/vw/pIII_7751/vxWorks
inet on ethernet (e) : 131.215.113.79:ffffff00
inet on backplane (b):
host inet (h)        : 131.215.113.20
gateway inet (g)     :
user (u)             : controls
ftp password (pw) (blank = use rsh):
flags (f)            : 0x0
target name (tn)     : c1iscey
startup script (s)   :
other (o)            :

value = 0 = 0x0

By updating the the host (name of machine where its mounting /cvs/cds from - i.e. linux1), inet on ethernet (the IP of c1iscey) and host inet (linux1's ip address), we should be able to change all the vxWorks machines.

LINUX1

The DNS server running on linux1 will need to be updated with the new IPs and domain information.  The host file on linux1 will also need to be updated for all the new IP addresses as well.

This will need to be handled carefully as the last time I tried getting away without the host file on linux1, it broke NFS mounting from other machines.  However, as long as the host on linux1 is kept in sync with the dns server files everything should work.

  2869   Mon May 3 01:16:50 2010 ranaHowToElectronicsMarconi phase noise measurement setup

 To try the 3-corner hat method on the Marconis, I started to set up the measurement into the DAQ system.

I have set the bottom 2 in the PSL rack to 11.1 MHz. I use a ZP-3MH level 13 mixer as the phase detector. The top one is the LO, it has an output of +13 dBm.

The bottom one is the test unit, it has an output of +6 dBm (should be close to the right level - the IP3 point is +9 dBm). The top one has external DC FM modulation enabled with a FM dev range of 10 Hz.

Mixer output goes through a 50 Ohm in-line termination and then a BLP-5 low pass filter (Steve, please order ~7 of the BLP-1.5 or BLP-1.9 low pass filter from Mini-Circuits) and then into

the DC coupled of a SR560. After some gain and filtering that feedback goes back to the FM input of the top-Marconi to close the PLL. I adjusted the gain to be as small as possible and still stay locked and not

saturate the ADC.

The input to the SR560 is Tee'd into another SR560 with AC coupled input, G = 1000, low-noise. Its output is going directly to the ADC channel - C1:IOO-MC_DRUM1.

I calibrated the channel by opening the loop and setting the AC coupled gain to 1. This lets the Marconis beat at several Hz. The peak-peak signal is equivalent to pi radians.

 

As usual, I was befuddled by the FM input. For some reason I always forget that since its a straight FM input, we don't need any filtering to get a plain 1/f loop. The attached plot shows how we get bad gain peaking if you forget this and use a 0.03 Hz pole in the SR560.

The grey trace is the ADC signal with everything hooked up, but the RF input set to zero (via setting Carrier = OFF in the bottom Marconi). It is the measurement noise.

The BLUE trace is very close to the true phase noise beat of the two Marconis with a calibration error of ~5%. I have not corrected for the loop gain: its right now around a 1 Hz UGF and 1/f. Next, I will measure the loop and compensate for it in the DTT calibration.

Then I'll measure the relative phase noise of 3 of the signal generators to get the individual noises.

Bottom line is that the sensitivity of this approach is good and we should do this rather that use spectrum analyzers since its easy to get very long averages and high res spectra. To get 5x better sensitivity, we can just use the Rai-FET box instead of a SR560 for the readout, but just have to contend with its batteries. Also should try using BALUNs on the RF and LO signals to get rid of the ground loops.

  2879   Tue May 4 18:40:27 2010 ranaHowToElectronicsMarconi phase noise measurement setup

To check the UGF, I increased the gain of the PLL by 10 and looked at how much the error point got suppressed. The green trace apparently has a UGF of ~50 Hz and so the BLUE nominal one has ~5 Hz.

The second attachment shows the noise now corrected for the loop gain. IF the two signal generators are equally noisy, then you can divide the purple spectrum by sqrt(2) to get the noise of a single source.

The .xml file is saved as /users/rana/dtt/MarconiPhaseNoise_100504.xml

  2913   Tue May 11 18:58:49 2010 ranaHowToElectronicsMarconi phase noise measurement setup

Just a little while ago, at 2330 UTC on 5/11, I swapped the phase noise setup to use another Marconi - this time its the 3rd one from the top beating with the 4th one from the top (2nd from the bottom).

After a little while, I swapped over to beat the 33 w/ the 199. I now have all the measurements. For the measurement of the last pair, I inserted BALUN 1:1 transformers on the outputs of both signal generators'.

This last pair appears to be the quietest of the 3 and also has less lines. The lines are mainly at high frequency and are harmonics of 120 Hz. Probably from the Sorensen switching supplies in the adjacent rack.

I double checked that the 10 MHz sync cable was NOT plugged in to any of these during this and that the front panel menu was set to use the internal frequency standard. In the closed loop case, the beat frequency between the 33/199 pair changes by less than ~0.01 Hz over minutes (as measured by calibrating the control signal).

 

  2914   Wed May 12 02:21:56 2010 ranaHowToElectronicsMarconi phase noise measurement setup

Finally got the 3-cornered-hat measurement of the IFRs done. The result is attached.

s12, s23, & s31, are the beat signals between the 3 signal generators.

s1, s2, & s3 are the phase noise of the individual generators made by the following matlab calculation:

%% Do the hat
s1 = sqrt((s12.^2  + s31.^2 - s23.^2) / 2);
s2 = sqrt((s12.^2  + s23.^2 - s31.^2) / 2);
s3 = sqrt((s31.^2  + s23.^2 - s12.^2) / 2);

As you can see, there is now an estimate of the individual noises. We can do better by doing some fitting of the residuals.

The real test will be to replace the noise one here with the good Wenzel oscillator and see how well we can estimate its noise. If the 11 MHz crystals don't show up, I can just try this with the 21.5 MHz one for the PSL.

  3126   Mon Jun 28 11:27:08 2010 MeganUpdateElectronicsMarconi Phase Noise

Using the three Marconis in 40m at 11.1 MHz, the Three Cornered Hat technique was used to find the individual noise of each Marconi with different offset ranges and the direct/indirect frequency source of the rubidium clock.

Rana explained the TCH technique earlier - by measuring the phase noise of each pair of Marconis, the individual phase noise can be calculated by:

S1 = sqrt( (S12^2 + S13^2 - S23^2) / 2)

S2 = sqrt( (S12^2 + S23^2 - S13^2) / 2)

S3 = sqrt( (S13^2 + S23^2 - S12^2) / 2)

I measured the phase noise for offset ranges of 1Hz, 10Hz, 1kHz, and 100kHz (the maximum allowed for a frequency of 11.1Mhz) and calculated the individual phase noise for each source (using 7 averages, which gives all the spikes in the individual noise curves). The noise from each source is very similar, although not quite identical, while the noise is greater at higher frequencies for higher offset ranges, so the lowest possible offset range should be used. It appears the noise below a range of 10Hz is fairly constant, with a smoother curve at 10Hz.

The phase noise for direct vs indirect frequency source was measured with an offset range of 10Hz. While very similar at high and low frequencies for all 3 Marconis, the indirect source was consistently noisier in the middle frequencies, indicating that any Marconis connected to the rubidium clock should use the rubidium clock as a direct frequency reference.

