The particle count channel names were changes yesterday to follow naming conventions used at the sites. Following are the new names:
The legacy count channels are kept alive with C1:PEM-count_full copying C1:PEM-BS_DUST_1000NM channel and C1:PEM-count_half copying C1:PEM-BS_DUST_500NM channel.
Attachment one is the particle counter trend since 8:30 am morning today when the HVAC wokr started. Seems like there was some peak particle presence around 11 am. The particle counter even counted 8 counts of particles size above 5um!
SVG doesn't work in my browser(s). Can we use PDF as our standard for all graphics other than photos (PNG/JPG) ?
rethinking what I said on Wednesday - its not a good idea to put the particle counter on a vac chamber with optics inside. The rumble from the air pump shows up in the acoustic noise of the interferometer. Let's look for a way to mount it near the BS chamber, but attached to something other than vacuum chambers and optical tables.
I have placed a GT321 particle counter on top of the MC1/MC3 chamber next to the BS chamber.
I have done some reading about where would be the best place to put the particle counter. The ISO standard (14644-1:2015) for cleanrooms is one every 1000 m^2 so one for every 30m x 30m space. We should have the particle counter reasonably close to the open chamber and all the manufactures that I read about suggest a little more than 1 every 30x30m. We will have it much closer than this so it is nice to know that it should still get a good reading. They also suggest keeping it in the open and not tucked away which is a little obvious. I think the best spot is attached to the cable tray that is right above the door to the control room. This should put it out of the way and within about 5m of where we are working. I ordered some cables to route it over there last night so when they come in I can put it up there.
On thursday Oct 21 2021, Yehonathan and I opened the door to BSC and took some photos. We setup the HEPA stand next to the door with anti-static curtains covering all sides. We spend about 15 minutes trying to understand the current layout and taking photos and a video. Any suggestions on improvement in our technique and approach would be helpful.
Links to photos:
[Anchal, Paco, Ian]
We removed the following optics from the BSC table and stored them in X-end flowbench with fan on. See attachment 1 and 2.
We also changed the direction of clamp of MMT1 to move it away from the center of the able (where PRM will be placed)
We screwed in the earthquake stops on PRM and BS from front face and top.
We unscrewed the cable post for BS and PRM oplevs and loved it in between SR3 and BS and screwed it lightly.
We moved the PRM, turned it anti-clockwise 90 degrees and brought it in between TT2 and BS. Now there is a clear line of sight between TT2 and PR2 on ITMY table.
These are next few days of work. We need atleast one SOS ready by Thursday.
Photos after today's work: https://photos.app.goo.gl/EE7Mvhw5CjgZrQpG6
Modifications and testing of SatAmp units COMPLETE. Attachments 1 & 2 show all 19 units, one installed unit and the remaining 18 units are stacked and ready for install. Detailed notes of the modification for each unit are presented in the summary document in the dcc.
We opened the laser head shutter. Then, we scanned around the PMC resonance and locked it. We then opened the PSL shutter, touched the MC1, MC2 and MC3 alignment (mostly yaw) and managed to lock the IMC. The transmission peaked at ~ 1070 counts (typical is 14000 counts, so at 10% of PSL power we would expect a peak transmission of 1400 counts, so there might still be some room for improvement). The lock was engaged at ~ 16:53, we'll see for how long it lasts.
There should be IR light entering the BSC!!! Be alert and wear laser safety goggles when working there.
We should be ready to move forward into the TT2 + PR3 alignment.
[Ian, Anchal, Paco]
After the Koji found that there was a problem with the power source Anchal and I fixed the power then reran the measurment. The only change this time around is that I increased the excitation amplitude to 100. In the first run the excitation amplitude was 1 which seemed to come out noise free but is too low to give a reliable value.
link to previous results
The new plots are attached.
Before we could start working on Part II, which is to relocate TT2 to new location, we had to clear space in front of injection chamber door and clean the floor which was very dusty. This required us to disconnect everything we could safely from OMC North short electronics rack, remove 10-15 BNC cables, 4-5 power cords and relocate some fiber optic cables. We didn't had caps for fiber optic cables handy, so we did not remove them from the rack mounted unit and just turned it away. At the end, we mopped the floor and dried it with a dry cloth. Before and after photos in attachments.
