[Jenne, Kiwamu, Sheila, JeffK]

Today, the interferometer decided that it didn't want to go from ASC_PART2 to ASC_PART3 without some hand-tuning each lock.  However, after some investigation, it's still not entirely clear what the right thing to do is :(

The things we were playing with were the offsets in the CSOFT and DSOFT pitch filter banks (can only be tweaked *after* the loops are on, since there's an integrator always on in each of those filter banks) and the transmon qpds' ASC-[x,y]_TR_[a,b]_[pit,yaw]_OFFSETs.  These things are kind of the same, but you need to adjust the transmon offsets if you want to do some adjusting before the loops are closed, and you need to adjust the CSOFT and DSOFT offsets if you want to do some adjusting after the loops are closed.

We've had locks where we didn't survive if we didn't re-zero the qpd offsets before going to part3, and we've had locks where we didn't survive part3 if we didn't adjust the CSOFT and DSOFT offsets.  But, we've also had locks where the opposite was true.

Anyhow, at this point, I think our advice is to try going through the guardian like normal (no by-hand offsetting), and if that fails one or more times, call a commissioner (it's me for now, so please call).  For example, the last lock, I re-set the qpd offsets during asc part 2, but forgot to engage the CSOFT and DSOFT offsets, and we seemed to be just fine.  So, it's not totally clear yet what the final prescription should be.

GRB alert arrived at 01:37:28UTC, and it's currently 2:22UTC.

H1 was locked before the GRB arrived, and is still locked.

We are about 10 minutes from completing the stand-down time.

Title: 1/6 Shift 16:00-24:00 UTC (8:00-16:00 PST).  All times in UTC.

State of H1: Locking/Commissioning

Shift Summary: We have been struggling to acquire lock all day due to issues with ASC loops.  Commissioners are working on it and hopefully we are nearing success.  Microseism is trending up and is currently at 0.6 um/s.  Wind is calm.

Incoming operator: Cheryl

Activity log:

19:00 Kyle and Gerardo to Mid Y

19:54 Kyle and Gerardo back

23:34 Kyle to Mid Y

23:54 Kyle back

HWInjReport 1132272017 - 1133039434

Performed a run spanning the time period from 1132272017 (Nov 23 2015 00:00:00 UTC) to 1133039434 (Dec 01 2015 21:10:17 UTC)

Parameters

The following parameters were used for this run:

• GPS Start Time = 1132272017 # Beginning of time span, in GPS seconds, to search for injections
• GPS End Time = 1133039434 # Ending of time span, in GPS seconds, to search for injections
• Check Hanford IFO = True # Check for injections in the Hanford IFO frame files.
• Check Livingston IFO = True # Check for injections in the Livingston IFO frame files.
• IFO Coinc Time = 0.012 # Time window, in seconds, for coincidence between IFO injection events.
• Check ODC_HOFT = True # Check ODC-MASTER_CHANNEL_OUT_DQ channel in HOFT frames.
• Check ODC_RAW = True # Check ODC-MASTER_CHANNEL_OUT_DQ channel in RAW frames.
• Check ODC_RDS = True # Check ODC-MASTER_CHANNEL_OUT_DQ channel in RDS frames.
• Check GDS_HOFT = True # Check GDS-CALIB_STATE_VECTOR channel in HOFT frames.
• Check CAL_RAW = True # Check CAL-INJ_ODC_CHANNEL_OUT_DQ channel in RAW frames.
• Report Normal = True # Include normal (IFO-coincident (network injections only), consistent, scheduled, and of known type) injections in report
• Report Anomalous = True # Include anomalous (non-IFO-coincident (network injections only), inconsistent, unscheduled, or of unknown type) injections in report
• Use CONDOR optimizations = True # Enable optimizations that assume execution on a CONDOR machine

Scheduled Injections

There were no injections scheduled to occur within this time period.

