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ID Date Author Typeup Category Subject
  3996   Tue Nov 30 12:33:27 2010 kiwamuSummaryIOOcabling of in-vac PZT mirrors

  4010   Fri Dec 3 15:56:50 2010 Joonho, Jenne.SummaryElectronicsRF distribution unit plan

The last time(Moonday) Jenne and I worked on the RF distribution unit's structure.

We are making RF distribution unit for RF upgrade which is designed by Alberto.

 

Rana, Koji, Jenne suggested a better design for RF Distribution unit.

So Jenne and I gathered information of parts and decided what parts will be used with specific numbers.

Specific circuit is shown in the attached picture.

 

Any suggestion would be really appreciated.

  4011   Sun Dec 5 22:28:39 2010 ranaSummaryall down cond.power outage

Looks like there was a power outage. The control room workstations were all off (except for op440m). Rosalba and the projector's computer came back, but rossa and allegra are not lighting up their monitors.

linux1 and nodus and fb all appear to be on and answering their pings.

I'm going to leave it like this for the morning crew. If it

  4012   Mon Dec 6 11:53:20 2010 josephb, kiwamuSummaryall down cond.power outage

The monitors for allegra and rossa's seemed to be in a weird state after the power outage.  I turned allegra and rossa on, but didn't see anything.  However, I was after awhile able to ssh in.  Power cycling the monitors did apparently got them talking with the computers again and displaying.

I had to power cycle the c1sus and c1iscex machines (they probably booted faster than linux1 and the fb machines, and thus didn't see their root and /cvs/cds directories).  All the front ends seem to be working normally and we have damped optics.

The slow crates look to be working, such as c1psl, c1iool0, c1auxex and so forth.

Kiwamu turned the main laser back on.

Quote:

Looks like there was a power outage.

 

  4013   Mon Dec 6 11:57:21 2010 KojiSummaryall down cond.power outage

I checked the vacuum system and judged there is no apparent issue.

The chambers and annulus had been vented before the power failure.
So the matters are only on the TMPs.

TP1 showed the "Low Input Voltage" failure. I reset the error and the turbine was lift up and left not rotating.
TP2 and TP3 seem rotating at 50KRPM and the each lines show low pressur (~1e-7)
although I did not find the actual TP2/TP3 themselves.

Quote:

Looks like there was a power outage. The control room workstations were all off (except for op440m). Rosalba and the projector's computer came back, but rossa and allegra are not lighting up their monitors.

linux1 and nodus and fb all appear to be on and answering their pings.

I'm going to leave it like this for the morning crew. If it

 

  4049   Mon Dec 13 22:21:41 2010 kiwamuSummarySUSfunny output matrix of ETMX: solved !

I found that a few connections in the simulink model of c1scx was incorrect, so I fixed them correctly.

It had been a mystery why we had to put a funny matrix on ETMX (see this entry).

But now we don't have to do such a voodoo magic because the problem was solved.

Now the damping of ETMX is happily running with an ordinary output matrix.


 --(details)

 I looked at the wiring diagram of the ETMX suspension (it's on Ben's web page) and confirmed that the coils are arranged in order of UL, LL, UR, LR.

But then I realized that in our simulink model they had been arranged in order of UL, UR, LL, LR.

So UR and LL had been swapped incorrectly !

So I just disconnected and plugged them into the right outputs in the simulink model.

   I rebooted c1iscex in order to reactivate c1scx front end code.

After rebooting it, I changed the output matrix to the usual one, then everything looked okay.

(actually it's been okay because of the combination of the wrong connections and the funny matrix).

  4056   Wed Dec 15 12:46:18 2010 KojiSummaryIOOFinishing up the vac work

What else?

v: Edit on Dec 15 10PM
v: Edit on Dec 16 10PM

JD:  We should check OSEMs for all optics *after* table leveling.  Some of them (esp. BS and ITMX) are currently close to their limits right now.

KA: Check green alignment.

Take photos of the tables.

Fix the leveling weights



Location    Optics            Action
--------------------------------------------------------------
@ITMX -     v POX             alignment
            v POP1/POP2       alignment
            v Table Leveling

@ITMY -     POY               mirror replacement (45deg->0deg) / alignment
            v SR2-TT          alignment
            v SRM Tower       alignment / EQ-stop release
            v SRM             alignment
            v SRM OSEM
            vvSRM OPLEV (X2)  install (VIS)/ alignment
            v ITMY OPLEV (X2)   install (VIS)/ alignment
            v OM1/OM2         install (DLC 45deg)/ alignment       
            v Table Leveling

@BSC -      v OM3             install (DLC 45deg/ alignment)
            v OM4(PZT)          neutralize, adjustment
            IPPOS steering    alignment
            v BS OPLEV        alignment
           
v PRM OPLEV(x2)     alignment
            Beam dumps
            Table Leveling

@IMC -      v REFL              mirror replacement (45deg->0deg)

@ETMX -     Al foil removal
            Table Leveling

@ETMY -     ETMY damping
            OSEM
            OPLEV
            Al foil removal
            Table Leveling

@OMC -      v OM5(PZT)        neutralize, adjustment

@ITM/ETM -  Mirror Wiping

  4084   Tue Dec 21 16:34:42 2010 kiwamuSummaryVACAll the test masses have been wiped

 [Jenne and Kiwamu]

 We wiped all the test masses with isopropyl alcohol.

They became apparently much cleaner.

(how to)

 At first we prepared the following stuff:

  * syringe

  * isopropyl alcohol 

  * lens papers

  * cleaned scissors

  Then we cut the lens papers into the half by the scissors such that the long side can remain.

This is because that the SOSs have relatively narrow spaces at their optic surfaces for putting a piece of paper. 

   We did vertical and horizontal wiping using the lens paper and appropriate amount of isopropyl alcohol.

Each wiping (vertical and horizontal) requires two or three times trials to appropriately remove dusts.

Amount of isopropyl:

   * vertical 15 [ul]

   * horizontal 10 [ul]

In addition to this, we also used the ionizer gun for blowing big dusts and fiber away from the surface.

 

 

(surface inspection)

   Before wiping them, all the test masses had small dusts uniformly distributed on the HR surfaces.

Especially ETMX was quite dirty, many small spots (dusts) were found when we shined the surface with the fiber illuminator.

