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ID Date Author Type Category Subject
1444   Mon Mar 30 13:29:40 2009 YoichiUpdateSUSMC1 drift investigation continued

 Quote: Maybe we can temporarily just disconnect the bias and just use the SUS sliders for bias if there's enough range?

We could do this, but I'm suspicious of the cables between the coil driver and the coils (including the satellite box). In this case, disabling the bias won't help.
Since the MC1 has been quiet recently, I will just lock the MC and resume the locking.
1445   Mon Mar 30 15:51:27 2009 steveUpdateElectronicsHP4291A left the lab to be repaired

Eric Gustafson is handling the old HP4291A rehabilitation. Tarac picked both units up today.

March of 2008 Tucker Electronics failed to fix it's intermittent ~25MHz 0.5V oscillation at the swept sine output

See 40m-elog id:398 on 3-24-2008 by Rob Ward

1447   Tue Mar 31 09:42:32 2009 steveUpdatePEMETMY sus damping restored again

The Caltech gasoline storage tank is being upgraded.

They are jack hammering and digging with bulldozer 50 yards south of  ETMY

1448   Wed Apr 1 10:22:13 2009 steveUpdateVACRGA logging is working

Thanks to Joe B who made the SRS RGA working with linux

Last data file logged at 2008 Oct 24 with old Dycor unit

First data file logged at  2009 Feb 10 with SRS

1449   Wed Apr 1 15:47:48 2009 YoichiUpdateLocking3.8kHz peak looks like a real optical response of the interferometer
Yoichi, Peter

To see where the 3.8kHz peak comes from, we locked the interferometer with the CARM fed back only to ETM and increased the arm power to 4.
The CARM error signal was taken from the transmission DC (not PO_DC).
The attached plots show the CARM transfer functions taken in this state (called ETM lock in the legends) compared with the ones taken when the CARM is locked by the feedback to the laser frequency (called "Frequency lock").
The first attachment is the TFs from the CARM excitation (i.e. the ETMs were actuated) to the TR_DC and PO_DC signals.

The second attachment is the AO path loop TFs. This is basically the TF from the frequency actuator to the PO_DC error signal.
I injected a signal into the B-excitation channel of the common mode board (with SR785) and measured the TF from TP2B to TP2A of the board.
For the ETM lock case, the AO loop was not closed because I disabled the switch between TP2A and TP1B.

The observation here is that even with no feedback to the laser frequency, the 3.8kHz peak is still present.
This strongly suggests that the peak is a real optical response of the interferometer.

To realize the ETM lock with arm_power=4, I had to tweak the CM loop shape.
I wrote a script to do this (/cvs/cds/caltech/scripts/CM/ETM_CARM_PowerUp).
You can run this script after drstep_bang has finished.
1450   Wed Apr 1 16:14:36 2009 YoichiUpdateLocking3.8kHz peak does not change with SRC offset
Yoichi, Peter

We suspected that maybe the 3.8kHz peak is the DARM RSE somehow coupled to the CARM.
So we added an offset to the SRC error signal to see if the peak moves by changing the offset.
It didn't (at least by changing the SRC offset by +/-1000).
(I had a nice plot showing this, but dtt corrupted the data when I saved it. So no plot attached.)

I also played with the PRC, DARM offsets which did not have any effect on the peak.
The only thing, I could find so far, having some effect on the peak is the arm power. As the arm power is increased, the peak height goes up and the frequency shifts slightly towards lower frequencies.
1452   Fri Apr 3 10:01:50 2009 steveUpdateVACrgascan with temp plot

Rga scan of day 231 since pumpdown pd66-m-d231

m stands for maglev pumping speed, vacuum normal condition of valves,

cc4 cold cathode gauge at the rga location,

cc1 is real ifo pressure from the 24" tube at the pumpspool,

PEM-count temp: vac envelope temp at the top of IOO chamber

1454   Fri Apr 3 17:20:05 2009 YoichiUpdateLockingThe 3.8kHz peak seems like the DARM RSE (not 100% sure though)
Yoichi, Kentaro,

Last night, we took several measurements of the AO path loop TFs with various offsets/demod. phases tweaked.
The first attachment shows the AO path loop TF as a function of the offset (in counts) added to the DARM error signal.
Though it is a bit crowded plot, you can see a general tendency that the peak becomes lower in height and higher in frequency as
the DARM offset goes from negative to positive. Since the peak height also depends on the arm power and it fluctuates during the measurements,
the change is not monotonic function of the offset though.

Being suspicious of the demodulation phase of the DARM error signal (AS166), we scanned it (see the second attachement).
But there is no significant change.
Note that the phase of the TF is 180 degrees different from the first attachment. This is because I changed the measurement point of the returning signal
on the CM board from TP2A to OUT2 to see POX_1I signal as well. These points should give the same signal for PO_DC except for the sign.

