aLIGO LHO Logbook

H1 CAL (ISC)

jeffrey.kissel@LIGO.ORG - posted 22:33, Sunday 09 August 2015 (20363)

ALS DIFF VCO / PLL Open Loop Gain TFs

J. Kissel, C. Cahillane, J. Driggers

Today we explored some of the potential systematics in using the ALS DIFF VCO to calibrate the DARM ETM actuation scale factor, as has been done prior to ER7 (see LHO aLOG 18711). Specifically, we've tried to precisely measure the frequency dependence of the the famous z:p = (40:1.6) [Hz] filter just before the low-noise VCO (see LowNoiseVco, and D0900609). However, because the VCO (an MFC9119-10) is a non-linear actuator, it must be locked to a carrier frequency. We want the carrier to be what is nominally used to control the arms during ALS DIFF using the same Phase-Locking Loop (D1300812) and Frequency Difference Divider (see T1400317) to remain in the regime where we get the same amount of [Hz/ct] out of the PLL's control signal.

I attach a PDF of the entire system which is a copy of what was discussed in T1500383. Also attached are plots of the measurement.

The idea: 
- Lock the PLL to an independent frequency reference (a marconi in the CER) in place of the DIFF RFPD input to the Phase-Frequency discriminator. The IFR carrier is tuned to be of frequency roughly the nominal ALS DIFF frequency 157.84 [MHz], but refined further to make the H1:ALS-C_DIFF_PLL_CTRL_INMON as close to zero as possible. It's that PLL_CTRL signal that's used as an error signal for the ALS DIFF arm feedback when ALS DIFF is locked. Today, the carrier was tuned to 157.783 [MHz] to minimize PLL_CTRL. Again, this ensures that the [Hz/ct] of the DIFF_CTRL_INMON signal (or more precisely the VCO itself) remains in the linear regime exactly surrounding the carrier frequency we use for during a nominal ALS DIFF lock.
- Measure the PLL Open Loop Gain TF, using an SR785 connected to the PLL (whose inputs are in the back of the rack); Source -> EXC, Test2 -> Ch1A (Ch1B 50 [Ohm] terminated), Test1 -> Ch2A (Ch2B 50 [Ohm] terminated). Once we have the Open Loop Gain transfer function -- down to the very *very* low frequency of ~1 [Hz], then we can model the entire loop, extracting out all of the frequency dependence -- namely, the 40:1.6 Hz filter.

It turns out, measuring this OLGTF is hard and time consuming, given the extreme amount of gain the loop has at low frequency. In other words, in the nominal configuration, with a 55 [kHz] UGF loop and boosts, the PLL is *very* good at suppressing your 10 [Vpp], ~1-100 [Hz] excitation, so you have to drive at the limit of your analog driver, and integrate for a very long time. Indeed, the only way to get *any* coherence below ~1 [kHz] is to turn the boosts OFF.

As such, we took a ~2 [hr] long TF of the loop with boosts OFF, and then characterized the boosts independently.

Craig and I continue to model the results, but the GPIB templates for the measurements, the measurements themselves, and notes on the measurements live here:
/ligo/svncommon/CalSVN/aligocalibration/trunk/Runs/PreER8/H1/Measurements/ALSDIFF/2015-08-09/
# notes
Notes_ALSdiffPLL_9Aug2015.txt

# templates
TFSR785_DiffBoostsOLGTF_10_100k_09Aug2015.yml
TFSR785_DiffPLLOLGTF_0p5_200_09Aug2015.yml
TFSR785_DiffPLLOLGTF_100_100k_09Aug2015.yml

# olgtfs
PLLOLGTF/TFSR785_09-08-2015_144001.txt   << High Freq, Boosted
PLLOLGTF/TFSR785_09-08-2015_144447.txt   << High Freq, No Boosts
PLLOLGTF/TFSR785_09-08-2015_155915.txt   << Low Freq, No Boosts

# boost TFs
PLLBoostTF/TFSR785_09-08-2015_190215.txt   << Boost 1, z:p = (2k:40) [Hz]
PLLBoostTF/TFSR785_09-08-2015_185858.txt   << Boost 2, z:p = (17k:2k) [Hz] 

As it stands, the UGF of the ALS DIFF PLL (in the nominal, boosted configuration) is 54.8 [kHz], with a phase margin of 48 [deg].

Many thanks to Jenne for her help today!

Non-image files attached to this report

ALSDIFF_FundamentalSchematic.pdf

2015-08-09_ALSDIFFOLGTF.pdf

2015-08-09_ALSDIFFBoostTF.pdf

H1 ISC

Link

sheila.dwyer@LIGO.ORG - posted 21:49, Sunday 09 August 2015 (20364)

phasing refl 9 WFS

Jenne, Gabriele, Sheila

After the calibration work and before the Solomon Islands earthquake, we got a chance to try phasing refl 9 WFS. The first of the attached screenshots show the phase before we started, and the second shows the phases now.

We tuned them by injecting a line in the mode cleaner length at 11Hz, with the ASC on and 3 Watts of input power. When we started the signal in I and Q was about equal, when we finished most of the quadrants had a factor of 3-4 more signal in I than Q. REFL B quadrant 1 was strange, we weren't able to change the amplitude of the line, but the noise in the two quadrants was clearly changing as we rotated the phase.

We then made a pitch excitation in CHARD and saw about 8 dB more signal in I than Q for both REFL A and B.

We think these settings should be OK for relocking, because the IFO stayed locked while we were changing them. We haven't tested this though because of the earthquake.

Images attached to this report

H1 AOS

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jeffrey.kissel@LIGO.ORG - posted 11:08, Sunday 09 August 2015 - last comment - 23:12, Sunday 09 August 2015(20360)

H1 CAL CS Model Restarted to install new TDEP Infrastructure; Frame Builder Restarted

J. Kissel, J. Betzweiser, D. Barker
WP: 5418
ECR: E1500332
II: 1091

I'll put in a more detailed entry describing all the changes once I've finished with the MEDM screen updates, but I've installed an updated CAL-CS front-end model as per all of the documentation mentioned above. This required a DAQ restart, which thankfully was much more successful than is has been in the recent past.

I've confirmed that all old CAL model, bare-essentials, functionality is up and running:
- Whitening filter recently installed for DELTAL_CTRL has been moved to DELTAL_CTRL_SUM, because the filter bank has changed name
- Turned on the newly named DARM_LINE oscillator at 37.3 [Hz], with an amplitude of 0.08 [ct] (I don't think this amplitude is right; I'll confirm the amplitude with Darkhan shortly, it hasn't been aLOGged).
- Filled in the new TM_OUTPUT_MTRX to pass through ETMY into DELTAL CTRL.