ETMY was not so bad, only a couple of small dusts were at around the center.  ITMX/Y had several dusts, they were not as dirty as ETMX, but not cleaner than ETMY.

   After we wiped them,  we confirmed no obvious dusts were around the centers of the optics. They looked pretty good !

 

 

  4098   Wed Dec 29 18:53:11 2010 ranaSummaryelogfound hung - restarted

This was the error today:

GET /40m/ HTTP/1.1
Host: nodus.ligo.caltech.edu:8080
User-Agent: Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.6; en-US; rv:1.9.2.3) Gecko/20100401 Firefox/3.6.3
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Language: en-us,en;q=0.5
Accept-Encoding: gzip,deflate
Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7
Keep-Alive: 115
Connection: keep-alive
Referer: http://www.ligo.caltech.edu/~ajw/40m_upgrade.html
Cookie: elmode=threaded; __utma=65601905.411937803.1291369887.1291369887.1291369887.1; __utmz=65601905.1291369887.1.1.utmcsr=(direct)|utmccn=(direct)|utmcmd=(none); SITESERVER=ID=4981c5fd42ae53c9c9e0980f2072be4f

  4102   Mon Jan 3 10:32:27 2011 kiwamuSummaryelogfound hung - restarted

Found exactly the same error messages at the end of the log file.

Quote: #4098

This was the error today:

GET /40m/ HTTP/1.1
Host: nodus.ligo.caltech.edu:8080
User-Agent: Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.6; en-US; rv:1.9.2.3) Gecko/20100401 Firefox/3.6.3
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Language: en-us,en;q=0.5
Accept-Encoding: gzip,deflate
Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7
Keep-Alive: 115
Connection: keep-alive
Referer: http://www.ligo.caltech.edu/~ajw/40m_upgrade.html
Cookie: elmode=threaded; __utma=65601905.411937803.1291369887.1291369887.1291369887.1; __utmz=65601905.1291369887.1.1.utmcsr=(direct)|utmccn=(direct)|utmcmd=(none); SITESERVER=ID=4981c5fd42ae53c9c9e0980f2072be4f

 

  4109   Wed Jan 5 00:23:30 2011 ranaSummaryDAQFrameBuilder fails in a new way

Since Leo was trying to demo his LIGO Data Listener code, he noticed that there was and NDS2 issue. The NDS2 guy (JZ) noticed that the FrameBuilder had an issue.

We investigated. At 4PM on Dec 31, the GPS timestamp of the frame file names started to be recorded wrong. In fact, it started to give it a file name matching the correct time from 1 year in the past.

So that's our version of the Y2011 bug. Here's the 'ls' of /frames/full:

drwxr-xr-x 2 controls controls 252K Dec 26 03:59 9773
drwxr-xr-x 2 controls controls 260K Dec 27 07:46 9774
drwxr-xr-x 2 controls controls 256K Dec 28 11:33 9775
drwxr-xr-x 2 controls controls 252K Dec 29 15:19 9776
drwxr-xr-x 2 controls controls 244K Dec 30 19:06 9777
drwxr-xr-x 2 controls controls 188K Dec 31 16:00 9778
drwxr-xr-x 2 controls controls 148K Jan  1 08:53 9463
drwxr-xr-x 2 controls controls 260K Jan  2 12:39 9464
drwxr-xr-x 2 controls controls 252K Jan  3 16:26 9465
drwxr-xr-x 2 controls controls 248K Jan  4 20:13 9466
drwxr-xr-x 2 controls controls  36K Jan  5 00:22 9467
controls@fb /frames/full $

The culprit is the directory who's name starts out as 9463 whereas it should be 9779.

 

  4112   Wed Jan 5 16:00:11 2011 rana, alexSummaryDAQFrameBuilder fails in a new way

Email from Alex:

Turned out to be the lack of current year information in the IRIG-B signal
received by the Symmetricom GPS card in the frame builder machine caused
this. I have added a constant in daqdrc to bring the seconds forward:

controls@fb /opt/rtcds/caltech/c1/target/
fb $ grep symm daqdrc
#set symm_gps_offset=-1;
set symm_gps_offset=31536001;

Hopefully we will be upgrading to the newer timing system at the 40M this
year, so this will not happen again next year.


 

Doing an 'ls -lrt' in /frames/full/ now shows that the names are correct:

drwxr-xr-x 2 controls controls 249856 Dec 30 19:06 9777
drwxr-xr-x 2 controls controls 192512 Dec 31 16:00 9778
drwxr-xr-x 2 controls controls 151552 Jan  1 08:53 9463
drwxr-xr-x 2 controls controls 266240 Jan  2 12:39 9464
drwxr-xr-x 2 controls controls 258048 Jan  3 16:26 9465
drwxr-xr-x 2 controls controls 253952 Jan  4 20:13 9466
drwxr-xr-x 2 controls controls 151552 Jan  5 13:54 9467
drwxr-xr-x 2 controls controls  12288 Jan  5 15:57 9783

  4113   Wed Jan 5 16:11:17 2011 kiwamuSummaryIOOtemporary PZT connection

PZTconnection.png

This is a connection diagram for the input PZTs (i.e. PZT1 and PZT2).

As drawn in the diagram, the signals don't go through the anti-imaging filter D000186 in the current configuration.

  4115   Wed Jan 5 22:14:41 2011 ranaSummaryDAQFrameBuilder fails in a new way

Just a proof that the DAQ is working - ran DTT on nodus from 3 hours ago.

  4132   Tue Jan 11 11:19:13 2011 josephbSummaryCDSStoring FE harddrives down Y arm

Lacking a better place, I've chosen the cabinet down the Y arm which had ethernet cables and various VME cards as a location to store some spare CDS computer equipment, such as harddrives.  I've added (or will add in 5 minutes) a label "FE COMPUTER HARD DRIVES" to this cabinet.

  4139   Tue Jan 11 21:08:19 2011 JoonhoSummaryCamerasCCD cables upgrade plan.

Today I have made the CCD Cable Upgrade Plan for improvement of sysmtem.

I have ~60 VIDEO cables to be worked for upgrades so I would like to ask all of your favor in helping me of replacing cables.

 

1. Background

Currently, VIDEO system is not working as we desire.

About 20 cables are of impedance of 50 or 52 ohm which is not matched with the whole VIDEO system.