We also took the AO path TFs by changing the MICH offset (the third attachment). Again, there is no big change.

With the CARM locked with the PO_DC signal, we took the transfer function from the AO path actuation signal to the response of the POX_1I (4th attachment).
There is a huge 3.8kHz peak.

Finally, we measured the DARM response by exciting the ETMs differentially (the PDF attachment).
The shape of the 3.8kHz resonance looks like the DARM RSE peak.

It is speculated that somehow the DARM RSE resonance is coupled into the CARM loop. Don't know how though.
I'm now working on an Optickle simulation to get an insight into this issue.
1455   Mon Apr 6 19:09:15 2009 JenneUpdatePEMOld Guralp is hooked back up to the ADC

Old Guralp is hooked back up, the new one is sitting next to it, disconnected for now.

1456   Mon Apr 6 21:50:43 2009 ranaUpdateLSCArm Locking via pushing MC2
Inspired by our 'No Refcav' scheme here, I was inspired to re-explore the idea of locking the
CARM DOF using only feedback to the MC/laser. Last week I got this to work on the single arm and
full IFO at Livingston.
I also estimate the MC noise there.

Today I found the settings to allow X-arm locking here without any feedback to the ETM or ITM:

- Set the LSC Output Matrix to feed the XARM signal to MC2.
- Turn OFF the input of the LSC-ETMX filter bank (this does not disable tickling).
- Turn OFF FM7 (0.1:10) in MC2-MCL.
- Turn ON MC2-LSC with a gain of 0.2 and FM3 FM4 FM5.

That's enough to lock the arm - its pretty stable. This also assumes that the LSC-MC2 bank has its nominal gain of -0.178.

To determine the gain of +0.2 in the MC2-LSC filter bank, I measured the TF from MC2->PD3_I and from ETMX->PD3_I. I adjusted
the gain to be equal at 150 Hz for acquisition and the sign to be opposite to account for the (-) in LSC-MC2. The TF is
attached.

After locking, I type a zero into the MC2-MCL filter bank and that shuts off the feedback from the MC servo to MC2. This is
now topologically similar to the standard CM servo configuration.

The second attachment has the trends of this locking. You can see that the MC_F goes off into the weeds, but the MCL signal
does not so much. I think maybe the MC length is drifting a lot - not the arm.

The third attachment shows the spectra.
1458   Wed Apr 8 02:47:42 2009 YoichiUpdateLockingLocking status
This is a summary of activities in the last few nights, although there is not much progress.

The attachment 1 and 2 show the CARM and DARM responses around 3.8kHz at different arm power levels.
The CARM error signal was PO_DC and the DARM error signal was AS2Q.
The excitations were both applied to the ETMs (I temporarily modified the output matrix so that the unsed XARM filter bank can be used to excite CARM and DARM).
DARM and CARM show very similar behavior as the power goes up.

The third attachment shows transfer functions to various signals from CARM and DARM excitations (ETMs).
Though the plot contains many curves, look at PO_DC curves (green and black).
PO_DC is used as CARM error signal but it has a larger response to DARM than CARM (by 10dB or so).
This is not good.

Although the 3.8kHz problem still exists, tonight I was able to go up to arm power = 80 a couple of times, where we are ready to hand off from PO_DC to the RF CARM signal. The hand off failed. I'm now optimizing the hand off gain, but it is difficult because the interferometer is unstable at this power level.
1462   Thu Apr 9 11:27:19 2009 steveUpdateVACvac gauge reading problem

Cold cathode gauge CC4  is reading normal.

CC1 is glitching, it is probably dirty.

CC2 is fluctuating too much and it is cutting out for 6-7 minutes. It must be insulated by deposits and there is no emission current.

I think the same goes for P1

They will have to be replaced at the next vent

1463   Thu Apr 9 12:23:49 2009 peteUpdateLockingtuning ETM common mode

Pete, Yoichi

Last night, we put the IFO in FP Michelson configuration.  We took transfer functions of CARM and DARM, first using CM excitations directly on the ETMs, and then using modulations of the laser frequency via MC excitation.  We found that there was basically no coupling into DARM using the MC excitation, but that there was coherence in DARM using the ETM excitation.  Therefore, I tuned the ETM common mode in the output matrix.  I did this by taking transfer functions of PD1_Q with PD2_I (see attached plot).  I changed the  drdown_bang script to set C1:LSC-BTMTRX_14 0.98 and C1:LSC-BTMTRX_24 1.02.

1467   Fri Apr 10 01:24:08 2009 ranaUpdateComputersallegra update (sort of)

I tried to play an .avi file on allegra. In a normal universe this would be easy, but because its linux I was foiled.