Network and IFO Injections

Only a single CAL-INJ reset in L1 was found to occur within this time period

• CALRESET 1132710277.000 (L1)

This was, of course, UNSCHEDULED.

Discussion of Anomalies

No anomalies of interest were found.

HWInjReport 1132084817 - 1132350679

Performed a run spanning the time period from 1132084817 (Nov 20 2015 20:00:00 UTC) to 1132350679 (Nov 23 2015 21:51:02 UTC)

Parameters

The following parameters were used for this run:

• GPS Start Time = 1132084817 # Beginning of time span, in GPS seconds, to search for injections
• GPS End Time = 1132350679 # Ending of time span, in GPS seconds, to search for injections
• Check Hanford IFO = True # Check for injections in the Hanford IFO frame files.
• Check Livingston IFO = True # Check for injections in the Livingston IFO frame files.
• IFO Coinc Time = 0.012 # Time window, in seconds, for coincidence between IFO injection events.
• Check ODC_HOFT = True # Check ODC-MASTER_CHANNEL_OUT_DQ channel in HOFT frames.
• Check ODC_RAW = True # Check ODC-MASTER_CHANNEL_OUT_DQ channel in RAW frames.
• Check ODC_RDS = True # Check ODC-MASTER_CHANNEL_OUT_DQ channel in RDS frames.
• Check GDS_HOFT = True # Check GDS-CALIB_STATE_VECTOR channel in HOFT frames.
• Check CAL_RAW = True # Check CAL-INJ_ODC_CHANNEL_OUT_DQ channel in RAW frames.
• Report Normal = True # Include normal (IFO-coincident (network injections only), consistent, scheduled, and of known type) injections in report
• Report Anomalous = True # Include anomalous (non-IFO-coincident (network injections only), inconsistent, unscheduled, or of unknown type) injections in report
• Use CONDOR optimizations = True # Enable optimizations that assume execution on a CONDOR machine

Scheduled Injections

There were no injections found to be scheduled during this time period.

Network and IFO Injections

There were no injections found to occur during this time period.

Discussion of Anomalies

No anomalies found during this time period.

RickS, Darkhan,

Yesterday, Jan 5, 2016, we took Pcal end-station calibration measurements at EX using WS1 calibration standard. The measurement procedure is described in T1500063.

Rough numbers from dataviewer and GPS times were noted in the attached scan (blank form is taken from T1500062).

A generated report (comparison with previous measurements) was uploaded to DCC T1500129-v3.

At first when we started the measurements we found out that laser power in PcalX is modulated through Pcal hardware injection channels H1:CAL-PINJX_*, we had to restart the measurements after tuning off these excitations.

O1 days 108-110

No restarts reported on any of these days. No CDS front end or DAQ maintenance Tues 5th.

Bottom line: I don't see this mass centering made any difference.  Although I did get the mass within spec, and it remains so, it was difficult as in it took many attempts.  This may still indicate that the machine is not well enough leveled or still something more difficult to fix.

Attached are spectra of the STS2-B (ITMY) and STS2-C (HAM5) and coherences between them early Tuesday and Wednesday morning to compare them before and after the centering done yesterday, I adjusted the times to avoid an EQ Tuesday am.   STS2-A remains rotated out of position so is not included in this comparison.

The attached spectra and coherences don't reveal any great improvement from the centering.  The reference traces are after and the current traces are before the centering.  The coherence and ASD continues to show that the Y channel looks pretty good and the X and Z channels much less so.  If you look at the STS2 channel/axis orientations (see second attachment,) you'll see that the Y channel does not use the U axis sensor, and, the centering of the U axis was the problem axis.  This is why I want to play with the level of the U axis and continue this examination.