Moreover, some cameras and monitors are out of connection.

 

2. What I have worked so far.

I have checked impedance of all cables so I figured out which cables can be used or should be replaced.

I measured cables' pathes along the side tray so that we can share which cable is installed along which path.

I have made almost of cables necessary for VIDEO system upgrades but no label is attached so far.

 

3. Upgrade plan (More details are shown in attached file)

 

0 : Cable for output ch#2 and input ch#16 is not available for now
1 : First, we need to work on the existing cables. 
1A : Check the label on the both ends and replace to the new label if necessary
1B : We need to move the existing cable's channel only for those currently connected to In #26 (from #26 to #25)
2 : Second, we need to implement new cables into the system
2A : Make two cable's label and attach those on the both ends
2B : Disconnect existing cables at the channel assigned for new cables and remove the cables from the tray also
2C : Move 4 quads into the cabinet containing VIDEO MUX
2D : Implement the new cable into the system along the path described and connect the cables to the assgined channel and camera or monitor

 

 

4. This is a kind of  a first draft of the plan.

Any comment for the better plan is always welcome.

Moreover, replacing all the cables indicated in the files is of great amount of work.

I would like to ask all of your favors in helping me to replace the cables (from 1. to 2D. steps above).

 

  4180   Thu Jan 20 22:17:12 2011 ranaSummaryLSCFPMI Displacement Noise

I found this old plot in an old elog entry of Osamu's (original link).

It gives us the differential displacement noise of the arms. This was made several months after we discovered how the STACIS made the low frequency noise bad, so I believe it is useful to use this to estimate the displacement noise of the arm cavity today. There are no significant seismic changes. The change of the suspension and the damping electronics may produce some changes around 1 Hz, but these will be dwarfed by the non-stationarity of the seismic noise.

  4213   Thu Jan 27 17:12:02 2011 Aidan, JoeSummaryGreen LockingDigital Frequency to Amplitude converter

Joe and I built a very simple digital frequency to amplitude converter using the RCG. The input from an ADC channel goes through a filter bank (INPUT), is rectified and then split in two. One path is delayed by one DAQ cycle (1/16384 s) and then the two paths are multiplied together. Then the output from the mixer goes through a second filter bank (LP) where we can strip off twice the beat frequency. The DC output from the LP filter bank should be proportional to the input frequency.

Input Channel: C1:GFD-INPUT_xxx

Output Channel: C1:GFD-LP_xxx

Joe compiled the code and we tested it by injecting a swept sine [100, 500]Hz in the input filter bank. We confirmed that output of the LP filter bank changed linearly as a function of the input frequency.

The next thing we need to do is add a DAC output. Once that's in place we should inject the output from a 4kHz VCO into the ADC. Then we can measure the transfer function of the loop with an SR785 (driving the VCO input and looking at the output of the DAC) and play around with the LP filter to make sure the loop is fast enough.

The model is to be found here:

/opt/rtcds/caltech/c1/core/advLigoRTS/src/epics/simLink/c1gfd.mdl

The attached figures show the model file in Simulink and a realtime dataviewer session with injecting a swept sine (from 500Hz to 100Hz) into the INPUT EXC channel. We've had some frame builder issues so the excitation was not showing on the green trace and, for some reason, the names of the channels are back to front in dataviewer (WTF?), - the lower red trace in dataviewer is actually displaying C1:GFD-LP_OUT_DAQ, but it says it is displaying C1:GFD-INPUT_OUT_DAQ - which is very screwy.

However, the basic principle (frequency to amplitude) seems to work.

  4216   Thu Jan 27 23:21:50 2011 ranaSummaryGreen LockingDigital Frequency Discriminator

That's some pretty fast work! I thought we would be taking up to a week to get that happening. I wonder what's the right way to measure the inherent frequency noise of this thing?

Also, should the comparator part have some hysteresis (ala Schmidt trigger) or is it best to just let it twirl as is? Is it sensitive to DC offsets on the input or is there a high pass filter? What's the correct low pass filter to use here so that we can have a low phase lag feedback to the ETM?

  4217   Fri Jan 28 09:03:38 2011 AidanSummaryGreen LockingDigital Frequency Discriminator

Quote:

That's some pretty fast work! I thought we would be taking up to a week to get that happening. I wonder what's the right way to measure the inherent frequency noise of this thing?

Also, should the comparator part have some hysteresis (ala Schmidt trigger) or is it best to just let it twirl as is? Is it sensitive to DC offsets on the input or is there a high pass filter? What's the correct low pass filter to use here so that we can have a low phase lag feedback to the ETM?

 

We could try inputing a 4kHz carrier modulated width a depth of a few Hz at a modulation frequency of F1. Then we could take an FFT of the output of the discriminator and measure the width of the peak at F1 Hz. This seems like an arduous way to measure the frequency noise at a single frequency though.

It'll definitely be sensitive to DC offsets but there is already a filter bank on the INPUT filter so we can shape that as necessary. We could probably band-pass that from [4.5 - 5.3kHz] (which would correspond to a range of [73,87] MHz into a 2^14 frequency divider.

 

  4218   Fri Jan 28 10:27:46 2011 Aidan, JoeSummaryGreen LockingDigital Frequency Discriminator - calibration

 One more thing ... we can calibrate the output of the LP filter to give a result in Hz with the following calibration:

LP_OUT = -1/(2*dt)*(LP_IN -1), where dt is 1/16384, the delay time of the delayed path.

Therefore LP_OUT = -8192*(LP_IN-1).

  4227   Sun Jan 30 17:15:09 2011 AidanSummaryGreen LockingDigital Frequency discriminator - frequency noise

I've had a go at trying to estimate the frequency noise of the digital frequency discriminator (DFD). I input a 234.5Hz (0.5Vpp) signal from a 30MHz function generator into the ADC. The LP output of the DFD measured 234.5Hz. However, this signal is clearly modulated by roughly +/- 0.2Hz at harmonics of 234.5Hz (as you can see in the top plot in the dataviewer screenshot below). So the frequency noise can be estimated as rms of approximately 0.2Hz.

This is supported by taking the spectra of the LP output and looking at the RMS. Most of the power in the RMS frequency noise (above the minimum frequency) comes from the harmonics of the input signal and the RMS is approximately 0.2Hz.