I can see that this functionality has returned, as Evan is able to get the IFO back to some power level, and the DELTAL ASD lies roughly on the reference.

Stay tuned for more detail!

Comments related to this report

jeffrey.kissel@LIGO.ORG - 12:26, Sunday 09 August 2015 (20361)

Link

You can follow along in T1500377. Or said more correctly, you'll *need* this document open to help follow along.

We have found actuation strength of the QUAD is varying slowly as a function of time, and we're quite confident that slow, time-dependent, charge on the test mass is changing the test mass actuation strength alone (relative to the upper stages of the quad). As such, and before the PUM / TST crossover is in the gravitational wave band, we need to be able to independently track the ESD strength as a function of time, with respect to the overall actuation strength. We have explored several different methods for potentially compensating the variation that we see (see T1500422 for discussion), and the method that results in the least amount of systematic error in the correction needs new front-end infrastructure. This update is to install said infrastructure.

Some of the details:
(1) New channels stored into science frames for storing each stage of actuation independently. These new channels are stored at 4096 [Hz].
$(IFO):CAL-DELTAL_CTRL_TST_DQ
$(IFO):CAL-DELTAL_CTRL_PUM_DQ
$(IFO):CAL-DELTAL_CTRL_UIM_DQ
Just like the $(IFO):CAL-DELTAL_CTRL_DQ channel, these channels will be whitened to avoid single-precision errors. Note that, for now, I've installed the same whitening filters, i.e.
      zpk([1;1;1],[500;500;500],1,"n)
but we'll need to do the same kind of study that Shivaraj did to make sure they're not limited by precision errors.

Also, in doing so, I've *reduced* the frame rate for $(IFO):CAL-DELTAL_CTRL_DQ also to 4096 [Hz].

Note, for offline analysis, this means one now needs to account for the DAQ down sampling filter between 16 [kHz] and 4 [kHz], which is detailed as the "x4" filter in T1400719.

(2) There are LOTS of new EPICs records to support the calculations defined in Eqs. 9, 11, 12, and 15 of T1500377. While we thought that the GDS calibration pipeline would be able to simply absorb EPICs records that housed the model parameter values (e.g. A_{0}^{tst}, A_{0}^{pu}, C_{0}, G_{0}) at each calibration line frequency, Maddie tested the new code, and found memory issues with all of the calucaltions that were necessary.

As such, now, we not only store the "raw" parameters values, but from those values, the contant / reference / "_{0}" terms in the above mentioned equations are calculated in the front-end. It's a mess of complex analysis, but the new EPICs records, and there associated relation to the above equations are mentioned below. 
for f_{tst} @ ~ 35 [Hz]
    User entered EPICs records:
    $(IFO):CAL-CS_TDEP_ESD_LINE1_REF_OLG_$(REAL,IMAG)             G_{0}                @ f_{tst}
    $(IFO):CAL-CS_TDEP_ESD_LINE1_REF_D_$(REAL,IMAG)               D                    @ f_{tst}
    $(IFO):CAL-CS_TDEP_ESD_LINE1_REF_C_$(REAL,IMAG)               C_{0}                @ f_{tst}
    $(IFO):CAL-CS_TDEP_ESD_LINE1_REF_C_NOCAVPOLE_$(REAL,IMAG)     C_{res}              @ f_{tst}
    $(IFO):CAL-CS_TDEP_ESD_LINE1_REF_A_TST_$(REAL,IMAG)           A_{0}^{tst}          @ f_{tst}
    $(IFO):CAL-CS_TDEP_ESD_LINE1_REF_A_PUM_$(REAL,IMAG)           A_{0}^{pum}          @ f_{tst}
    $(IFO):CAL-CS_TDEP_ESD_LINE1_REF_A_UIM_$(REAL,IMAG)           A_{0}^{uim}          @ f_{tst}
    $(IFO):CAL-CS_TDEP_ESD_LINE1_REF_A_TOP_$(REAL,IMAG)           A_{0}^{top}          @ f_{tst}

    Calcalulated records:
    $(IFO):CAL-CS_TDEP_ESD_LINE1_REF_A_TST_MODSQ                  |A_{0}^{tst}|^2      @ f_{tst}
    $(IFO):CAL-CS_TDEP_ESD_LINE1_REF_A_TST_NEGINV_$(REAL,IMAG)    - (1 / A_{0}^{tst})  @ f_{tst}    for Eq. 9
    $(IFO):CAL-CS_TDEP_ESD_LINE1_REF_A_USUM_$(REAL,IMAG)           A_{0}^{pu}          @ f_{tst}    = A_{0}^{top} + A_{0}^{uim} + A_{0}^{pum}
    $(IFO):CAL-CS_TDEP_ESD_LINE1_REF_A_USUM_MODSQ                 |A_{0}^{pu}|^2       @ f_{tst}
    $(IFO):CAL-CS_TDEP_ESD_LINE1_REF_A_USUM_INV_$(REAL,IMAG)      (1 /  A_{0}^{pu})    @ f_{tst}         
    $(IFO):CAL-CS_TDEP_ESD_LINE1_REF_C_MODSQ                      |C_{0}|^2            @ f_{tst}
    $(IFO):CAL-CS_TDEP_ESD_LINE1_REF_INVCLG_$(REAL,IMAG)          (1 + G_{0}) / C_{0}  @ f_{tst}    for Eq. 9

for f_{pcal} @ ~ 35 [Hz] (which are currently running on PCALY)
    User entered EPICs records:
    $(IFO):CAL-CS_TDEP_PCALY_LINE1_REF_OLG_$(REAL,IMAG)           G_{0}                @ f_{pcal}
    $(IFO):CAL-CS_TDEP_PCALY_LINE1_REF_D_$(REAL,IMAG)             D                    @ f_{pcal}
    $(IFO):CAL-CS_TDEP_PCALY_LINE1_REF_C_$(REAL,IMAG)             C_{0}                @ f_{pcal}
    $(IFO):CAL-CS_TDEP_PCALY_LINE1_REF_C_NOCAVPOLE_$(REAL,IMAG)   C_{res}              @ f_{pcal}
    $(IFO):CAL-CS_TDEP_PCALY_LINE1_REF_A_TST_$(REAL,IMAG)         A_{0}^{tst}          @ f_{pcal}    
    $(IFO):CAL-CS_TDEP_PCALY_LINE1_REF_A_PUM_$(REAL,IMAG)         A_{0}^{pum}          @ f_{pcal}
    $(IFO):CAL-CS_TDEP_PCALY_LINE1_REF_A_UIM_$(REAL,IMAG)         A_{0}^{uim}          @ f_{pcal}
    $(IFO):CAL-CS_TDEP_PCALY_LINE1_REF_A_TOP_$(REAL,IMAG)         A_{0}^{top}          @ f_{pcal}
    
