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ID Date Author Typeup Category Subject
  4417   Mon Mar 21 13:26:25 2011 KojiUpdatePSLPMC Trans/RFPDDC

PMC TRANS/REFL on MEDM showed red values for long time.
TRANS (a.k.a C1:PSL-PSL_TRANSPD) was the issue of the EPICS db.

REFL (a.k.a. C1:PSL-PMC_RFPDDC) was not physically connected.
There was an unknown BNC connected to the PMC DC output instead of dedicated SMA cable.
So they were swapped.

Now I run the following commands to change the EPICS thresholds:

ezcawrite C1:PSL-PMC_PMCTRANSPD.LOW 0.85

ezcawrite C1:PSL-PMC_RFPDDC.HIHI 0.05
ezcawrite C1:PSL-PMC_RFPDDC.HIGH 0.03
ezcawrite C1:PSL-PMC_RFPDDC.LOW 0.0
ezcawrite C1:PSL-PMC_RFPDDC.LOLO 0.0

As these commands only give us the tempolary fix, /cvs/cds/caltech/target/c1psl/psl.db was accordingly modified for the permanent one.

        field(DESC,"RFPDDC- RFPD DC output")
        field(SCAN,".1 second")
        field(INP,"#C0 S32 @")

        field(DESC,"PMCTRANSPD- pre-modecleaner transmitted light")
        field(SCAN,".1 second")
        field(INP,"#C0 S10 @")

  4418   Mon Mar 21 16:31:02 2011 steveUpdateSAFETYBryan Barr received safety training

Bryan Barr is visiting us from Glasgow for a month. He received 40m specific safety training on Friday.

  4420   Mon Mar 21 18:34:10 2011 kiwamuUpdateGreen Lockingadded a new ADC channel on 1X9

I added a new ADC channel for a DC signal from the X end green PD.

It is called C1:GCX-REFL_DC and connected to adc_0_1, which is the second channel of ADC_0.


By the way, when I tried connecting it to an ADC I found that most of the channels on the AA board on 1X9 were not working.

Since the outputs form the board are too small the circuits may have benn broken. See the picture below.

In addition to that  I realized that the signal from the PDH box for the temperature actuation is limited by +/- 2V due to the range of this AA board.

In fact the signal is frequently saturated due to this small voltage range.

We have to enlarge the range of this AA board like Valera did before for the suspensions (see this entry).


  4424   Tue Mar 22 16:39:51 2011 kiwamuUpdateGreen Lockingcomaprator installed : 80 pm residual displacement

 A comparator has been installed before the MFDs (mixer-based frequency discriminator) to eliminate the effect from the amplitude fluctuation (i.e. intensity noise).

As a result we reached an rms displacement of 580 Hz or 80 pm.


(differential noise measurement)


  Here is the resultant plot of the usual differential noise measurement.

The measurement has been done when the both green and red lasers were locked to the X arm.

In the blue curve I used only MFD. In the black curve I used the combination of the comparator and the MFD.

Noise below 3 Hz become lower by a factor of about 4, resulting in a better rms integrated from 40 Hz.

Note that the blue and the black curve were taken while I kept the same lock.

A calibration was done by injecting a peak at 311 Hz with an amplitude of 200 cnt on the ETMX_SUS_POS path.



  Yesterday Koji modified his comparator circuit such that we can take a signal after it goes thorough the comparator.

The function of this comparator is to convert a sinusoidal signal to a square wave signal so that the amplitude fluctuation doesn't affect the frequency detection in the MFD.

I installed it and put the beat-note signal to it. Then the output signal from the comparator box is connected to the MFDs.

The input power for the comparator circuit has been reduced to -5 dBm so that it doesn't exceeds the maximum power rate.

  4426   Wed Mar 23 00:51:47 2011 kiwamuUpdateGreen Lockingplan for tomorrow

  - Plan for tomorrow

    * Video cable session (I need ETMY_TRNAS) (team)

    * Characterization of the Y end laser  (Bryan / Suresh)

    * LPF for the X end laser temperature control (Larisa)

    * Frequency Divider  (Matt)

    * X end mechanical shutter (Kiwamu)

  4427   Wed Mar 23 05:11:08 2011 kiwamuUpdateGreen Lockingservo handig off

Succeeded in handing off the servo from the green to the red.




(noise performance)

 This time we found that the fluctuation in the IR signals became lesser as the gain of the ALS servo increased.

Therefore I increased the UGF from 40 Hz to 180 Hz to have less noise in the IR PDH signal.

Here is a preliminary plot for today's noise spectra.


The blue curve is the ALS in-loop spectrum, that corresponds to the beat fluctuation.

The red curve is an out-of-loop spectrum taken by measuring the IR PDH signal.

Since the UGF is at about 180 Hz the rms is integrated from 200 Hz.

The residual displacement noise in the IR PDH signal is now 1.2 kHz in rms.

I am going to analyze this residual noise by comparing with the differential noise that I took yesterday (see the last entry ).