I believe this stems from the rather basic LP filter (three or four poles around 10Hz?) that is used in the LP filter to remove the higher frequency components that exist after the mixing stage. (The currently loaded LPF filter is not the same as the saved one in Foton - and that one won't load at the moment, so I'm forced to remember the shape of the current filter).

 The attached screen capture from data viewer shows the LP_OUT hovering around 234.5Hz.

  4228   Sun Jan 30 19:26:03 2011 KojiSummaryGreen LockingPrototype freq divider

A prototype freq divider has been made which works up to ~40MHz.

74HC4060 (14bit binary ripple counter) divides the freq of the input signal, which is comverted by the comparator LT1016
into the rectangular signal. The division rate is 2^14.

Attachment1: Circuit diagram

Attachment2:
Photo, the prototype bread board

Attachment3:
Photo, the spectrum of the freq divided output. The 40MHz input has been divided into 2.4k.
There are the 3rd and 5th harmonics seen. The peak was pretty sharp but the phase noise was not evaluated yet.


The circuit was made on the prototype bread board which is apparently unsuitable for RF purposes.
Indeed, it was surprising to see its working up to 40MHz...

In order to increase the maximum freq of the system we need the following considerations

  • RF PCB board
  • Input RF buffer (or amplifier) with a 50Ohm input impedance.
  • Faster comparator. LT1016 has the response time of 10ns, which is not enough fast.
  • Faster counter. Faster chip 74HC4020 has already been ordered.
  4229   Mon Jan 31 07:03:59 2011 AidanSummaryGreen LockingDFD - noise spectra

Quote:

I've had a go at trying to estimate the frequency noise of the digital frequency discriminator (DFD). I input a 234.5Hz (0.5Vpp) signal from a 30MHz function generator into the ADC. The LP output of the DFD measured 234.5Hz. However, this signal is clearly modulated by roughly +/- 0.2Hz at harmonics of 234.5Hz (as you can see in the top plot in the dataviewer screenshot below). So the frequency noise can be estimated as rms of approximately 0.2Hz.

This is supported by taking the spectra of the LP output and looking at the RMS. Most of the power in the RMS frequency noise (above the minimum frequency) comes from the harmonics of the input signal and the RMS is approximately 0.2Hz.

I believe this stems from the rather basic LP filter (three or four poles around 10Hz?) that is used in the LP filter to remove the higher frequency components that exist after the mixing stage. (The currently loaded LPF filter is not the same as the saved one in Foton - and that one won't load at the moment, so I'm forced to remember the shape of the current filter).

 The attached screen capture from data viewer shows the LP_OUT hovering around 234.5Hz.

 Here is the spectrum of the input into the DFD (a 234.5Hz sine wave, 0.5 Vpp) and the spectrum and RMS of the LP output. The linewidth of the input signal is clearly much less than 0.1Hz, where as the RMS noise (above 2mHz) is approximately 0.2Hz and the main contributions are clearly the harmonics of the 234.5Hz signal.

  4237   Wed Feb 2 03:27:20 2011 KojiSummaryGreen Locking85MHz Freq divider

The freq divider was built and installed in the beat detection path.

Attachment 1: Circuit diagram

  • Input stage:  Wideband RF amp with DC block at the input and the output. The gain is 10dB typ.
  • 2nd stage: Ultra fast comparator AD9696. Note: AD9696 is an obsolete IC and there are only a few extra at Wilson house.
    The output is TTL/CMOS compatible.
  • 3rd stage: 14bit binary ripple counter (fmax~100MHz.)

Note: I have added 7805/7905 regulators to the circuit as I could not find -5V supply on the 1X1/2 racks.

Attachment 2: Packaging

  • The box is german made Eurocard size box from Techno-Isel Linear Motion http://www.techno-isel.com/lmc/Products/EnclosureProfiles11055.htm
    The box is excellent but I didn't like the fixing bolts as they are self-tapping type. I tapped the thread and used #6-32 screws.
     
  • The prototyping board is BPS's (BusBoard Prototype System http://www.busboard.us/)  SP3UT. The card size is 160mm x 100mm.
    The other side is a ground plane and the small holes on the board are through holes to the ground plane.
    This particular card was not easy to use.
     
  • The input is SMA. Unfortunately, it is not isolated. The output is an isolated BNC.
     
  • The supply voltage of +/-15V is given by the 3pin D-connector. The supply voltages have been obtained from the cross connect of 1X1.

Attachment 3: Input specification

  • The input frequency is 10MHz~85MHz. At lower frequency chattering of the comparator against the multiple zero crossing of the (relatively) slow sinusoidal waves.
  • The input amplitude. There are no apparent degradation of the freq jitter when the input power was larger than -30dBm.

 

  4238   Wed Feb 2 09:56:55 2011 KojiSummaryGreen LockingInstalled the freq divider and Rana's PFD

- The freq divider and Rana's PFD were hooked up to the ADCs. (Attachment 1)
(I leave the analog PFD not explained in this entry.)
For this purpose, the VCO feedback signal has been disconnected and the beat signal was moved from the VCO loop to the analog PFD.

The output level of the splitter was +12dBm and was too high for the freq divider.
So, I had to stupidly add an attenuator of 10dB before the box.

- Gain of the digital PFD LPF

The LPF of the digital PFD had the gain of -4096 to let the output signal indicate the direct frequency reading.

The gain has been changed to -67.108864
such that the output shows the direct reading of the beat freq in the unit of MHz

-4096*2^14/10^6 = -67.108864

 

- Attachment 2 shows the acquired beat note through the freq divider.
The blue is the beat note between "green locked" and "IR locked only to MC" (i.e. MC vs XARM)
The red is the beat note with the both beam locked to the arm

The freq divider is a bit flaky in some freq region as the divided output sometimes shows freq jumps or the captured at a freq.
I still don't know why it happens. We have to check why this happens.

  4239   Wed Feb 2 10:44:26 2011 KojiSummaryGreen LockingFreq fluctuation measured by the freq divider and Rana's analog PFD

The freq fluctuation of the beat note has been measured with the following condition

  • The IR beam only locked to the MC. The green beam locked to the arm
  • Both of the IR and green locked to the x-arm

Calibration
- The output of the freq divider is already calibrated to have the unit of MHz.

