Kiwamu and I looked at all the electronics that are currently in place for the green locking on the X-arm and have made a set of block diagrams of the rack mounted units that we should build to replace the existing ... "works of art" that sprawl around out there at the moment.
1. "ETM Green Oscillator/PDH support box". Not a great name but this would provide the local oscillator signal for the end PDH (with a controllable phase rotator) as well as the drive oscillator for the end laser PZT. Since we need to hit a frequency of 216.075kHz with a precision that Kiwamu needs to determine, we'd need to be able to tune the oscillator ... it needs to be a VCO. It'd be nice to be able to measure the output frequency so I've suggested dividing it down by N times to put it into the DAQ - maybe N = 2^7 = 128x to give a measured frequency of around 1.7kHz. Additionally this unit will sum the PDH control signal into the oscillation. This box would support the Universal PDH box that is currently at the X-end.
2. "Vertex X-arm beatnote box" - this basically takes the RF and DC signals from the beatnote PD and amplifies them. It provides a monitor for the RF signal and then converts the RF signal into a square wave in the comparator.
3. "Mixer Frequency Discriminator" - just the standard MFD setup stored in a box. For temperature stability reasons, we want to be careful about where we store this box and what it is made of. That's also the reason that this stage is separated from the X-arm beatnote box with it's high-power amps.
4. RS232 and EPICS control of the doubling ovens
5. Intensity stabilization of the End Laser
P.S. I used Google Diagrams for the pictures.
I tidied up some of the stuff that was on the SP table. The ISS box that has been sitting on there for months is now underneath the X-arm on top of the spare Marconi which is stored there.
Last Friday, we discovered a bug in the RCG where the delay part was not actually delaying. We reported this to Alex who promptly put a fix in the same day. This allowed Matt's newly proposed frequency discriminator to work properly.
It also required a checkout of the latest RCG code (revision 2328), and rebuild of the various codes. We backed up all the kernel and executables first such as mbuf.ko and awgtpman.
We did the following:
1) Log into the fb machine.
2) Go to /opt/rtcds/caltech/c1/core/advLigoRTS/src/drv/mbuf and run make. Copy the newly built mbuf.ko file to /diskless/root/modules/126.96.36.199/kernel/drivers/mbuf/mbuf.ko on the fb machine.
3) Use "sudo cp" to copy the newly built mbuf.ko file to /diskless/root/modules/188.8.131.52/kernel/drivers/mbuf/
4) Go to /cvs/cds/rtcds/caltech/c1/core/advLigoRTS/src/gds and run make.
5) Copy the newly built awgtpman executable to /opt/rtcds/caltech/c1/target/gds/bin/
6) Go to /opt/rtcds/caltech/c1/core/advLigoRTS/src/mx_stream/ and run make.
7) Copy the newly built mx_stream executable to /opt/rtcds/caltech/c1/target/fb/
Koji was unable to build his c1lst model first thing this morning. Turns out there was a bug with RCG parser that was introduced on Friday when we did the RCG updates. We talked Alex who did a quick comment fix. The diff is as follows:
--- Parser3.pm (revision 2328)
+++ Parser3.pm (working copy)
@@ -1124,8 +1124,8 @@
print "Flattening the model\n";
print "Finished flattening the model\n";
- CDS::Tree::do_on_nodes($root, \&remove_tags, 0, $root);
- print "Removed Tags\n";
+ #CDS::Tree::do_on_nodes($root, \&remove_tags, 0, $root);
+ #print "Removed Tags\n";
CDS::Tree::do_on_nodes($root, \&remove_busses, 0, $root);
This was some code to remove TAGs from the .mdl file for some reason which I do not understand at this time. I will ask tommorrow in person so I can understand the full story.
Koji then rebuilt and started the c1lst process. This is his new test version of the LSC code. We descovered (again) that when you activate too many DAQ channels (simply uncommenting them, not even recording them with activate=1 in the .ini file) that the frame builder crashes. In addition, the c1lsc machine, which the code was running on, also hard crashed.