  4428   Wed Mar 23 08:50:36 2011 AidanUpdateGreen Lockingservo handig off

Nicely done!



Succeeded in handing off the servo from the green to the red.





Attachment 1: green-to-red.jpg
  4429   Wed Mar 23 09:48:20 2011 steveUpdatePSLPSL enclosure: gets new window & laser

Solid door, numbered 4 at south west corner of PSL enclosure was replaced by laser protective window.

The carpenter shop's Mark is making 4 more identical ones for the east side.


The Lightwave NPRO126 of 700mW was moved from the AP-table into the PSL-enclosure temporarily.

It's emergency shutdown switch can be seen at the center bottom picture

Attachment 1: P1070471.JPG
  4431   Wed Mar 23 10:34:17 2011 josephbUpdateCDSTrend issue fixed

[Joe, Alex]

Yesterday during the day, Alex ran a script to fix the time stamps in the trends files we had messed up back during the daqd change overs around Feb 17th and 23rd.  See this elog for more information on the trend problem.

Due to how the script runs, basically taking all the data and making a new copy with the correct time stamps, the data collected while the script was running didn't get converted over.  So when he did the final copy of the corrected data, it created a several hour gap in the data from yesterday during the day time.

The original files still exist on the fb machine in /frames/trend/minute_raw_22mar2011 directory.


  4434   Wed Mar 23 16:06:20 2011 Larisa ThorneUpdateElectronicsUpdate on cable laying

 [Steve, Suresh, Larisa]

The following cables were laid today: ETMYT, ETMY, IFOPO, MC1, OMCR, AS Spare, and MC2T.


Though the paper suggested 135' for the MC2T, we used a 110'. This is too short: need at least another 15' for the MC2T.

The RCR cable wasn't crossed off on the list, but a cable exists at the RCR cable which is black and is labeled (old label, 75 ohms)

There was no indication of which length was needed for MC1, so a 95' cable was used.

  4438   Thu Mar 24 13:56:05 2011 josephbUpdateelogelog restarted at 1:55pm

Restarted elog.

  4441   Thu Mar 24 19:48:13 2011 Aidan, KiwamuUpdateGreen LockingDesigns for permanent electronics for ALS

Kiwamu and I looked at all the electronics that are currently in place for the green locking on the X-arm and have made a set of block diagrams of the rack mounted units that we should build to replace the existing ... "works of art" that sprawl around out there at the moment.

Main items

1. "ETM Green Oscillator/PDH support box". Not a great name but this would provide the local oscillator signal for the end PDH (with a controllable phase rotator) as well as the drive oscillator for the end laser PZT. Since we need to hit a frequency of 216.075kHz with a precision that Kiwamu needs to determine, we'd need to be able to tune the oscillator ... it needs to be a VCO. It'd be nice to be able to measure the output frequency so I've suggested dividing it down by N times to put it into the DAQ - maybe N = 2^7 = 128x to give a measured frequency of around 1.7kHz. Additionally this unit will sum the PDH control signal into the oscillation. This box would support the Universal PDH box that is currently at the X-end.

2. "Vertex X-arm beatnote box" - this basically takes the RF and DC signals from the beatnote PD and amplifies them. It provides a monitor for the RF signal and then converts the RF signal into a square wave in the comparator.

3. "Mixer Frequency Discriminator" - just the standard MFD setup stored in a box. For temperature stability reasons, we want to be careful about where we store this box and what it is made of. That's also the reason that this stage is separated from the X-arm beatnote box with it's high-power amps.

Other things

4. RS232 and EPICS control of the doubling ovens

5. Intensity stabilization of the End Laser

P.S. I used Google Diagrams for the pictures.

Attachment 1: GreenLockingElectronics.pdf
Attachment 2: GreenEndPDHsupportboxandLO.pdf
Attachment 3: VertexBeatnoteAmplifierandComparator.pdf
Attachment 4: MixerFrequencyDiscriminator.pdf
  4443   Fri Mar 25 08:58:38 2011 AidanUpdateTreasureCleared stuff off SP table

I tidied up some of the stuff that was on the SP table. The ISS box that has been sitting on there for months is now underneath the X-arm on top of the spare Marconi which is stored there.



Attachment 1: ISS_box.JPG
  4445   Mon Mar 28 15:18:04 2011 josephbUpdateCDSCDS updates on Friday

Last Friday, we discovered a bug in the RCG where the delay part was not actually delaying.  We reported this to Alex who promptly put a fix in the same day.  This allowed Matt's newly proposed frequency discriminator to work properly.

It also required a checkout of the latest RCG code (revision 2328), and rebuild of the various codes.  We backed up all the kernel and executables first such as mbuf.ko and awgtpman.

We did the following:

1) Log into the fb machine.

2) Go to /opt/rtcds/caltech/c1/core/advLigoRTS/src/drv/mbuf and run make.  Copy the newly built mbuf.ko file to /diskless/root/modules/ on the fb machine.

3) Use "sudo cp" to copy the newly built mbuf.ko file to /diskless/root/modules/

4) Go to /cvs/cds/rtcds/caltech/c1/core/advLigoRTS/src/gds and run make.