I went inside the ITMX Chamber to read off specs from PR2 edge. This was required to confirm our calculations of LO power for BHR later. The numbers that I could read from the edge were kind of meaningless "0.5 088 or 2.0 088". To make it more worthwhile this opening of the chamber, we decided to remove the PR2 suspension unit so that the optic can be removed and installed on an SOS in the cleanroom. We covered the optic in clean aluminum foil inside the chamber, then placed in on another aluminum foil to cover completely. Then I traveled slowly to the C&B room, where I placed it on a flow bench.
Later on, we decided to use a dummy fixed mount mirror for PR2 initially with the same substrate thickness, so that we get enough LO power in transmission for alignment. In the very end, we'll swap that with the PR2 mounted on an SOS unit.
We opened BSC and Injection Chamber doors. We removed two stacked counterweights from near the center of the BS table, from behind TT2 and placed them in the Xend flow bench. Then we unscrewed TT2 and relocated it to the new BHR layout position. This provided us with the target for the alignment of MMT1 and MMT2 mirrors.
While aligning MMT1 and MMT2, we realized that the BHR layout underestimated the clearance of the beam from MMT2 to TT2, from the TT1 suspension unit. The TT1 suspension stage was clipping our beam going to TT2. To rectify this, we decided to move the MMT2 mirror mount about a cm South and retry. We were able to align the beam to the TT2 optic, but it is a bit off-center. The reflection of TT2 now is going in the general direction of the ITMX chamber. We stopped our work here as fatigue was setting in. Following are some thoughts and future directions:
Thu Oct 28 17:00:52 2021 After Photos: https://photos.app.goo.gl/wNL4dxPyEgYTKQFG9
Closed the PSL shutter @18:11
During the vent, we want to keep the cavity unlocked if not necessary.
- Moving the MMT2 south by a cm is fine. This will give you ~0.5cm at TT1 without changing the other alignment much.
- IMC mode is moving because of your presence + HEPA blow.
- 2cm at Faraday is plenty for the beam diameter of a few mm.
1. The rack we cleaned today (came from West Bridge) will be placed between 1X3 and 1X4, right next to 1X4 (after removing the plastic boxes). (Attachment 1)
For easier work at the side of the 1X4, the side panel of the 1X4 should be removed before placing the new rack. Note that this rack is imperial and has 10-32 threads
2. In terms of the other rack for the Y arm, we found the rack in the storage is quite dirty. Anchal pointed out that we have a few racks standing along the Y arm (as the storage of the old VME/Euro card electronics) (Attachments 2/3)
They are not too dirty and also doing nothing there. Let's vacate one of them (the one right next to the optics preparation table). Use this space as a new storage area placing a wire shelving rack for something.
BTW, I thought it is good to have the rack at the vertex side of 1Y1 (as 1Y0?), but the floor has "KEEP OUT" marking. I have no idea why we have this marking. Is this for crane operation??? Does any one know?
[Ian, Paco, Anchal]
We turned off the BSC oplev laser by turning the key counterclockwise. Ian then removed the following optics from the east end in the BSC:
We placed them in the center-front area of the XEND flow bench.
We cleared 1Y1 rack today removing the following items. This stuff is sitting on the floor about 2 meters east of 1Y3 (see attachment 1):
We also moved the power relay ethernet strip from the middle of the rack to the bottom of the rack clearing the space marked clear in Koji's schematics. See attachment 2.
There was nothing to clear in 1Y3. It is ready for installing c1sus2 I/O chassis and FE once the testing is complete.
We also removed some orphaned hanging SMA RG-405 cables between 1Y3 and 1Y1.
After the new 1Y0 rack was placed near the 1Y1 rack by Chub and Anchal, today we worked on the 1Y1 rack. We removed some rails from spaces ~ 25 - 30. We then drilled a pair of ~ 10-32 thru-holes on some L-shaped bars to help support the c1sus2 machine weight. The hole spacing was set to 60 cm; this number is not a constant across all racks. Then, we mounted c1sus2. While doing this, Paco's knee clicked some of the video MUX box buttons (29 and 8 at least). We then opened the rack's side door to investigate the DC power strips on it before removing stuff. We did power off the DC33 supplies on there. No connections were made to allow us to keep building this rack.