Ops Owl Summary: 8:00-16:00UTC

State of H1: unlocked

Commissioners: Jenne, Sheila (fellow), JeffK

Shift Summary:

9:00 Lock and Observing finally

11:45 I realize the LVEA lights were still on, LLO is still down, so briefly out of Observe and I go turn them off, back to Observing right as LLO comes back up

13:45 An earthquake in Mexico knocks us out

14:15 Start trying to lock

15:00 Richard arrives and starts spreading sand around parking lot

15:00 I start initial alignment, high microseism is making locking difficult

Currently in observing at about 75 Mpc. So far everything looks better than last night. Sheila did some ASC tweeking before she left and it seems to have prevented the POP decay so far. Microseism is high-ish, wind is low. EX ISI is occasionally ringing up but I think the microseism is maybe to high to switch to higher blends.

Sheila, Cheryl, Jenne

When Cheryl locked the interferometer after maintence day and calibration work was done this afternoon, the recycling gain was again low, (POP_A_LF around 15500 cnts), around the level we have started at in locks where the recycling gain degraded until loosing the lock over the last few days.  (When the recyclcing gain is stable this is normally around 16500 cnts).  Since LLO was not locked, we took some time to open the refl beam diverter and look at the camera for a msalignement. 

We then opened the PRC1 ASC loops (POP A to PRM, slow loop) and moved PRM by hand, very slowly so that the CHARD and CSOFT loops had time to catch up.  We moved PRMI pit alignment slider from -1419 to -1405 urad, and yaw from 518 to 537 urad.  This increased POP A by about 400 counts.  At the slightly better recycling gain the offsets on POP A were -0.35 for Yaw and -0.3 for pitch.  As Cheryl mentioned in her alog, we lost the lock for reasons I don't really understand while adjusting pitch.  There didn't seem to be any environmental problem, so it would seem likely that it was my PRM pitch adjustment that is to blame, but I was not doing anything different from what I had been doing for the previous half hour. 

We may want to try these QPD offsets as a new set point for the PRC1 loop, depending on what the reccyling gain looks like when Jim finishes locking. 

Cheryl and I also spent some time debugging the PRMI branch, which has had some bugs in it for a while that have probably been causing problems. 

Ops Eve Summary: 00:00-08:00UTC, 16:00-23:59PT

State of H1: unlocked

Commissioners: Jenne, Sheila (fellow), JeffK

Incoming Operator: JimW

Shift Summary:

• H1 unclocked for calibration measurements at EY when I arrived
• I tried locking and ended up doing an initial alignment
• One H1 lock about half way through the shift with good range to start, but low POP_A_LF
• Sheila and Jenne worked of increasing POP_A_LF using PRM, which did improve the signal
• Lockloss, not alignment work, based on the ASC signals before lock loss
• PRM was moved, however it's new position was reset during locking (old p/y offsets -1412.7/515.3, new p/y offsets -1405.3/530.1)
• Relocking revealed some Guardian issues with PRMI to DRMI transition
• Currently H1 has lcoked and made it through DRMI but did not make it to Engage ASC part 1
• POPAIR RF18 and RF90 are popping to 100 or more, but at this time, no locked DRMI
• PRM is in it's old alignment position at 8:12UTC
• Handing off to JimW and Sheila is here

J. Kissel

In efforts to finally nail down the mysterious "zero" around 50 [Hz] in the UIM (see LHO aLOG 24296), I've measured the TOP, UIM, and PUM driver using three different measurement configurations. The hope is that, with this "matrix" of differences, we can find out what's going on with the UIM to see if its something specific to the driver, or specific to the OSEM chain upstream of the driver. From what I've seen watching the measurements go by on the SR785, both the TOP and PUM stage show similar zero-like behavior as the UIM, though the TOP mass has a pole-like behavior above the zero and eventually rolls off. Both the PUM and the UIM look as though they are rolling up to "infinity" by 10 [kHz], without even a phase shift indicating their might be a pole "soon" in frequency.  More detailed analysis and plots to come.