- The transfer function between the analog PFD channel and the digital PFD output was measured to be -23dB = 0.7.
  The gain of the XARM-FINE channel was changed to 0.7 such that the output is calibrated in MHz.

Results

- I have not checked the analog noise level of the analog PFD path. We may need more whitening gain (by icreasing the gain of SR560).

- The analog PFD is always better than the digital PFD above 20Hz.

- Both the digital and analog PFD showed good agreement below 20Hz.
  Note the measurement was not simultaneous.

- When the arm is locked with the ETMX being actuated , the fluctuation of the arm length must be stabilized by a huge factor
(~10^5 according to Kiwamu's entry) However, we only could see the stabilization factor of 30.

As this residual is the difference of the freq noise felt by the IR and the green,
this is a real issue to be tackled.

- The RMS fluctuations of the arm with and without the IR beam being locked are 2MHz and 0.1MHz,
which correcponds to the arm length motion of 250nm and 13nm, respectively.
Ed: I had to use 532nm in stead of 1064nm. The correct numbers are 130nm and 7nm.

- Without the IR locked, The typical peak-to-peak fluctuation of the beat freq was 10MHz.

  4240   Wed Feb 2 12:55:34 2011 KojiSummaryGreen LockingFreq fluctuation measured by the freq divider and Rana's analog PFD

I found that some flakiness of the beat signals comes from the RF components for the beat detection.
They are touching the racks in an indefinite way. If we move the components the output of the analog PFD
goes crazy.

Once Kiwamu is back I will ask him to clean up all of the green setting in an appropriate way.

 

  4254   Sat Feb 5 23:03:04 2011 rana, kojiSummaryElectronicsAnalog Frequency Discriminator: splitter + mixer + long cable

This diagram shows the setup of the analog Mixer-Frequency Discriminator (MFD).

The idea is similar to the one of the Schnupp Asymmetry for our Michelson interferometers. The signal from the PD (or any signal source for which you want to know the frequency) is split into two legs; one leg is much longer than the other. The two legs are recombined at a mixer/demodulator. The demodulator output varies sinusoidally with the phase difference of two legs, the same as when we try to measure the phase noise of an oscillator, for example. This is the same concept as the digital frequency discriminator that Aidan and Joe put into the GFD FE system recently.

With a ~1m cable length asymmetry, we get 180 deg of phase shift for a ~100 MHz signal (recall that the speed of light in most of our cables is ~2 x 10^8 m/s). The mixer gives a linear output at 50 MHz (and 150 MHz, 250 MHz, etc.).

This single mixer based setup is fine for most everything we do. In order to get even more resolution, one can just use 2 mixers by splitting the signal with a 4-way instead of 2-way mixer. One setup can have a 0.5-1 m asymmetry to have a large range. The other can have a ~10-30m asymmetry to get a comb of linear readouts.

Typically, we will have some kind of weak signal at the photodiode and will use a 20 or 40 dB gain RF amp to get the signal into the mixer. In this case, the mixer output noise will be at the level of tens of nV/rHz. Any usual low noise audio amplifier (SR560 variety) will be enough to read out the signal.

Why the 50 Ohm terminator? If you look at the specs of the BLP-1.9 filter from Mini-Circuits (its the same for almost all of their LP filters) you see that there's ~90 dB of attenuation above ~30 MHz (where our signals 2*f product will show up). If we use an RF input signal of ~0 dBm, this means that we get a high frequency product of -95 dBm (~10 uVrms) which is OK. But the return loss is 0 dB above 5 MHz - this means that all of the high frequency content is reflected back into the mixer! The 50 Ohm terminator is there to absorb the RF signals coming out of the mixer so as to prevent them from going back into the mixer and mixing with the RF/LO signals. The 50 Ohm terminator does attenuate the DC/audio frequency signals we get out of the mixer by a factor of two, but that's OK since we are not limited by the mixer's thermal noise.


Noise Measurement:

To checkout the noise, we used a 6m RG-58 cable in one leg. We used the DS345 signal generator for the source. We adjusted the frequency to (~21 MHz) give a ~zero mean signal at the demod output. The 6m cable makes the demod output's peak-peak swing correspond to ~16 MHz. We then used an SR560, DC coupled, G=1000, low-noise, 2pole low pass at 1 kHz, to get the signal into the ADC.

 fsm.png

The attached plot shows the noise. We have caibrated the digital gain in the channel to make the output into units of Hz. The high frequency noise floor is ~0.3 Hz/rHz and the 1/f knee is at 10 Hz. This setup is already good enough for all of the green locking work at the 40m. In order to make this useful for the reference cavity work or the gyro, we will have to use a longer cable and a lower noise audio amplifier.

As can be seen from the plot, the ADC noise is below the measured noise. The noise of the SR560 with the input terminated is shown in grey - the measured noise of the MFD is very close to this. In order to improve the performance, the next step should be to use a longer cable. There's clearly going to be some trade-off between the temperature dependent effects which come with long cables (dphi/dT gets bigger) and trying to use a high gain ~1 nV/rHz amplfier at the mixer output.


Temperature Drift of the long cable:

Untitled.png

This 24-hour minute-trend shows the frequency wander as well as the room temperature. This is not proof of a temperature dependence, but if it is then we get ~3 kHz/deg for the sensitivity. If this is actually the cable and not the amplifier, then we'll have to hunt for a lower tempco cable and put it in a box to isolate it.

  4259   Tue Feb 8 10:23:02 2011 AidanSummaryGreen LockingDigital Frequency Discriminator - reference

 

Here's the reference for the self-reference frequency detection idea. See Figure 2.

http://www.phys.hawaii.edu/~anita/new/papers/militaryHandbook/mixers.pdf

  4260   Tue Feb 8 13:26:11 2011 AidanSummaryGreen LockingTemperature dependence of phase change of green on reflection

 I did a quick back of the envelope calculation of the expected green phase change on reflection from the aLIGO ITM.

The phase change per nm, K1 = delta phi/delta Lambda, around 532nm is ~1.5 degrees/nm (from the LMA data) [this number is approximately 100x smaller at 1064nm]

I assumed that very small changes in the thickness of the coating appear equivalent to shifting the spectra for reflection/transmission/phase-change-on-reflection up or down by delta lambda, where

delta Lambda/Lambda = delta h/h

where h is the total thickness of the coating and delta h is the change in the thickness of the coating.