Since I can't adjust settings of the Marconis at the moment, I have yet to finish measurements of the phase noise at 160 MHz and 80 MHz (those used in the PSL lab), but using the data I have for only the first 2 Marconis (so I can't finish the TCH technique), the phase noise appears to be lowest using the 100kHz offset except at the higher frequencies. The 160 MHz signal so far is noisier than the 11.1 MHz signal with offset ranges of 1 kHz and 10 Hz, but less noisy with a 100 kHz offset.

I still haven't measured anything at 80 MHz and have to finish taking more data to be able to use the TCH technique at 160 MHz, then the individual phase noise data will be used to measure the noise of the function generators used in the PSL lab.

  15011   Mon Nov 4 19:02:25 2019 YehonathanUpdatePSLMapping the PSL electronics

I created a spreadsheet (Attached) by taking Koji's c1psl sheet from slow_channel_list and filtering out the channels that do not need an Acromag. I added in the QPD channels that are relevant to the PSL from the c1iool0 sheet.

I began mapping the PSL related Eurocrates connectors to their respective VME channels starting with the PMC electronics.

I am confused about the TTFSS interface (D040423): While it is a Eurocrate card, in the schematics it seems to have 50 pin connectors.

I found old wiring schematics that might help with identifying the channels once the connector issue is clarified.

 

 

  15099   Tue Dec 17 00:23:28 2019 YehonathanUpdatePSLMapping the PSL electronics

I added to the PSL wiring list the ioo channels and the laser shutter (See attached pdf for an updated list).

The total channel numbers for now:

ai 57
ao 13
bi 1
bo 36

I counted each mbbo as 1 bo but I am not sure that's correct.

Still need to allocate Acromags.

  15100   Tue Dec 17 18:05:06 2019 YehonathanUpdatePSLMapping the PSL electronics

Updated the channel list (Attached):

1. Removed the MC steering mirror PZT channels

2. Added Sourcing/Sinking column

3. Recounted the mbbos correctly

4. Allocated Acromags:

Model Purpose No. Spare channels
XT1221 ai 7 11
XT1541 ao + src bo 2 9 ao
XT1121 src bo 2 4
XT1121 sink bo 1 4

I think we can start wiring.

  15103   Fri Dec 20 18:33:21 2019 YehonathanUpdatePSLMapping the PSL electronics

Final (hopefully) PSL channel list is attached with allocated Acromag channels. Wiring spreadsheet coming soon.

Current Acromag count:

AI 8
AO 2
BIO 4
Number of channels 8*8+2*8+4*16=144
Number of wires 144*2=288

 

  15104   Mon Dec 23 19:30:20 2019 YehonathanUpdatePSLMapping the PSL electronics

PSL wiring spreadsheet is ready. (But the link was stripped. Koji)

Link to a wiki page  with the link to the wiring spreadsheet (Yehonathan)

  15108   Wed Jan 1 04:53:11 2020 gautamUpdatePSLMapping the PSL electronics

For the IMC servo board, it'd be easiest to copy the wiring scheme for the BIO bits as is configured for the CM board (i.e. copy the grouping of the BIO bits on the individual Acromag units). This will enable us to use the latch code with minimal modifications (it was a pain to debug this the first time around). I don't see any major constraint in the wiring assignment that'd make this difficult.

Quote:

PSL wiring spreadsheet is ready. (But the link was stripped. Koji)

Link to a wiki page  with the link to the wiring spreadsheet (Yehonathan)

  15110   Wed Jan 1 16:04:37 2020 YehonathanUpdatePSLMapping the PSL electronics

Done.

Quote:

For the IMC servo board, it'd be easiest to copy the wiring scheme for the BIO bits as is configured for the CM board (i.e. copy the grouping of the BIO bits on the individual Acromag units). This will enable us to use the latch code with minimal modifications (it was a pain to debug this the first time around). I don't see any major constraint in the wiring assignment that'd make this difficult.

Quote:

PSL wiring spreadsheet is ready. (But the link was stripped. Koji)

Link to a wiki page  with the link to the wiring spreadsheet (Yehonathan)

 

  6904   Mon Jul 2 18:28:09 2012 JenneUpdatePhotosMany photos taken

Many photos were taken by many different people....most of the fuzzy ones are by yours truely (doing a reach-around to get to hard-to-reach places), so sorry about that.

I put all the photos from yesterday and today into 6 new albums on Picasa:  https://picasaweb.google.com/foteee

The album titles are generally descriptive, and I threw in a few comments where it seemed prudent.

Big note:  The tip tilt on the ITMX table does, in fact, have the arrow pointing in the correct direction.  Photo is in the TT album from today.

  11479   Wed Aug 5 10:56:07 2015 ericqUpdateCDSMany models crashed

Last night around 1AM, many of the the frontend models crashed due to an ADC timeout. (But none of the IOPs, and all the c1lsc models were fine.)

 
First, on c1sus (Wed Aug  5 00:56:46 PDT 2015)
[1502036.695639] c1rfm: ADC TIMEOUT 0 46281 9 46153
[1502036.945259] c1pem: ADC TIMEOUT 0 56631 55 56695
[1502036.965969] c1mcs: ADC TIMEOUT 1 56706 2 56770
[1502036.965971] c1sus: ADC TIMEOUT 1 56706 2 56770

Then, simultaneously on c1ioo, c1iscex, and c1iscey. (Wed Aug  5 01:10:53 PDT 2015)

[1509007.391124] c1ioo: ADC TIMEOUT 0 46329 57 46201
[1509007.702792] c1als: ADC TIMEOUT 1 63128 24 63192

[2448096.252002] c1scx: ADC TIMEOUT 0 46293 21 46165
[2448096.258001] c1asx: ADC TIMEOUT 0 46669 13 46541

[1674945.583003] c1scy: ADC TIMEOUT 0 46297 25 46169
[1674945.685002] c1tst: ADC TIMEOUT 0 52993 1 52865

I'm still working on getting things back up and running. Just restarting models wasn't working, so I'm trying some soft reboots...


UPDATE: A soft reboot of all frontends seems to have worked,

  15743   Mon Dec 21 18:18:03 2020 gautamUpdateCDSMany model changes

The CDS model change required to get the AS WFS signals into the RTCDS system are rather invasive.

  • We use VCS for these models. Linus Torvald may question my taste but I also made local backups of the models, just in case...
  • Particularly, the ADC1 card on c1ioo is completely reconfigured.
  • I also think it's more natural to do all the ASC computations on this machine rather than the c1lsc machine (it is currently done in the c1ass model). So there are many IPC changes as well.
  • I have documented everything carefully, and the compile/install went smoothly.
  • Taking down all the FE servers at 1830 local time
    1. To propagagte the model changes
    2. To make a hardware change in the c1rfm card in the c1ioo machine to configure it as "ROGUE MASTER 0"
    3. To clear the RFM errors we are currently suffering from will require a model reboot anyways.
  • Recovery was completed by 1930 - the RFM errors are also cleared, and now we have a "ROGUE MASTER 👾" on the network. Pretty smooth, no major issues with the CDS part of the procedure to report.
  • The main issue is that in the AA chassis I built, Ch14 (with the first channel as Ch1) has the output saturated to 28V (differential). I'm not sure what kind of overvoltage protection the ADC has - we frequently have the inputs exceed the spec'd +/-20 V (e.g. when the whitening filters are engaged and the cavity is fringing), but pending further investigation, I am removing the SCSI connection from the rear of the AA chassis.