When a channel gets added to the .ini file (or uncommented) it is sent to the framebuilder, irregardless of whether its recorded or not by the frame builder. There is only about 2 megabytes per second bandwidth per computer. In this case we were trying to do something like 200 channels * 16384 Hz * 4 bytes = 13 megabytes per second.
The maximium number of 16384 channels is roughly 30, with little to no room for anything else. In addition, test points use the same allocated memory structure, so that if you use up all the capacity with channels, you won't be able to use testpoints to that computer (or thats what Alex has led me to believe).
The daqd process then core dumped and was causing all sorts of martian network slowdowns. At the same time, the c1lsc computer crashed hard, and all of the front end processes except for the IOP on c1sus crashed.
We rebooted c1lsc, and restarted the c1sus processes using the startc1SYS scripts. However, the c1susfe.ko apparently got stuck in a wierd state. We were completely unable to damp the optics and were in general ringing them up severely. We tried debugging, including several burt restores and single path checks.
Eventually we decided to reboot the c1sus machine after a bit of debugging. After doing a burt restore after the reboot, everything started to damp and work happily. My best guess is the kernel module crashed in a bad way and remained in memory when we simply did the restart scripts.
I measured some laser powers associated with the beat-note detection system on the PSL table.
The diagram below is a summary of the measurement. All the data were taken by the Newport power meter.
The reflection from the beat-note PD is indeed significant as we have seen.
In addition to it the BS has a funny R/T ratio maybe because we are using an unknown BS from the Drever cabinet. I will replace it by a right BS.
During my work for making a noise budget I noticed that we haven't carefully characterize the beat-note detection system.
The final goal of this work is to draw noise curves for all the possible noise sources in one plot.
To draw the shot noise as well as the PD dark noise in the plot, I started collecting the data associated with the beat-note detection system.
* Estimation and measurement of the shot noise
* measurement of the PD electrical noise (dark noise)
* modeling for the PD electrical noise
* measurement of the doubling efficiency
* measurement of an amplitude noise coupling in the frequency discriminators
In the last week Matt and I modified the MFD configuration because the mixer had been illegally used.
Since the output from the comparator is normally about 10 dBm, a 4-way power splitter reduced the power down to 4 dBm in each output port.
In order to reserve a 7 dBm signal to a level-7 mixer, we decided to use an asymmetric power splitter, which is just a combination of 2-way and 3-way splitter shown in the diagram above.
With this configuration we can reserve a 7 dBm signal for a mixer in the fine path.
However on the other hand we sacrificed the coarse path because the power going to the mixer is now 2.2 dBm in each port.
According to the data sheet for the mixer, 1 dB compression point for the RF input is 1dBm. Therefore we put a 1 dB attenuator for the RF port in the coarse system.
In the delay line of the fine path we found that the delay cable was quite lossy and it reduced the power from 2.2 dBm to about 0 dBm.
Using 2 dBm for a Level 7 mixer is so bogus, that I will dismantle this as soon as I come over.
PLEASE DO NOT DISMANTLE THE SETUP !
Actually we tried looking for a level-3 or a smaller mixer, but we didn't find them at that moment. That's why we kept the level-7 mixer for the coarse path.
As you pointed out we can try an RF amplifier for it.
I (think) I have finished the new PMC base riser. The eDrawing of it (so you can view it on any computer) has been uploaded to the PMC wiki page.
I also attach it here, for comments.
Its going to need some kind of way to locate the PMC on the top. In the previous design, we had the 3 balls to decouple the body from the base. That design was flawed due to the roughness of the holes in the PMC body.
Also probably need some kind of relief on the bottom. Its possible that it would be OK like this, but I am unsure if the shop can maintain the flatness we want over the whole length and/or the flatness of any given (OLD) optical table over ~8". Its probably not a good idea to have to torque this (aluminum?) to make it conform to the optical table's shape.