Assume that delta h/h = alpha deltaT, where alpha is the coefficient of thermal expansion and delta T is the change in temperature. (approximately 1K)

Then delta phi = K1* Lambda * alpha * delta T = 1.5 degrees/nm * 532nm * 10^-5 K^-1 * 1.0 K =  8 * 10^-3 degrees.

Assume that 360 degree phase change corresponds to one FSR.

Therefore, the frequency shift due to temperature change in the coating = 8*10^-3/360 * FSR = 2.2 *10^-5 * FSR.

Therefore, the expected frequency shift per degree temperature change = 2.2*10^-5 * FSR [Hz/K]

  4293   Mon Feb 14 23:29:04 2011 ranaSummarySUSETMX Fitlers moved around

All of the SUS used to have only 1 filter module for SIDE. They now have 3 filter modules for SIDE just like the other DOFs.

Today I moved the filters around so that the sensor filters are in SDSEN, the servo filters are in SUSSIDE, and the dewhitening for the coil is in SDCOIL.

I noticed along the way that the bounce/roll mode notches for all of the suspensions are still set for the frequencies of the previous suspensions. Suresh has 'volunteered' to find the new frequencies and make the new bandstop filters by looking up the seminal work on this by Dan Busby / Sam Waldman.

  4294   Tue Feb 15 02:13:16 2011 kiwamuSummaryASCa daytime task : small signals on ETMX OL

Rana and I found that the QPD for the optical lever at X end are showing small signals.

At this moment each of the segments exhibits approximately 200 counts when the oplev beam is centered.

These small numbers may be due to the coating of ETMX, but we are not sure.

Probably we have to increase the gain of the QPD depending on situations.

 

So a set of the tomorrow's daytime task is:

   1. check the trend data of the QPD outputs to see how much signals were there in the past.

   2. check the whitening filters to make sure if it's on or off.

   3. If it's necessary, increase the gain of the QPD to have reasonable readouts.

I am going to ask somebody to do this task.

  4299   Tue Feb 15 11:53:02 2011 kiwamuSummaryGeneraltoday's missions

I think this week is going to be an "alignment week".

The goal is to get a good alignment on X arm for both the green and the IR beam in order to reduce a2l couplings.

 

Today's missions are :

 - fixing the oplev channel names (see here)

 - fixing the oplev gain issue (see here)

 - engage the oplev servos

 - f2p adjustment

 - make a realtime lockin model for the f2p measurement and the dithering technique

 - alignment of the MC incident beam  (because we installed a new PMC this morning)

 - manual alignment of the IR beam by steering PZT1 and PZT2 (this procedure will be replaced by an automatic way soon)

 - bounce roll filters (see here)

 

  4310   Thu Feb 17 00:43:13 2011 kiwamuSummaryGeneralto do list for tomorrow

Let's share our tasks !

 

==== daytime ===

 . mode matching for MC  (Jenne/Koji)

 . mode matching for doubling crystal on PSL table (Suresh/Koji)

 . f2p adjustment (Kiwamu)

 . fix daq and CDS issues (Joe)

 . increase oplev gain (low priority)

 . make ITMY camera nicer (Steve)

 . c1ass simlink model (Valera/Joe)

 . Bounce Roll notches (Suresh)

 

==== nighttime (after 7pm) ====

 . align everything   (at first green beam, then X arm cavity and finally IR beam)

 . update the noise spectrum of the green locking

 . estimate the noise from angle to length coupling

  4317   Thu Feb 17 22:51:04 2011 josephb, valeraSummary dither alignment model

We made a model for the dither angular stabilization system c1ass.mdl. The attached file shows the diagram.

The idea is to dither a combination of 6 optics (ETMs, ITMs, PZTs) at different frequencies and demodulate three PDs (TRX, TRY, REFL11I). Then form the DOFs from demodulted signals, filter, and send each DOF to a combination of optics.

This is enough to get started with arm cavities alignment (we may need to add the BS for the Y arm). More optics and PD can be added as they become available and/or needed.

The DAC for the fast PZT  are not connected and have to be commissioned.

  4322   Fri Feb 18 00:35:21 2011 kiwamuSummaryGeneralto do list for Feb. 18th

DAYTIME

  -  more precise F2P measurement and modify lockin simlink model (Kiwamu)

  -  run  C1ASS to check it (Valera)

  -  take care of CDS (Joe)

  -  MC mode matching (Jenne/Koji)

   -  RF stuff  (Suresh)

  -  mode matching for doubling crystal at PSL table (low priority)

  -  OPLEV (low priority)

NIGHITTIME

 -  update the noise spectra of green locking

 -  make noise budgets

  4326   Fri Feb 18 18:46:08 2011 kiwamuSummarySUSf2p done on ETMX and ITMX

The f2p measurements are done on ETMX and ITMX with the real time lockin systems.

I don't explain what is the f2p measurement in this entry, but people who are interested in it can find some details on an old elog entry here or somewhere on DCC.

So far the resultant filters looked reasonable compared with the previous SRM f2p filters.

 

- backgrounds -

  Some times ago I found that the coils on ETMX had not  been nicely balanced, and it made a POS to angle coupling when I tried green locking (see here).

In addition to that, accuracy of A2L kind of measurement including the dithering techniques depend on how well the coils are balanced.  Therefore we need to balance the coils basically at all the suspended optics.

There used to be a script for this particular purpose, called f2praio.sh. This script does measure the imbalances and then balance the coils.

However this time I used the realtime lockin system to measure the imbalances instead of using the old f2p script.

One of the reasons using the real time system is that,  some of the ezca and tds commands for the old script don't work for some reasons.

Therefore we decided to move on to the real time system like Yuta did for the A2L measurement a couple of months ago.

The f2p measurement finally gives us parameters to generate a proper set of filters for POS and also the coil gains. We apply those filters and the gains in order to eliminate the POS to angle coupling and to balance the coils.

 

- results -

The followers are the resultant filters and coil gains.