When coming back to the control room, we noticed 3/4 video feed (analog) for the Test masses had gone down... why?
Update Tue Nov 2 18:52:39 2021
[Ian, Tega, Raj]
This is the rough plan for the testing of the new suspension models with the created plant model. We will test the suspensions on the plant model before we implement them into the full
MEDM file location
For ITMX display, use:
hsss_tega_gautam>medm -x -macro "site=caltech,ifo=c1,IFO=C1,OPTIC=ITMX,SUSTYPE=IM,DCU_ID=21,FEC=45" SUS_CUST_HSSS_OVERVIEW.adl
For ITMX display, use:
hsss_tega_gautam>medm -x -macro "site=caltech,ifo=c1,IFO=C1,OPTIC=ITMX,SUSTYPE=IM,DCU_ID=21,FEC=45" SUS_CUST_HSSS_OVERVIEW.adl
I have visited the binder file for the 40m wiring file in the control room.
The 12V power supply on 1Y1 is for the CCD cameras. So we still want to keep the 12V 0.8A power and the side connections for these. It is not necessary to be Sorensen. Can we replace it with an AC-DC adapter with +12V/1A for example? BTW, the video matrix and quads are AC-powered.
The mysterious thick cables and cross-connects (green wires) on the side panel (labeled AP1/AP2/SP/IMCREFL) are for "EO shutters". It was meant for the protection of the PDs from bright beams.
I don't think they have been used. And we don't need them.
Today I opened the ITMY chamber and removed the following optics and placed them in Xend flow bench (See attachment 1-3 for updated photograph):
I also unscrewed SRM and parked it near the Western end of the table where no optical paths would intersect it. Later we will move it in place once the alignment of the rest of the optics has been done.
While doing this work, I found two unnoted things on the table:
Removed all sorensen power supplies from this rack except for 12 VDC one; that one got pushed to the top of the rack and is still powering the cameras.
Updated the rack layout. Now there is an issue.
We were supposed to have 1U space at the top, but it was occupied by the 12V.
We need to either lower the c1sus2 and IO chassis 1U or move the Sorensen at the bottom.
In reference to Koji's concern (see previous elog), we have completely removed sorensen power supplies from 1Y1. We added a 12 Volts / 2 Amps AC-to-DC power supply for the cameras and verified it works. We stripped off all unused hardware from shutters and other power lines in the strips, and saved the relays and fuses.
We then mounted SR2, PR3, PR2 Sat Amps, 1Y1 Sat amp adapter, and C1SUS2 AA (2) and AI (3) boards. We made all connections we could make with the cables from the test stand, as well as power connections to an 18 VDC power strip.
After talking with Rana we have an updated plan. We will be working on this plan step by step in this order.
We have moved c1sim computer from the test stand to the server rack in the office area. (see picture)
It is connected to the general campus network. Through the network switch at the top of the rack. This switch seeds the entire Martian network.
Test to show that I am not lying:
c1sim is now as connected to the 40m network as my mom's 10-year-old laptop.
unfortunately, I have not been able to get the x2go client to connect to it. I will have to investigate further. It is nice to have access to the GUI of c1sim occasionally.
Now that the computer is in its new rack I have copied over the filter two files that I will use in the plant and the controller from pianosa:/opt/rtcds/caltech/c1/chans to the docker system in c1sim:/home/controls/docker-cymac/chans. That is to say, C1SUP.txt -> X1SUP.txt and C1SUS.txt -> X1SUS_CP.txt, where we have updated the names of the plant and controller inside the txt files to match our testing system, e.g. ITMX -> OPT_PLANT in plant model and ITMX -> OPT_CTRL in the controller and the remaining optics (BS, ITMY, PRM, SRM) are stripped out of C1SUS.txt in order to make X1SUS_CP.txt.