In terms of computational load, the c1ioo model seems to be able to handle the extra load no issues - ~35us/60us per cycle. The RFM model shows no extra computational time

After this work, the IMC locking and POX/POY locking, and dither alignment servos are working okay. So I have some confidence that my invasive work hasn't completely destroyed everything. There is some hardware around the rear of 1X2 that I will clear tomorrow.

  5050   Wed Jul 27 15:49:56 2011 steveUpdateSAFETYManuel receives safety training

Our surf student Manuel Marchiò received 40m specific safety training today.

  14395   Thu Jan 10 11:32:40 2019 ChubUpdateVACManual valve interfaced with CDS

Connected the manual gate valve status indicator to the Acromag box this morning.  Labeled the temporary cable (a 50' 9p DSUB, will order a proper sized cable shortly) and the panel RV2.  

  5034   Mon Jul 25 23:43:20 2011 ManuelHowToElectronicsManual for 1201 Low Noise Preamplifier

I found the manual for the Low Noise Preamplifier Model 1201 at this link and I attached it.

The one we have in the lab (S/N 48332) miss the battery packs and miss also the remote programming options input/output. Its inside battery compartment is empty and I found 2 unscrewed screws with washers and nuts inside the preamplifier box. The battery cable are disconnected and they have 2 green tape labels (-) and 2 red tape label (+).

 

 

  976   Mon Sep 22 15:02:45 2008 ranaFrogsTreasureMantis found outside the 40m door at night
  13013   Thu May 25 16:42:41 2017 jigyasaUpdateComputer Scripts / ProgramsMaking pylon installation on shared directory

I have been working on interfacing with the GigE’s. I went through Joe Be’s paper and the previous elogs and verified that the code files are installed.

I then downloaded and extracted a copy of the Pylon software onto my home directory on Allegra. Gautam helped me find installation instructions on Johannes’ directory so that I could make the installation on the shared directory.

So far , according to instructions, these commands need to be executed so that the installation takes place and the rules for camera permissions are set up.

sudo tar –C /opt/rtcds/caltech/c1/scripts/GigE –xzf pylon SDK*.tar.gz

followed by ./setup-usb.sh

The Pylon viewer can then be accessed with /scripts/GigE/pylon5/bin/PylonViewerApp 

Should I go ahead with the installation in the shared directory?

  13014   Thu May 25 18:37:11 2017 jigyasaUpdateComputer Scripts / ProgramsMaking pylon installation on shared directory

Gautam helped me execute the commands mentioned above and Pylon has now been installed on the shared directory. We extracted the pylon installation from Johannes's directory to the shared drive and executing the command tar –C /opt/rtcds/caltech/c1/scripts/GigE –xzf pylon SDK*.tar.gz created an unzipped pylon5 folder in /scripts. The ./setup-usb.sh set up the udev rules for the GigE.

The installation took place without any errors.

The Pylon viewer app can now be accessed at /opt/rtcds/caltech/c1/scripts/GigE/pylon5/bin followed by ./PylonViewerApp 

Quote:

Should I go ahead with the installation in the shared directory?

 

  5558   Tue Sep 27 15:33:03 2011 JenneUpdateComputersMaking models, wreaking havoc

[Jenne, Mirko, Den]

We have entered into an adventure in model compiling.  What follows is a stream-of-consciousness report of what the hell we're doing, so Jamie can figure it out and fix it if everything goes to hell.

Note that for the first part of things, we have used a new version of the Adaptive XFCODE, which Mirko and Den modified last night to be able to handle multiple control signal inputs.  

On c1lsc, make uninstall-daq-c1oaf, make clean-c1oaf, make c1oaf.

***ERROR: The following IPCx RECEIVER module(s) not found in the file /opt/rtcds/caltech/c1/chans/ipc/C1.ipc:

                C1:RFM_OAF_MCL

On c1sus, make uninstall-daq-c1sus, make clean-c1sus, make c1sus.  (This was an accident.  I should have been making c1rfm.  Oops.)  Then make install-c1sus.  It looks like this automatically did make install-daq-c1sus and make install-screens-c1sus, so I'm not doing those. 

On c1sus, make uninstall-daq-c1rfm, make clean-c1rfm, make c1rfm.

***ERROR: The following IPCx RECEIVER module(s) not found in the file /opt/rtcds/caltech/c1/chans/ipc/C1.ipc:

                C1:IOO-RFM_MCL


On c1ioo, make uninstall-daq-c1ioo, make clean-c1ioo, make c1ioo.  No errors.

On c1lsc, make c1oaf.  Here's some of the ouptut, with some of the error stuff:

: warning: ISO C90 forbids mixed declarations and code
/opt/rtcds/caltech/c1/core/branches/branch-2.1/src/fe/c1oaf/../controller.c:2954: warning: ISO C90 forbids mixed declarations and code
make[3]: *** [/opt/rtcds/caltech/c1/core/branches/branch-2.1/src/fe/c1oaf/c1oaffe.o] Error 1
make[2]: *** [_module_/opt/rtcds/caltech/c1/core/branches/branch-2.1/src/fe/c1oaf] Error 2
make[2]: Leaving directory `/usr/src/linux-2.6.34.1-cs'
make[1]: *** [default] Error 2
make[1]: Leaving directory `/opt/rtcds/caltech/c1/core/branches/branch-2.1/src/fe/c1oaf'
make: *** [c1oaf] Error 2

Again on c1lsc, make clean-c1oaf, make c1oaf.  Here are some things:

Warning:  variable "sysnum" is used but not declared.

In file included from build/c1oafepics/c1oaf.i:38:
src/include/fmReadCoeff.h:4:1: warning: "NO_FM10GEN_C_CODE" redefined
<command-line>: warning: this is the location of the previous definition

build/c1oafepics/c1oaf.i:5156: warning: passing argument 2 of 'strcpy' discards qualifiers from pointer target type
/usr/include/string.h:127: note: expected 'const char * __restrict__' but argument is of type 'volatile char *'

/opt/rtcds/caltech/c1/core/branches/branch-2.1/src/fe/c1oaf/../../include/drv/inputFilterModule1.h:5: note: expected 'double *' but argument is of type 'long unsigned int *'

/opt/rtcds/caltech/c1/core/branches/branch-2.1/src/fe/c1oaf/../controller.c:2780: warning: ISO C90 forbids mixed declarations and code

make[3]: *** [/opt/rtcds/caltech/c1/core/branches/branch-2.1/src/fe/c1oaf/c1oaffe.o] Error 1
make[2]: *** [_module_/opt/rtcds/caltech/c1/core/branches/branch-2.1/src/fe/c1oaf] Error 2
make[1]: *** [default] Error 2
make: *** [c1oaf] Error 2

Again, on c1lsc, make clean-c1oaf, make c1oaf.  More errors, pretty similar.  Then we changed the name of the adaptive filtering code, so maybe it will work now?  We had called the block "TOP_XFCODE", but that was the name of the old .c code.  The block used to be called "XFCODE", in a subsystem "TOP".  So now we named the .c code "ADAPT_XFCODE" since the block is "XFCODE", and the subsystem is "TOP".

