SR2 Top Satellite Box OSEM Photodiode Oscilloscope Traces
The oscilloscope traces attached show a comparison of the time domain signals between SR2 Top OSEM Photodiode A and SR2 OSEM Photodiode B, as seen from connector J2 "Analog Rack". (We use the satellite box signal and connector naming conventions as shown on D1400098-v1.) OSEM Photodiode A was from the SR2 Top OSEM, the suspect channel. In the images, the upper trace, labeled "1", is from OSEM Photodiode B, satellite box connector J2 pin 2. The lower trace, labeled "2", is from OSEM Photodiode A, satellite box connector J2 pin 1, the noisey channel under investigation.
Two x10 probes were used. The vertical scale factors for images 1 and 2 are 0.200 V/div. The vertical scale factor for image 3 is 0.050 V/div.
Image 1 shows the satellite box as found, all cables connected. Photodiode A shows significantly more noise.
Image 2 shows the photodiode signals with the "Vacuum Tank" cable, connector J1, disconnected. All quiet.
Image 3 shows the photodiode signals with the "Vacuum Tank" cable reconnected to J1. Both photodiode signals now have the same amplitudes. (Note the more sensitive scale factor for image 3.)
An intermitant? A poorly seated connector? Pickup from the SEI CPS 25kHz? Betsy reported that the noise spectrum did not change!
After the above investigation, FIl also powered off the HAM CPS clock synchronizing fanout. The spectra still showed the noise while this was off, although it may have been a little bit reduced. Then, Fil reseated the SAT AMP cable at the feedthru of the chamber which has these channels on it. After reseating the noise was still there. So, we've now tried multiple power switched cable reseating with no luck. Our next tries will be to power cycle the h1sush34 computer (the only one not done today!) and lock closer at the CPS clock sync.
So to recap, there are a few channels which show a "bouncy" type noise spectrum (based on Andy L. tool plots, which I'll ask him to rerun soon) which appeared before or after the power outage:
PR2 M1 T2
PR2 M3 LL
PR2 M3 UL
SR2 M1 T1
SR2 M1 T3
SR2 M1 LF
A scan through all other OSEMs do not show any other OSEMs with this specific noise shape. Attached is the spectra of the still present SR2 noise from today (bottom pane) with some other healthier channels (upper pane).
Continuation of alog 27893.
(Richard M, Fil C, Ed M, Daniel S)
ECR E1600192.
Split Whitening Chassis S/N S1101627:
AA Chassis S/N S1102788 & S1202201:
The attached plots show the transfer functions of
Whitening chassis S1101603 was removed from ICS-R5 U18. New chassis S1101627 was reinstalled with modifications listed above. New unit is the split variant.
[Kiwamu, Carl]
First indications are that the DCPD HF channels are behaving as expected. With the OMC locked on an RF sideband the DCPD A is compared to the new DCPD HF A. The transfer function between them at low frequency has a 'f' relation which transistion fto f^3 at 10kHz as expected from the AC coupling change and the removal of 2 poles at 10kHz. Coherence is lost at about 20kHz.
I have changed the whitening gain of the AHF DCPD path (A and B) to 15dB. This pushed the noise floor in the 15-29kHz region to a factor ~2 above what I guess is ADC noise. In the attached plots the original DCPD can be seen to reach a common noise floor with the AHF DCPD path with no whitening gain at about 17kHz. Turning the whitening gain up we can get some coherence with the shot noise of the DCPD through original electronics.
A forest of new peaks is visible, mainly in the 17-29kHz region. There are 80 peaks in teh 25-26kHz band. I stepped the ETMX ring heater at 7:01 up by 0.5W and down again at teh end of lock at 7:22. This may give some mode identificatiion data.
This morning we removed the Twin T notch on the AA board by removing C3, C4, C5, C10, C11 leaving in the 100 Ohm resistors in place.