Once the filter files were copied over need to add them to the filters that are in my models to do this I run the commands:
$ cd docker-cymac
$ eval $(./env_cymac)
# cd /opt/rtcds/tst/x1/medm/x1sus_cp
# medm -x X1SUS_OPT_PLANT_TM_RESP.adl
see this post for more detail
Unfortunately, the graphics forwarding from the docker is not working and is giving the errors:
canAccess('X1SUS_OPT_PLANT_TM_RESP.adl', 4) = 0
can directly access 'X1SUS_OPT_PLANT_TM_RESP.adl'
locateResource(X1SUS_OPT_PLANT_TM_RESP.adl...) returning 1
Error: Can't open display:
This means that the easiest way to add the filters to the model is through the GUI that can be opened through X2go client. It is probably easiest to get that working. graphics forwarding from inside the docker is most likely very hard.
unfortunately again x2go client won't connect even with updated IP and routing. It gives me the error: unable to execute: startkde. Going into the files on c1sim:/usr/bin and trying to start startkde by myself also did not work, telling me that there was no such thing even though it was right in front of me.
unable to execute: startkde.
Today we populated 4 Sat Amp boxes for LO1, Lo2, AS1, and AS4, 2 BO boxes for C1SU2, and 1 Sat Amp Adaptor box, at 1Y0 according the latest rack plan. We also added 2 Sorenson power supplies in 1Y0 at the top slots to power +/- 18V DC strips on both 1Y1 and 1Y0. All wiring has been done for these power connections.
Yehonathan and Tega found that the new PR3 and SR3 delivered in 2020 is in fact 3/4" in thickness (!). Digging the past email threads, it seems that the spec was 10mm but the thickness was increased for better relieving the residual stress by the coatings.
There are a few issues.
1. Simply the mirror is too thick for the ring. It sticks out from the hole. And the mirror retainers (four plastic plates) are too far from the designed surface, which will make the plates tilted.
2. The front side of the mirror assembly is too heavy and the pitch adjustment is not possible with the balance mass.
Some possible solutions:
- How about making the recess deeper?
In principle this is possible, but the machining is tricky because the recess is not a simple round hole but has "pads" where the mirror sits. And the distance of the retainer to the thread is still far.
And the lead time might become long.
- How about making new holes on the ring to shift the clamp?
Yes it is possible. This will shift the mirror assembly by a few mm. Let's consider this.
- How about modifying the wire blocks?
Yes it is equivalent to shift the holes on the ring. Let's consider this too.
1. How to hold the mirror with the retainer plates
[Attachment 1] The expected distance between the retainer plate and the threaded hole is 13.4mm. We can insert a #4-40 x L0.5" stand off (McMaster-Carr 91197A150, SUS316) there. This will make the gap down to 0.7mm. With a washer, we can handle this gap with the plate. Note that we need to use vented & silver plated #4-40 screws to hold the plates.
[Attachment 2] How does this look like when the CoM is aligned with the wire plane? Oh, no... the lower two plates will interfere with the EQ stops and the EQ stop holders. We have to remove them. [Attachment 3]
We need to check with the suspension if the EQ stop screws may hit the protruded optics and can cause chipping/cracking.
2. Modifying the wire block
[Attachment 4] The 4x thru holes of the wire block were extended to be +/-0.1" slots. The slots are too long to form ovals and produce thin areas. With the nominal position of the balance mass, the clamp coordinates are y=1.016 (vertical) and z=-2.54mm (longitudinal).
==> The CoM is 0.19mm backside (magnet side) and 0.9134 mm lower from the wire clamping points. This looks mathematically doable, but the feasibility of the manufacturing is questionable.
[Attachment 5] Because the 0.1" shift of the CoM is large, we are able to make new #2-56 thread holes right next to the original ones. The clamp coordinates are y=1.016 (vertical) and z=-2.54mm (longitudinal).
==> The CoM is 0.188mm backside (magnet side) and 0.9136 mm lower from the wire clamping points. With the given parameters, the expected pitch resonant frequency is 0.756Hz
- Modify the metal ring to shift the #2-56 threads by 0.1"
- The upper two retainer plates will have #4-40 x 0.5" stand off. Use vented Ag-coated #4-40 screws.