The data has been committed to the repo here:
/ligo/svncommon/CalSVN/aligocalibration/trunk/Runs/PostO1/H1/Measurements/Electronics/
EYPUMDriver/2016-01-05/TFSR785*.txt
EYTOPDriver/2016-01-05/TFSR785*.txt
EYUIMDriver/2016-01-05/TFSR785*.txt
where the key to each driver's measurement set is in the log files,
/ligo/svncommon/CalSVN/aligocalibration/trunk/Runs/PostO1/H1/Measurements/Electronics/
EYPUMDriver/2016-01-05/2016-01-05_EYTOP_Measurement_log.txt
EYTOPDriver/2016-01-05/2016-01-05_EYUIM_Measurement_log.txt
EYUIMDriver/2016-01-05/2016-01-05_EYPUM_Measurement_log.txt

I also attach a white board sketch that indicates each of the measurement configurations.
   (0) [Not shown] The "reference" measurement is identical to the reference setup shown in page 2 of the 2nd attachment in 18518, which is divided out of every transfer function to get rid of the response of the differential driver.
   (1) This is measuring the response of the coil driver as it is typically measured on the bench by CDS. It uses a differential to single-ended receiver and the 40 [ohm] internal load (as I only found out later, the documentation on this box, D1000931 leaves something to be desired), so the response differs from configuration (2) only by a scale factor of 2.
   (2) This is measuring the response of the coil driver as is typically done in the field when the OSEM and/or satellite amplifier is not available. The box (D1100278) is, as far as the coil chain is concerned, only a two 20 [ohm] (for a total of 40 [Ohm]) resistor load.
   (3) This is the "real life" scenario, where we measure the response of the driver with the full SatAmp and OSEM included as a load on the output of the driver. It is in this configuration is where the magic happens, apparently.

After notifying the operator I drove past the CS @ 00:02 and arrived at Y-Mid station @ 00:07.
Started filling CP3 @ 00:08, opened the exhaust check valve bypass valve, then opened LLCV bypass valve 1/2 turn, started to notice flow @ 00:18. and closed the LLCV bypass valve @ 00:19.
5 minutes later I closed the exhaust check valve bypass valve.

Started driving back from Y-Mid @ 00:26, arrived at the CS @ 00:30.

svn up at .../SusSVN/sus/trunk/QUAD/Common/MatlabTools/QuadModel_Production

All current model features are summarized in a table in G1401132.

Update to existing features

The main change in existing features is that the top mass damping now sees both the suspension and the cage, as in real life because we use OSEMs. Consequently, if you input seismic noise to a damped suspension it will enter both mechanically as usual, as well as through the damping loops. See Seismic_Noise_Propagation_2016_01_01.pdf. Page 1 shows longitudinal transfer functions from seismic noise to the test mass with and without the OSEMs seeing the cage. The second page shows the ratio of these transfer functions. Note that the ratio is greater than a factor of 2 at 4.5 Hz. Beyond 10 Hz the maximum is about 20% at about 10.5 Hz.

Two new features 

1. Additional inputs and outputs added to reflect the relative nature of the OSEMs - i.e. they measure relative displacements and actuate between two points

2. Suspension point reaction forces

The discussion above is one consequence of the first new feature. Another is that you can now make transfer functions between seismic noise and the top mass OSEMs, which is dramatically different from the seismic noise to top mass transfer function. See Seismic_to_Top_OSEMs_2016_01_01-2.pdf. These are obtainable in the model with the new 'toposem' field in the 'out' structure given by the generate_QUAD_Model_Production function.

The second new feature is that there are now outputs for the suspension point reaction forces on the ISI. These are obtainable in the model with the new 'suspoint' field in the 'out' structure given by the generate_QUAD_Model_Production function. These reaction forces allow us to dynamically couple the quad model to the ISI model. Thus, if we wanted, we can make one big ISI-SUS model.