5) Copy the newly built awgtpman executable to /opt/rtcds/caltech/c1/target/gds/bin/

6) Go to /opt/rtcds/caltech/c1/core/advLigoRTS/src/mx_stream/ and run make.

7) Copy the newly built mx_stream executable to /opt/rtcds/caltech/c1/target/fb/

  4446   Mon Mar 28 15:49:18 2011 josephbUpdateCDSLessons from LST



Koji was unable to build his c1lst model first thing this morning.  Turns out there was  a bug with RCG parser that was introduced on Friday when we did the RCG updates.  We talked Alex who did a quick comment fix.  The diff is as follows:

Index: Parser3.pm

--- Parser3.pm  (revision 2328)
+++ Parser3.pm  (working copy)
@@ -1124,8 +1124,8 @@
  print "Flattening the model\n";
  print "Finished flattening the model\n";
-  CDS::Tree::do_on_nodes($root, \&remove_tags, 0, $root);
-  print "Removed Tags\n";
+  #CDS::Tree::do_on_nodes($root, \&remove_tags, 0, $root);
+  #print "Removed Tags\n";
  #print "TREE\n";
  CDS::Tree::do_on_nodes($root, \&remove_busses, 0, $root);

This was some code to remove TAGs from the .mdl file for some reason which I do not understand at this time.  I will ask tommorrow in person so I can understand the full story.


Koji then rebuilt and started the c1lst process.  This is his new test version of the LSC code.  We descovered (again) that when you activate too many DAQ channels (simply uncommenting them, not even recording them with activate=1 in the .ini file) that the frame builder crashes.  In addition, the c1lsc machine, which the code was running on, also hard crashed.

When a channel gets added to the .ini file (or uncommented) it is sent to the framebuilder, irregardless of whether its recorded or not by the frame builder.  There is only about 2 megabytes per second bandwidth per computer.  In this case we were trying to do something like 200 channels * 16384 Hz * 4 bytes = 13 megabytes per second.

The maximium number of 16384 channels is roughly 30, with little to no room for anything else.  In addition, test points use the same allocated memory structure, so that if you use up all the capacity with channels, you won't be able to use testpoints to that computer (or thats what Alex has led me to believe).

The daqd process then core dumped and was causing all sorts of martian network slowdowns.  At the same time, the c1lsc computer crashed hard, and all of the front end processes except for the IOP on c1sus crashed.

We rebooted c1lsc, and restarted the c1sus processes using the startc1SYS scripts.  However, the c1susfe.ko apparently got stuck in a wierd state.  We were completely unable to damp the optics and were in general ringing them up severely.  We tried debugging, including several burt restores and single path checks.

Eventually we decided to reboot the c1sus machine after a bit of debugging.  After doing a burt restore after the reboot, everything started to damp and work happily.  My best guess is the kernel module crashed in a bad way and remained in memory when we simply did the restart scripts.


  4448   Mon Mar 28 16:24:35 2011 kiwamuUpdateGreen Lockingpower budget on PSL table

   I measured some laser powers associated with the beat-note detection system on the PSL table.

The diagram below is a summary of the measurement. All the data were taken by the Newport power meter.

 The reflection from the beat-note PD is indeed significant as we have seen.

In addition to it the BS has a funny R/T ratio maybe because we are using an unknown BS from the Drever cabinet. I will replace it by a right BS.



 During my work for making a noise budget I noticed that we haven't carefully characterize the beat-note detection system.

The final goal of this work is to draw noise curves for all the possible noise sources in one plot.

To draw the shot noise as well as the PD dark noise in the plot, I started collecting the data associated with the beat-note detection system.


(Next actions)

 * Estimation and measurement of the shot noise

 * measurement of the PD electrical noise (dark noise)

 * modeling for the PD electrical noise

 * measurement of the doubling efficiency

 * measurement of an amplitude noise coupling in the frequency discriminators

  4449   Mon Mar 28 17:06:15 2011 kiwamuUpdateGreen Lockinga mixer school

In the last week Matt and I modified the MFD configuration because the mixer had been illegally used.



Since the output from the comparator is normally about 10 dBm, a 4-way power splitter reduced the power down to 4 dBm in each output port.

In order to reserve a 7 dBm signal to a level-7 mixer, we decided to use an asymmetric power splitter, which is just a combination of 2-way and 3-way splitter shown in the diagram above.

With this configuration we can reserve a 7 dBm signal for a mixer in the fine path.

However on the other hand we sacrificed the coarse path because the power going to the mixer is now 2.2 dBm in each port.

According to the data sheet for the mixer, 1 dB compression point for the RF input is 1dBm. Therefore we put a 1 dB attenuator for the RF port in the coarse system.

In the delay line of the fine path we found that the delay cable was quite lossy and it reduced the power from 2.2 dBm to about 0 dBm.