- The lower two are to be removed.
- Take care of the EQ stops.
- Of course, the best solution is to redesign the holder for 3/4" optics. Can we ask Protolab for rapid manufacturing???
Why did we need to place the mass forward to align the 1/4" thick optic?
We were supposed to adjust the CoM not to have too much adjustment. But we had to move the balance mass way too front for the proper alignment with a 1/4" thick optic. Why...?
This is because the ring was designed for a 3/8" thick optic... It does not make sense because the depth of the thread holes for the retainer plate was designed for 1/4" optics...
When the balance mass is located at the neutral position, the CoM coordinate is
x 0.0351mm (x+: left side at the front view)
y 0.0254mm (y+: vertical up)
z 0.4493mm (z+: towards back)
So, the CoM is way too behind. When the balance mass was stacked and the moved forward (center of the axis was moved forward by 0.27"), the CoM coordinate is (Attachment 6)
This makes sens why we had to move the balance mass a lot for the adjustment.
We are working on three fronts for the suspension plant model:
Here are the State-space matrices:
A few notes: If you want the values for these parameters see the .yml file or the State-space model file. I also haven't been able to find what exactly this s is in the matrices.
UPDATE [11/16/21 4:26pm]: I updated the matrices to make them more general and eliminate the "s" that I couldn't identify.
The input vector will take the form:
where x is the position, theta is the pitch, phi is the yaw, and y is the y-direction displacement
Updated A, B, C, D matrices for the state-space model to remove bugs in the previous estimate of the system dynamics. Updated the last post to represent the current matrixes.
We used MatLab to get the correct time-series filter coefficients in ZPK format and added them to the filters running in the TM_RESP filter matrix.
Get the pos-pos transfer function from the CDS model. Strangely, this seems to take a lot longer than anticipated to generate the transfer function, even though we are mainly probing the low-frequency behavior of the system.
For example, a test that should be taking approximately 6 minutes is taking well over an hour to complete. This swept sine (results below) was on the low settings to get a fast answer and it looks bad. This is a VERY basic system it shouldn't be taking this long to complete a Swept sine TF.
Noticed that we need to run eval $(./env_cymac) every time we open a new terminal otherwise CDS doesn't work as expected. Since this has been the source of quite a few errors already, we have decided to put it in the startup .bashrc script.
I went through the optics list (in the BHD procurement google spreadsheet) and summarized how to build them.
The red ones are what we need to purchase. Because of the strange height of the LMR mounts, the post needs to have none half-integer inch heights.
They need to be designed as the usual SS posts are not designed to be vac compatible (not because of the material but the design like screw hole venting).
We also need to check how many clean forks we have.
-> The components were ordered except for the custom posts.
[Ian, Raj, Tega]
Here is the comparison between the results of Raj's python model and the transfer function measurement done on the plant model by Tega and me.
As You can see in the graphs there are a few small spots of disagreement but it doesn't look too serious. Next we will measure the signals flowing through the entire plant and controller.
For a nicer (and printable) version of these plots look in the zipped folder under Plots/Plant_TF_Individuals.pdf
1. Investigate cross-coupling btw the various degrees of freedom (dof) - turn on noise for each dof in the plant model and measure the transfer function of the other dofs.
2. Get a closed-loop transfer function using noise injection and give a detailed outline of the procedure in elog - IN1/IN2 for each TM_RESP filter while the others are turned off.
3. Derive analytic model of the closed-loop transfer functions for comparison.
4. Adapt control filters to fit optimized analytical solutions.
I added mpmath to the quantization noise code. mpmath allows me to specify the precision that I am using in calculations. I added this to both the IIR filters and the State-space models although I am only looking at the IIR filters here. I hope to look at the state-space model soon.
I also added a new notebook which you can find HERE. This notebook creates a signal by summing two sine waves and windowing them.
Then that signal is passed through our filter that has been limited to a specific precision. In our case, we pass the same signal through a number of filters at different precisions.