Again, on c1lsc, make clean-c1oaf, make c1oaf.  Errors, they look the same.

Mirko is now modifying c1oaf.mdl to look more like the old version, with only one control signal input, so that we can use the old XFCODE that has been around for years.

First, we completely took out the .c code entirely.  Now the c1oaf.mdl is just signals and matricies, no c-code is called.  We did make clean-c1oaf, make c1oaf, and pretty much all of the same errors are present.
 

We took out the buses, and did make clean-c1oaf, make c1oaf, and we got a whole lot of warnings, but no "Error 2"'s.  This seems good.  We're going to try replacing those buses with Muxes, and see how that goes.

Now we're going to try to install the c1oaf, because maybe all the errors and shit we're seeing is just useless crap, and there aren't actually problems...here we go!

That seemed to work, and the c1oaf model on the GDS status screen seems happy.  Numbers are moving around, which is my only current diagnostic.

Okay, now Mirko is going back to the full, new c1oaf, but replacing the Buses with Muxes. 

Did a make clean-c1oaf, make c1oaf, got errors again.

Once again removed the .c code.  Just put in a matrix instead. Did make clean-c1oaf, make c1oaf.  No errors. 

Den did a reorganization of the .c code, and we put it back in to the simulink model.  Trying again the making stuff.  Fail..Basically the same errors as before.

Next up:  Putting in .c-code, but something which basically does nothing.  Just defines all the outs as zeros.  Make stuff.  Still had problems, same errors.  Grrrr, argh. 

Found the RCG manual:  T080135-v4.  In it, when talking about including c-code, it had an example of totally simple code.  We tried out their version of simple code, and it worked.  No errors!  Now to figure out what is same and different between our simple code and theirs.

 PUT THE RIGHT STUFF in the Block Properties for the c-code, including name of the .c file, and path to the .c file.  This is critical!!  Now we can make some of our simple versions work, but not all.  We're slowly increasing complexity of our c-code...

 At some point in the last hour, I tried a make install-c1oaf, and then checked the screens, and they all had bad white boxes.  So even though the model seemed to compile (at one point), the channels and screens aren't happy yet.  But that's really a project for after the code compiles happily.

Okay, some progress was made to get the c-code running, and compiling, but it's not all there yet.  We're putting in a simple, useless version of the c-code so we can try compiling everything else.

Everything is compiled, installed, there are no red lights on the GDS_STATUS screen.  All seems okay for locking for tonight.

 

  13845   Tue May 15 20:51:27 2018 gautamConfigurationElectronicsMaking PLL setup more permanent

[jon, steve, gautam]

Some points which Jon will elaborate upon (and put photos of) in his detailed elog about this setup:

  • PLL electronics (mixer, coupler, ZFL500HLN amplifier and DC power supply for the beatnote, SR560 servo) all reside on the newly installed lower level PSL shelf.
  • Cross connect channel C1:PSL-126MOPA_126CURADJ hijacked for remote temperature control of the AUX NPRO. Note that shield of front panel BNC is ground and so even though the manual says the controller accepts +/-10V, this is not a differential input. BNC cable was routed from cross connect to PSL enclosure, MEDM slider will be setup.
  • There was an SMA cable running from the VEA to the control room which we decided to use for monitoring of the beatnote amplitude on the control room analyzer. Yesterday, Steve and I routed the end of this inside the VEA, near 1X2 originally, to inside the PSL table where it is hooked up to the (20dB) coupled amplifier output. This required some work on the cable tray, we were careful but in case there is some wonkiness in some signals, perhaps this work is to blame.

We are now in a state where the PLL can be locked remotely from the control room by tweaking the AUX laser temperature laugh. Tomorrow, Keerthana will work on getting Craig's/Johannes' Digital Frequency Counter script working here, I think we can easily implement a PLL autolocker if we have some diagostic that tells us if the PLL us locked or not.


Steve informed me that there is an acoustic hum inside the PSL enclosure which wasn't there before. Indeed, it is at ~295Hz, and is from the Bench power supply used to power the ZFL500HLN amplifier. This will have to go...

  14832   Tue Aug 6 14:55:23 2019 gautamUpdateCDSMaking Matlab R2015b the default

ML2013 is unable to open Simulink on any of the workstations. We decided to make the default version of Matlab R2015b (the default of the version of RCG we are using).

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.

Currently the branch and tag are protected - once we verify that everything works as expected post migration, I will open it up. I changed the directory structure of the models, need to confirm that the rtcds compilers don't have any hardcoded paths which may break due to my change.

The symlink to Matlab R2013 was deleted and a new symlink to R2015b was made. I activated the license using the Caltech campus license. Now running matlab from shell starts up R2015b yes. Simulink even works 😲 .

  175   Thu Dec 6 18:11:15 2007 robHowToComputer Scripts / ProgramsMaking DMF monitors

I was able to use the matlab compiler to compile a version of the linetracker written by Rana, and run the compiled version on mafalda.

I believe I made the necessary edits to our mDV config file so that it should be easy for others to follow these steps:

1) Write the DMF routine you want, as a matlab function (not a script).

2) If it runs correctly in matlab, then from the matlab command line compile
it using the -m flag (i.e., mcc -m myfun.m). You should run the
compiler from the directory where you want the executable to end up (don't use the mDV/extra
directory so it doesn't get all cluttered).

3) prior to running the resulting executable (which should be called simply myfun),
prepend the directories
/cvs/cds/caltech/apps/linux/matlab/bin/glnx86
/cvs/cds/caltech/apps/linux/matlab/sys/os/glnx86/

to the LD_LIBRARY_PATH enviroment variable. These directories must be prepended as the
versions that already exist in /usr/lib don't work; I'm loathe to do this in the cshrc.40m
for fear of later conflicts, so it will need to be done in some sort of shell script which
calls the matlab executable.
  1132   Thu Nov 13 11:33:25 2008 AlbertoHowToTreasureMaking (good) Matlab figures
Just a little summary of some useful ways to change plot settings in Matlab that I wanted to share and remember for the future:

http://saig.phys.ualberta.ca/toolbox/Matlab/making_figures.html
  13120   Sat Jul 15 16:19:00 2017 gautamUpdateCamerasMakeshift PyPylon

Some days ago, I stumbled upon this github page, by a grad student at KIT who developed this code as he was working with Basler GigE cameras. Since we are having trouble installing SnapPy, I figured I'd give this package a try. Installation was very easy, took me ~10mins, and while there isn't great documentation, basic use is very easy - for instance, I was able to adjust the exposure time, and capture an image, all from Pianosa. The attached is some kind of in-built function rendering of the captured image - it is a piece of paper with some scribbles on it near Jigyasa's BRDF measurement setup on the SP table, but it should be straightforward to export the images in any format we like. I believe the axes are pixel indices.