The default video player (Totem) doesn't play .avi or .wmv format. The patches for this work in Suse but not Fedora. Kubuntu but not CentOS, etc.I also tried installing Kplayer, Kaffeine, mplayer, xine, Aktion, Realplay, Helix, etc. They all had compatibility issues with various things but usuallylibdvdread or some gstreamer plugin.So I pressed the BIG update button. This has now started and allegra may never recover. The auto update wouldn't work in default mode becauseof the libdvdread and gstreamer-ugly plugins, so I unchecked those boxes. I think we're going to have this problem as long as we used any kind ofadvanced gstreamer stuff for the GigE cameras (which is unavoidable).

1469   Fri Apr 10 04:54:24 2009 YoichiUpdateLockingREFL_DC for CARM
Suggested by Rob and Rana's simulation works, I tried to use REFL_DC for the CARM error signal.

My current guess for the cause of the 3.8kHz peak is the following.
The AF sidebands created by the laser frequency drive are reflected by the IFO to the symmetric port if the arms are perfectly symmetric.
However, if there is asymmetry in the arm cavities (such as loss imbalance, ITM transmission difference etc) the sidebands are scattered from the common mode to the differential mode. If our CARM error signal has a large response also to the differential mode (i.e. DARM), the loop is closed. At the DARM RSE frequency, the AF sideband in the differential mode is enhanced and creates a peak in the CARM response.
What Rob's plots show is that PO_DC has a larger response to DARM than REFL_DC has. You can see this from the curves of CARM offset = 0 (black ones).
When the CARM offset is zero, the CARM signal should go to zero. Therefore, the black curves show the residual DARM response. In the case of PO_DC, the black curve is very large suggesting a large DARM coupling.

Now I changed the cabling at the LSC rack to put REFL_DC into the REFL2 input of the CM board.
The REFL_DC signal is put through a 160kHz RC LPF and split to the ADC and the CM board (AC coupled by a large capacitor).
I modified the cm_step script to use PD4_DC as CARM error signal. (The old script is saved as cm_step.podc).
Since the polarity of the REFL_DC signal is opposite to the PO_DC, I flipped the polarity switch of the CM board.
This will flip the sign of the RF CARM signal because this switch flips the polarity of the both inputs.
We have to flip the sign of the RF CARM signal with the SR560 sitting on the LSC rack, which I haven't done yet.

With some tweaks of the gains and addition of two lag-lead filters to PD4_DC, I was able to completely hand off the CARM error signal to REFL_DC.
The attached plot shows the AO path loop gain at arm power = 7. The 3.8kHz is gone, although there is some phase ripple around 3.8kHz.

Since the gain behavior of the REFL_DC is different from the PO_DC, I'm now working on the power up part of the script, adjusting the gains as the power goes up.
1470   Fri Apr 10 18:11:18 2009 JenneUpdatePSLISS has a bad cable?

[Rob, Jenne]

I noticed that the ISS Mean Value and CS Saturation were both RED and unhappy. (The alarms were going off, and they were both red on the MEDM screen).  None of the MEDM settings seemed off kilter, so we went out to take a look at the PSL table.

Rob checked that light is indeed going to both of the ISS photodiodes (Morag and Siobhan).  Next we checked that all the cables were good, and that the power to the ISS box was plugged in. In this process, Rob wiggled all the cables to check that they were plugged in.  Just after doing this, the Mean Value and CS Sat were happy again.  Rob thinks the current shunt connection might be bad, but we don't really know which one it was since all of the cables were jiggled between our checking the screens.

Right now, everything is happy again, but as with all bad-cabling-problems, we'll probably see this one again.

I don't know why in particular the connection decided to spaz out this afternoon...I don't think anyone opened the PSL table before Rob and I went to investigate.  I was working on the PMC servo (checking the LO levels...to be posted in a couple minutes), but didn't have anything to do with the ISS. After I was done, I put everything back, and locked the PMC and the MC, and everything was good, until some time later when the ISS started flipping out.

1471   Fri Apr 10 19:09:48 2009 JenneUpdatePSLPMC LO Calibration
I measured the RF LO output level from the PMC's LO board which goes directly into the LO input on the PMC Servo board. This goes hand-in-hand with Rana's thoughts
that we might be giving the PMC mixer a too-low LO value, and we might need to switch out the mixer. Steve ordered some new mixers today to try out.

The RF Output Adjust slider (on the C1:PSL_PMC_PS screen) goes from 0-10V; The nominal value (or at least the value I found it at today) is 2.014V.

To measure the RF level: I unlocked the Mode Cleaner and turned off the ISS servo per Yoichi's suggestion. I then unplugged the input to the PMC servo board's LO input,
and put that cable into a 300MHz 'scope, with 12dB attenuation. The 'scope was AC coupled, with the input set to 50Ohms.

I then changed the RF Output Adjust slider in increments of 0.5, and measured the peak-to-peak values on the scope. In the table and on the plots, I've taken into account
the 12dB attenuation. i.e I actually measured 964mV, so 964mV*10^.6 = 3838mV.