Hmmm, so, this was just meant to be a riser that goes underneath the old PMC mount, to raise it from 3" beam height to 4" beam height. I will make another one that is a complete mount, designed for 4" beam height. Please hold........... .......... ....... ..... ... .
This is the log of the work on Wednesday 23rd.
1. Power Supply of the freq divider box
Kiwamu claimed that the comparator output of the freq div box only had small output like ~100mV.
The box worked on the electronics bench, we track down the power supply and found the fuse of the +15V line
brew out. It took sometime to notice this fact as the brown-out-LED of the fuse was not on and the power
supply terminal had +15V without the load. But this was because of the facts 1) the fuse is for 24V, and 2)
the large resistor is on the fuse for lighting the LED when the fuse is brown out.
I found another 24V fuse and put it there. Kiwamu is working on getting the correct fuses.
2. MC locking problem
After the hustle of the freq divider, the MC didn't lock. I tracked down the problem on the rack and found
there was no LO for the MC. This was fixed by pushing the power line cable of the AM Stabilizer for the MC LO, which was a bit loose.
This is the continuation of http://nodus.ligo.caltech.edu:8080/40m/4402
The first picture is of the actual component, where the resistor is 1M and capacitor is 10uF.
But before the component can be put into place, its transfer function had to be checked to make sure it was doing what we calculated it would do. The results of these are in the graphs generated: frequency vs. gain, and frequency vs. phase.
According to these graphs, we are not achieving the targeted cutoff frequency: need to recalculate and compensate for the extra 100k resistance being encountered.
For bode plot:
USE LOG-LOG plot for the amplitude
USE LOG-LINEAR plot for the phase
Search "Bode Plot" on web
* Temporary strain relief for the heliax cables on 1X2 (Steve)
* RF diagrams and check lists (Suresh)
=> In the lunch meeting we will discuss the details about what we will do for the RF installation.
* Electronics design and plan for Green locking (Aidan / Kiwamu)
=> In the lunch meeting we will discuss the details.
* LSC model (Koji)
* Video cable session (team)
* LPF for the laser temperature control (Larisa)
[Steve / Kiwamu]
As a part of the video cable session, we reconnected some power cords on 1Y1 rack.
During the work we momentarily turned off c1aux, which handles DMF, Illumintators, mechanical shutters and the old video epics.
I think it automatically reverted the things, but we may need to check them.
[Steve, Suresh, Kiwamu, Larisa]
Only the PRM/BS cable was laid today.
In one of the previous updates on cable laying, it was noted that the MC2 cable needed an additional 10' and the MC2T needed an additional 15' to reach their destinations. We cut and put BNC ends on 10' and 15' cables and connected them to the original cables in order to make them long enough.
This concludes the laying of new cables. Suresh is currently working on the QUADs...
The attached table shows the amplitude of the green beat note when the end laser was in various states. We can increase the beat note amplitude dramatically by switching to a different states.
C1:GCX-GRN_REFL_DC: 638 counts
C1:GCV-XARM_BEAT_DC: (PSL blocked) 950 avg counts (zero = -794 counts)
amplitude of beat note: -23dBm (after PD + amps) (f ~ 30 MHz)?
C1:GCX-SLOW_SERVO2_OUT: 318 counts
C1:GCX-GRN_REFL_DC: 180 counts
C1:GCV-XARM_BEAT_DC: (PSL blocked) 1270 avg counts (zero = -794 counts)
C1:GCV-XARM_BEAT_DC: (PSL unblocked) 1700 avg counts (zero = -794 counts)
amplitude of beat note: -7dBm (after PD + amps) f = 60MHz
amplitude of beat note: 0dBm (after PD + amps) f = 30MHz
C1:GCX-SLOW_SERVO2_OUT: 290 counts
C1:GCX-GRN_REFL_DC: 220 counts
C1:GCV-XARM_BEAT_DC: (PSL blocked) 1120 avg counts (zero = -794 counts)
C1:GCV-XARM_BEAT_DC: (PSL unblocked) 1520 avg counts (zero = -794 counts)
amplitude of beat note: 0dBm (after PD + amps) f = 15MHz
C1:GCX-SLOW_SERVO2_OUT: 305 counts
PSL temp = ??