  4450   Mon Mar 28 18:13:32 2011 ranaUpdateGreen Lockinga mixer school

Using 2 dBm for a Level 7 mixer is so bogus, that I will dismantle this as soon as I come over.


  4451   Mon Mar 28 18:22:43 2011 kiwamuUpdateGreen Lockinga mixer school


Actually we tried looking for a level-3 or a smaller mixer, but we didn't find them at that moment. That's why we kept the level-7 mixer for the coarse path.

As you pointed out we can try an RF amplifier for it.


Using 2 dBm for a Level 7 mixer is so bogus, that I will dismantle this as soon as I come over.



  4452   Mon Mar 28 21:12:14 2011 JenneUpdatePSLNew PMC Base Riser Design

I (think) I have finished the new PMC base riser.  The eDrawing of it (so you can view it on any computer) has been uploaded to the PMC wiki page.

I also attach it here, for comments.

Attachment 1: PMC_riser.eprt
  4453   Mon Mar 28 22:56:14 2011 ranaUpdatePSLNew PMC Base Riser Design

Its going to need some kind of way to locate the PMC on the top. In the previous design, we had the 3 balls to decouple the body from the base. That design was flawed due to the roughness of the holes in the PMC body.

Also probably need some kind of relief on the bottom. Its possible that it would be OK like this, but I am unsure if the shop can maintain the flatness we want over the whole length and/or the flatness of any given (OLD) optical table over ~8". Its probably not a good idea to have to torque this (aluminum?) to make it conform to the optical table's shape.

  4454   Mon Mar 28 23:51:54 2011 JenneUpdatePSLNew PMC Base Riser Design


Its going to need some kind of way to locate the PMC on the top. In the previous design, we had the 3 balls to decouple the body from the base. That design was flawed due to the roughness of the holes in the PMC body.

 Hmmm, so, this was just meant to be a riser that goes underneath the old PMC mount, to raise it from 3" beam height to 4" beam height.  I will make another one that is a complete mount, designed for 4" beam height.  Please hold........... .......... ....... ..... ... .

  4455   Tue Mar 29 00:00:55 2011 KojiUpdateIOOFixing MC/Freq Divider Box

This is the log of the work on Wednesday 23rd.

1. Power Supply of the freq divider box

Kiwamu claimed that the comparator output of the freq div box only had small output like ~100mV.
The box worked on the electronics bench, we track down the power supply and found the fuse of the +15V line
brew out. It took sometime to notice this fact as the brown-out-LED of the fuse was not on and the power
supply terminal had +15V without the load. But this was because of the facts 1) the fuse is for 24V, and 2)
the large resistor is on the fuse for lighting the LED when the fuse is brown out.

I found another 24V fuse and put it there. Kiwamu is working on getting the correct fuses.

2. MC locking problem

After the hustle of the freq divider, the MC didn't lock. I tracked down the problem on the rack and found
there was no LO for the MC. This was fixed by pushing the power line cable of the AM Stabilizer for the MC LO, which was a bit loose.

  4456   Tue Mar 29 15:01:58 2011 Larisa ThorneUpdateElectronicsLow pass filter for X arm laser temperature control

 This is the continuation of http://nodus.ligo.caltech.edu:8080/40m/4402


The first picture is of the actual component, where the resistor is 1M and capacitor is 10uF. 

But before the component can be put into place, its transfer function had to be checked to make sure it was doing what we calculated it would do. The results of these are in the graphs generated: frequency vs. gain, and frequency vs. phase.




According to these graphs, we are not achieving the targeted cutoff frequency: need to recalculate and compensate for the extra 100k resistance being encountered.

Attachment 1: DSC_2889.JPG
Attachment 2: LPFgraph.pdf
LPFgraph.pdf LPFgraph.pdf LPFgraph.pdf LPFgraph.pdf
  4457   Tue Mar 29 15:50:21 2011 KojiUpdateElectronicsLow pass filter for X arm laser temperature control

For bode plot:

USE LOG-LOG plot for the amplitude

USE LOG-LINEAR plot for the phase


Search "Bode Plot" on web

  4458   Tue Mar 29 22:29:16 2011 kiwamuUpdateGeneralsome tasks tomorrow

 *  Temporary strain relief for the heliax cables on 1X2 (Steve)

 *  RF diagrams and check lists (Suresh)

      => In the lunch meeting we will discuss the details about what we will do for the RF installation.

 *  Electronics design and plan for Green locking (Aidan / Kiwamu)

      => In the lunch meeting we will discuss the details.

 *  LSC model (Koji)

 *  Video cable session (team)

 * LPF for the laser temperature control (Larisa)

  4461   Wed Mar 30 16:57:13 2011 kiwamuUpdateGeneralturned off c1aux

[Steve / Kiwamu]

 As a part of the video cable session, we reconnected some power cords on 1Y1 rack.

During the work we momentarily turned off c1aux, which handles DMF, Illumintators, mechanical shutters and the old video epics.

I think it automatically reverted the things, but we may need to check them.