Next, we take the output from the filter with the highest precision, because this one should have the lowest quantization noise by a significant margin, and we subtract the outputs of the lower precision filters from it. In summary, we are subtracting a clean signal from a noisy signal; because the underlying signal is the same, when we subtract them the only thing that should be left is noise. and since this system is purely digital and theoretical the limiting noise should be quantization noise.
Now we have a time series of the noise for each precision level (except for our highest precision level but that is because we are defining it as noiseless). From here we take a power spectrum of the result and plot it.
After this, we can calculate a frequency-dependent SNR and plot it. I also calculated values for the SNR at the frequencies of our two inputs.
This is the procedure taken in the notebook and the results are shown below.
Analysis of Results:
The first thing we can see is that the precision levels 256 and 128 bits are not shown on our graph. the 256-bit signal was our clean signal so it was defined to have no noise so it cant be plotted. The 128-bit signal should have some quantization noise but I checked the output array and it contained all zeros. after further investigation, I found that the quantization noise was so small that when the result was being handed over from mpmath to the general python code it was rounding those numbers to zero. To overcome this issue I would have to keep the array as a mpmath object the entire time. I don't think this is useful because matplotlib probably couldn't handle it and it would be easier to just rewrite the code in C.
The next thing to notice is sort of a sanity check thing. In general, low precision filters yield higher noise than high precision. This is a good quick sanity check. However, this does not hold true at the low end. we can see that 16-bit actually has the highest noise for most of the range. Chris pointed out that at low precisions that quantization noise can become so large that it is no longer a linearly coupled noise source. He also noted that this is prone to happen for low precision coefficients with features far below the Nyquist frequency like I have here. This is one explanation that seems to explain the data especially because this ambiguity is happening at 16-bit and lower as he points out.
Another thing that I must mention, even if it is just a note to future readers, is that quantization noise is input dependent. by changing the input signal I see different degrees of quantization noise.
Analysis of SNR:
One of the things we hoped to accomplish in the original plan was to play around with the input and see how the results changed. I mainly looked at how the amplitude of the input signal scaled the SNR of the output. Below I include a table of the results. These results were taken from the SNR calculated at the first peak (see the last code block in the notebook) with the amplitude of the given sine wave given at the top of each column. this amplitude was given to both of the two sine waves even though only the first one was reported. To see an example, currently, the notebook is set up for measurement of input amplitude 10.
As we can see from the table above the SNR does not seem to relate to the amplitude of the input. in multiple instances, the SNR dips or peaks in the middle of our amplitude range.
This looks great. I think what we want to see mainly is just the noise in the 32 bit IIR filtering subtracted from the 64 bit one.
It would be good if Tega can look through your code to make sure there's NO sneaky places where python is doing some funny casting of the numbers. I didn't see anything obvious, but as Chris points out, these things can be really sneaky so you have to be next level paranoid to really be sure. Fox Mulder level paranoia.
And, we want to see a comparison between what you get and what Denis Martynov put in an appendix of his thesis when comparing the Direct Form II, with the low-noise form (also some slides from Matt Evans on thsi from a ~decade agoo). You should be able to reproduce his results. He used matlab + C, so I am curious to see if it can be done all in python, or if we really need to do it in C.
And then...we can make this a part of the IFOtest suite, so that we point it at any filter module anywhere in LIGO, and it downloads the data and gives us an estimate of the digital noise being generated.
Tega and I have gone through the IIR Filter code and optimized it to make sure there aren't any areas that force high precision to be down-converted to low precision.
For the new biquad filter we have run into the issue where the gain of the filter is much higher than it should be. Looking at attachments 1 and 2, which are time series comparisons of the inputs and outputs from the different filters, we see that the scale for the output of the Direct form II filter shown in attachment 1 on the right is on the order of 10^-5 where the magnitude of the response of the biquad filter is on the order of 10^2. other than this gain the responses look to be the same.
I am not entirely sure how this gain came into the system because we copied the c code that actually runs on the CDS system into python. There is a gain that affects the input of the biquad filter as shown on this slide of Matt Evans Slides. This gain, shown below as g, could decrease the input signal and thus fix the gain. However, I have not found any way to calculate this g.
With this gain problem we are left with the quantization noise shown in Attachment 4.