    Calcalulated records:
    $(IFO):CAL-CS_TDEP_PCALY_LINE1_REF_A_USUM_$(REAL,IMAG)        A_{0}^{pu}           @ f_{pcal}    = A_{0}^{top} + A_{0}^{uim} + A_{0}^{pum}
    $(IFO):CAL-CS_TDEP_PCALY_LINE1_REF_G_MODSQ                    |G_{0}|^{2}          @ f_{pcal}
    $(IFO):CAL-CS_TDEP_PCALY_LINE1_REF_G_TWICEREAL                2 Re{G_{0}}          @ f_{pcal}
    $(IFO):CAL-CS_TDEP_PCALY_LINE1_REF_ONEPLUSG_MODSQ             |1+G_{0}|^2          @ f_{pcal}    
    $(IFO):CAL-CS_TDEP_PCALY_LINE1_REF_CLG0_$(REAL,IMAG)          C_{0} / (1 + G_{0})  @ f_{pcal}    for Eq. 9 and Eq. 11

for f_{ctrl} @ ~ 35 [Hz]
    User entered EPICs records:
    $(IFO):CAL-CS_TDEP_DARM_LINE1_REF_OLG_$(REAL,IMAG)            G_{0}                @ f_{ctrl}
    $(IFO):CAL-CS_TDEP_DARM_LINE1_REF_D_$(REAL,IMAG)              D                    @ f_{ctrl}
    $(IFO):CAL-CS_TDEP_DARM_LINE1_REF_C_$(REAL,IMAG)              C_{0}                @ f_{ctrl}
    $(IFO):CAL-CS_TDEP_DARM_LINE1_REF_C_NOCAVPOLE_$(REAL,IMAG)    C_{res}              @ f_{ctrl}
    $(IFO):CAL-CS_TDEP_DARM_LINE1_REF_A_TST_$(REAL,IMAG)          A_{0}^{tst}          @ f_{ctrl}    
    $(IFO):CAL-CS_TDEP_DARM_LINE1_REF_A_PUM_$(REAL,IMAG)          A_{0}^{pum}          @ f_{ctrl}    
    $(IFO):CAL-CS_TDEP_DARM_LINE1_REF_A_UIM_$(REAL,IMAG)          A_{0}^{uim}          @ f_{ctrl}    
    $(IFO):CAL-CS_TDEP_DARM_LINE1_REF_A_TOP_$(REAL,IMAG)          A_{0}^{top}          @ f_{ctrl}    

    Calcalulated records:
    $(IFO):CAL-CS_TDEP_DARM_LINE1_REF_A_TST_MODSQ                 |A_{0}^{tst}|^2      @ f_{ctrl}
    $(IFO):CAL-CS_TDEP_DARM_LINE1_REF_A_TST_NEGINV_$(REAL,IMAG)   - (1 / A_{0})        @ f_{ctrl}
    $(IFO):CAL-CS_TDEP_DARM_LINE1_REF_A_USUM_$(REAL,IMAG,MODSQ)   A_{0}^{pu}           @ f_{ctrl}  = A_{0}^{top} + A_{0}^{uim} + A_{0}^{pum}
    $(IFO):CAL-CS_TDEP_DARM_LINE1_REF_A_USUM_INV_$(REAL,IMAG)     1 / A_{0}            @ f_{ctrl}  This is the constant part of Eq. 12
    $(IFO):CAL-CS_TDEP_DARM_LINE1_REF_C_MODSQ                     |C_{0}|^{2}          @ f_{ctrl}
    $(IFO):CAL-CS_TDEP_DARM_LINE1_REF_INVCLG_$(REAL,IMAG)         (1 + G_{0}) / C_{0}  @ f_{ctrl}  

For Eq 9,
    Calculated Record:
    $(IFO):CAL-CS_TDEP_REF_INVA_CLGRATIO_TST_$(REAL,IMAG)         - (1 / A_{0}^{tst})|f_tst *  C_{0} / (1 + G_{0})|f_pcal * (1 + G_{0}) / C_{0}|f_tst
                                                                  This is the constant part of Eq. 9
For Eq 11,
    Calculated Record:
    $(IFO):CAL-CS_TDEP_REF_CLGRATIO_CTRL_$(REAL,IMAG)             C_{0} / (1 + G_{0})|f_pcal * (1 + G_{0}) / C_{0} |f_ctrl
                                                                  This is the constant part of Eq. 11

for f_{pcal2} @ ~330 [Hz] (which are currently running on PCALY)
    User entered EPICs records:
    $(IFO):CAL-CS_TDEP_PCALY_LINE2_REF_OLG_$(REAL,IMAG)           G_{0}                @ f_{pcal}
    $(IFO):CAL-CS_TDEP_PCALY_LINE2_REF_D_$(REAL,IMAG)             D                    @ f_{pcal}     For Eq. 15 
    $(IFO):CAL-CS_TDEP_PCALY_LINE2_REF_C_$(REAL,IMAG)             C_{0}                @ f_{pcal}
    $(IFO):CAL-CS_TDEP_PCALY_LINE2_REF_C_NOCAVPOLE_$(REAL,IMAG)   C_{res}              @ f_{pcal}     For Eq. 15 
    $(IFO):CAL-CS_TDEP_PCALY_LINE2_REF_A_TST_$(REAL,IMAG)         A_{0}^{tst}          @ f_{pcal}     For Eq. 15 
    $(IFO):CAL-CS_TDEP_PCALY_LINE2_REF_A_PUM_$(REAL,IMAG)         A_{0}^{pum}          @ f_{pcal}
    $(IFO):CAL-CS_TDEP_PCALY_LINE2_REF_A_UIM_$(REAL,IMAG)         A_{0}^{uim}          @ f_{pcal}
    $(IFO):CAL-CS_TDEP_PCALY_LINE2_REF_A_TOP_$(REAL,IMAG)         A_{0}^{top}          @ f_{pcal}
    