Of course this is only a temporary solution as I don't know if this package will be amenable to interfacing with EPICS servers etc, but seems like a useful tool to have while we figure out how to get SnapPy working. For instance, the HDR image capture routine can now be written entirely as a Python script, and executed via an MEDM button or something.

A rudimentary example file can be found at /opt/rtcds/caltech/c1/scripts/GigE/PyPylon/examples - some of the dictionary keywords to access various properties of the camera (e.g. Exposure time) are different, but these are easy enough to figure out.

 

  14930   Thu Oct 3 12:08:47 2019 gautamUpdateGeneralMake the Jenne-laser setup fiber-coupled

I propose the following re-organization of the PDFR measurement breadboard. We have all the parts on hand, just needs ~30mins of setup work and some characterization afterwards. The fiber beamsplitter will not be PM, but for this measurement, I don't think that matters (the patch fiber from the diode laser head isn't PM anyways). We have one spare 1 GHz BW NF1611 that is fiber coupled (used to live on the ITMY in-air table, and is (conveniently) labelled "REF DET", but I'm not sure what the function of this was). In any case, we have at least 1 free-space NF1611 photodiode available as well. I suggest confirming that the FC version works as expected by calibrating against the free space PD first.

Update 245pm: Implemented, see Attachment #2. Aaron is testing it now, and will post the characterization results.

  14931   Thu Oct 3 14:32:37 2019 ranaUpdateGeneralMake the Jenne-laser setup fiber-coupled

I'm curious to see if we really need the 1611, or if we can calibrate the diode laser vs. the 1611 one time and then just use that calibration to get the absolute cal for the DUT.

  14932   Thu Oct 3 14:54:33 2019 KojiUpdateGeneralMake the Jenne-laser setup fiber-coupled

I'm afraid that the RF modualtion of the laser is nonlinear and the electrical and optical resoponse is dependent on the LD pumping current and RF input power. So I feel safe if we keep the reference PD. Of course, this is my feeling and it should be quantitatively tested.

  14934   Thu Oct 3 21:05:04 2019 aaronUpdateGeneralMake the Jenne-laser setup fiber-coupled

I measured the RF response of the fiber-coupled NewFocus 1611, calibrating out the cable delay. The laser current was set to 20.0 mA, and the RF power going into the splitter was -10 dBm. The DC voltage was 1.87 V, and Gautam and I measured the power from the fiber at 344uW.

Something still looks very wrong -- the PD is supposed to be flat out to 1GHz, and physical units pending, need food.

  14936   Thu Oct 3 23:15:39 2019 KojiUpdateGeneralMake the Jenne-laser setup fiber-coupled

The 1GHz PD has a bit more flat response, but the laser and the driving network have more frequency dependence as you saw.

  14937   Fri Oct 4 00:30:31 2019 gautamUpdateGeneralMake the Jenne-laser setup fiber-coupled

I think the metric of interest here is the consistency of the AC transimpedance of the proposed new "Reference PD" (= fiber coupled NF1611) vs the old reference (free space NF1611), since everything will be calibrated against that.

Quote:

Something still looks very wrong -- the PD is supposed to be flat out to 1GHz, and physical units pending, need food.

  14940   Fri Oct 4 14:25:59 2019 aaronUpdateGeneralMake the Jenne-laser setup fiber-coupled

Summary:

The fiber-coupled PD seems to have a factor of ~1.5 difference in responsivity compared to the free-space PD. There are some differences in the two ways I made the measurement that I don't yet understand.

Details

I measured relative responsivities of the fiber and free coupled NewFocus 1611 PDs (scaled by the Jenne AM transfer function).

I made the measurement in two ways, see attachment threeIn attachment oneI show the response for separately measuring the two PDs relative to a pickoff of the source (two-port thru calibration). In attachment two I measure the relative responses directly, without picking off a reference (three-port calibration). I scaled the transfer functions by their DC voltages; both PDs have transimpedances of 700 V/A.

However, there are some clear differences in the response (overall factor of 0.5dB offset that may be explained by a miscalibrated DC level; apparent periodicity in attachment 1) that I don't yet understand.The free path of the non-fiber PD is ~5-6 inches, which accounts for the ~45 degrees of phase advance of the fiber relative to free coupled PD signal. (12.7cm / (c / 300 MHz) * 360 degrees ~ 45 degrees)

I didn't find Agilent's manual very helpful for learning about the available calibration schemes, and didn't find a resource online that I liked -- is there a good one?
I think I want to characterize the WFS heads treating the DUT as a three-port device (AM in, ref PD, WFS segment PD).
  4993   Tue Jul 19 23:39:11 2011 Jamie, JenneUpdateLSCMajor overhaul of LSC rack; binary switching of whitening filters now working

Yesterday we started going through the LSC binary whitening switching to make sure the new switching control in the LSC model was working.  Jenne and I hooked up a fancy home-brew white noise generator [0] into all of the LSC whitening filter inputs and started switching the whitening filters to see what would happen.  We found that some of the channels were switching, but the majority were not, or worse yet switching the wrong channels.  Upon closer inspection, and after finally finding the LSC wiring schematic, we found that the LSC rack cross-connect/back-plane cabling was pretty much a complete mess, and didn't at all correspond to the channel layout in Suresh's diagram.

Given that the back-plane wiring had to be almost completely redone, we decided to completely redo the LSC electronics layout, to be a little more self-consistent and to use the given space more efficiently.  We'll post an updated electronics drawing soon.  The LSC model was also updated to reflect the new layout.

We then went through and verified that all of the whitening switching was working with the new layout.  As described previously, the first filter in the PD input filter bank is used to control the switching.  We did indeed verify that all the switching is working, but we noticed that switching logic was inverted, such that the whitening filter engaged when the filter was turned off.  This was fixed in the model and all the switching logic was verified to be working as expected.

Everything has now been hooked back up, but we need to verify that we're getting all of the PD demodulated RF and DC outputs as expected.  We need to check the RF phases, as some of the RF cable lengths have changed.

[0] a 50k resistor

Links:

 

  7075   Thu Aug 2 00:43:55 2012 JenneUpdateASSMajor cleanup of the ASS model

[Jamie, Jenne]

We are trying to figure out what the story is with the ASS, and in order to make it more human parse-able, we cleaned up the c1ass.mdl. 

So far, we have made no changes to how the signals are routed.  The local oscillators from each lockin still get summed, and go directly to the individual optics, and the demodulated signals from each lockin go through the sensing matrix, the DoF filters, then the control output matrix, and then on to the individual optics.  So far, so good.