The OMC DCPDs have proven to be useful for monitoring the test mass acoustic modes around 15 kHz, but there is a lot of low-pass filtering in the readout chain that render them less useful for monitoring higher frequency acoustic modes. This is now being changed with modifications to the electronics that will provide separate, faster channels for PI monitoring:
The attached plot shows the magnitude response of the low-pass filtering in the previous case, and with the poles removed from the whitening and AA channels. It is no wonder that no PI modes have been seen above the 15-16 kHz grouping, as there is 40 dB of relative attenuation already at 25 kHz.
I also attach a 1kHz - 10 MHz transfer function of the in-vacuum DCPD readout that Koji measured at Caltech:
Here are the transfer functions with the AA notch included. I had forgotten that the notch is a passive twin-T type, which by design has a Q = 1/4, so it is quite wide and should be taken into account. In future the AA notches should also be removed.
The infrasound mics have already been upgraded at LLO but today I removed the sensors at LHO. I removed the sensors from the microphones in the CS, at EX, and at EY. This meant unscrewing the bottom of the instrument box and pulling out some of the equipment. As far as I could tell everything went as planned and the equipment will now be sent away for upgrades.
WP 5954 All of the 18bit DAC cards in h1susb123 and h1sush2a now successfully pass the autocal on both power up and restart of the IOP models. Results shown below: h1susb123 - power up [ 61.694760] h1iopsusb123: DAC AUTOCAL SUCCESS in 5344 milliseconds [ 67.057232] h1iopsusb123: DAC AUTOCAL SUCCESS in 5340 milliseconds [ 72.850938] h1iopsusb123: DAC AUTOCAL SUCCESS in 5344 milliseconds [ 78.213461] h1iopsusb123: DAC AUTOCAL SUCCESS in 5345 milliseconds [ 85.247010] h1iopsusb123: DAC AUTOCAL SUCCESS in 6571 milliseconds [ 90.610149] h1iopsusb123: DAC AUTOCAL SUCCESS in 5344 milliseconds [ 95.973497] h1iopsusb123: DAC AUTOCAL SUCCESS in 5345 milliseconds [ 101.336018] h1iopsusb123: DAC AUTOCAL SUCCESS in 5340 milliseconds h1susb123 - IOP model restart [ 911.921930] h1iopsusb123: DAC AUTOCAL SUCCESS in 5344 milliseconds [ 917.282286] h1iopsusb123: DAC AUTOCAL SUCCESS in 5345 milliseconds [ 923.070351] h1iopsusb123: DAC AUTOCAL SUCCESS in 5341 milliseconds [ 928.430617] h1iopsusb123: DAC AUTOCAL SUCCESS in 5344 milliseconds [ 935.453979] h1iopsusb123: DAC AUTOCAL SUCCESS in 6576 milliseconds [ 940.814416] h1iopsusb123: DAC AUTOCAL SUCCESS in 5345 milliseconds [ 946.174750] h1iopsusb123: DAC AUTOCAL SUCCESS in 5345 milliseconds [ 951.535191] h1iopsusb123: DAC AUTOCAL SUCCESS in 5341 milliseconds h1sush2a - power up [ 48.086815] h1iopsush2a: DAC AUTOCAL SUCCESS in 5344 milliseconds [ 53.450158] h1iopsush2a: DAC AUTOCAL SUCCESS in 5345 milliseconds [ 60.479701] h1iopsush2a: DAC AUTOCAL SUCCESS in 6576 milliseconds [ 65.843077] h1iopsush2a: DAC AUTOCAL SUCCESS in 5344 milliseconds [ 71.640028] h1iopsush2a: DAC AUTOCAL SUCCESS in 5345 milliseconds [ 77.001396] h1iopsush2a: DAC AUTOCAL SUCCESS in 5344 milliseconds [ 82.364713] h1iopsush2a: DAC AUTOCAL SUCCESS in 5345 milliseconds h1sush2a - IOP model restart [ 1252.909059] h1iopsush2a: DAC AUTOCAL SUCCESS in 5344 milliseconds [ 1258.269410] h1iopsush2a: DAC AUTOCAL SUCCESS in 5344 milliseconds [ 1265.292831] h1iopsush2a: DAC AUTOCAL SUCCESS in 6572 milliseconds [ 1270.653176] h1iopsush2a: DAC AUTOCAL SUCCESS in 5344 milliseconds [ 1276.441059] h1iopsush2a: DAC AUTOCAL SUCCESS in 5344 milliseconds [ 1281.801414] h1iopsush2a: DAC AUTOCAL SUCCESS in 5344 milliseconds [ 1287.161817] h1iopsush2a: DAC AUTOCAL SUCCESS in 5345 milliseconds
Last week, Rana was inquiring about how locklosses affect oplev sums.