The plots below show new f2p filters according to the measurement.

f2p_ITMX.png       f2p_ETMX.png

 

ITMX (assuming pendulum POS has f0 = 1 Hz and Q = 1)

ULPOS  fz = 1.009612   Qz = 1.009612 

URPOS fz = 1.125965   Qz = 1.125965  

LLPOS  fz = 0.873725   Qz = 0.873725    

LRPOS  fz = 0.974418   Qz = 0.974418  

C1:SUS-ITMY_ULCOIL_GAIN      -1.103044

C1:SUS-ITMY_URCOIL_GAIN      0.884970

C1:SUS-ITMY_LLCOIL_GAIN      0.950650

C1:SUS-ITMY_LRCOIL_GAIN      -1.060326

 

 

ETMX (assuming pendulum POS has f0 = 1 Hz and Q = 1)

ULPOS  fz = 1.055445   Qz = 1.055445   

URPOS  fz = 1.052735   Qz = 1.052735   

LLPOS  fz = 0.944023   Qz = 0.944023   

LRPOS  fz = 0.941600   Qz = 0.941600   

C1:SUS-ETMX_ULCOIL_GAIN      -0.887550

C1:SUS-ETMX_URCOIL_GAIN      1.106585

C1:SUS-ETMX_LLCOIL_GAIN = 1.07233

C1:SUS-ETMX_LRCOIL_GAIN      -0.931013

  

The precision of the coil gains looked something like 1% because every time I ran the measurement script, the measured imbalances fluctuated at this level.

The precision of the filter gain at DC (0.01 Hz) could be worse, because the integration cycles for the measurement are fewer than that of the coil gains done at high frequency (8.5 Hz).

Of course we can make the precisions by increasing the integration cycles and the excitation amplitudes, if we want to.

  4327   Fri Feb 18 20:06:59 2011 kiwamuSummarySUScheck f2p function on ETMX

 The plot below shows how the f2p filters work.

At -2 min I turned on the f2p filters.

 f2p_ETMX.png

  4328   Fri Feb 18 20:17:07 2011 JoonhoSummaryElectronicsIsolation of Voltage regulator

Today I was working on RF distribution box.

So far I almost finished to electronically isolate voltage regulators from the box wall by inserting mica sheet, sleeve, and washers.

 

The problem I found is the resistance between wall and the voltage regulator is order of M ohms

I checked my isolation (mica sheet and sleeve and washer) but there is no problem there.

But I found that the power switch is not completely isolated from the wall.( around 800 kohm)

and that the resistance between the regulator and the wall is smaller for the regulator closer to the power switch

and greater for the regulator less closer to it.

So I think we need to put washer or sleeve to isolate the powersitch electronically from the box wall.

Suresh or I will fix this problem

[ To Suresh, I can finish the isolation when I come tomorrow. Or you can proceed to finish isolation.]

  4329   Sat Feb 19 01:58:20 2011 ranaSummaryElectronicsLow Noise BJT Pre-Amp

Frank put his low noise preamp info here.

I suggest that we build these (using Altium) but replace the cheapo transistors with the high class MAT03 matched BJT pair from Analog Devices.

This will allow us to have a pre-amp better matched to the noise of the mixers down to low frequency.

  4333   Mon Feb 21 17:29:57 2011 ranaSummaryIOOMyterious data loss: FB needs investigation

Looks like there was a mysterious loss of data overnight; since there's nothing in the elog I assume that its some kind of terrorism. I'm going to call Rolf to see if he can come in and work all night to help diagnose the issue.

Untitled.png

  4334   Mon Feb 21 23:00:06 2011 ZachSummaryelogrestarted

 again

  4343   Wed Feb 23 10:37:02 2011 josephbSummaryIOOMyterious data loss: FB needs investigation

Friday: 

In addition to the other fixes, Alex rebuilt the daqd process. I failed to elog this. When he rebuilt it, he needed change the symmerticom gps offset in the daqdrc file (located in /opt/rtcds/caltech/c1/target/fb). 

On Friday night, Kiwamu contacted me and let me know the frame builder had core dumped after a seg fault.  I had him temporarily disable the c1ass process (the only thing we changed that day), and then replaced Alex's rebuilt daqd code with the original daqd code and restarted it.  However, I did not change the symmetricom offset at this point.  Finally, I restarted the NDS process.  At that point testpoints and  trends seemed to be working.

Sunday:

The daqd process was restarted sometime on Sunday night (by Valera i believe).  Apparently this restart finally had the symmetricom gps offset kick in (perhaps because it was the first restart after the NDS was restarted?).  So data was being written to a future gps time.

Monday:

Kiwamu had problems with testpoints and trends and contacted me.  I tracked down the gps offset and fixed it, but the original daqd process only started once successfully, after that is was segfault, core dump non-stop. I tried Alex's rebuilt daqd (along with putting the gps offset to the correct value for it), and it worked.  Test points, trends, excitations were checked at the point and found working.

I still do not understand the underlying causes of all these segmentation faults with both the old and new daqd codes.  Alex has suggested some new open mx drivers be installed today.

Quote:

Looks like there was a mysterious loss of data overnight; since there's nothing in the elog I assume that its some kind of terrorism. I'm going to call Rolf to see if he can come in and work all night to help diagnose the issue.


 

  4357   Fri Feb 25 13:28:14 2011 kiwamuSummaryGeneralto do list
 Because it maybe useful to share this kind of information among us, I just put a to-do-list which has been continuously noted in my laptop.
 I guess those items can be applied for the coming two months (i.e. March and April). Anything else ?

-- Alignment

     - C1ASS

           * finalize the model and make user friendly scripts and medm screens
           * adjustment of phase rotations
           * cavity auto alignment for green

     - MC WFS 

          * put sensing matrices
          * whitening ?

    - OPLEVs

        * binary output for OPLEV whitening
        * calibration of OPLEVs  [rad/count]
        * characterization of OPLEV servos
        * bigger trans impedance gains to have reasonable readouts


-- Optimization of Suspended Optics

  - diagonalizations

         * input matrices
         * f2p with higher precision

  - damping control

        * fix ETMY damping
         * Bounce Roll notches
         * Q adjustment for damping

  - upgrading of electronics

        * bigger trans impedance gain for OSEMs
        * widen the voltage range of AA filter boards
   

   - weekly check

       * a routine script for measuring free swinging spectra


-- Input Optics

   - PMC

         * mode matching
         * epics LO HI values

   - FSS and ISS

        * recover FSS
        * make ISS working

   - EOM

       * AM minimization
       * triple resonant box

   - doubling and RFPD for green

        * mode matching to doubling crystal
        * connect RFPD_DC_MON to ADC
        * string +/-150 V and +/-15power cables from 1X1 rack to RFPDs
        * visibility check and loss investigations for the beat RFPD
        * rearrange RF amplifiers (ZLN series) for the RFPD
        * realgin Jenne's DCPD

 

-- Length Sensing and Control

   - digital system and electronics

       * characterization of RFPDs ==> SUresh/UG
       * installation of RF generation box and distribution box ==> Suresh/U
       * new LSC model and start making useful scripts (csh ? perl ? python ?)
       * binary outputs for PD whitening
       * make item lists for ordering (?)
       * draw cool diagrams for RF cable distribution and map of LSC rack.