 RF Output Adjust Output measured on scope Oscillator Output Monitor [V] [Vpp] [no units given on MEDM screen] All \pm 0.0159 all of this column is NEGATIVE 0.0000 3.838 0.007 0.5000 3.854 0.007 1.0000 3.838 0.006 1.5000 3.838 0.007 2.0000 3.838 0.006 2.5000 3.838 0.007 3.0000 3.838 0.007 3.5000 3.838 0.007 4.0000 3.838 0.007 4.5000 3.822 0.007 5.0000 3.822 0.012 5.5000 3.790 0.076 6.0000 3.758 0.257 6.5000 3.694 0.555 7.0000 3.615 0.931 7.5000 3.535 1.277 8.0000 3.456 1.532 8.5000 3.392 1.709 9.0000 3.344 1.829 9.5000 3.312 1.908 10.0000 3.296 1.966

I think it's kind of funky that it's so flat for ~half the slider. Also, the third column includes the Oscillator Output Monitor value from the MEDM screen at various RF Adjust slider values. All of these should be negative (i.e. -0.007), but the TABLE function doesn't like "-" signs. I don't know if this information is degenerate with the 'scope measurements, or if it's an indicator of what (might be) wrong.

After finishing, I plugged the cable back into the PMC servo board as it was, turned back on the ISS and relocked the PMC and the MC.
1472   Fri Apr 10 19:10:53 2009 JenneUpdateGeneralXarm locked?

I don't know who left the X arm locked, but I just ran the Align Full IFO script, so everything is good in case Yoichi/someone comes in to lock the IFO this weekend.

1473   Sat Apr 11 00:45:41 2009 YoichiUpdatePSLPMC LO Calibration

 Quote: I then changed the RF Output Adjust slider in increments of 0.5, and measured the peak-to-peak values on the scope. In the table and on the plots, I've taken into account the 12dB attenuation. i.e I actually measured 964mV, so 964mV*10^.6 = 3838mV.

The mixer for the PMC demodulator is level 23. So 16dBm is insufficient.
What is the level of the new mixer Steve ordered ? 13 ?
1475   Sun Apr 12 19:27:20 2009 ranaUpdatePSLPMC LO Calibration

 Quote: 3.8Vpp is about 16dBm. The mixer for the PMC demodulator is level 23. So 16dBm is insufficient. What is the level of the new mixer Steve ordered ? 13 ?

Since Steve and Jenne were on it, I'm sure they ordered the optimum values...

From the table, it looks like the drive level adjuster is busted. Its not supposed to just give a
1-2 dB change over the full range. We'll have to think about what exactly to do, but we should
probably install the level 13 mixer and put in the right attenuation to make the LO be ~13.5 dBm
including the filter. Also need to calibrate the LO readback on the board like what Peter did for
the FSS.
1477   Mon Apr 13 08:59:57 2009 steveUpdatePSLmixers on order

Quote:

 Quote: I then changed the RF Output Adjust slider in increments of 0.5, and measured the peak-to-peak values on the scope. In the table and on the plots, I've taken into account the 12dB attenuation. i.e I actually measured 964mV, so 964mV*10^.6 = 3838mV.

The mixer for the PMC demodulator is level 23. So 16dBm is insufficient.
What is the level of the new mixer Steve ordered ? 13 ?

I ordered mixers level 13, 17 on Friday and level 23 now.
They should be here Tuesday

NOTE: level 23 power is illegal to use in the 40m lab
They get hot
1478   Mon Apr 13 17:55:37 2009 JenneUpdatePSLPMC LO Mon Calibration

I have calibrated the PMC LO Mon (C1:PSL-PMC_LODET) on the PMC's EPICS screen, by inputting different RF LO levels into the LO input of the PMC servo board.

Since the RF output adjust slider on the PMC's Phase Shifter screen doesn't do a whole lot (see elog 1471), I used a combination of attenuators and the slider to achieve different LO levels. I measured the level of the attenuated RF out of the LO board using the 4395A in spectrum analyzer mode, with the units in dBm, with 50dB attenuation to make it stop complaining about being overloaded.  For each row in the table I measured the RF level using the 4395, then plugged the cable back into the PMC servo board to get the EPICS screen's reading.

The last 2 columns of the table below are the 'settings' I used to get the given RF LO level.

 RF LO Input to PMC Servo Board [dBm] LO Mon on EPICS Screen [no units] RF Output Adjust Slider [V] Attenuators used [dB] 16.004 +- 0.008 0.1200 +- 0.0003 0 0 15.001 +- 0.004 0.0708 +- 0.0008 0 1 14.079 +- 0.008 0.0318 +- 0.0001 8 1 13.002 +- 0.006 0.0126 +- 0.0004 0 3 11.992 +- 0.010 0.0024 +- 0.0008 0 4 10.994 +- 0.010 -0.0024 +- 0.0003 0 4+1=5 9.993 +- 0.008 -0.0047 +- 0.0007 0 3+3=6

When the new mixers that Steve ordered come in (tomorrow hopefully), I'll put in a Level 13 mixer in place of the current Level 23 mixer that we have.  Also, Rana suggested increasing the gain on the op-amp which is read out as the LO Mon so that 13dBm looks like 1V.  To do this, it looks like I'll need to increase the gain by ~80.