Under-the-hood updates

This update includes significant under-the-hood modifications to how the pieces of the model are put together. Essentially, Simulink files now define the connections and signal flow, where previously this was all done with append/connect commands in the generate script. The motivation for this change is to make the model more extensible and maintanable by humans. The append/connect commands had become virtually unreadable with the dozens of inputs and outputs now in the model. Now someone can look at a more intuitive graphical representation in a simulink file to read or modify how the model is layed out.

There are 4 simulink files defining the 4 possible layouts of the quad model:

For reference, this is a summary of the history of model revisions in the svn:

* generate_QUAD_Model_Production.m

rev 7359: now reads foton files for main chain and reaction damping

rev 7436: Changed hard coded DAMP gains to get the correct values for LHO ETMX specifically.

rev 7508: Restored damping filter choice for P to level 2.1 filters as opposed to Keita's modification. Cleaned up error checking code on foton filter files, and allowed handling of filter archive files and files with the full path.

rev 7639: renaming lho etmy parameter file

rev 7642: Adding custom parameter file for each quad. Each one is a copy of h1etmy at this point, since that one has the most available data.

rev 7646: added ability to read live filters from sites, and ability to load custom parameter files for each suspension

rev 7652: updated to allow damping filters from sites from a specific gps time (in addition to the live reading option)

planned future revision - seismic noise will progate through the damping filters as in real life. i.e the OSEMs are relative sensors and measure the displacement between the cage and the suspension.

rev 7920: big update - added sus point reaction forces, top OSEMs act between cage and sus, replaced append/connect command with simulink files

* ssmake4pv2eMB5f_fiber.m

no recent (at least 4 years) functional changes have been made to this file.

* quadopt_fiber.m

- rev 2731: name of file changed to quadopt_fiber.m, removing the date to avoid confusion with Mark Barton's Mathametica files.

- rev 6374: updated based on H1ETM fit in 10089.

- rev 7392: updated pend.ln to provide as-built CM heights according to T1500046

- rev 7912: the update described in this log, where the solidworks values for the inertias of the test mass and pum were put into the model, and the model was then refit.  Same as h1etmy.m.

* h1etmy.m

- rev 7640: created the H1ETMY parameter file based on the fit discussed in 10089.

- rev 7911: the update described in this log, where the solidworks values for the inertias of the test mass and pum were put into the model, and the model was then refit. Same as quadopt_fiber.m.

HWInjReport 1129593617 - 1131828544

Performed a run spanning the time period from 1129593617 (Oct 23 2015 00:00:00 UTC) to 1131828544 (Nov 17 2015 20:48:47 UTC)

Parameters

The following parameters were used for this run:

• GPS Start Time = 1129593617 # Beginning of time span, in GPS seconds, to search for injections
• GPS End Time = 1131828544 # Ending of time span, in GPS seconds, to search for injections
• Check Hanford IFO = True # Check for injections in the Hanford IFO frame files.
• Check Livingston IFO = True # Check for injections in the Livingston IFO frame files.
• IFO Coinc Time = 0.012 # Time window, in seconds, for coincidence between IFO injection events.
• Check ODC_HOFT = True # Check ODC-MASTER_CHANNEL_OUT_DQ channel in HOFT frames.
• Check ODC_RAW = True # Check ODC-MASTER_CHANNEL_OUT_DQ channel in RAW frames.
• Check ODC_RDS = True # Check ODC-MASTER_CHANNEL_OUT_DQ channel in RDS frames.
• Check GDS_HOFT = True # Check GDS-CALIB_STATE_VECTOR channel in HOFT frames.
• Check CAL_RAW = True # Check CAL-INJ_ODC_CHANNEL_OUT_DQ channel in RAW frames.
• Report Normal = True # Include normal (IFO-coincident (network injections only), consistent, scheduled, and of known type) injections in report
• Report Anomalous = True # Include anomalous (non-IFO-coincident (network injections only), inconsistent, unscheduled, or of unknown type) injections in report
• Use CONDOR optimizations = True # Enable optimizations that assume execution on a CONDOR machine

Scheduled Injections

Only two injections were found to be scheduled during this period:

• CBC 1131397639.000 (coherentbbh0_1126259455_)
• CBC 1131405159.000 (coherentbbh0_1126259455_)

However, neither of these injections were found to actually occur within the examined time period.