C1:PSL-FSS_SLOWM = -3.524
The video work has crossed a milestone.
Kiwamu and Steve have shifted the three quads from the control room to the Video MUX rack (1Y1) and have wired them to the MUX.
The monitors in the control room have been repositioned and renumbered. They are now connected directly to the MUX.
Please see the new cable list for the input and output channels on the MUX.
As of today, all cables according the new plan are in place. Their status indicated on the wiki page above is not verified . Please ignore that column for now, we will be updating that soon.
I shifted the MC1F/MC3F camera and the MC2F cameras onto the new cables. Also connected the monitors at the BS chamber and end of the X arm to their respective cables. I have removed the RG58B BNC (black) cables running from MC2 to BS and from ETMXF to the top of the Flow Bench.
Some of the old video cables are still in place but are not used. We might consider removing them to clear up the clutter.
Some of the video cables in use are orange and if the lab's cable color code is to be enforced these will have to be replaced with blue ones..
Some of the cables in use running from the MUX to the monitor in the control room are the white 50 Ohm variety. There are also black RG59 Cables running the same way ( we have surplus cables in that path) and we have to use those instead of the white ones.
There are a number of tasks remaining:
a) The inputs from the various existing cameras have to be verified.
b) There are quite a few cameras which are yet to be installed.
c) The Outputs may not not be connected to their monitors. That the monitors may still be connected to an old cable which is not connected to the MUX. The new cable should be lying around close by. So if you see a blank monitor please connect it to its new cable.
d) The status column on the wiki page has to be updated.
e) Some of the currently in place may need to be replaced and some need to be removed. We need to discuss our priorities and come up with a plan for that.
After checking everything we can certify that the video cabling system is complete.
I would like Joon Ho to take care of this verification+documenting process and declaring that the job is complete.
Steve attached these two pictures.
After I did several things to add new DAQ channels on c1iscex it suddenly became out of network. Maybe crashed.
Then c1iscex didn't respond to a ping and all the epics values associated with c1iscex became not accessible.
I physically shut it down by pushing the reset button. Then it came back and is now running fine.
(how I broke it)
Since activateDAQ.py has screwed up the 'ini' files including C1SCX.ini, I was not able to add a channel to C1SCX.ini by the usual daqconfig GUI.
So I started editing it in a manual way with an editor and changed some sentences to that shown below
Then I rebooted fb to reflect the new DAQ channels.
After that I looked at the C1_FE_STATUS.adl screen and found some indicator lights were red.
So I pushed "Diag reset" button and "DAQ Reload" button on the C1SCX_GDS_TP.adl screen and then c1iscex died.
After the reboot the new DAQ channels looked acquired happily.
This is my second time to crash a front end machine (see this entry)
I made a coarse noise budget in order to decide our next actions for the X arm green locking.
So be careful, this is not an accurate noise budget !
Some data are just coming from rough estimations and some data are not well calibrated.
Assuming all the noise are not so terribly off from the true values, the noise at high frequency is limited by the dark noise of the PD or it already reaches to the IR inloop signal.
The noise at low frequency is dominated by the intensity noise from the transmitted green light although we thought it has been eliminated by the comparator.
In any case I will gradually make this noise budget more accurate by collecting some data and calibrating them.
According to the plot what we should do are :
* More accurate PD noise measurement
* More accurate shot noise estimation
* Searching for a cause of the small beat signal (see here) because a bigger beat signal lowers the PD noise.
* Investigation of the Intensity noise
I unpacked the STS2 seismometers that we borrowed from LLO. They are sitting underneath the Xarm, in the middle of the mode cleaner, near the other seismometer stuff.
It turned out that the dark noise from the beat PD and the shot noise on the beat PD was overestimated.