  4462   Wed Mar 30 17:01:08 2011 Larisa ThorneUpdateVIDEOCable laying...continued

[Steve, Suresh, Kiwamu, Larisa]


Only the PRM/BS cable was laid today.

In one of the previous updates on cable laying, it was noted that the MC2 cable needed an additional 10' and the MC2T needed an additional 15' to reach their destinations.  We cut and put BNC ends on 10' and 15' cables and connected them to the original cables in order to make them long enough.


This concludes the laying of new cables. Suresh is currently working on the QUADs...

  4472   Wed Mar 30 21:46:10 2011 Aidan, KiwamuUpdateGreen LockingStates of the Green beat note

The attached table shows the amplitude of the green beat note when the end laser was in various states. We can increase the beat note amplitude dramatically by switching to a different states.

State 1
C1:GCX-GRN_REFL_DC:             638 counts
C1:GCV-XARM_BEAT_DC: (PSL blocked)    950 avg counts (zero = -794 counts)
amplitude of beat note:            -23dBm (after PD + amps) (f ~ 30 MHz)?
C1:GCX-SLOW_SERVO2_OUT:            318 counts

State 2
C1:GCX-GRN_REFL_DC:             180 counts
C1:GCV-XARM_BEAT_DC: (PSL blocked)    1270 avg counts (zero = -794 counts)
C1:GCV-XARM_BEAT_DC: (PSL unblocked)    1700 avg counts (zero = -794 counts)
amplitude of beat note:            -7dBm (after PD + amps) f = 60MHz
amplitude of beat note:            0dBm (after PD + amps) f = 30MHz
C1:GCX-SLOW_SERVO2_OUT:            290 counts

State 3
C1:GCX-GRN_REFL_DC:             220 counts
C1:GCV-XARM_BEAT_DC: (PSL blocked)    1120 avg counts (zero = -794 counts)
C1:GCV-XARM_BEAT_DC: (PSL unblocked)    1520 avg counts (zero = -794 counts)
amplitude of beat note:            0dBm (after PD + amps) f = 15MHz
C1:GCX-SLOW_SERVO2_OUT:            305 counts

PSL temp = ??
C1:PSL-FSS_SLOWM = -3.524

  4474   Thu Mar 31 08:31:44 2011 SureshUpdateVIDEOCable laying...continued

The video work has crossed a milestone.    

Kiwamu and Steve have shifted the three quads from the control room to the Video MUX rack (1Y1) and have wired them to the MUX.

The monitors in the control room have been repositioned and renumbered.  They are now connected directly to the MUX. 

Please see the new cable list for the input and output channels on the MUX.

As of today, all cables according the new plan are in place.  Their status   indicated on the wiki page above is not verified .  Please ignore that column for now, we will be updating that soon.

I shifted the MC1F/MC3F camera and the MC2F cameras onto the new cables.  Also connected the monitors at the BS chamber and end of the X arm to their respective cables.  I have removed the RG58B BNC (black) cables running from MC2 to BS and from ETMXF to the top of the Flow Bench. 

Some of the old video cables are still in place but are not used.   We might consider removing them to clear up the clutter. 

Some of the video cables in use are orange and if the lab's  cable color code is to be enforced these will have to be replaced with blue ones..

Some of the cables in use running from the MUX to the monitor in the control room are the white 50 Ohm variety.  There are also black RG59 Cables running the same way ( we have surplus cables in that path)  and we have to use those instead of the white ones. 

There are a number of tasks remaining:

a)  The inputs from the various existing cameras have to be verified. 

b) There are quite a few cameras which are yet to be installed.

c) The Outputs may not not be connected to their monitors.  That the monitors may still be connected to an old cable which is not connected to the MUX.  The new cable should be lying around close by.  So if you see a blank monitor please connect it to its new cable. 

d) The status column on the wiki page has to be updated.

e) Some of the currently in place may need to be replaced and some need to be removed.  We need to discuss our priorities and come up with a plan for that.

After checking everything we can certify that the video cabling system is complete.

I would like Joon Ho to take care of this verification+documenting process and declaring that the job is complete. 


Steve attached these two pictures.

Attachment 1: P1070489.JPG
Attachment 2: P1070494.JPG
  4478   Thu Mar 31 19:58:11 2011 kiwamuUpdateCDSc1iscex crashed

After I did several things to add new DAQ channels on c1iscex it suddenly became out of network. Maybe crashed.

Then c1iscex didn't respond to a ping and all the epics values associated with c1iscex became not accessible.

I physically shut it down by pushing the reset button. Then it came back and is now running fine.


(how I broke it)

Since activateDAQ.py has screwed up the 'ini' files including C1SCX.ini, I was not able to add a channel to C1SCX.ini by the usual daqconfig GUI.

So I started editing it in a manual way with an editor and changed some sentences to that shown below


Then I rebooted fb to reflect the new DAQ channels.

After that I looked at the C1_FE_STATUS.adl screen and found some indicator lights were red.

So I pushed "Diag reset" button and "DAQ Reload" button on the C1SCX_GDS_TP.adl screen and then c1iscex died.