    Calcalulated records:
    $(IFO):CAL-CS_TDEP_PCALY_LINE2_REF_A_USUM_$(REAL,IMAG)        A_{0}^{pu}           @ f_{pcal}    = A_{0}^{top} + A_{0}^{uim} + A_{0}^{pum},  For Eq. 15 
    $(IFO):CAL-CS_TDEP_PCALY_LINE2_REF_G_MODSQ                    |G_{0}|^{2}          @ f_{pcal}
    $(IFO):CAL-CS_TDEP_PCALY_LINE2_REF_G_TWICEREAL                2 Re{G_{0}}          @ f_{pcal}
    $(IFO):CAL-CS_TDEP_PCALY_LINE2_REF_ONEPLUSG_MODSQ             |1+G_{0}|^2          @ f_{pcal}    
    $(IFO):CAL-CS_TDEP_PCALY_LINE2_REF_CLG0_$(REAL,IMAG)          C_{0} / (1 + G_{0})  @ f_{pcal}    for Eq. 9 and Eq. 11


I've not yet installed all of the above user defined EPICs records, bare with us while we get the MEDM infrastructure updated, and then we'll fill in the values needed. Note, the only difference from what I installed on Friday (see LHO aLOG 20291), is what was quoted for the "ESD_LINE" there is now called "DARM_LINE," and I need to install new values for the *actual* "ESD_LINE".

Also, I've committed all model changes to the userapps svn repo, and I have captured all of the new new settings (thus far) in the SDF system, initializing new channels, and removing old channels.

Images attached to this comment

darkhan.tuyenbayev@LIGO.ORG - 23:12, Sunday 09 August 2015 (20365)

Link

JeffK, Darkhan

MEDM screens are undergoing changes to repliate recent front-end model changes (see attached screenshots). The screens are currently in the state at which we can input parameters needed for calibration: C_0, D_0, A_0^{tst}, A_0^{pum}, A_0^{uim}, A_0^{top}, line frequency and amplitude.

Current status of the screens have been committed to SVN (@ r11235). The modification process will continue tomorrow.

We also found a bug in front-end model that need to be fixed (using Im instead of Re part of a quantity, see attachment).

Images attached to this comment

H1 SEI

Link

hugh.radkins@LIGO.ORG - posted 10:31, Sunday 09 August 2015 (20359)

EndX HEPI Pump Controller Appears to be frozen

Not just lost communications as from 20333. This is an SEI system. If this system has only lost communications then sure do nothing. But that state should be confirmed. If it isn't actually running then more action is call for.

At the end station, the controller computers front panel heartbeat light is not flashing. The VFD Frequency output to the motor is not changing. These two indicators convince me that the control is in fact not running. The analog pressure gauge at the pump station is reading about 78 PSI. This indicates that we got lucky and the fixed output to the VFD is pretty close to what we need to maintain the ideal pressure. About 80psi out of the pump station is nominal. Looking at the trends of the pressures and motor drive, attached, it appears they latched below the average of the normal variation. So while the pressures are trending down (only based on where the trends froze and the analog gauge,) they are doing so at a slow rate and we could be lucky and make it to Tuesday.

The IFO just dropped and Evan gave me the okay to restart. The SSH failed though so a power cycle of the computer is called for. This will certainly take down the Pump Station and therefore the SEI platforms. So we elect to wait.

If the trend had been steeper, the next indicator would have been a tripping of the HEPI as the pressures dropped too low to drive the requested offset. Meanwhile the performance of the platform would likely have become weird as the actuators were attemping to work at a pressure outside their design. Had the trend been up rather than down, if the actuators were still working at 125psi, next the in-line pressure relief valve would have opened and closed repeatedly as the pressure exceeded and dropped below the threshold. Who knows if the HEPI platform would survive this but eventually enough fluid would have been lost to the pressure relief path that the reservoir fluid trip would abruptly trip the pump station and of course the platfrom, ISI, IFO and recovery would be more painful.

Images attached to this report

H1 ISC

Link

jenne.driggers@LIGO.ORG - posted 20:32, Saturday 08 August 2015 - last comment - 00:01, Sunday 09 August 2015(20356)

Locking attempts with higher TCS power

[Jenne, Gabriele]

It's been quite a struggle to get the IFO relocked today. Last night, Evan et al. ran a TCS tuning test, which left the TCSX CO2 power at 0.43 W. Yesterday, it had been at 0.23 W.

Just now (03:12:00-ish UTC) we returned the TCSX power to 0.23 W, and we're leaving it to re-equilibrate.

Separately, although we don't think this affected our ability to lock, the SYS_DIAG guardian is dead. It went into error at some point, and reloading it didn't clear the error. Stefan tried to restart it, but it never came back up. We await expert advice on fixing this.

It looks like (see log messages below) there is a syntax error somewhere, although no one (in the control room at least....) was editing it. Perhaps we entered some "if" loop that doesn't usually get run, so that's why this hasn't been caught before?

2015-08-09T00:33:40.06923   File "/opt/rtcds/userapps/release/sys/h1/guardian/SYS_DIAG_tests.py", line 403
2015-08-09T00:33:40.06929     yield 'ISI {} WD saturation count is greater than 75% of max'.format(chamber)
2015-08-09T00:33:40.06932         ^
2015-08-09T00:33:40.06939 SyntaxError: invalid syntax
2015-08-09T00:33:40.09600 guardian process stopped: 255 0

Comments related to this report

evan.hall@LIGO.ORG - 23:58, Saturday 08 August 2015 (20357)GRD

Link

There were some typos in the SEI_STATE test that were preventing the node from restarting.

I destroyed and created the node (probably unnecessary), and then started it.

Also, SYS_DIAG_tests.py had not been checked in to the SVN for quite some time.

jameson.rollins@LIGO.ORG - 00:01, Sunday 09 August 2015 (20358)

Link

Thanks, Evan. It was definitely unecessary to destroy/recreate the node, but it doesn't hurt anything. Probably all you needed to do was just reload.

H1 DetChar (DetChar)

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gabriele.vajente@LIGO.ORG - posted 18:35, Saturday 08 August 2015 - last comment - 11:27, Thursday 13 August 2015(20355)

Dust glitches

I looked into the glitches created by Robert's dust injections. In brief: some of the glitches, but not all of them, look very similar to the loud glitches we are hunting down

Here is the procedure:

select all drops of the range in the two hours of injection
for each one, load three minutes of data, compute the 30-300 Hz BLRMS and find the glitch tims as the maximum of the BLRMS peaks

In this way I could detect a total of 42 glitches. The last plot shows the time of each glitch (circles) compared with the time of Robert's taps (horizontal lines). They match quite well, so we can confidently conclude that all the 41 glitches are due to dust. The times of my detected glitches are reported in the attached text file, together with a rough classification (see below)

I then looked at all the glitches, one by one, to classify them based on the shape. My goal was to see if they are similar to the glitches we've been hunting.