So I corrected them in the plot of the last noise budget (#4482).
Additionally I added the end laser error signal in the plot. Here is the latest plot.
The end laser error spectrum is big enough to cover most of the frequency range.
(although it was taken at a different time from the other curves.)
[Steve, Kiwamu, Larisa]
Having finished laying new cable last week, we moved on to connecting those on PSL table and AP table.
--RCR, RCT, PMCR (all three are blue)
--OMCR (blue cable, ***now has a camera***), PMCT, IMCR, REFL, AS (white cable), OMCT (***now has camera***)
Unless otherwise noted, the cables are black on the AP table. Also on the AP table: cables were connected directly to the power source.
The wiki has been updated accordingly.
Steve noted that MC2T and POP cameras are not there.
The PSL enclosure now have 4 windows on each side. The bottom rail guides on the east side will be replaced by one U-channel for smoother, more gentle sliding.
Door position indicator- interlock switches are not wired yet.
The controls (fast and slow both) think ITMX is ITMY and ITMY is ITMX.
After some poking around today, I have convinced myself it is sufficient to simply swap all instances of ITMX for ITMY in the C1_SUS-AUX1_ITMX.db file, and then rename it to C1_SUS-AUX1_ITMY.db (after having moved the original C1_SUS-AUX1_ITMY.db to a temporary holding file).
A similar process is then applied to the original C1_SUS-AUX1_ITMY.db file. These files live in /cvs/cds/caltech/target/c1susaux. This will fix all the slow controls.
To fix the fast controls, we'll modify the c1sus.mdl file located in /opt/rtcds/caltech/c1/core/advLigoRTS/src/epics/simLink/ so that the ITMX suspension name is changed to ITMY and vice versa. We'll also need to clean up some of the labeling
At Kiwamu and Bryan's request, this will either be done tomorrow morning or on Monday.
So the steps in order are:
1) cd /cvs/cds/caltech/target/c1susaux
2) mv C1_SUS-AUX1_ITMX.db C1_SUS-AUX1_ITMX.db.20110408
3) mv C1_SUS-AUX1_ITMY.db C1_SUS-AUX1_ITMY.db.20110408
4) sed 's/ITMX/ITMY/g' C1_SUS-AUX1_ITMX.db.20110408 > C1_SUS-AUX1_ITMY.db
5) sed 's/ITMY/ITMX/g' C1_SUS-AUX1_ITMY.db.20110408 > C1_SUS-AUX1_ITMX.db
8) Modify c1sus model to swap ITMX and ITMY names while preserving wiring from ADCs/DACs/BO to and from those blocks.
9) code; make c1sus; make install-c1sus
10) Disable all watchdogs
11) Restart the c1susaux computer and the c1sus computer
The measured power levels of the RF source harmonics are given below:
We are considering inclusion of bandpass filters centered on 11 and 55 MHz to suppress the harmonics and meet the requirements specified in Alberto's thesis (page 88).
I started to modify another green PD set.
It so far has the transimpedance of 240 Ohm on CLC409 for the RF output.
It shows the BB output upto ~100MHz.
The measurement shows the transimpedenca of ~90Ohm which is ~25% smaller than the expected gain of 120Ohm.
It is calibrated based on the transimpedances of Newfocus 1611 (10kOhm and 700Ohm for AF and RF).
The next step is to change the transimpedance resister to 2k and replace the PD to S3399 Si PD, which has the diameter of 3mm.
Then, the noise level will be measured. (and replace the RF opamp if necessary)
Ooh. Can you explain the purpose of the resistors which are connected to the (+) inputs? It looks like some real electronics ninjitsu.
51 Ohm for CLC409
The datasheet of CLC409 uses 25Ohm there. This is to cancel the input bias current of the two inputs of the opamp.
The source impedance (series) of SGD444 is 50Ohm. So I used 50Ohm for the + input shunting.
However, I could probably use anything between 0-50Ohm as the datasheet itself tells that the bias currents are
not related between the two inputs. In addition, I am not sure how much the real series resistance of the PD is.