After the reboot the new DAQ channels looked acquired happily.

This is my second time to crash a front end machine (see this entry)

  4482   Fri Apr 1 23:05:58 2011 kiwamuUpdateGreen Lockingnoise budget

I made a coarse noise budget in order to decide our next actions for the X arm green locking.

So be careful, this is not an accurate noise budget !

 Some data are just coming from rough estimations and some data are not well calibrated.


 Assuming all the noise are not so terribly off from the true values, the noise at high frequency is limited by the dark noise of the PD or it already reaches to the IR inloop signal.

The noise at low frequency is dominated by the intensity noise from the transmitted green light although we thought it has been eliminated by the comparator.

In any case I will gradually make this noise budget more accurate  by collecting some data and calibrating them.


According to the plot what we should do are :

  * More accurate PD noise measurement

  * More accurate shot noise estimation

  * Searching for a cause of the small beat signal (see here) because a bigger beat signal lowers the PD noise.

  * Investigation of the Intensity noise

  4484   Mon Apr 4 11:52:13 2011 JenneUpdatePEMSTS2s unpacked

I unpacked the STS2 seismometers that we borrowed from LLO.  They are sitting underneath the Xarm, in the middle of the mode cleaner, near the other seismometer stuff. 

  4491   Wed Apr 6 02:41:01 2011 kiwamuUpdateGreen Lockingnoise budget : some more noise

It turned out that the dark noise from the beat PD and the shot noise on the beat PD was overestimated.

So I corrected them in the plot of the last noise budget (#4482).

Additionally I added the end laser error signal in the plot. Here is the latest plot.


 The end laser error spectrum is big enough to cover most of the frequency range.
 (although it was taken at a different time from the other curves.)

Quote from #4482

According to the plot what we should do are :

  * More accurate PD noise measurement

  * More accurate shot noise estimation

  4492   Wed Apr 6 16:02:07 2011 Larisa ThorneUpdateElectronicsCable laying...continued

[Steve, Kiwamu, Larisa]


Having finished laying new cable last week, we moved on to connecting those on PSL table and AP table.

Cables connected:

--RCR, RCT, PMCR (all three are blue)

--OMCR (blue cable, ***now has a camera***), PMCT, IMCR, REFL, AS (white cable), OMCT (***now has camera***)


Unless otherwise noted, the cables are black on the AP table. Also on the AP table: cables were connected directly to the power source.

The wiki has been updated accordingly.


Steve noted that MC2T and POP cameras are not there.



  4496   Thu Apr 7 11:38:56 2011 steveUpdatePSLenclosure windows on the east side of the PSL

The PSL enclosure now have 4 windows on each side. The bottom rail guides on the east side will be replaced by  one  U-channel for smoother, more gentle sliding.

Door position indicator- interlock switches are not wired yet.

Attachment 1: P1070538.JPG
  4499   Thu Apr 7 13:14:23 2011 josephbUpdateCDSProposed plan for ITMX/ITMY control switch


The controls (fast and slow both) think ITMX is ITMY and ITMY is ITMX.


After some poking around today, I have convinced myself it is sufficient to simply swap all instances of ITMX for ITMY in the C1_SUS-AUX1_ITMX.db  file, and then rename it to C1_SUS-AUX1_ITMY.db (after having moved the original C1_SUS-AUX1_ITMY.db to a temporary holding file).

A similar process is then applied to the original C1_SUS-AUX1_ITMY.db file.  These files live in /cvs/cds/caltech/target/c1susaux.  This will fix all the slow controls.

To fix the fast controls, we'll modify the c1sus.mdl file located in /opt/rtcds/caltech/c1/core/advLigoRTS/src/epics/simLink/ so that the ITMX suspension name is changed to ITMY and vice versa.  We'll also need to clean up some of the labeling

At Kiwamu and Bryan's request, this will either be done tomorrow morning or on Monday.

So the steps in order are:

1) cd /cvs/cds/caltech/target/c1susaux

2) mv C1_SUS-AUX1_ITMX.db C1_SUS-AUX1_ITMX.db.20110408

3) mv C1_SUS-AUX1_ITMY.db C1_SUS-AUX1_ITMY.db.20110408

4) sed 's/ITMX/ITMY/g' C1_SUS-AUX1_ITMX.db.20110408 > C1_SUS-AUX1_ITMY.db

5) sed 's/ITMY/ITMX/g' C1_SUS-AUX1_ITMY.db.20110408 > C1_SUS-AUX1_ITMX.db

6) models

7) matlab

8) Modify c1sus model to swap ITMX and ITMY names while preserving wiring from ADCs/DACs/BO to and from those blocks.

9) code; make c1sus; make install-c1sus

10) Disable all watchdogs

11) Restart the c1susaux computer and the c1sus computer


  4503   Fri Apr 8 01:05:45 2011 SureshUpdateRF SystemRF Source Harmonics


 The measured power levels of the RF source harmonics are given below:



We are considering inclusion of bandpass filters centered on 11 and 55 MHz  to suppress the harmonics and meet the requirements specified in Alberto's thesis (page 88).