Network and IFO Injections

There were no normal injections that occurred within the examined period. There were a number CAL-INJ resets, all single-IFO with the same curious pattern to the frame flags as denoted in the immediately prior HWInj report (https://alog.ligo-wa.caltech.edu/aLOG/index.php?callRep=23485). There was a single-IFO burst injection in H1

BURST 1129673117.000 (H1)

with the only anomaly being that it is UNSCHEDULED. There was a single UNKNOWN injection in L1

UNKNOWN 1129673117.000 (L1)

This injection was confirmed to occur only within the CAL-INJ channel of RAW frames with the TRANSIENT bit indicating an injection but none of the specific injection-type bits, CBC, BURST, DETCHAR, or STOCHASTIC, indicating an injection. It was confirmed to not occur in ODC HOFT, ODC RDS, ODC RAW, or GDS HOFT frames.

Discussion of Anomalies

It is interesting that the single-IFO injections BURST 1129673117.000 (H1) and UNKNOWN 1129673117.000 (L1) are found to occur at the exact same time but within different IFOs. Even further, the fact the BURST injection in H1 is perfectly normal, other than being UNSCHEDULED, while the UNKNOWN injection in L1, in addition to being UNSCHEDULED, is inconsistent. HWInjReport currently does not check the HW bit or the CW bit in the CAL-INJ channel for RAW frames for the presence of injections; however, upon examining these bits directly, it was found that while the HW bit indicated an injection, along with the TRANSIENT bit, the CW bit did not indicate an injection (my first thought was that this may be a CW injection only occurring in L1). This means this was a truly UNKNOWN, UNSCHEDULED injection occurring only with L1. Given both injections occur at the exact same time and the L1 injection is a truly UNKNOWN type (practically a ghost injection, by the bits), it is likely this was intended to be a normal network injection; however either user-error or a catastrophic software error corrupted the proper setting of the bits.

I have been silently checking the signal chain of the REFLAIR and POPAIR RFPDs using the AM laser (a.k.a. PD calibrator) to make sure that they are functional expectedly.

Summary

• REFLAIR_A and POPAIR_A looked good as they showed reasonable signal gains
• On the other hand, REFLAIR_B and POPAIR_B RFPDs showed relatively large discrepancy from the expected values. I might have missed some gain factors somewhere. I will revisit these RFPDs later when I get a chance.

The RF frequency of the AM modulation was adjusted in each measurement such that the demodulated IF signal was below 50 Hz.

Calibration of the amplitude modulation depth

We recalibrated the AM laser.

The current setting of the laser was changed recently because we opened up the current driver when we thought the laser diode had been dead in the early December. Then the laser head and its current driver were sent to Rich at Caltech for his extensive testing although the laser magically fixed itself and he didn't find anything wrong. So this was the first time for us to use the AM laser which had been fixed. Because of that mysterious event, I wanted to recalibrate the laser. First of all, Yuta and I measured the power to be 2 mW with an Ophir Vega without the attenuation filter. Then we measured the modulation depth for the amplitude modulation by using a Newfocus 1611 as a reference.

The new calibration for the amplitude modulation is:

P_am =  5.13 mW x (P_dc / 1 mW) * (1 V / V_drive)

where P_dc is the laser power at DC and V_drive is the drive voltage when it is driven by a 50 Ohm source. For example, if one puts this laser to a PD which then shows a DC laser power of say 2 mW, the AM coefficient is now 5.13 mW x ( 2 mW / 1 mW) /V_drive = 10.26 mW/V_drive.