1480   Tue Apr 14 02:59:02 2009 YoichiUpdateLockingPower up until 26
Yoichi, Peter,

With careful adjustments of the common mode gains, we were able to go up to arm power = 26, sort of robustly (more 50% chance).
At this arm power level, the common mode loop shape still looks good. But the interferometer loses lock easily.
I have to check other DOFs, but the interferometer does not stay locked long enough.
Today, lock losses of the IFO were associated with the lock loss of the PMC whereas the FSS stayed locked.
Probably the AO path got large kicks, which could not be handled by the PMC PZT.

The cause for the IFO lock loss is under investigation.
1482   Tue Apr 14 17:20:36 2009 YoichiUpdateComputer Scripts / ProgramsParallel Optickle
I wrote a parallel version of tickle() function for Optickle.
The attached ptickle.m, which provides ptickle() command, can be used as a drop-in replacement of tickle() command.
This command will run multiple instances of Matlab to calculate the frequency responses in parallel.
The speed gain is roughly proportional to the number of CPU cores you use.

To use multiple cores, you have to run matlabpool() command first. See the comment at the beginning of ptickle.m for more detail.
The progress bar is disabled at this moment because it is not clear for me how to make a single progress bar from multiple instances of Matlab.

I sent the code to Matt, so this may be included in the next release of Optickle.
1484   Wed Apr 15 02:20:46 2009 rana, yoichiUpdateDMFDMF now working copy

We found that DMF/ was not an SVN working copy, so I wiped out the SVN version, imported the on-disk copy, moved it to DMFold/ and then checked out the SVN version.

We can delete DMFold/ whenever we are happy with the SVN copy.

1485   Wed Apr 15 03:52:27 2009 ranaUpdateDMFNDS client32 updated for DMF
Since our seisBLRMS.m complains about 'can't find hostname' after a few hours, even though matlab is able to ping fb40m,
I have recompiled the NDS mex client for 32-bit linux on mafalda and stuck it into the nds_mexs/ directory. This time I

compiled using the 'gcc' compiler instead of the 'ANSI C' compiler that is recommended in the README (which, I notice,

is now missing from Ben Johnsons web page!). Let's see how long this runs.

1487   Wed Apr 15 17:11:37 2009 JenneUpdatePSLEdited c1psl.db to calibrate PMC's LO mon


Following the method in Peter's Elog,

I edited c1psl.db to include the following:

grecord(calc, "C1:PSL-PMC_LOCALC")
{
field(INPB,"C1:PSL-PMC_LODET")
field(SCAN,".1 second")
field(PREC,"4")
field(CALC,".955*LOGE(B)-17.11")
}

I restarted c1psl (had to go hit the physical reset button since it didn't come back after telnet-ing and "reboot"ing) to make this take effect.

Next step is to tell the PMC screen to look at this _LOCALC rather than _LODET, and the screen will be calibrated into dBm.

Right now, the screen is as it always has been, because after relooking at the calibration, I no longer believe it.  This calibration claimes -19dBm for an LOmon value of 0.1200, when I actually measured +16dBm for this LOmon value.  So I've screwed something up in doing my MatLAB calibration.  I'll fix it tomorrow, and put in the correct calibration before I change the PMC screen.

RefCav, PMC, MC are all back and locked after my shenanigans.

1488   Thu Apr 16 11:17:56 2009 JenneUpdatePSLEdited c1psl.db to calibrate PMC's LO mon

 Quote:  I edited c1psl.db to include the following: grecord(calc, "C1:PSL-PMC_LOCALC") { field(INPB,"C1:PSL-PMC_LODET") field(SCAN,".1 second") field(PREC,"4") field(CALC,".955*LOGE(B)-17.11") }

As it turns out, I apparently can't tell X from Y when fitting a function in a rush.  The real calibration stuff which is now in c1psl.db is:

grecord(calc, "C1:PSL-PMC_LOCALC")
{
field(INPB,"C1:PSL-PMC_LODET")
field(SCAN,".1 second")
field(PREC,"4")
field(CALC,"1.004*LOGE(B)+17.76")
}

I restarted c1psl (again, had to go hit the physical reset button since it didn't come back after a telnet-reboot) to have it take in the changes.  The psl.db file that was in place before yesterday (before I touched it) is saved as psl.db.15Apr2009 just in case.