A few of them (4) are not clear (class 0), some others (14) are somehow slower than what we are looking for (class 3). Seven of them have a shape very close to the loud glitches we are looking for (class 1), and 16 more are less obvious but they could still be of the same kind, just larger (class 2).

See the attached plots for some examples of classes.

Images attached to this report

Comments related to this report

thomas.massinger@LIGO.ORG - 09:24, Wednesday 12 August 2015 (20473)DetChar

Link

It seems the text file of glitch times didn't make it into the attachments, would you mind trying to attach it again?

gabriele.vajente@LIGO.ORG - 09:37, Wednesday 12 August 2015 (20474)

Link

Ops! Here's the file with the glitch times.

Non-image files attached to this comment

dust_glitches.txt

stefan.ballmer@LIGO.ORG - 10:38, Thursday 13 August 2015 (20510)

Link

Gabriele,

Did you check which of Robert's glitches caused any ADC/DAC adjurations? The glitch shape will start changing significantly once the amplitude is big enough to start saturations. 

PS: The ODC master channel has a bit that will toggle to red (0) is any of the subsystems reports a saturation (with 16k resolution) - it might be exactly what you need in this case.

andrew.lundgren@LIGO.ORG - 11:27, Thursday 13 August 2015 (20511)

Link

Stefan, I checked for some ADC and DAC overflows during this data segment. The OMC DCPDs ADCs overflowed during several of these. There were still some with SNRs of 10,000 that didn't overflow like this. The segments are pasted below. They're a bit conservative because I'm using a 16 Hz channel without great timing. There were no ADC overflows in POP_A, and no DAC overflows in the L2 or L3 of the ETMs. I didn't check anything else. This is not quite the same as what the ODC does, which is a little more stringent. I'm just looking for changes in the FEC OVERFLOW_ACC channels.

    1123084682.4375 1123084682.5625
    1123084957.3750 1123084957.5000
    1123086187.3750 1123086187.5000
    1123086446.8125 1123086447.3750
    1123088113.0625 1123088113.1875
    1123088757.4375 1123088757.6250
    1123088787.1875 1123088787.3125
    1123088832.3125 1123088832.4375
    1123089252.6250 1123089252.7500
    1123089497.2500 1123089497.3750

H1 PEM (DetChar)

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robert.schofield@LIGO.ORG - posted 17:50, Saturday 08 August 2015 - last comment - 12:35, Monday 10 August 2015(20354)

Beam tube particulate injection

I injected particulate by tapping on the beam tube at various locations with a scissors, imitating the taps that the cleaners make by accident. The acceleration measured on the beam tube for similar taps was around 0.1 g with a frequency peak at about 1000 Hz (Link). At each location I made the first tap at the top of the minute and made a tap at every multiple of 5 seconds for 1 or 2 minutes. My tapping uncertainty was about 1 second.

To observe the glitches in DARM I filtered the time series of H1:CAL-DELTA_RESIDUAL_DQ to be dominated by the 120-1000 Hz band, with violin modes notched. The table shows the time and the fraction of taps that made glitches. The distribution of glitch sizes is shown in the Figure. There were roughly the same number of glitches in each size decade.

In summary:

1) Glitches were produced from most regions of the beam tube.

2) Only about 20% of taps produced glitches

3) 9/252 taps produced multiple glitches

4) Only 1 glitch of size comparable to the particulate glitches was observed more than 1s from a tap time in the entire 2 hour lock (DetChar may want to double check this). Thus the data suggest that there is not a reservoir of particles that are freed by the taps but fall later at an exponentially decreasing rate (so it is very unlikely that midnight glitches are particles freed by cleaning and cleaning is unlikely to have increased the background rate).

5) The figure shows that the number of glitches in each size decade was about the same, not increasing with smaller size.

Location on beamtube	Time of first tap. Aug. 8 UTC	Tap spacing (seconds)	Duration (minutes)	Number of taps	Large glitches in DARM within 1s	Large glitches not within 1s
Y2-8 double	15:52:00	5	1	12	4	0
Y2-2 double	15:57:00	5	1	12	2	1, 2s
Y1-2 double	16:02:00	5	1	12	5	0
X2-8 double	16:22:00	5	2	24	7	0
X2-2 double	16:27:00	5	2	24	1	0
X1-2 double	16:33:00	5	2	24	0	0
Y2-8 +1Y single	16:44:00	5	2	24	0	0
Y2-4 +1Y single	16:48:00	5	2	24	1	0
Y1-4 +1Y single	16:53:00	5	2	24	13	0
X2-8 +1X single	17:05:00	5	2	24	13	0
X2-4 +1X single	17:12:00	5	2	24	5	0
X1-4 +1X single	17:18:00	5	2	24	5	0
Number of taps that produced glitches (percentage)					42 (17%)
Total number of glitches					56

Non-image files attached to this report

BTGlitchSizeDist.pdf

Comments related to this report

michael.zucker@LIGO.ORG - 10:34, Monday 10 August 2015 (20375)

Link

This is very interesting. Can you sort and plot the raw time series of the larger glitches according to X vs. Y arm? (The attack should be unipolar and of opposite sign for the two arms.)  

It will also be interesting to note if there is a FWHM dependence on axial position.

andrew.lundgren@LIGO.ORG - 12:35, Monday 10 August 2015 (20377)DetChar

Link

I've attached a list of all Omicron triggers in the lock with SNRs above 100. The columns are the GPS time, peak frequency, and SNR. Rows marked with an X have an ADC overflow in the OMC DCPDs, so they may not be as useful for determining the shape of the glitches.

Several of the glitches have very messy shapes in OMC DCPD. There's a few in the Y arm that have a fairly unambiguous single upward spike, for instance 1123084687.570. The whitened timeseries is attached. The shape is a triangle with a base of roughly 1 or 2 milliseconds. I haven't found anything in the X arm yet with a simple unambiguous shape, but I haven't checked everything.