• Some details for derivation:
  • DC transimpedance of NF1611= 10k Ohm
  • AC transimpedance of NF1611 = 700 Ohm
  • Responsivity of NF1611 at 980 nm = 0.5 A/W
  • Measured DC voltage = 7.36 mV
    • => DC laser power of 7.36 mV / 10kOhm / 0.5 A/W = 1.47 uW
  • Measured AC voltage when driven by 0.5 Vpp at 10 MHz = 1.32 mVpp (measured by a 50 Ohm oscilloscope)
    • => P_am = 1.32 mV / 700 Ohm / 0.5 A/W = 3.771 uW
    • => AM coefficient is 7.54 uW / V_drive
  • Therefore the AM calibration is:
    • 7.54 uW / 1.47 uW x 1 mW = 5.13 mW x (P_dc / 1 mW) * (1 V / V_drive)

REFLAIR_A_RF9 (S1203919)

Remarks:

The signal chain is OK. The PD response is smaller by 15% for some reason.

It seems as if the transimpedance is smaller by 15% than what had been measured at Caltech (LIGO-S1203919). The cable loss from the RFPD to the rack was measured to be 0.47 dB. Be aware that the demod gain is half of the quad I/Q demodulator because this is a dual channel demod (see E1100044). The demod conversion gain is assumed to be 10.9 according to LIGO-F1100004-v4.

• Measured DC at BNC jack = 108 mV
  • DC laser power = 108 mV / 100 Ohm / 0.67 A/W = 1.61 mW
• Expected AM signal when driven by 0.1 Vpp = 5.13 mW x (1.61 mW / 1 mW) x 0.1 Vpp x 0.67 A/W x 245 Ohm = 135.6 mVpp
• Measured AM signal at the SMA jack of the RFPD enclosure = 115 mVpp
  • This is already smaller by 15%.
  • If we blame the transimpedance, it must be 208 Ohm rather than 245 Ohm.
• Measured AM signal at the rack = 109 mVpp
  • cable loss = 0.47 dB
• Expected IF signal = 135.6 mVpp x 10.9 / 2. = 622 mVpp
• Measured IF signal = 570 mVpp
  • If we take the 15% and 0.47 dB losses into account, we would expect this to be 527 mVpp.
• Expected ADC counts = 135.6 mVpp x 10.9 x 2^16 counts /40 V x 1/2 = 1209 counts pp
• Measured ADC counts = 900 counts pp
  • If we take the 15% and 0.47 dB losses into account, we would expect this to be 973 counts pp.
  • This is within 10% divation. Good enough.

REFLAIR_A_RF45 (S1203919)

Remarks:

The signal chain is healthy.

Found cable loss of about 1.5 dB. The measurements excellently agree with the loss-included expectation.

• DC laser power = 1.61 mW (the same as REFLAIR_A_RF9)
• Expected AM signal when driven by 0.1 Vpp = 5.13 mW x (1.61 mW / 1 mW) x 0.1 Vpp x 0.67 A/W x 341 Ohm = 188.7 mVpp
• Measured AM signal at the SMA jack of the RFPD enclosure = 190 mVpp
  • Very good agreement !
• Measured AM signal at the rack = 160 mVpp
  • Corresponds to loss of 1.5 dB
• Expected IF signal = 188.7 mVpp x 10.9 = 1028 mVpp
  • If the loss is taken into account, it is going to be 1028 mVpp x -1.5 dB = 865 mVpp
• Measured IF signal = 880 mVpp
  • Consistent with the loss-included expectation
• Expected ADC counts =1028 mVpp x 2^16/40 x 2 = 3369 counts pp
  • If the loss is taken into account, it should be 3368. x -1.5 dB = 2837 counts pp
• Measured ADC counts = 2784 counts pp
  • Good agreement with the loss-included model

POPAIR_A_RF9 (S1300521)

Remarks:

The signal chain is healthy.

The measurement suggests that there is loss of 1 dB somewhere. I didn't measure the cable loss this time.