I edited the PMC EPICS screen to have the LO mon look at C1:PSL-PMC_LOCALC, which is the calibrated channel in dBm.  I also stuck a little label on the screen saying what units it's in, because everyone likes to know what units they're looking at.

1489   Thu Apr 16 16:26:57 2009 peteUpdateLockingWed. night locking
yoichi, pete

We installed the watchLockLoss script in scripts/AutoDTT/.  This script monitors arm power and uses command line
DTT to save 5 s snapshot of the interferometer when it senses loss of lock.  We ran it on linux and it seemed to
save an xml file about half the time; we'll try it on solaris.

I managed to get up to arm power of about 20 a couple of times.  IFO lost lock a couple of times after turning
off moving zero.  MC2 would often get tripped by lock loss and need resetting.  Maybe we will try to stiffen the
op levs.
1490   Thu Apr 16 16:37:42 2009 AlbertoUpdateAuxiliary lockingthe zipper

It takes 18 months to double the computational power of microprocessors but it took man thousands of years to invent the zipper. I never really understood that till these days.

Here is a sample of my latest results from Optickle simulations of the locking signal for the Power Recycling Cavity.

Thanks also to Rob's revolutionary bidimensional rotating matrix idea (I can see entire books of linear algebra going to be rewritten now because of that) I could find the way to determine the optimal demodulation phases for the demod signals.

There were also an other couple of missing details. But that came easily along.

The parfor function for the parallel computation in Matlab sped up some loops by a factor of 100.

In these particular plots there's still no CARM offset scan. That's what I'm going to post next on the elog, together with the signals for the other degrees of freedom.

1491   Thu Apr 16 17:19:44 2009 AlbertoUpdateAuxiliary lockingthe zipper

 Quote: It takes 18 months to double the computational power of microprocessors but it took man thousands of years to invent the zipper. I never really understood that till these days. Here is a sample of my latest results from Optickle simulations of the locking signal for the Power Recycling Cavity. Thanks also to Rob's revolutionary bidimensional rotating matrix idea (I can see entire books of linear algebra going to be rewritten now because of that) I could find the way to determine the optimal demodulation phases for the demod signals. There were also an other couple of missing details. But that came easily along. The parfor function for the parallel computation in Matlab sped up some loops by a factor of 100.   In these particular plots there's still no CARM offset scan. That's what I'm going to post next on the elog, together with the signals for the other degrees of freedom.

Just to show that I'm confident I'm getting reasonable results, I'll post two PRC scans for different CARM. One set of plots is for the current 40m with -19.78 deg of SRM detuning phase, the other is for the Old Upgrade (9 Mhz vs the 11 currently planned) with no detuning phase.

I'm going to put together the results and get some conclusion about the 3f locking scheme for the current 40m and the upgrade.

1493   Fri Apr 17 11:05:22 2009 YoichiUpdateLockingThursday night locking status
The last night, it was sort of robust to go up until arm power = 26.
The REFL_DC gain seems to change a lot around this region. So I did fine adjustments of the gain with small incremental steps of the arm power.
This work will continue.
The AutoDTT shows that the lock loss happens with an oscillation of CARM at around 100Hz. This indicates that the cross-over is the culprit.
I was also able to increase the CM UGF up to 10kHz.
1495   Sun Apr 19 03:34:05 2009 YoichiUpdateLockingSaturday night lock
Tonight I was able to go up to arm power = 33, by mainly tweaking the DARM gain. A small progress.
In order to give more phase margin to the CARM MC_L path, I added a 300:100 filter to C1:LSC-MC.
To reduce the load to the lsc computer I deleted several filters from the filter bank, which were not used in the locking scripts.
Before I deleted the filters, I checked in the current chans directory into the svn repository.
If you want to restore the deleted filters, go back to the revision 36142.
1497   Sun Apr 19 11:51:05 2009 josephbUpdateCamerasMafalda may need an update

I tried installing libusb-dev on mafalda in order to try getting the usb frame grabber to work on it, but could not as it could not download the package.

I then tried to do a sudo apt-get update, which failed completely, as the repository seems to have ceased existing.  Basically I had all 404 Not Found errors.

Turns out Mafalda is still running Ubuntu 7.04, whose support ended late 2008.  So there's a couple things that can be done:

1) Ignore it, and simply not update Mafalda anymore.  This also means some newer software and hardware simply won't work with it (like the usb frame grabber)

2) Try to find another, unofficial repository which still has all of the Ubuntu 7.04 packages.

3) Upgrade to a newer, still supported Ubuntu, such as 7.10, 8.04, or 8.10.

I'd personally lean towards the 3rd option, and go to the 8.04 long term support version.  If people agree with it, I could do the upgrade sometime Monday or Tuesday.