Much of the cleanup work involved making a big library part, which is then called once for PIT and once for YAW in the ass top level, rather than have 2 code-copies, which give Jamie conniptions.  Inside the library part GoTo and From tags were used, rather than having all the lines cross over one another in a big spaghetti mess.

One of the big actual changes to the ass was some name changes. Rather than having mysterious "ASS-LOCKIN(1-30)", they are now named something like "ASS-PIT_LOCKIN_ETMY_TRY", indicating that this is in the pitch set, actuating on ETMY, and looking at TRY for the demodulated signal.  The "DOF" channels are similar to what they were, although we would like to change them in the future.....more on this potential change later.  Previously they were "ASS-DOF(1-10)", but now they are "ASS-PIT_DOF(1-5)" and "ASS-YAW_DOF(1-5)". This channel naming, while it makes things make more sense, and is easier to understand, means that all of the ASS scripts need to be fixed.  However, they all needed updating / upgrading anyway, so this isn't the end of the world.

This channel name fixing also included updating names of IPC (shmem/dolphin/rfm things) blocks, which required matching changes in the SUS, RFM and LSC models.  All 4 models (ASS, SUS, RFM, LSC) were recompiled and installed.  They all seem fine, except there appears to be a dolphin naming mismatch between OAF and SUS that showed up when the SUS was recompiled, which presumably it hadn't been in a while.  We need to figure this out, but maybe not tonight.  Den, if you have time, it would be cool if you could take a look at the OAF and SUS models to make sure the names match when sending signals back and forth.

______________________

We also had a long chat about the deeper meaning of the ASS. 

What should we be actuating on, and what should we be sensing?  A potential thought is to rename our DOF channels to actual DoF names: input axis translation, input axis angle, cavity axis translation, cavity axis angle.  Then actuate the dither lines on a cavity degree of freedom, sense the influence on TRX, TRY and an LSC PD (as is currently done), then actuate on the cavity degree of freedom.

Right now, it looks like the actuation is for individual optics, the sensing is the influence on TRX, TRY and an LSC PD, then actuate on a cavity degree of freedom.  So the only change with the new idea is that we actuate in the DoF basis, not the optics basis.  So the Lockin local oscillators would go through the control output matrix.  This makes more sense in my head, but Jamie and I wanted to involve more people in the conversation before we commit. 

The next question would be: how do we populate the control output matricies?  Valera (or someone) put something in there, but I couldn't find anything on the elog about how those values were measured/calculated/came-to-be.  Any ideas?  If we want to dither and then push on isolated degrees of freedom, we need to know how much moving of which optics affects each DoF.  Is this something we should do using only geometry, and our knowledge of optic placements and relative distances, or is this measurable?

  7081   Thu Aug 2 23:31:04 2012 JenneUpdateASSMajor cleanup of the ASS model

Jamie re-redid the ASS model a few hours ago.

I have just compiled it, and restarted c1ass.  (The model from last night is currently called c1ass3.mdl)  I had to delete and re-put inthe goto and from tags for the LSC signal coming in from the shmem.  For some reason, it kept claiming that the inputs using the from tags were not connected, even when I redid the connections.  Finally deleting and dragging in new goto and from tags made the model happy enough to compile.  Whatever.  I'm going to let Jamie do the svn-ing, since he's the one who made the changes.  Before I had figured out that it was the tags, I was concerned that the shmem was unhappy, so there was no signal connecting to the input of the goto tag, and that was somehow bad....anyhow, I recompiled the LSC model to re-create the shmem sender, but that had no effect, since that wasn't the problem.

The change from last night is that now the library parts are by DoF.  There is only one matrix in each library part, before the servo filters. Now we can DC-actuate on a single mode (ETM or ITM, pitch or yaw), and see how it affects all 4 sensors (the demodulated signals from the lockins). We need to measure the sensing matrix to go from the several sensors to the servo input.

  11346   Fri Jun 5 11:59:59 2015 ericqBureaucracyGeneralMaintenance Tasks, IFO upgrades

At wednesday's meeting, Rana, Koji, Steve, and I started making a list of maintenence tasks that should be done/checked on a regular basis. The actual scheduling of these has not yet been considered. They include:

  • N2 Tank pressure / cylinder replacement
  • Headlamp, walkie talkie battery recharge
  • Workstation software updates
  • Coffee bean and filters
  • Multimeter battery levels
  • Sorensen DC power supply voltage settings and current draws
  • UPS' status (Vacuum, NFS host, workstations)
  • SR560s, battery powered scopes plugged in
  • Rack Fuses intact
  • Take pictures of electronics racks, optical tables
  • Replace PSL HEPA filter

Next, we brainstormed work that can be done to improve the interferometer performance, and what order/precedence they should take. 

In the end, it was decided that the plan for the next few weeks was to focus on improving the ALS noise levels, and, more importantly, seeking to make the performance more consistent. We need to know what is limiting us, and what we extent we can expect to improve things. To this end, I am working on reviving a ALS noise budget; using the noise budget from the green locking paper to inform a simulinkNB kind of thing.

Here are all of the items we listed during this brainstorming session.

Some near-term/priority tasks are:

  • Installing the accelerometers near MC1 and 2
  • Installing green steering PZT mirrors at the Y end table, commission dither alignment
  • Improving the X end green mode matching
  • ALS noise budgeting
  • Upgrade the realtime system to RCG v2.9

More down the line, other things we thought about were:

  • Cleanup of bench power supplies (FSS box has one, where else?)
  • Fixing the ETMX suspension issues 
  • Upgrade SOS suspension code to the appropriate aLIGO block
  • Upgrade to the green PDH electronics
  • Understanding / tuning the FSS servo laser PZT vs. PC crossover
  • Undestanding / tuning the 11MHz vs 55MHz modulation phase
  • Replacing the slow vxworks machines with the Acromag setup Aiden has set up for the CTN lab
  • QPD upgrade
  • New/better green beatbox
  • Finalize the manifestation of the IR beat control (Freq counter vs. fast DFD)
  • Explore the idea of using an analog output of the ALS beatbox as fast input to the CM board
  • Replace triple resonant EOM driving circuit with double resonant one
  • X end table layout/enclosure upgrade
  14436   Tue Feb 5 19:30:14 2019 gautamUpdateVACMain volume at 20 uTorr

Pumpdown looks healthy, so I'm leaving the TPs on overnight. At some point, we should probably get the RGA going again. I don't know that we have a "reference" RGA trace that we can compare the scan to, should check with Steve. The high power (1 W) beam has not yet been sent into the vacuum, we should probably add the interlock condition that shuts off the PSL shutter before that.

  15279   Wed Mar 18 21:43:26 2020 gautamUpdateVACMain vol pressure jump

There was a jump in the main volume pressure at ~6pm PDT yesterday. The cause is unknown, but the pressure doesn't seem to be coming back down (but also isn't increasing alarmingly).

I wanted to look at the RGA scans to see if there were any clues as to what changed, but looks like the daily RGA scans stopped updating on Dec 24 2019. The c0rga machine responsible for running these scans doesn't respond to ssh. Not much to be done until the lockdown is over i guess...