-- Green Locking

    - X end station

           * eliminate undesired multiple spots on RFPD
           *  connect REFLPD_DCMON to ADC
           *  remote local boost
           * demodulation phase adjustment
           *  look for a high voltage amp. (bipoler)
           * installation of a mechanical shutter
           *  ETMX_TRANS CCD camera
           * analog low pass filter for temperature control

    - Y arm green locking ==> Suresh/Bryan

        * item lists
        * preparation of base mounts
        * mode matching estimation
        * mode measurement of input beam from Lightwave
        * temeperature scanning for beat location finding with IR beam
        * Installation
       * modification of PDH box

    - digital control systems

           * user friendly medm screens
           * apply proper filters for AC-DC whitened signal blending
           * add MC2 feedback path

      - noise budget

          * in-loop and out-of-loop evaluation
          * shot noise  
          * RFPD noise modeling
          * how intensity noise couples through MFD
          * electrical noise
          * frequency noise contribution from end laser and PSL
          * calibration of arm PDH signal

   - cavity scan and handing off

         * optimization of open loop transfer function for ALS
         * auto scripts   

-- misc.

   - CCD camera
        * color filters to separate IR and green (?)
   - lab laptops
        * a laptop for each end station (?)
    - dichroic TT (?)
        * large wegded and AR coated for 532nm (?)
    - epics for RS232C      
        * RS232C for doubling oven temperature

 

  4359   Fri Feb 25 14:50:16 2011 KojiSummaryGeneralto do list

- Put priority on the list

- Put names on the items

- Where is the CDS TO DO ==> Joe

-

- Remote disconnection of the greeen PDH 

- What is the situation of the PD DC for the LSC PDs?

- SUS Satelite box Resister replacement ==> Jamie

- IMC mode matching ==> Jamie/Larisa 

- Mechanical shutters everywhere

- SRM OPLEV Connection

- MC OAF

- Better LSC whitening boards

- DAFI 

Quote:
 Anything else ?

  4364   Mon Feb 28 11:22:40 2011 josephbSummaryGeneralto do list
Quote:

- Where is the CDS TO DO ==> Joe

CDS To Do:

1) Get ETMY working - figure out why signals are not getting past the AI board (D000186) to the coils.

2) Get TDS and command line AWG stuff working

3) Get c1ass and new c1lsc (with Koji) fully integrated with the rest of the system.

4) Get CDS software instructions up to date and well organized.

5) Redo cabling  and generally make it a permanent installation instead of hack job:

   a) Measure cable lengths, check connectors, wire with good routes and ensure strain relief.  Ensure proper labeling

   b) Get correct length fiber for c1sus RFM and timing.

   c) Fix up final BO adapter box and DAC boxes.

   d) Make boxes for the AA filter adapters which are currently just hanging.

   e) Get two "faceplates" for the cards in the back of the ETMY IO chassis so they can screwed down properly.

   f) Remove and properly store old, unused cables, boards, and anything else.

6) Create new documentation detailing the current 40m setup, both DCC documents and interactive wiki.

7)  Setup an Ubuntu work station using Keith's wiki instructions

 

Simulated Plant To Do:

1)Create simulated plant to interface with current end mass controls (say scx).

2) Create proper filters for pendulum and noise generation, test suspension.

3) Propagate to all other suspensions.

4) Working on simulated IFO plant to connect to LSC.  Create filters for near locked (assume initial green control perhaps) state.

5) Test LSC controls on simulated IFO.

6) Fix c code so there's seamless switching between simulated and real controls.

CDS Status:

MC damp dataviewer diaggui AWG c1lsc c1ioo c1sus c1iscex c1iscey RFM The Dolphins Sim.Plant Frame builder TDS Cabling
                             
  4371   Wed Mar 2 22:57:57 2011 sureshSummaryGeneralStuff from LLO

Here is a partial list of stuff which is being packed at LLO to be shipped to CIT.  The electronics ckt boards are yet to be added to this list.  Will do that tomorrow.

 

 

  4375   Thu Mar 3 20:30:03 2011 ranaSummaryPSLPMC Sweeps @ different input power levels to measure the Finesse

Its been well noted in the past that sweeping the PMC at high power leads to a distortion of the transmitted power curve. The explanation for this was coating absorption and thermo-elastic deformation of the front face of the mirrors.

Today, I did several sweeps of the PMC. I turned off its servo and tuned its PZT so that it was nearly resonating. Then I drove the NPRO via the HV driver (gain=15) with 0-150 V (its 1.1 MHz/V) to measure the PMC transmitted light. I adjusted the NPRO pump diode current from 2A on down to see if the curves have a power dependent width.

In the picasa web slideshow:

There are 3 significant differences between this measurement and the one by John linked above: its a new PMC (Rick says its the cleanest one around), the sweep is faster - since I'm using a scope instead of the ADC I feel free to drive the thing by ~70 MHz in one cycle. In principle, we could go faster, but I don't want to get into the region where we excite the PZT resonance. Doing ~100 MHz in ~30 ms should be OK. I think it may be that going this fast avoids some of the thermal distortion problems that John and others have seen in the past. On the next iteration, we should increase the modulation index for the 35.5 MHz sidebands so as to get a higher precision calibration of the sweep's range.

By eye I find that the FWHM from image #4 is 11 ms long. That corresponds to 300 mV on the input to the HV box and 15 V on the PZT and ~16.5 MHz of frequency shift. I think we expect a number more like 4-5 MHz; measurement suspicious.

  4381   Mon Mar 7 17:58:14 2011 sureshSummaryGeneralStuff from LLO

Here is the updated list. These lists were used as packing lists and therefore are organised by Box #.
ELOG V3.1.3-