1kOhm for OP27
This resister is to ensure the (+) input to have a high impedance at high frequencies.
As far as OP27 is behaving as an ideal opamp, the (+) input has a high impedance.
Also if the inductor behaves as the ideal inductor, no photocurrent comes to the AF path.
However, if both of the op27 and the inductor show similar impedances to the RF transimpedance of 240Ohm,
the AF path absorbs some photocurrent and affects the RF transimpedance of the RF output.
We know that the inductor has a self resonance where the shunt capacitance take over the impedance of the coil.
Above that frequency, the inductor is no longer the inductor. The self resonant freq of this inductor is ~300MHz. It is OK, but not
too far from the freq of interest if we like to see clear cut off at around f>100MHz.
Also OP27 is an AF amplifier and I had no confidence about the input impedance of the OP27 at 100~300MHz.
If I put 1k in the (+) input of the OP27, I can ensure the entire AF path has the impedance of ~1k (at least 500Ohm even when L and OP27 are shorted).
I think the chip resister easily works as a resister up to 1GHz.
The daqd process was dying every minute or so when it couldn't write frame. This was slowing down the network by writing a 2.9G core dump over NFS every minute or so. (In /opt/rtcds/caltech/c1/target/fb/).
The problem was /frames/ was 100% full.
Apparently, when we switched the fb over to Gentoo, we forgot to install crontab and a wiper script.
We will install crontab and get the wiper script installed.
[Joe, Jamie, Alex]
I asked Alex which cron to use (dcron? frcron?). He promptly did the following:
rc-update add dcron default
Copied the wiper.pl script from LLO to /opt/rtcds/caltech/c1/target/fb/
At that point, I modified wiper.pl script to reduce to 95% instead of 99.7%.
I added controls to the cron group on fb:
sudo gpasswd -a controls cron
I then added the wiper.pl to the crontab as the following line using crontab -e.
0 6 * * * /opt/rtcds/caltech/c1/target/fb/wiper.pl --delete &> /opt/rtcds/caltech/c1/target/fb/wiper.log
Note, placing backups on the /frames raid array will break this script, because it compares the amount in the /frames/full/, /frames/trends/minutes, and /frames/trends/seconds to the total capacity.
Apparently, we had backups from September 27th, 2010 and March 22nd, 2011. These would have broken the script in any case.
We are currently removing these backups, as they are redundant data, and we have rsync'd backups of the frames and trends. We should now have approximately twice the lookback of full frames.
As part of the RF system upgrade some of the demod boards in the lab were modfied. The filter U5 (see the circuit schematic) was replaced. These changes are tabulated below.
Next, I and Q phase has to be checked for orthogonality. And noise levels of the cards have to measured.
I brought TTFSS set #7 to 40m and kept it in the electronic cabinet.
note that Q4 transistor has not been replaced back to PZT2907A yet. It's still GE82.
Q3 is now pzt3904, not PZT2222A.
The (-) input has been decoupled by the capacitor. So the series resistance of the PD is not the matter.
In this sense, we should use 0Ohm for the (+) input shunting.
However, I could probably use anything between 0-50Ohm as the datasheet itself tells that the bias currents are
not related between the two inputs. In addition, I am not sure how much the real series resistance of the PD is.
I am a little concerned about using these low pass filters so close to the band edge. Recall that there is no on-board preamp for the RF input to the mixer.
So, if the input impedance of the filters is not 50 Ohms, we will get some unwanted reflections and sensitivity to cable length.
I think its worth while to check the impedance or S-parameters of these things with the LO activated to find out if we need to remove them or not.
The steps from this elog were followed.
In addition, I did a burt restore of c1sus, c1mcs.
I then swapped all the gain settings from ITMX to ITMY, and reenabled the watchdogs.
I did some basic kick tests (1000 counts into UL coil) and confirmed channels like C1:SUS-ITMX_ULPD_VAR (watchdogs mV readback) corresponded to the correct optic. I also checked that the POS, PIT, YAW, SIDE produced reasonable damping when engaged.