• Measured DC at the BNC jack = 95.6 mV
• Estimated DC laser power = 95.6 mV / 100 Ohm / 0.67 A/W = 1.42 mW
• Expected AM signal = 5.13 mW x (1.42 mW / 1 mW) x  0.1 Vpp x 0.67 A/W x 741 Ohm = 361.7 mVpp
• Expected ADC counts = 361.7 mVpp x 10.9 x 2^16/40 counts/V = 6454 counts pp
• Measured ADC counts = 5705 counts pp
  • If we assume this discrepancy is from a loss, it corresponds to loss of 1.07 dB.

POPAIR_A_RF45 (S1300521)

Remarks:

The signal chain is OK. Though loss sounds a bit too high.

The measurement suggests a possible loss of 2.6 dB somewhere. I didn't measure the cable loss.

• Estimated DC laser power = 1.42 mW
• Expected AM signal = 5.13 mW x (1.42 mW / 1 mW) x 0.1 Vpp x 0.67 A/W x 837 Ohm = 408.5 mVpp
• Expected ADC counts = 408.5 mW x 10.9 x 2^16/40 counts/V = 7295 counts pp
• Measured ADC counts = 5391 counts pp
  • If the discrepancy is assumed to be from loss somewhere, the loss should be 2.6 dB.

REFLAIR_B_RF27 (S1200234)

Remarks:

The signal gain is bigger than the expectation by a factor of 2.3.

• Measured DC at the BNC jack = 836 mV
  • This corresponds to a laser power of 836 mV / 2000 Ohm / 0.4 A/W = 1.045 mW
• Expected AM signal = 5.13 mW x (1.045 mW / 1 mW) x 0.05 V_drivepp x 0.4 x 1000 Ohm = 107.2 mVpp
• Expected ADC counts = 18 dB x 107.2 mVpp x 10.9 x 2^16/40 counts/V = 15206 counts pp
  • I assumed that the gain factor of the diplexer (LIGO-D1300989) to be 18 dB at 27 MHz.
• Measured ADC counts = 35431 counts pp
  • This is bigger than the expected by a factor of 2.3

REFLAIR_B_RF135 (S1200234)

Remarks:

The signal gain is bigger than the expectation by a factor of 1.5

• Measured DC laser power = 1.045 mW
• Expected AM signal = 5.13 mW x (1.045 mW / 1 mW) x 0.0014 Vdrivepp x 0.4 A/W x 1000 Ohm = 3 mVpp
• Expected ADC counts = 43 dB x 3 mVpp x 10.9 x 2^16/40 counts/V = 7573 counts pp
• Measured ADC counts = 11689 counts pp
  • This is bigger than the expected by a factor of 1.54

POPAIR_B_RF18 (S1200236)

Remarks:

The signal gain is bigger than the expectation by a factor of 2.3

• Measured DC at the BNC jack = 744 mV
• DC laser power = 744 mW / 2000 Ohm / 0.4 A/W = 0.93 mW
• Estimated AM signal = 5.13 mW x (0.93 mW / 1 mW) x 0.1 Vdrivepp x 0.4 A/W x 1000 Ohm = 191 mVpp
• Estimated ADC counts = 191 mVpp x 10.9 x 2^16/40 counts/V = 3404 counts pp
• Measured ADC counts = 7803 counts pp
  • This is bigger than the expected by a factor of 2.3

POPAIR_B_RF90 (S1200236)

Remarks:

The signal gain matches with the expected value, but I don't believe this.

• DC laser power = 0.93 mW
• Estimated AM signal = 5.13 mW x (0.93 mW / 1 mW) x 0.1 Vppdrive x 0.4 A/W x 1000 Ohm = 191 mVpp
• Estimated ADC counts = 191 mVpp x 10.9 x 2^16/40 counts/V = 3408 counts pp
• Measured ADC counts = 3549 counts pp
  • This suspiciousely shows an excellent agreement with the expected one.