1499   Mon Apr 20 11:57:27 2009 robUpdateCamerasMafalda may need an update

 Quote: I tried installing libusb-dev on mafalda in order to try getting the usb frame grabber to work on it, but could not as it could not download the package. I then tried to do a sudo apt-get update, which failed completely, as the repository seems to have ceased existing.  Basically I had all 404 Not Found errors. Turns out Mafalda is still running Ubuntu 7.04, whose support ended late 2008.  So there's a couple things that can be done: 1) Ignore it, and simply not update Mafalda anymore.  This also means some newer software and hardware simply won't work with it (like the usb frame grabber) 2) Try to find another, unofficial repository which still has all of the Ubuntu 7.04 packages. 3) Upgrade to a newer, still supported Ubuntu, such as 7.10, 8.04, or 8.10. I'd personally lean towards the 3rd option, and go to the 8.04 long term support version.  If people agree with it, I could do the upgrade sometime Monday or Tuesday.

I don't see a reason to proliferate operating systems.  Is there any reason we actually need Ubuntu? Can we put CentOS on it?

1501   Mon Apr 20 18:36:37 2009 ranaUpdateCamerasMafalda may need an update
Sadly, the sensoray crap doesn't seem to build on CentOS. I too would prefer a homogenous solution,
but I don't know how to make this happen without punishing Joe with sensoray driver development on CentOS.
1506   Tue Apr 21 18:18:27 2009 steveUpdateVACmaglev failed

Our Osaka TG360MB maglev failed with CSB error message. This means that the dry emergency landing bearing has to be replaced.

I will consalt with Osaka about the choice of replacing bearing or installing new spare  tomorrow.

Mean while V1 is closed and the vac envelope is not pumped.

Valve configuration: BG -background, pumping on the RGA-only

High voltage to IOO PZT steering mirrors and OMC are turned off.

PSL output shutter is closed and manual block is in place.

I will start cooling the CYO pump in the morning, so the IFO will be pumped by noon.

Outgassing plus leakrate after  10 hrs the pressure is 2.3 mTorr

This rate of rise is normal and it is safe to work with the ifo.

1508   Thu Apr 23 13:55:43 2009 josephb, peterUpdateComputersRCG example

We successfully compiled and installed the Real time Code Generator "Hello World" example (which is a skeleton for the ETMX suspension controller) on megatron.  In order to get it to compile, we had to add a flag indicating the computer is stand alone, and not using a myrinet card at the moment.  This was done by adding the shmem_daq = 1 flag to the cdsParameters module.  The symptom was it was unable to find gm.h (and there is no installed /opt/gm directory).

It is called "sam".  It was installed to /cvs/cds/caltech/target/sam, and produced medm screens in /cvs/cds/caltech/medm/c1/sam.  As nothing points to these, I figure it won't harm any of the current configuration, but lets us play around a bit.  If by some strange reason, these do cause problems, feel free to remove them.

1509   Thu Apr 23 16:27:24 2009 YoichiUpdateLockingLocking with the cryo-pump
The last night, the IFO was unstabler than usual and the locking script often failed before reaching the power up stage.
The failure happened at random points.
I'm not sure if this is related to the operation of the cryo-pump.
The mode cleaner reflection image seemed to move around more than usual. Maybe it was just a high seismic night.
1511   Thu Apr 23 16:38:33 2009 steveUpdateVACvac valve relay box is shorting

Ben and I found this vacuum valve relay box intermittently shorthing yesterday.

It effects V4, V5, VA6 and VM1........   Please do not touch this box under the beam pipe next to the vac rack!

The function of this box to send 120VAC to the vacuum valve to move.

1512   Thu Apr 23 18:09:11 2009 YoichiUpdateEnvironmentEffect of cryopump
The attached is the trend plot of the MC1 accelerometer for 3 days.
It is evident that the seismic level increased by a factor of two on Wednesday morning (when Steve started the cryopump).
1514   Fri Apr 24 03:57:30 2009 YoichiUpdateLockingDARM demod phase
Tonight, I was able to go up to arm power = 40 by tweaking the DARM demodulation phase.
I think the DARM loop became unstable because the demodulation phase was not right and the error signal contained some junk from I-phase.
I did not do any sophisticated demodulation phase optimization. Rather I just tweaked the phase so that the dark port image becomes stable.
I will do more careful demodulation phase tuning next time.
1515   Fri Apr 24 04:38:49 2009 YoichiUpdateLockingDARM demod phase

 Quote: Tonight, I was able to go up to arm power = 40 by tweaking the DARM demodulation phase. I think the DARM loop became unstable because the demodulation phase was not right and the error signal contained some junk from I-phase. I did not do any sophisticated demodulation phase optimization. Rather I just tweaked the phase so that the dark port image becomes stable. I will do more careful demodulation phase tuning next time.