Currently the c1scy, c1mcs, and c1rfm models are reporting an error with receiving some data sent over the GE Fanuc Reflected memory cards.
To be more exact, the C1:SUS-ETMY_ALS signal from the c1gcv FE code on the c1ioo computer going too the Y end is not being received. However, the C1:SUS-ETMY_LSC signal is. So the physical RFM card seems to be working.
Similarly, the TRY signal is being sent correctly from the Y end computer. The X end is working fine and receiving both LSC and ALS signals.
The c1mcs and c1rfm models also receive data from the c1ioo computer and reporting receiving errors.
Because the RFM cards are transmitting and receiving at least some channels, I'm guessing there was changes made to the C1.ipc file, which defines the memory locations of these various channels on the RFM network, and that when a model was rebuilt, a different one using the previous IPC file was not, and thus one of the computer is going to the wrong place to either read or write data.
Tomorrow, I'm planning on the following:
1) Clean out the C1.ipc file (/opt/rtcds/caltech/c1/chans/ipc/)
2) Rebuild all models
3) Run activate_daq.py script
4) Restart models via script
If this doesn't clear up the problem, I'll continue to bug hunt.
I switched the ITMX and ITMY control channels yesterday, but forgot to update the IFO_ALIGN.adl file (/opt/rtcds/caltech/c1/medm/c1ifo/) which had the control labels swapped to make life easier.
I swapped ITMX and ITMY control locations on the screen.
Are there any other screens involving ITMX and ITMY that had controls reversed to make life easier?
The following Video MUX inputs(cameras) and outputs(monitors) have been checked:
MC2F, FI, AS Spare, ITMYF, ITMXF, ETMYF, ETMXF, PSL Spare, ETMXT, MC2T, POP, MC1F/MC3F, SRMF, ETMYT, PRM/BS, CRT1(MON1), ETMY Monitor, CRT2(MON2), CRT4(MON4), MC1 Monitor, CRT3(MON3), PSL1 Monitor, PSL2 Monitor, CRT6(MON6), CRT5(MON5), ETMX Monitor, MC2 Monitor, CRT9, CRT7(MON7), CRT10, and Projector.
Their respective statuses have been updated on the wiki: (wiki is down at the moment, I will come back and add the link when it's back up)
[Jamie, Jenne, Koji]
We installed the new c1lsc and started the process.
We still need to configure bunch of the EPICS variables, matrices, and some of the filters.
This should be done in order to transmit the signals to the suspensions.
Jenne is going to work on this task tomorrow (Friday) morning,
and Koji will take over the task afternoon/evening.
Target: To lock the Michelson with the new RF/LSC
RF generation box: READY - already ready to go to the IOO rack. (Suresh)
RF distribution box: In Progress - the internal components are to be connected. (13th evening - Suresh)
Placing PD and CCD: Done - PD and CCD on the AP table (13th Afternoon - Aidan, Larisa with supervision of Kiwamu)
Cabling1: Done - PD signal AP table to the demodulator (13th Afternoon - Jamie with supervision of Suresh)
Cabling2: Done - RF generation box (IOO Rack) to the demodulator
Demodulator: In Progress - Test and install (13th night - Kiwamu with supervision of Suresh)
LSC model: Done - Run the new LSC model. (It is named as "C1LST" so far) (13th evening - Jamie)
LSC medm: Done on 14th - Modify the current LSC medm screens Update the EPICS database Adjust the matrices (- Jenne with supervision of Koji)
There were red lights on the status screen indicating RFM errors for the c1scy, c1mcs and c1rfm processes.
The c1iscey, c1sus machines were receiving data sent over the RFM network from the c1ioo computer with a bad time stamp, a few cycles too late. The c1iscex computer was receiving data from c1ioo fine.
