Alex, Gautam and Steve,
Single mode fiber 50m long is layed out into cable tray that is attached to the beam tube of the Y arm.
It goes from ETMY to PSL enclosure. It is protected at both ends with " clear- pvc, slit corrugated loom tubing " 1.5" ID
The fiber is not protected between 1Y1 and 1Y4
Calibration data for the POP QPD has been taken, with the PRMI locked on sideband (with AS55Q and REFL33I, since it stayed locked longer with those 2). ASC was on, AC coupled.
We didn't get too far on either side of center of the QPD, since the ASC servo would go unstable, so we only explored the roughly linear region. Data / plots / analysis to follow.
Jenne just rebooted c1scy and daqd on the framebuilder. We will do the actual test after lunch.
I was bad, and forgot to elog the most important part of my work yesterday - that I had rotated the POP QPD by 90 degrees, so that I could fit the micrometer onto the table. There is a sticker on the front of the QPD to indicate which direction is "X" and "Y" for the output of the readout box. Right now (and the way that I will mount the QPD to the table, after I redo the calibration today), X is PITCH, and Y is YAW. Koji and Nic swapped the cables to the ADC to make this all consistent.
Yesterday, I locked the PRM-ITMY half cavity, and tried to take calibration data. However, with no ASC servo engaged, the beam was still moving. Also, with only the half-cavity, I had very little light on the QPD, and since it has internal normalization, the outputs can get a little funny if there isn't enough light. I had checked, and even with the gain cranked up to maximum, the "light level too low" LED was illuminated. So, my calibration data from yesterday isn't really useful.
Today, hopefully after lunch, I will lock the PRMI with the new AC-coupled ASC servo, so that I can have the servo on, and the PRMI locked on the sideband, so that I have more light on the QPD.
After that, it seems that the final thing we need to do before we vent is hold an arm near, but off resonance, lock the PRMI, and then swing the arm in and out of resonance a bit.
The bank marked channel 9-16 is free, but the connector is a 40 pin IDC and I need to know the exact pin-out configuration before I can set about making the custom ribbon cable that will send the control signals from the DAC card to the PZT driver board.
The DAC interface board on rack 1Y4 seems to be one of the first versions of this board, and has no DCC number anywhere on it. Identical modules on other racks have the DCC number D080303, but this document does not exist and there does not seem to be any additional documentation anywhere. The best thing I could find was the circuit diagram for the ADL General Standards 16-bit DAC Adapter Board, which has what looks like the pin-out for the 68 pin SCSI connector on the DAC Interface board. Koji gave me an unused board with the same part number (D080303) and I used a multimeter and continuity checking to make a map between DAC channels, and the 40 pin IDC connector on the board, but this needs to be verified (I don't even know if what is sitting inside the box on 1Y4 is the same D080303 board).
Jenne suggested making a break-out cable to verify the pin-outs, which I did with a 40-pin IDC connector and a bit of ribbon wire. The other end of the ribbon wire has been stripped so that we can use some clip-on probes and an oscilloscope to verify the pin-outs by sending a signal to DAC channels 9 through 16 one at a time. On the software side, Jenne did the following:
We have not restarted c1scy yet as Annalisa is working on some Y-arm stuff right now. We will restart c1scy and use awggui to perform the test once she is done.
Pink edits by JCD
- Locked PRMI with REFL165 I/Q
- Aligned the POP beam on the QPD. We found that the vertical motion of the beam appeared in the yaw signal, and horizontal motion in the pitch signal.
This was fixed by swapping the cables to the ADC. Later it turned out that this was caused by the calibration setup for the QPD.
We requested Jenne to fix the QPD on the table with the current orientation.
- Re-implemented the AC-coupled ASC servo. The filters were just copied from the previous PRM ASC servo (in the SUS ASC filter).
The same filter was installed to the pitch and yaw filter modules for now. The gains were adjusted to have some stable lock stretches.
The power spectra of C1:ASC-PRCL_YAW_IN1 and C1:ASC-PRCL_PIT_IN1 were attached.
The reference curves are the ones with the servo on. The other two are the free-running stability of the QPD output.
- Modified the up and down scripts for the PRM ASC for the new setup.
It first turns on the inputs of the filters and then turn on FM2/3.
It assumes that the outputs are engaged all time.