Images attached to this comment

Non-image files attached to this comment

list_of_beamtube_glitches.txt

H1 ISC

Link

eleanor.king@LIGO.ORG - posted 12:44, Saturday 08 August 2015 (20352)

Attempting to measure SRC gouy phase

Dave O and I have been talking about measuring the SRC guoy phase by dithering optics in teh corner station and looking at the motion of the beam at the AS port. This should allow us to work out the ray transfer matrix for the SRC cavity. I misaligned PRM, and ITMX, and misaligned the SRM slightly so that two beams could be seen on the AS camera: a straight shot beam through the SRM and a beam that had made one round trip of SRY. I put exictations on the optic align stage of BS and PR3 auapensions and tracked the beam motion. I now need to do some further analysis on this. All optics have been returned to their nominal positions.

H1 ISC

Link

jeffrey.kissel@LIGO.ORG - posted 11:57, Saturday 08 August 2015 - last comment - 19:57, Saturday 15 August 2015(20351)

Where StripTool Templates Live

J. Kissel

I always forget where the StripTool templates for the wall displays live, and my first instinct is to search the aLOG for ".stp". For future me, here're there locations:
/ligo/home/ops/Templates/StripTool/
ASC_Pitch.stp
ASC_WFS_Central_1.stp
ASC_WFS_Central_2.stp
ASC_Yaw.stp
BOUNCE_ROLL_DAMP.stp
bounceroll.stp
DAMP_ROLL.stp
ETMs.stp
IFO_LOCKING.stp
IfoLock.stp
initial_alignment.stp
oldPRMIsb.stp
oplevsPIT.stp
oplevsYAW.stp
PITCH_ASC_CONTROL_SIGNALS.stp
PRC-SRC.stp
PRMIsb.stp      <<< This is what usually is displayed to show the lock acquisition process
RM-OM.stp
X-Arm.stp
Y-Arm.stp
YAW_ASC_CONTROL_SIGNALS.stp

Comments related to this report

evan.hall@LIGO.ORG - 19:57, Saturday 15 August 2015 (20558)

Link

While we're at it, the I copied the seismic FOM into userapps/isc/h1/scripts/Seismic_FOM_split.xml and checked it into the SVN, since the original directory (/ligo/home/controls/FOMs/) is not version controlled.

H1 ISC (DetChar, ISC, SUS)

Link

daniel.hoak@LIGO.ORG - posted 05:27, Saturday 08 August 2015 - last comment - 13:22, Saturday 08 August 2015(20345)

violin mode first harmonic whack-a-mole

Dan, Nutsinee, Evan

Tonight we explored the damping settings for the first harmonic of the violin modes. Our goal was to reduce the intensity fluctuations on the DCPDs enough that we could engage a second stage of whitening.

We were able to damp nearly all of the peaks that were visible between 1002-1010Hz, these correspond to the ETMs and are well separated in frequency. The phases required for the damping filters are not amenable to broad bandpass filters (ETMX in particular is pretty random). In the end I dealt with each mode one at a time, by hand.

After a while I got tired of saving the filters, so I just recorded the gain and phase that led to smooth damping. These settings can be easily replicated using a 20mHz bandpass filter around the frequency of the line.

We worked on the modes in order of height. Eventually we ran out of steam, but the first harmonic lines in the spectrum have been reduced by a factor of five compared to the reference. The RMS of the DCPD signals (about 300 counts) is now dominated by the residual length motion around 3-4Hz. We should be able to engage more whitening if we want to get some headroom over the ADC noise.

The frequencies in the table below are from Keith Riles' list o' lines in ER7: alog 19190. Eventually this will get propagated to Nutsinee's new violin mode wiki page.

Mode Frequency	Optic	Damping gain & phase	Filter settings for damping
991.7478
991.9345
992.4256
992.7944	ITMX	266dB, +/-180deg
994.2767	ITMX	260dB, +/-180deg
994.6456
994.7331
994.8973
995.3650
995.6447	ITMX	260dB, 0deg
996.2517
996.5296	ITMX	260dB, 0deg
997.7169
997.8868
998.6645
998.8050

1003.6673	ETMX	260dB, -60deg	ETMX L2 DAMP MODE2 FM6, FM8, FM9, gain=-50
1003.7788	ETMX	260dB, 130deg	ETMX L2 DAMP MODE3 FM6, FM8, FM9, gain=50
1003.9071	ETMX	280dB, 0deg	ETMX L2 DAMP MODE8 FM6, FM9, gain=1000
1004.0782	ETMX	272dB, +/-180deg
1004.5370	ETMX	260dB, 0deg	ETMX L2 DAMP MODE1 FM6, FM9, gain=100
1005.1694	ETMX	266dB, 0deg
1005.9378	ETMX	266dB, +/-180deg
1006.5031	ETMX	266dB, +/-180deg

1008.4502
1008.4938	ETMY	272dB, 83deg	ETMY L2 MODE3 FM1, FM3, FM4, gain=400
1009.0273	ETMY	266dB, +/-180deg	ETMY L2 MODE7 FM6, FM9, gain=-200
1009.2089
1009.4402	ETMY	272dB, 67deg	ETMY L2 MODE3 FM1, FM3, FM4, gain=400
1009.4863	ETMY	272dB, 67deg	ETMY L2 MODE3 FM1, FM3, FM4, gain=400
1009.6234
1009.6825

Images attached to this report

Comments related to this report

nutsinee.kijbunchoo@LIGO.ORG - 13:22, Saturday 08 August 2015 (20353)

Link

Added to the Wiki.

H1 SUS (DetChar)

Link

nutsinee.kijbunchoo@LIGO.ORG - posted 03:32, Saturday 08 August 2015 (20346)

Violin Mode Wikipage!

Dan, Nutsinee

Since the knowledge of the violin mode damping is scatted all over the alog, here's the H1 Violin Mode wikipage. The table includes frequencies, test masses, damp settings, and the filters that are being used to damp those modes. All the violin fundamentals are in. Harmonics are coming.

Enjoy!

H1 ISC (ISC)

Link

stefan.ballmer@LIGO.ORG - posted 22:28, Friday 07 August 2015 (20344)

501.606Hz mode on ITMY

Increased the damping of ITMY MODE5 to 400. This now makes the 501.606Hz mode fall at a rate of just under a decade per hour.

H1 CAL (SUS)

Link

kiwamu.izumi@LIGO.ORG - posted 22:06, Friday 07 August 2015 - last comment - 09:25, Tuesday 11 August 2015(20334)

Pcal now uses sus dynamical models

The Pcal RX and TX photodetectors now have filters which simulate the suspension dynamical response in order to convert the signals into displacements. The filters are installed and enabled.