The c1iscex RFM card had gotten into a bad state and was somehow slowing things down/corrupting data. It didn't affect itself, but due to the loop topology was messing everyone else up. Basically the only one who wasn't throwing an error was the culprit.
Hard power cycling the c1iscex computer reset the RFM card and fixed the problem.
The PD signals are transmitted to the suspension now.
The trigger thresholds were set to -1. This means the triggers are always on.
[Koji / Kiwamu]
The Michelson was locked with the new LSC realtime code.
(what we did)
-- Fine alignment of the Michelson, including PZTs, BS and ITMY.
Since the X arm has been nicely aligned we intentionally avoided touching ITMX. The IR beam now is hitting the center of both end mirrors.
At the end we lost X arm's resonance for IR. This probably means the PZTs need more careful alignments.
-- Signal acquisition
We replaced the RFPD (AS55) that Aidan and Jamie nicely installed by POY11 because we haven't yet installed a 55MHz RF source.
The maximum DC voltage from the PD went to about 50 mV after aligning steering mirrors on the AP table.
The RF signal from the PD is transferred by a heliax cable which has been labeled 'REFL33'.
Then the RF signal is demodulated at a demodulation board 'AS11', which is one of the demodulation boards that Suresh recently modified.
Although we haven't fully characterized the demod board the I and Q signal looked healthy.
Finally the demod signals go to ADC_0_3 and ADC_0_4 which are the third and fourth channel.
They finally show up in REFL33 path in the digital world.
With the new LSC code we fedback the signal to BS. We put anti-whitening filters in the I and Q input filter banks.
We found that dataviewer didn't show correct channels, for example C1LSC_NREFL33I showed just ADC noise and C1LSC_NREFL33Q showed NREFL_33I.
Due to this fact we gave up adjusting the digital phase rotation and decided to use only the I-phase signal.
Applying a 1000:10 filter gave us a moderate lock of the Michelson. The gain was -100 in C1LSC_MICH_GAIN and this gave us the UGF of about 300 Hz.
Note that during the locking both ETMs were intentionally misaligned in order not to have Fabry-Perot fringes.
While Kiwamu was working on the RF cabling at the LSC rack, I removed 80% of SMA cables which were not connected anywhere.
The rack is cleaner now, but not perfect yet. We need patch panels/strain relieving for heliaxes, cleaning up of the RF/LO cables, etc.
During checking the 11MHz demod boards I found that the I-Q relative phase showed funny LO power dependence.
It is now under investigation.
In the plot above the green curve represents the I-Q phase of a 11MHz demod board (see here).
It showed a strong dependence on the LO power and it changes from -60 deg to -130 deg as the LO power changes.
This is not a good situation because any power modulation on the LO will cause a phase jitter.
For a comparison I also took I-Q relative phase of a 33MHz demod board, which hasn't been modified recently.
It shows a nice flat curve up to 5 dBm although it looks like my rough measurement adds a systematic error of about -5 deg.
- to do -
* check RF power in every point of LO path on the circuit
* check if there is saturation by looking at wave forms.
Plotting the data points yielded by the spec analyzer of my first LPF yielded a result that was not expected: the desired cutoff frequency wasn't achieved because of some extra 100k resistance that wasn't taken into consideration. (see here ). I have redrawn the Bode graphs for this configuration so that it is easier to see that it is wrong (first attachment)
After some calculation adjustments, it was found that the capacitor value could remain at 10uF, but the resistance needed to be changed to 100k to maintain a gain of 0.5 and critical frequency at 0.1Hz. Second attachment is the Bode graph that results from this configuration.
Note: Bode graphs are both in Log-Linear scales (Wikipedia said so)
[Rana, Koji, Kiwamu]
Moreover the amplitude of the I and Q signals are highly unbalanced, depending on the LO power again.
This implies the coil for a 90 degree splitting won't work at 11 MHz since the coil is home made and used to be designed for a specific frequency (i.g. 24.5 MHz).
We decided to use a Mini circuit 90 deg splitter instead. Steve will order few of them soon and we will test it out.