Took a random sample of locklosses from O1 and came up with fairly consistent results for after a lockloss, so here's the nitty gritty:
Attached is an example of a lockloss from Nov.
There's a DCC document and even a tool to look at these things.
We adjusted the pressure on the pwrmtr water circuit from its nominal 5 bar to 4.5 bar. The flow rate to the laser heads decreased somewhat. Put the pressure back to ~5 bar to set the flow rate in the circuit to be over 1.25 l/min. In doing so, the other flow rates seemed to behave as expected. We will monitoring the flow rates and pressures over the the next few days to see if anything settles out/down. Jeff, Peter
Have been monitoring the PSL chiller trends during the day. The attached plot is for an 8 hour period. The spikes at 06:50 (PT) are when Peter and I varied the pressures regulators. The pressures and flows have flattened out, which is good. The head flows have also flattened out, which is also good. The head temperatures have been moving around a bit (by 0.1 degree). It appears that varying these pressures regulators may have stabilized the pressure and flows. Will check again in the morning to see if these trends hold.
Measured ~18 mV, 20 ohms between the table surface and the chassis of the ISS AOM. Installed DC block. Measured the same afterwards, so I removed the DC block. This clearly does not work as well as the one on the FSS AOM (for whatever reason).
I have set the level setpoint to 90% to exercise the new PID control.
Found that the PI output for CP5 was 0% even though the pump level is at 83% -> I switched CP5 to manual control with LLCV %open of 90% -> The other vacuum group members have been experimenting with CP5 of late so I'll "stay out of the kitchen" and let them continue/investigate.
Changing to 35% while transfer line cools -> Need to do stuff in other room and will monitor exhaust pressure sporadically.
Back to PID at 08:00 as the PID output had risen to 90%.
Jenne, Carl, Sheila, TJ, Stefan, Lisa We have a quite reliable locking sequence to 40W at this point (recycling gain ~28.5, same SOFT offset strategy as over the week-end with one set of offsets engaged before power up, one at 40W; SRM alignment done by end), so tonight we started going back to low noise while doing PI testing. Here is the list of things we successfully did; we still need to modify the ISC LOCK code to be compatible with some of those (note that we are still on POPX, so the POP beam diverter is open):
Plot 1: Noise spectrum for tonight. Below 60Hz is due to ASC, and can still be addressed.
Plot 2: Auxiliary loops noise. Note the increased coupling of the mechanical resonances just below 60Hz. I suspect that we still are not quite centered in the recycling cavity.
Plot 3: Aux loop coherences
After this lock broke Carl and I turned on the ITM ring heaters to 0.5 Watts each, and left the end stations at 1.5 Watts each. Carl thinks that this will help with PI, and this will also set us up to try some common TCS tuning tomorow.
Some of the things that Lisa mentioned are now in the guardian.
Attached is a screenshot of when (in PSL power terms) the OMC ASC rails.
For the first almost 3 hours of this lock we were toggling the gain of CSOFT P by 20 dB every 10 seconds because of a logic problem in the guardian. Should be fixed now.
Filters for PI damping have been broadened to 10Hz as the phase change over 0.5Hz for some of the filters being used was greater than 200 degrees.