Since each signal chain is whitened, one needs to apply two poles at 1 Hz with a gain of 1 when using these signals.

[Background]

Traditionally Pcal uses a free-mass approximation for the suspension responses which is a simple 1/f^2. This can introduce undesired inaccuracy at low frequencies. Even though we know the accuracy is not too terrible at around 30 Hz, where the lowest frequency Pcal lines are, we decided to replace the old 1/f^2 approximation with the dynamical suspension model.

[Tagging suspension models]

Prior to the update of the filters, we take this opportunity to tag our suspension models. As usual, I used Jeff's code to create tags. The scripts is in:

/ligo/svncommon/SusSVN/sus/trunk/Common/MatlabTools/tagsusdynamicalmodel.m @rv7754

Also, I updated h1etmx.m which is a parameter file dedicated for creating the h1etmx suspension model. I only updated the fundamental violin mode. I confirmed that the mass was correct since this is critical for Pcal. As for h1etmy.m, it was already good from the beginning. The mass is correct and the violin modes are specified up to 8th harmonics. So I did not update it.

The tagged models are now in SVN:

quadmodelproduction-rev7652_ssmake4pv2eMB5f_fiber-rev3601_h1etmx-rev7641_released-2015-08-07.mat
quadmodelproduction-rev7652_ssmake4pv2eMB5f_fiber-rev3601_h1etmy-rev7640_released-2015-08-07.mat

[Script does all at once]

I wrote a matlab script which picks up the tagged suspension models and subsequently quack them into the Pcal TX and RX PD filters. For convenience, the suspension responses are divided into three pieces -- normalized suspension response, zpk([], [1,1], 1, "n") and DC gain in [m/N]. Combining all three makes the complete suspension response. The normalized suspension response has a gain of 1 at DC (technically speaking at 10 mHz) and all the zeros and poles except for two poles at 1 Hz. The two-pole filters are intentionally turned off in order to whiten the whole signal chain. Therefore one has to apply the two poles when calibrating the signals. The attached is a screen shot of how they look in the medm screens.

The script can be found at

/ligo/svncommon/CalSVN/aligocalibration/trunk/Runs/PreER8/H1/Scripts/Pcal/quad_response.m

/ligo/svncommon/CalSVN/aligocalibration/trunk/Runs/PreER8/H1/Scripts/PcThe Pcal RX and TX photodetectors now have filters which simulates the suspension dynamical response in order to convert the signals into displacements. The filters are installed and enabled.

Since each signal chain is whitened, one needs to apply two poles at 1 Hz with a gain of 1 when using these signals.

[Backgrounds]

Traditionally Pcal uses a free-mass approximation for the suspension responses which is a simple 1/f^2. This can introduce undesired inaccuracy at low frequencies. Even though we know the accuracy is not too terrible at around 30 Hz, where the lowest frequency Pcal lines are, we decided to replace the old 1/f^2 approximation with the dynamical suspension model.

[Tagging suspension models]

Prior to the update of the filters, we take this oportunity to tag our suspension models. As usual, I used Jeff's code to create tags. The scripts is in:

/ligo/svncommon/SusSVN/sus/trunk/Common/MatlabTools/tagsusdynamicalmodel.m @rv7754

Also, I updated h1etmx.m which is a paramter file dedicated for creating the h1etmx suspension model. I only updated the fundamental violin mode. I confirmed that the mass was correct since this is critical for Pcal. As for h1etmy.m, it was already good from the beginning. The mass is correct and the violine modes are specificed up to 8th harmonics. So I did not update it.

The tagged models are now in SVN:

quadmodelproduction-rev7652_ssmake4pv2eMB5f_fiber-rev3601_h1etmx-rev7641_released-2015-08-07.mat

quadmodelproduction-rev7652_ssmake4pv2eMB5f_fiber-rev3601_h1etmy-rev7640_released-2015-08-07.mat

[Script does all at once]

I wrote a matlab script which picks up the tagged suspension models and subsequently quack them into the Pcal TX and RX PD filters. For convenience, the suspension responses are divided into three pieces -- normalized suspension response, zpk([], [1,1], 1, "n") and DC gain in [m/N]. Combining all three makes the complete suspension response. The normalized suspension response has a gain of 1 at DC (technically speaking at 10 mHz) and all the zeros and poles except for two poles at 1 Hz. The two-pole filters are intentionally turned off in order to whiten the whole signal chain. Therefore one has to apply the two poles when calibrating the signals. The attached is a screen shot of how they look in the medm screens.

The can be found at

/ligo/svncommon/CalSVN/aligocalibration/trunk/Runs/PreER8/H1/Scripts/Pc

Images attached to this report

Comments related to this report

sudarshan.karki@LIGO.ORG - 14:13, Sunday 09 August 2015 (20362)

Link

Prior to this change, photodiodes (TX and Rx PD) calibartion coeffcient were reported in metres/Volt *(1/f^2). Now with the suspension model in place, we have calibrated the photodiodes in terms of Force Coefficient (N/V). The filter banks, as shown in the attachement above, now reflect these new N/V calibration factors. Appropriate changes have been made to the DCC document (T1500252) as well.

kiwamu.izumi@LIGO.ORG - 09:25, Tuesday 11 August 2015 (20420)

Link

This is an additional note about the quack function -- when I was using quack, I had a difficulty in quacking an state-space suspension model into a foton filter. See the detail below.

In matlab, I had been using something like:

quad.d = minreal( zpk( c2d(quad.ss, smaplingTime, 'tustin' ), tolerance )

where quad.ss is a state-space representation of the quad suspension response, and samplingTime in this case is 1/16384 sec. The reason why I used the minreal function is that otherwise it would come with too many number of poles and zeros which exceeded the number of poles and zeros that foton can handle. I tried adjusting the tolerance of minreal in order to reduce the number of poles and zeros, but it was extremely difficult because it ended up with either too many poles/zeros or too few poles and zeros.

Instead, I tried the following command which at the end worked fine:

quad.d = c2d( minreal( zpk(plant.ss), tolerance ), samplingTime, 'tustin');

The combination of the functions are exactly the same, but the ordering is different. It does minreal before c2d. This allowed me for having a reasonable number of poles and zeros.

H1 ISC

Link

stefan.ballmer@LIGO.ORG - posted 21:50, Friday 07 August 2015 - last comment - 08:16, Wednesday 12 August 2015(20342)

2nd thermal tuning tun started

Evan's script to automatically take frequency and intensity transfer functions is now running. 