In the next try, I was actually able to go up to arm power = 70 stably.
At this power level we are ready for the RF CARM hand off.
1516   Fri Apr 24 11:34:32 2009 robUpdateLockingDARM demod phase

Quote:

 Quote: Tonight, I was able to go up to arm power = 40 by tweaking the DARM demodulation phase. I think the DARM loop became unstable because the demodulation phase was not right and the error signal contained some junk from I-phase. I did not do any sophisticated demodulation phase optimization. Rather I just tweaked the phase so that the dark port image becomes stable. I will do more careful demodulation phase tuning next time.

In the next try, I was actually able to go up to arm power = 70 stably.
At this power level we are ready for the RF CARM hand off.

There's actually code in place in the LSC to dynamically adjust the demod phase for AS1. I've never made much use of it, because it's possible to get around the problem with some gain tweaking if you start at the right phase, or because I did the DC readout handoff earlier.

Attached is a cartoon showing how the demod phase at the dark port changes as the CARM offset is decreased.
1519   Fri Apr 24 17:26:57 2009 YoichiUpdateLockingDARM demod phase

 Quote: There's actually code in place in the LSC to dynamically adjust the demod phase for AS1. I've never made much use of it, because it's possible to get around the problem with some gain tweaking if you start at the right phase, or because I did the DC readout handoff earlier. Attached is a cartoon showing how the demod phase at the dark port changes as the CARM offset is decreased.

The cartoon is very nice.
I actually changed the demod phase continuously as the CARM offset was reduced to get up to arm power = 70.
As the CARM offset is changed, not only the DARM signal gain but also the phase margin around 100Hz changes if you use a fixed demodulation phase.
So it was necessary to change the demodulation phase to keep the DARM loop stable.
1522   Sat Apr 25 03:27:34 2009 YoichiUpdateLockingLocking status
Yoichi, Peter,

We are working on the final step of the lock acquisition, RF CARM hand off.
I was able to hand off the CARM error signal to RF once, but lost lock when decreasing the CARM offset to zero (it was too rapid).
I will try to make the process more robust tomorrow.
1523   Sun Apr 26 02:13:18 2009 YoichiUpdateLockingTwo more successes of RF CARM handoff
Tonight, the RF CARM hand off (mostly) succeeded twice.
But still, the IFO lost lock when I reduced the REFL_DC gain in the AO path to zero.

At the beginning of tonight's work, MICH DD hand off failed several times. This was because the the PD9 gains were set to zero.
I found that the offset script, which I called before starting the locking, fails to restore the gain values sometimes.
This happens when ezcaread fails to read the current gain. We have to be careful when running the LSCoffsets script.
1526   Tue Apr 28 04:30:16 2009 YoichiUpdateLockingRF full lock
Yoichi, Peter

I believe we have succeeded in the full lock of the interferometer with the RF signals.
The lock process is reasonably robust and repeatable.

I did a scan of the RF CARM offset and plotted the arm power as a function of the CARM offset (see the attachment).
The arm power goes maximum at non-zero CARM offset. I guess the RF CARM error signal has some offset.
Maybe the demodulation phase is wrong ? I will tweak this tomorrow.
The script to do this scan can be found at /cvs/cds/caltech/scripts/CM/CARMSweep.

I haven't tried DC readout yet.
1531   Wed Apr 29 04:03:51 2009 YoichiUpdateLockingCARM RF changed to REFL_2I
Yoichi, Peter

As Rob suggested, the optimal demodulation phase is easier to find for REFL_2I than POX_1I.
Moreover, for 166MHz LO, we have a phase shifter (delay line) already installed. So we can easily change the demodulation phase of REFL_2I.
Tonight, we switched the RF CARM signal to REFL_2I.
To do so, I changed the signal going to the REFL1 input of the common mode board from POX_1I to REFL_2I.
I moved a BNC-T installed at the output of POX_1I to the REFL_2I output to split the REFL_2I signal and send it to the CM board.
Since the gain of the REFL_2I was about 20dB lower than that of POX_1I, I increased the gain of the SR560, which is installed between the REFL_2 demodulation board and the CM board, from 1 to 10.

With some gain tweaks, we were able to hand off the CARM from REFL_DC to REFL_2I. We also succeeded in switching the REFL_2I ADC channel from PD11 to PD2_DC (the output of the length path from the CM board). This switching is necessary in order to engage the boost on the CM board.

There remains some offset in the CARM when the arm power is maximized. This is expected because the REFL_2I demodulation phase is probably not exactly right.
I will optimize the demodulation phase tomorrow.
1533   Wed Apr 29 15:56:43 2009 robUpdateLockingeffect of SRCL detune on ARM powers in a CARM sweep

With no DARM offset, sweeping CARM shows an asymmetry between the state where we lock to a DARM spring and the state with a DARM anti-spring.  This is why we have a link between the DARM and CARM optical springs.

For each DARM detune direction (positive or negative, spring or anti-spring), there is only one CARM direction which can yield a DC-based error signal lock with a CARM offset but no DARM offset, which is what we want.

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