Attachment 1: RF_Source_Harmonics_Sheet1.pdf
RF_Source_Harmonics_Sheet1.pdf RF_Source_Harmonics_Sheet1.pdf RF_Source_Harmonics_Sheet1.pdf RF_Source_Harmonics_Sheet1.pdf
  4506   Sun Apr 10 19:14:08 2011 KojiUpdateGreen LockingNew Green PD test1

I started to modify another green PD set.

It so far has the transimpedance of 240 Ohm on CLC409 for the RF output.

It shows the BB output upto ~100MHz.
The measurement shows the transimpedenca of ~90Ohm which is ~25% smaller than the expected gain of 120Ohm.
It is calibrated based on the transimpedances of Newfocus 1611 (10kOhm and 700Ohm for AF and RF).

The next step is to change the transimpedance resister to 2k and replace the PD to S3399 Si PD, which has the diameter of 3mm.
Then, the noise level will be measured. (and replace the RF opamp if necessary)


Attachment 1: SGD444A_240.png
Attachment 2: SGD444A_240_test.png
  4507   Mon Apr 11 09:49:53 2011 ranaUpdateElectronicsNew Green PD test1

 Ooh. Can you explain the purpose of the resistors which are connected to the (+) inputs? It looks like some real electronics ninjitsu.

  4508   Mon Apr 11 11:34:05 2011 KojiUpdateElectronicsNew Green PD test1


 Ooh. Can you explain the purpose of the resistors which are connected to the (+) inputs? It looks like some real electronics ninjitsu.

51 Ohm for CLC409

The datasheet of CLC409 uses 25Ohm there. This is to cancel the input bias current of the two inputs of the opamp.

The source impedance (series) of SGD444 is 50Ohm. So I used 50Ohm for the + input shunting.

However, I could probably use anything between 0-50Ohm as the datasheet itself tells that the bias currents are
not related between the two inputs. In addition, I am not sure how much the real series resistance of the PD is.

1kOhm for OP27

This resister is to ensure the (+) input to have a high impedance at high frequencies.

As far as OP27 is behaving as an ideal opamp, the (+) input has a high impedance.
Also if the inductor behaves as the ideal inductor, no photocurrent comes to the AF path.

However, if both of the op27 and the inductor show similar impedances to the RF transimpedance of 240Ohm,
the AF path absorbs some photocurrent and affects the RF transimpedance of the RF output.

We know that the inductor has a self resonance where the shunt capacitance take over the impedance of the coil.
Above that frequency, the inductor is no longer the inductor. The self resonant freq of this inductor is ~300MHz. It is OK, but not
too far from the freq of interest if we like to see clear cut off at around f>100MHz.
Also OP27 is an AF amplifier and I had no confidence about the input impedance of the OP27 at 100~300MHz.

If I put 1k in the (+) input of the OP27, I can ensure the entire AF path has the impedance of ~1k (at least 500Ohm even when L and OP27 are shorted).
I think the chip resister easily works as a resister up to 1GHz.

Attachment 1: SGD444A_240_test.png
  4509   Mon Apr 11 13:30:04 2011 josephb, JamieUpdateCDSNo Wiper script - Frames full over weekend


The daqd process was dying every minute or so when it couldn't write frame.  This was slowing down the network by writing a 2.9G core dump over NFS every minute or so. (In /opt/rtcds/caltech/c1/target/fb/).

The problem was /frames/ was 100% full.

Apparently, when we switched the fb over to Gentoo, we forgot to install crontab and a wiper script.


We will install crontab and get the wiper script installed.

  4510   Mon Apr 11 14:17:22 2011 josephb, jamieUpdateCDSFrame wiper script installed

[Joe, Jamie, Alex]


I asked Alex which cron to use (dcron? frcron?).  He promptly did the following:

emerge dcron

rc-update add dcron default

Copied the wiper.pl script from LLO to /opt/rtcds/caltech/c1/target/fb/

At that point, I modified wiper.pl script to reduce to 95% instead of 99.7%.

I added controls to the cron group on fb:

sudo gpasswd -a controls cron

I then added the wiper.pl to the crontab as the following line using crontab -e.

0 6 * * *       /opt/rtcds/caltech/c1/target/fb/wiper.pl --delete &> /opt/rtcds/caltech/c1/target/fb/wiper.log


Note, placing backups on the /frames raid array will break this script, because it compares the amount in the /frames/full/, /frames/trends/minutes, and /frames/trends/seconds to the total capacity. 

Apparently, we had backups from September 27th, 2010 and March 22nd, 2011.  These would have broken the script in any case. 

We are currently removing these backups, as they are redundant data, and we have rsync'd backups of the frames and trends.  We should now have approximately twice the lookback of full frames.

  4511   Mon Apr 11 19:09:59 2011 SureshUpdateRF SystemInstalled low pass filters in the demod boards


As part of the RF system upgrade some of the demod boards in the lab were modfied.  The filter U5 (see the circuit schematic) was replaced. These changes are tabulated below.