I have controlled the state space filter to act with a given precision level. However, my code is not optimized. It works by putting the input state through the first state-space equation then integrating the result, which finally gets fed through the second state-space equation.
This is not optimized and gives us the resulting quantization noise shown in attachment 5.
However, the state-space filter also has a gain problem where it is about 85 times the amplitude of the DF2 filter. Also since the state space is not operating in the most efficient way possible I decided to port the code chris made to run the state-space model to python. This code has a problem where it seems to be unstable. I will see if I can fix it
I am trying to replicate the simulation done by Matt Evans in his presentation (see Attachment 1 for the slide in particular).
He defines his input as so he has two inputs one of amplitude 1 at 1 Hz and one of amplitude 10^-9 at 1/4th the sampling frequency in this case: 4096 Hz
For his filter, he uses a fourth-order notch filter. To achieve this filter I cascaded two second-order notch filters (signal.iirnotch) both with locations at 1 Hz and quality factors of 1 and 1e6. as specified in slide 13 of his presentation.
I used the same procedure outlined here. My results are posted below in attachment 2.
Analysis of results:
As we can see from the results posted below the results don't match. there are a few problems that I noticed that may give us some idea of what went wrong.
First, there is a peak in the noise around 35 Hz. this peak is not shown at all in Matt's results and may indicate that something is inconsistent.
the second thing is that there is no peak at 4096 Hz. This is clearly shown in Matt's slides and it is shown in the input spectrum so it is strange that it does not appear in the output.
My first thought was that the 4kHz signal was being entered at about 35Hz but even when you remove the 4kHz signal from the input it is still there. The spectrum of the input shown in Attachment 3 shows no features at ~35Hz.
The Input filter, Shown in attachment 4 shows the input filter, which also has no features at ~35Hz. Seeing how the input has no features at ~35Hz and the filter has no features at ~35Hz there must be either some sort of quantization noise feature there or more likely there is some sort of sampling effect or some effect of the calculation.
To figure out what is causing this I will continue to change things in the model until I find what is controlling it.
I have included a Zip file that includes all the necessary files to recreate these plots and results.
4 units of Vertex SUS DAC adapter (https://dcc.ligo.org/LIGO-D2100035) ready.
The units are completely passive right now and has option to extend to have a dewhitening board added inside.
So the power switch does nothing.
Some of the components for the dewhitening enhancement are attached inside the units.
[Anchal, Yehonathan, Paco]
Today we opened ITMX chamber and removed the following optics and placed them in the Xend flow bench (see attachment 1):
Yehonathan brought his first SOS baby next to ITMX chamber. The suspension was carried by hands throughout. He gave me the suspension over the IMC beam tube from where I placed it on the table. I checked through the OSEMs and the face magnets were still on. I could not verify the side magnet but nothing seemed out of place.
I then moved LO1 near its planned place. I had to bolt it at 1 inch North and 0.5 inch West of its planned position because the side OSEM on ITMX is long and protrudes out of the base footprint. Even if it was small, the current layout would make the OSEM pins of the side OSEMs of ITMX and LO1 very near each other. So we can not place LO1 closer to ITMX from current position. This means the layout needs to be redesigned a bit for the modified position of LO1. I believe it will significantly shift and turn the beam from LO1 to LO2, so we might need to change the beam upstream from TT2 onwards. More discussion is required.
Unfortunately, what I thought was clicking photos was just changing modes between video and image mode, so I have no photos from today but only a video that I recorded in the end.
If ITMX already has another side magnet, we can migrate the side OSEM of ITMX to the other side. This way, the interference of the OSEMs can be avoided.
[Anchal, Yehonathan, Chub]
We today laid down 14 70 ft long DB25 cables from 1Y1 (6), 1Y0 (8) to ITMY Chamber (4), BS Chamber (6) and ITMX Chamber (4). The cables have been connected to respective satellite amplifier on the racks and the other ends are connected to the vacuum flange feedthru on ITMX for LO1 and PR2, while the others have been kept near the planned flange postions. LO1 is now ready to be connected to CDS by connecting the in-vacuum cable inside ITMX chamber to the OSEMs.