As a reminder, the summing note B path was repurposed for this run. The interferometer won't relock unless we reconnect them. 

At 4:20 UTC we started changing the TCS X CO2 power from 0.23W to 0.4W. The rotation stage took us on some full circles, but by 04:23 we reached 0.4W. 

At 4:45 I increased the frequency noise drive by a factor of 5 to gain back coherence.

At 6:04 I decreased the power to 0.35W - trying to find the minimal frequency noise point. (The coupling sign had changed.)

At 6:34 I reduced it to 0.3W.

Comments related to this report

evan.hall@LIGO.ORG - 06:07, Saturday 08 August 2015 (20348)

Link

It wasn't really clear from this run where the minimum in frequency coupling was (maybe because of the 5 W blast at the start), so I went back to 0.23 W of heating and let the frequency coupling reach a steady state (by driving the same line as before, this time with 100 ct amplitude). Around 2015-08-08 10:18:30 I kicked the TCS power to 0.53 W and started the datataking again.

Once the frequency coupling reached a steady state again, I made a guess for what TCS power we need to minimize the coupling. At 12:43:30 I changed the TCS power to 0.43 W.

I have revered the ALS/CARM cabling to its nominal configuration.

evan.hall@LIGO.ORG - 08:16, Wednesday 12 August 2015 (20470)

Link

Preliminary analysis from this second run suggests that, of the TCS powers that we probed, our current TCS power is the best in terms of intensity noise coupling.

The attached plot shows the transfer function which takes ISS outer loop PD #1 (in counts) to DCPD A (in milliamps). The coloring of the traces just follows the sequence in which they were taken. Black was taken at 0.23 W of TCS power, and the lightest gray was taken at 0.53 W of TCS power.

The measurements and the plotting script are in evan.hall/Public/Templates/LSC/CARM/FrequencyCouplingAuto/Run2.

Images attached to this comment

H1 AOS

Link

darkhan.tuyenbayev@LIGO.ORG - posted 21:25, Friday 07 August 2015 - last comment - 12:41, Tuesday 11 August 2015(20341)

Changed Delta L_{res} and Delta L_{ctrl} whitening filters

Shivaraj, Darkhan

Summary

We replaced whitening filters on Delta L_{res} output channel with 2 zeros and 2 poles zpk, and Delta L_{ctrl} with 3 zeros and 3 poles zpk.

Details

Madeline uses FIR filters to dewhiten Delta L_{res} and Delta L_{ctrl} in GDS scripts. To make it easier to generate shorter dewhitening FIR filters for these channels she requested to replace the existing 5 zeros and 5 poles zpk filters in both of these channels with simpler, less poles and zeros zpk's.

Shivaraj designed new FIR filters for both of these channels, and we implemented them today around 1pm.

Power spectrum of H1:CAL-CS_DARM_DELTAL_CTRL_WHITEN_OUT before applying new whitening filter plotted in attached "H1-CAL-CS_DARM_DELTAL_CTRL_WHITEN_OUT_z5x1_p5x100_MAG.pdf". After applying new whitening filter, zpk([1; 1; 1], [500; 500; 500], 1), unfortunately the interferometer wasn't stable to take a spectrum measurement after I changed the filter, so I couldn't evaluate "whiteness" of the output in this channel.

Power spectrum of H1:CAL-CS_DARM_RESIDUAL_WHITEN_OUT before applying new whitening filter plotted in "H1-CAL-CS_DARM_RESIDUAL_WHITEN_OUT_z5x1_p5x100_MAG.pdf". After applying zpk([1; 1], [500; 500], 1), the spectrum of the same channel is given in "H1-CAL-CS_DARM_RESIDUAL_WHITEN_OUT_z2x1_p2x500_MAG.pdf".

We also plan to implement similar whitening filers on new (not yet existing) channels for Delta L_{TST} and Delta L_{PUM/UIM}.

Images attached to this report

Non-image files attached to this report

H1-CAL-CS_DARM_DELTAL_CTRL_WHITEN_OUT_z3x1_p3x500_MAG.pdf

H1-CAL-CS_DARM_DELTAL_CTRL_WHITEN_OUT_z5x1_p5x100_MAG.pdf

H1-CAL-CS_DARM_RESIDUAL_WHITEN_OUT_z2x1_p2x500_MAG.pdf

H1-CAL-CS_DARM_RESIDUAL_WHITEN_OUT_z5x1_p5x100_MAG.pdf

Comments related to this report

shivaraj.kandhasamy@LIGO.ORG - 10:44, Saturday 08 August 2015 (20350)

Link

Below are plots showing the effect of differnet whitening filters including the one that was being used unitl now (5 x 1Hz zeros and 5 x 100 hz poles). These plots are the basis for new filters for DeltaL residual and DeltaL control. In those plots blue curve corresponds to actual data and other colors represent different whitening filters applied to the data.

Images attached to this comment

shivaraj.kandhasamy@LIGO.ORG - 12:41, Tuesday 11 August 2015 (20431)

Link

With the new filters installed we looked at the DeltaL residual and DeltaL control during a recent lock. Below we have attached the spectrum of both along with DeltaL external as a reference (which is still being used with old 5 x 1 Hz zeros and 5 x 100 Hz pole filter). In the plot the channels are dewhitened with the corresponding filters.

Images attached to this comment

H1 PSL

Link

keita.kawabe@LIGO.ORG - posted 10:42, Friday 07 August 2015 - last comment - 06:22, Saturday 08 August 2015(20319)

ISS injection turned off at 17:30-ish UTC (Jenne, Keita)

This morning, after the IFO was locked, DARM was super noisy in kHz region. ISS error point was also super noisy and the coherence between the two was big.

Turns out that the ISS got noisy at the tail end of the lock stretch from last night, at around 2015-08-07 12:00:00 UTC. That's 5AM in the morning.

We went to the floor and sure enough a function generator was connected to ISS injection point via SR560. We switched them off, disconnected the cable from the ISS front panel, but left the equipment on the floor so the injection can be restarted later.

Images attached to this report

Comments related to this report

evan.hall@LIGO.ORG - 06:22, Saturday 08 August 2015 (20349)

Link

When Stefan and I hooked the injection back up, we found that the digital enable/disable switches weren't doing their jobs. Toggling the outputs of H1:PSL-ISS_TRANSFER2_INJ and H1:PSL-ISS_TRANSFER1_INJ had no effect on the appearance of the noise in DARM.