Filters installed in the demod boards
Serial number Old name of the card New name of the card Filter installed Remarks
107 POY33 REFL33 SCLF-33+ R14=50Ohm
118 AP133, ASDD133 REFL55 SCLF-65  
114 PO199 REFL165 SCLF-190 R14=50Ohm
120 PO133 POP110 SCLF-135  
123 SP133 POP55 SCLF-65+ AT1 removed, R14=50Ohm
122 SP199, REFLDD199 AS165 SCLF-190  
121 SP166, REFL16 POP11 SCLF-10.7  
116 AP199 199 MHz POP165 SCLF-190  
126 AS166 33.3 MHz POX11 SCLF-10.7  
119 POX 33.3 MHz POY11 SCLF-10.7  
021 24.5 MHz (LLO) REFL11 SCLF-10.7  
020 24.5 MHz SCLF-45 POP22 SCLF-21.4  
022 24.5 MHz SCLF-45 AS11 with amp SCLF-10.7  
029 24.5          SCLF-f5 AS55 with amp SCLF-65  


Next, I and Q phase has to be checked for orthogonality. And noise levels of the cards have to measured.




  4512   Mon Apr 11 20:03:05 2011 taraUpdateElectronicsTTFSS for 40m

I brought TTFSS set #7 to 40m and kept it in the electronic cabinet.

note that Q4 transistor has not been replaced back to PZT2907A yet. It's still GE82.

Q3 is now pzt3904, not PZT2222A.


  4513   Mon Apr 11 21:13:15 2011 KojiUpdateElectronicsNew Green PD test1


The (-) input has been decoupled by the capacitor. So the series resistance of the PD is not the matter.
In this sense, we should use 0Ohm for the (+) input shunting.


51 Ohm for CLC409

The datasheet of CLC409 uses 25Ohm there. This is to cancel the input bias current of the two inputs of the opamp.

The source impedance (series) of SGD444 is 50Ohm. So I used 50Ohm for the + input shunting.

However, I could probably use anything between 0-50Ohm as the datasheet itself tells that the bias currents are
not related between the two inputs. In addition, I am not sure how much the real series resistance of the PD is.

  4514   Mon Apr 11 23:35:02 2011 ranaUpdateRF SystemInstalled low pass filters in the demod boards

I am a little concerned about using these low pass filters so close to the band edge. Recall that there is no on-board preamp for the RF input to the mixer.

So, if the input impedance of the filters is not 50 Ohms, we will get some unwanted reflections and sensitivity to cable length.

I think its worth while to check the impedance or S-parameters of these things with the LO activated to find out if we need to remove them or not.

  4515   Tue Apr 12 12:01:30 2011 josephbUpdateGeneralIFO controls, now with 10% less lying (ITMX/ITMY controls swapped)

The ITMX/ITMY control swap is complete.

The steps from this elog were followed.

In addition, I did a burt restore of c1sus, c1mcs.

I then swapped all the gain settings from ITMX to ITMY, and reenabled the watchdogs.

I did some basic kick tests (1000 counts into UL coil) and confirmed channels like C1:SUS-ITMX_ULPD_VAR (watchdogs mV readback) corresponded to the correct optic.  I also checked that the POS, PIT, YAW, SIDE produced reasonable damping when engaged.

  4516   Tue Apr 12 16:01:33 2011 josephbUpdateGeneralRFM errors


Currently the c1scy, c1mcs, and c1rfm models are reporting an error with receiving some data sent over the GE Fanuc Reflected memory cards.

To be more exact, the C1:SUS-ETMY_ALS signal from the c1gcv FE code on the c1ioo computer going too the Y end is not being received However, the C1:SUS-ETMY_LSC signal is.  So the physical RFM card seems to be working.

Similarly, the TRY signal is being sent correctly from the Y end computer.  The X end is working fine and receiving both LSC and ALS signals.

The c1mcs and c1rfm models also receive data from the c1ioo computer and reporting receiving errors.


Because the RFM cards are transmitting and receiving at least some channels, I'm guessing there was changes made to the C1.ipc file, which defines the memory locations of these various channels on the RFM network, and that when a model was rebuilt, a different one using the previous IPC file was not, and thus one of the computer is going to the wrong place to either read or write data.

Tomorrow, I'm planning on the  following:

1) Clean out the C1.ipc file (/opt/rtcds/caltech/c1/chans/ipc/)

2) Rebuild all models

3) Run activate_daq.py script

4) Restart models via script

If this doesn't clear up the problem, I'll continue  to bug hunt.

  4518   Wed Apr 13 11:34:07 2011 josephbUpdateCDSFixed IFO_ALIGN.adl


I switched the ITMX and ITMY control channels yesterday, but forgot to update the IFO_ALIGN.adl file (/opt/rtcds/caltech/c1/medm/c1ifo/) which had the control labels swapped to make life easier.


I swapped ITMX and ITMY control locations on the screen.


Are there any other screens involving ITMX and ITMY that had controls reversed to make life easier?

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