  15280   Wed Mar 18 22:10:41 2020 KojiUpdateVACMain vol pressure jump

I was in the lab at the time. But did not notice anything (like turbo sound etc). I was around ETMX/Y (1X9, 1Y4) rack and SUS rack (1X4/5), but did not go into the Vac region.

  14628   Tue May 21 00:15:21 2019 gautamUpdateSUSMain objectives of vent achieved (?)

Summary:

  1. ETMY now shows four suspension eigenmodes, with sensible phasing between signals for the angular DoFs. However, the eigenfrequencies have shifted by ~10% compared to 16 May 2019.
  2. PIT and YAW for ETMY as witnessed by the Oplev are now much better separated.
  3. ITMY can have its bias voltage set to zero and back to nominal alignment without it getting stuck.
  4. The sensing matrix for ETMY that I get doesn't make much sense to me. Nevertheless, the optic damps even with the "naive" input matrix.

So the primary vent objectives have been achieved, I think. 


Details:

  1. ETMY free-swinging data after adjusting LL and SIDE coils such that these were closer to half-light values
    • Attachment #1 - oplev witnessing the angular motion of the optic. PIT and YAW are well decoupled.
    • Attachment #2 - complex TF between the suspension coils. There is still considerable imbalance between coils, but at least the phasing of the signals make sense for PIT and YAW now.
    • Attachment #3 - DoFs sensed using the naive and optimized sensing matrices.
    • Attachment #4 - sensing matrix that the free swinging data tells me to implement. If the local damping works with the naive input matrix but we get better diagonality in the actuation matrix, I think we may as well stick to the naive input matrix.
  2. BR mode coupling minimization:
    • As alluded to in my previous elog, I tried to reduce the bounce mode coupling into the shadow sensor by rotating the OSEM in its holder.
    • However, I saw negligible change in the coupling, even going through a full pi radian rotation. I imagine the coupling will change smoothly so we should have seen some change in one of the ~15 positions I sampled in between, but I saw none.
    • The anomalously high coupling of the bounce mode to the shadow sensor readout is telling us something - I'm just not sure what yet.
  3. ITMY:
    • The offender was the LL OSEM, whose rotational orientation was causing the magnet to get stuck to the teflon part of the OSEM coil when the bias voltage was changed by a sufficiently large amount.
    • I rectified this (required adjustment of all 5 OSEMs to get everything back to half light again).
    • After this, I was able to zero the bias voltage to the PIT/YAW DoFs and not have the optic get stuck - huzzah 😀 
    • While I have the chance, I'm collecting the free-swinging data to see what kind of sensing matrix this optic yields.

Tomorrow and later this week:

  1. Prepare ETMY for first contact cleaning to remove the residual piece. 
    • Drag wipe the HR surface with dehydrated acetone 
    • Apply F.C. as usual, inspect the HR face after peeling for improvement if any.
    • This will give us a chance to practise the F.C.ing with the optic EQ-stopped (moving cage etc).
  2. Confirm ETMY actuation makes sense.
    • Use the green beam for an ASS proxy implementation?
  3. High quality close out pictures of OSEMs and general chamber layout.
  4. Anything else? Any other tests we can do to convince ourselves the suspensions are well-behaved?

While we have the chance:

  1. Fix the IPANG alignment? Because the TT drift/hysteresis problem is still of unknown cause.
  2. Check that the AS beam is centered on OMs 1-6?
  3. Recover the 70% AS light that is being diverted to the OMC?

Unrelated to this work: megatron is responding to ping but isn't ssh-able. I also noticed earlier to day that the IMC autolocker blinky wasn't blinking. So it probably requries a hard reboot. I left the lab for tonight so I'll reboot it tomorrow, but no nds data access in the meantime... 

  3777   Mon Oct 25 11:39:06 2010 JenneUpdateSUSMagnets glued to PRM
This morning I glued the magnets to the PRM. Now we wait, and tomorrow afternoon (at the earliest), Suresh and I can balance the PRM.
  2629   Mon Feb 22 21:07:26 2010 JenneUpdateCOCMagnets glued to ITMX

[Kiwamu, Jenne]

The magnets + dumbbell standoffs have been glued to ITMX.  We're waiting overnight for them to dry. 

Since I broke one of the magnet + dumbbells on the ITMY set, we've glued another dumbbell to the 6th magnet, and it should be ready for us to glue to ITMY tomorrow, once ITMX is dry and out of the fixture.  This doesn't put us behind schedule at all, so that's good.

We had been concerned that there might be a problem with the arm of the guiderod fixture being glued to ITMY, but it was fine after all.  Everything is going smoothly so far.

 

[Zach, Mott]

Zach and Mott are almost prepared to start cutting the viton for the earthquake stops.  We need 2 full sets by Wednesday morning, when we expect to begin hanging the ITMs.

  691   Thu Jul 17 16:39:58 2008 Max JonesUpdateDAQMagnetometer Installed
Today I installed the magnetometer near the beam splitter chamber. It is located on the BSC chamber at head height on the inner part of the interferometer (meaning I had to crawl under the arms to install it). I don't think I disturbed anything during installation but I think that's it's probably prudent to tell everyone that I was back there just in case. I plan to run 3 BNC cables (one for each axis) from the magnetometer to the DAQ input either tonight or tomorrow. Suggestions are appreciated. - Max.
  2307   Fri Nov 20 11:32:48 2009 HaixingUpdateSUSMagnetic levitation

I added an integrator to increase the gain at low frequencies (below 5 Hz). In addition, I increased

the band of the differentiator. The schematics for both integrator and differentiator are the following:

IntDiff.PNG

The magnetic is stably levitated.

S8007340.jpg

I turned off the light to get rid of 60Hz noise on the photodiode. I tried to measured the

open-loop transfer function of this setup, but somehow the SR560 is always saturate

when I injected the signal from SR785, which produces some weird results at

low-frequencies.

 

In addition, I found out that when the light is turned on, the levitation

can be stable even when I inverted the sign of the control loop. The control signal

on the osciloscope is the following:

S8007333.jpg

 

This oscillator is around 120 Hz, which should be  the harmonics of 60 Hz from light pollution.

I am not sure exactly why it is stable when the control-loop sign is flipped. This could

be similar to the Pauli trap in the iron trap, because the coil not only provides a force

but also provides the rigidity. The sign of such rigidity depends on the sign of the control

current. If such oscillating rigidity changes at a frequency much higher than the response

frequency of the magnet, it will stablize  the system simply by significantly increasing

the inertial of the magnet.More investigations are essential to completely understand it.

 

For information about Pauli trap, one can look at the wikipedia:

http://en.wikipedia.org/wiki/Quadrupole_ion_trap

 

 

 

  1933   Fri Aug 21 17:28:50 2009 Kevin, ranaSummaryPEMMagnetic Field Measurements Around the Lab

This goal of this test was to measure and map the AC (at 60 Hz) and DC magnetic fields around the interferometer. I've attached the final products which were drawn up with Google SketchUp.