These 10Hz wide filters may be problematic for the 15541.9 and 15542.6Hz modes. I have tested damping these modes at low amplitudes with the 10Hz wide filters and to damp, however as we reached 3 hours into this lock the 15541.9 and 15542.6 were slowly pushing their way up, the filters I have put in have about 60 degrees phase shift for 1Hz change in frequency.
I tested iwave on this pair of modes, it tracks the largest mode very well, however once damped to a level lower than the next highest mode it runs off and tracks that mode. This meant two iwave blocks running one on each etm pi model generally pushed their test mass with the largest amplitude mode. I was using tau of 10.
We have a SUS_PI guardian now. The gaurdian has 4 states managed by ISC_LOCK. IFO_DOWN, OMC_TRACKING, PI_DAMPING and ETMX_PI_DAMPING. The tracking state just turns on tracking for long term testing. The damping states turn on the bandpass damping chains with settings that have been tested today and very low gains for the settings in Terra's PI wiki. I will update the wiki tomorrow with some new settings.
The 0.5W increase in the ITM ring heaters should push the optical mode to lower frequencies, as we see PI in the 15540Hz group of modes close to the end of the RoC thermal transient (1.5-2hour in a 2-3hour transient) I am hoping this will be enough to make these instabilites a little less agressive. I have been doing some testing of the 15kHz mode in anticipation that this TCS change will make these modes ring up more at the beginning of lock.
Before leaving I stepped the ETMY Ring heater by 0.5W total to test the idea that we can push the 15542Hz modes appart with a little heating.
The ITM ring heaters that Sheila activated seemed to have introduced a substrate lensing of about 8 uD on each optic according to the TCS simulator. The ITMX HWS saw the consistent amount of change in the substrate lensing (~ 18 uD due to the round trip lensing which gives an extra factor of two). After the ring heaters were activated, the power recycling on average was higher than the previous 41 W stretch by 1%; this could be because the last lock stretch with the ring heaters was with a slightly lower PSL power of 39 W. I attach trend of the relevant channels.
Daniel, Ross, Carl, Kiwamu,
WP#: 5957
We made two modifications on the h1omspi, h1susetmxpi and h1susetmypi models as follows.
We are ready for tomorrow's model restart during the maintenance period.
[I and Q signals to science frame]
Since all the I and Q down sampled signals have been already recorded in commissioning frame, we just added a star symbol to each channel name in the DQ text field in the simulink models. In total, 24 channels (8 channels from each model) will newly go to science frame at 2 kHz.
[New DCPD signals]
We decided to do a quick hack on the OMC whitening board so that we don't suffer from the two 10 kHz poles (technically, 14 and 18 kHz from the differential receiver stage, see alog 21131) to obtain a better signal to noise ratio. Some more details of this quick hack will be reported by Daniel and Stefan later. In the mean time, we have edited the h1omcpi model so that it is capable of handling these two signals. In the first attachment it shows the two new ADC inputs (adc_0_14 and adc_0_15) which then go to a subblock called PI_DCPD. One can choose whether the normal DCPD is used for the PI error signal or the new signals by the two choice blocks that are behind the PI_DCPD block.
Once we become able to damp the PI modes using the new DCPD signals, we should get rid of the old DCPD signals. But for commissioning purpose, we are leaving the normal DCPDs available for now.
Also, we added these two new signals to commissioning frame at the full sampling rate at 64 kHz. So, in total, we now have four 64 kHz DQ channels, which should be reduced to 2 or 1 channels as we complete the commissioning at some point in future. The new DQ channels have the names as PI_DCPD_64KHZ_A(B)HF. Note that in order to save the test points for the normal DCPD signals, we pulled them out of a subblock and placed them at the top level as seen in the first attachment.
In the PI_DCPD subblock, we have placed controlled-IIR-fitlers so that they can be synchronized with the analog board settings as have been done in the LSC and ASC models. See the second attachment.
All the changes are checked into the SVN repo. We made sure that they compiled without errrors.
The addtion of two new DAQ channels for OMC PI monitoring also required a change to the TwinCAT code to enable the whitening switching.