I've updated the c1su2 model today with model suspension blocks for the 7 new SOSs (LO1, LO2, AS1, AS4, SR2, PR2 and PR3). The model is running properly now but we had some difficulty in getting it to run.
Initially, we were getting 0x2000 error on the c1su2 model CDS screen. The issue probably was high data transmission required for all the 7 SOSs in this model. Koji dug up a script /opt/rtcds/caltech/c1/userapps/trunk/cds/c1/scripts/activateDQ.py that has been used historically for updating the data rate on some of theDQ channels in the suspension block. However, this script was not working properly for Koji, so he create a new script at /opt/rtcds/caltech/c1/chans/daq/activateSUS2DQ.py.
[Ed by KA: I could not make this modified script run so that I replaces the input file (i.e. C1SU2.ini). So the output file is named C1SU2.ini.NEW and need to manually replace the original file.]
With this, Koji was able to reduce acquisition rate of SUSPOS_IN1_DQ, SUSPIT_IN1_DQ, SUSYAW_IN1_DQ, SUSSIDE_IN1_DQ, SENSOR_UL, SENSOR_UR, SENSOR_LL,SENSOR_LR, SENSOR_SIDE, OPLEV_PERROR, OPLEV_YERROR, and OPLEV_SUM to 2048 Sa/s. The script modifies the /opt/rtcds/caltech/c1/chans/daq/C1SU2.ini file which would get re-written if c1su2 model is remade and reinstalled. After this modification, the 0x2000 error stopped appearing and the model is running fine.
We notice that all our suspension models need to go through this weird python script modifying auto-generated .ini files to reduce the data rate. Ideally, there is a simpler solution to this by simply adding the datarate 2048 in the '#DAQ Channels' block in the model library part /cvs/cds/rtcds/userapps/trunk/sus/c1/models/lib/sus_single_control.mdl which is the root model in all the suspensions. With this change, the .ini files will automatically be written with correct datarate and there will be no need for using the activateDQ script. But we couldn't find why this simple solution was not implemented in the past, so we want to know if there is more stuff going on here then we know. Changing the library model would obviously change every suspension model and we don't want a broken CDS system on our head at the begining of holidays, so we'll leave this delicate task for the near future.
We want to maintain the 16 kHz sample rate for the COIL DAQ channels, but nothing wrong with reducing the others.
I would suggest setting the DQ sample rates to 256 Hz for the SUS DAMP channels and 1024 Hz for the OPLEV channels (for noise diagnostics).
Maybe you can put these numbers into a new library part and we can have the best of all worlds?
[Paco (Vacuum Work), Anchal]
Today we opened the ITMY Chamber and installed suspended AS1 and AS4 in their planned positions. In doing so, we removed the razor or plate mounted on a pico motor at the south end of the table (see 40m/16450). We needed to make way for AS4 to be installed.
We need more dog clamps for installing the suspensions, we have used temporary clamps for now. However, knows where new C&B clamps are, please let us know.
[Anchal, Koji] Part of elog: 40m/16549.
The magnets on the mirror face are arranged in a manner that the overall magnetic dipole moment is nullified faraway. Because of this, the coil output gains in all such optics need to have positive and negative signs in a butterfly mode pattern (eg. UL, LR: +ve and UR, LL: -ve).
In the particular case of LO1, we chose following coil output gains:
This ensures that all damping gains have positive signs. Following damping gain values were chosen:
Having said that, this is a convention and we need to discuss more on what we want to set a convention (or follow a previous one if it exists). My discussion with Koji came up with the idea of fixing the motion response of an OSEM with respect to coil offset by balancing the coil gains across all optics and use same servo gains for all optics afterwards. But it is a complicated thought coming out of tired minds, needs more discussion.
Added input filters, input matrix, damping filters, output matrix, coil filters, and copy the state over from LO1 into AS1 screen in anticipation for damping.
Added input filters, input matrix, damping filters, output matrix, coil filters, and copy the state over from LO1 into AS4 screen in anticipation for damping.
Added input filters, input matrix, damping filters, output matrix, coil filters, and copy the state over from ITMX into LO2 screen in anticipation for damping.