The notes on the maps make them more or less self explanatory: for each numbered point there's an X, Y, and Z measurement produced by the magnetometer. For the AC numbers I measured the Peak-to-Peak value, while for the DC I simply measured the Mean. The magnetometer's axes were always oriented about the same way, with the X arrow on the magnetometer pointing north. I tried to keep variables such as the lights constant as much as possible (they were all on for most measurements, with the exception of a few noted DC ones) and all measurements had the top of the magnetometer at about 32 inches.  The map is pretty close to scale and all the walls and numbered locations were measured out (though the location of objects and the laser tubes is somewhat estimated). I added "landmarks" in the room, which were pretty much the laser tubes, computer racks, and ISC tables.

For each laser room measurement I also took a screenshot using the oscilloscope as a means of recording the shape of the wave for each measurement. Ch1 corresponds to the X value, Ch2 to the Y, and Ch3 to the Z. The screenshots are numbered 1-29 corresponding to the numbers on the map. The zip folders containing the screenshots can be found on the wiki:  PEM:Magnetometers

I should also mention that there is no point #24 and accordingly no 24 screenshot. I realized after I was done that I had messed up the location of that one and instead of risking bad data decided to just remove it.

I decided on the location of the points mainly based on the location of outlets in the room (since I had to plug in the oscilloscope for the AC numbers to set it to 60 Hz). After an initial pass of the room, I went back and filled in some of the larger gaps by moving the magnetometer as far as I could while the oscilloscope remained plugged in to the wall. I used the same points for DC numbers.

Prior to measuring the laser room, I measured the field in other rooms as well. I have

  • AC numbers and screenshots for the control room and the adjoining office room.

  • DC numbers for the entry room and the office room, not including the control room. The X-axis arrow is pointed south (instead of north) for these numbers.

These numbers were sort of a warm up for me to figure out the process and how I would go about recording my data. Since they're not in really important locations and aren't guaranteed to be accurate, I decided not to map them, though the screenshots are still on this Dell Inspiron 1300 Laptop and the measurements in my notebook.

Here are the settings I used on the oscilloscope for all measurements (I merely changed the Vertical Coupling between DC and AC depending on what I was measuring):

  • Impedance: 1M ohms

  • Bandwidth: Full

  • Probe Setup: Voltage 1X

  • Trigger Type: Edge

  • Trigger Coupling: DC

  • Fast Trig: Normal

  • Trigger Mode: Auto

  • Trigger Source: AC Line

  • Acquire Mode: 512 Average

 The notebook that I used contains some additional info that I didn't include in the map, most importantly more precise descriptions of where each of the points is located and the measured distance between each of them (as well as slight changes I made to my measured distances in order to make the room a rectangle; the changes are slight enough that they shouldn't have any real effect on the data).

Since Kevin used our 3-axis Bartington Fluxgate magnetometer, we can guess that we can convert his voltage measurements (below) into magnetic field
by using the manual's guess of 10 uT /V or 10 V/Gauss. This is probably ok at the factor of 2 level, but one day we should calibrate it with a coil.

The punchline is that the DC fields in the lab are roughly what we expect from the Earth's field plus the rebar in our floors: ~1 Gauss. The 60 Hz fields are ~50-500 nT peak-peak.

  12328   Sun Jul 24 03:43:56 2016 ericqUpdateGeneralMagnet positioning

When Koji and I were gluing magnets to ETMY, we decided to position the side magnet based on the empirically observed offsets from the standoff groove seen at other side magnet locations. Specifically, we figured that the magnet should be glued 1.25mm closer to the HR surface than the wire groove.

However, Steve has told me that he believed that this distance should be something like 0.5mm. 

I used the 1.25mm figure when gluing the ETMX side magnets, which now do not align well to their OSEM mounts. While it is certainly possible that I made an error when shimming the fixture, I think it is also possible that this figure was incorrect. 

Sadly, after poring through the DCC and various elogs, I have not been able to come up with a definitive answer on what this offset should actually be.

One approach is to examine the suspension tower dimensions. I.e. when subject only to gravity, the wire loop should lie in the plane of the back face of the top block of the suspension, as it is constrained by the clamps. Thus, the standoff grooves also lie in this plane. The center of the side OSEM mounting holes are about 1.64mm in front of this plane, which is larger than the 1.25mm figure that Koji and I came up with. Examining the picture Gautam posted of the marginal magnet/OSEM alignement, we see that this figure would in fact move the magnet in the wrong direction...

ELOGs in which the intitial side magnet gluing and fixture shimming are detailed do not reference the absolute position of the side magnet, nor do they include any pictures of their fixture setup. (Some links for the curious: 2652 2654 2668)

The DCC isn't much help either, as it is not clear what version of the gluing fixture we actually have. There is a drawing for a 40m specific version, but it includes swappable side-magnet-pickle-picker-slots to achieve different positions for different (circa 2001) optics; this is not the kind of fixture we currently have in our possesion. (https://dcc.ligo.org/D010131) I have discovered that some versions of this fixture (https://dcc.ligo.org/d990168) include an assumed 0.5deg wedge angle and thus position the two side slots differently. Although the fixture we have has no identifying marks on it whatsoever (naturally), I measured the two side slots to be different in axial position by roughly 0.6mm, which is consistent with a 0.5deg wedge. Furthermore, the sign of this difference indicates that this fixture ring is designed for the opposite wedge orientation than our ETMs, which have a 2.5deg wedge, making this fixture wrong by 3deg (which is ~4mm over the diameter of the optic). 

We did not account for this for either ETMX or ETMY, so this is another source of error, but this does not give us much guidance on what the real absolute magnet position should be.

  2193   Fri Nov 6 12:56:30 2009 HaixingUpdateSUSMagnet has been levitated

  In this experiment, we used a feedback control to create a stable trap for a NdFeB permanent magnet. The block diagram is the following:

block_diagram.PNG

 

 

The displacement of the magnet is sensed by the Hall-effect sensor, whose output voltage is proportional to the magnetic flux produced

by the permanent magnet. It has a flat response within the frequencies we are interested in. It is driven by a 5 V power supplier and its

output has a DC voltagle of 2.5 V. We subtracted the DC voltage and used the resulting signal as the error signal. This was

simply achieved by using two channels "A" and "B". The output is "A-B" with a gain equal to one. We then put the error

signal into another  SR560 as a low-pass filter with a gain of 100 above 30 Hz. We used the "DC" coupling modes in both

preamplifers. The output is then used to drive a coil. The coil has a dimension of 1.5 inch in diameter and 2 inch in length.

The inductance of the coil is around 0.5 H and the resistance is 4.7 Om. Therefore, it has a corner frequency aournd 10/2pi Hz.

The coil has a iron core inside to enhance the DC force to the permanent magnet. The low-frequency 1/f response of the magnet is produced

by the eddy current damping of the aluminum plane that is below the magnet. This 1/f response is essential for a stable configuration. In the

next stage, we will remove the aluminum plane, and instead we will use a filter to create similar transfer function. At high-frequencies, it behaves as 

a free-mass and has a 1/f^2 response. Finally, the magnet is stably levitated.

 

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