I wanted to investigate on the ALS electronics(in particular the beatbox and the phase tracker) and find out if the beatbox is showing a linear behavior
as we expect it to and as to why we have been seeing sudden jumps at the phase tracker output.
I have been using the Xarm part of the beabox.
I used Marconi as well as signal generator to do frequency sweep/modulation at the RF input of the beatbox and looked at the I_MON output of the beatbox.
We observed sudden jumps in the beatbox output from time to time while we either varied the carrier frequency or the RF amplitude.
Also the beatbox output shows high frequency oscillations at ~95MHz (source unknown). It is for sure that the beatbox is not behaving the way it should
but we could not tell more or troubleshoot with the beatbox mounted on the rack.
I am going to let Annalisa do her Y arm ALS scan tonight and pull out the beatbox tomorrow to fix it.
Alex and Eric
For the photodetector frequency response automation project, we plan to add modules to rack 1y1 as shown in the attached picture (Note: boxes are approximately to scale).
The RF switch will choose which photodetector's output is sent to the Agilent 4395A Network Analyzer.
The Diode Laser Module is powered by Laser Power Supply, will be modulated by the Network Analyzer and will be output to a 1x16 optical splitter which is already mounted in another rack (not pictured).
The Transformer Module has not been built yet.
We would like to install the power supply and the laser module tomorrow and will not begin routing fibers and cables until we post a drawing in the elog.
Also, our reference photoreceiver arrived today.
I am prepping to do the POP QPD calibration, and so have turned off the POP QPD, and put it onto a micrometer stage. My plan is to (after fixing the ASC servo filters to make the servo AC coupled, rather than DC coupled) lock the PRM-ITMY half cavity, and use that beam to calibrate the QPD. While this isn't as great as the full PRMI, the PRMI beam moves too much to be useful, unless the ASC servo is engaged.
While on the table, I noticed 2 things:
* In order to place the micrometer, I had to temporarily move the POP55 RFPD (which has not been used in quite a long time). I think it's just that the panel-mount SMA connector isn't tight to the panel inside, but the RF out SMA cable connector is very loose. I have moved the POP55 RFPD to the very very south end of the SP table, until someone has time to have a quick look. (I don't want to get too distracted from my current mission, since we haven't put beam onto that PD for at least a year).
* The ITMX oplev beam setup isn't so great. The last steering mirror before the beam is launched into the vacuum is close to clipping (in yaw... pitch is totally fine), and the steering mirror outside of vacuum to put the beam on the QPD is totally clipping. The beam is falling off the bottom of this last steering mirror. Assuming the beam height is okay on all of the input optics and the in-vac table, we need to lower the last steering mirror before the oplev QPD. My current hypothesis is that by switching which in-vac steering mirror we are using (see Gautam's elog 8758) the new setup has the beam pointing downward a bit. If the problem is one of the in-vac mirrors, we can't do anything about it until the vent, so for now we can just lower the out of vac mirror. We should put it back to normal height and fix the oplev setup when we're at atmosphere.
With the help of an expansion card, I verified that the + 15V and + 24V from the eurocrate in the slot I've identified for the PZT driver boards are making their way to the board. The slot is at the right-most end of the eurocrate in 1Y4, and the rack door was getting in the way of directly measuring these voltages once I hooked up the driver board to the expansion card. So I just made sure that all the LEDs on the expansion card lit up (indicating that the eurocrate is supplying + 5, + 15 and + 24V), and then used a multimeter to check continuity between the expansion card and the driver board outside of the eurocrate. The circuit only uses + 15V and + 24V, and I checked for continuity at all the IC pins marked with these voltages on the schematic.
Since the whole point of this test was to see if the slot I identified was delivering the right voltages, I think this is sufficient. I will now need to fashion a cable that I can use to connect a DC power supply to the PZT driver boards so that these can be tested further.
The high voltage points (100V DC) remain to be tested.
Totally agree. The old suspension screen should be driven away.
Now that the 3f locking looks so cool for the PRMI, I suppose that the PRMI + arm stuff will be very successful.
At LLO, I've just noticed the screens that they have for the single pendulums / TTs. I'm attaching a screenshot of the one Zach is using for the steering into the OMC. We should grab these and replace our existing SUS screens with them.
- The new REFL165 PD was installed on the AP table
- The REFL165I/Q signals are now showing sensible and robust PRCL/MICH signals
- PRMIsb was locked only with these REFL165 signals
- Installation of the REFL165 PD
We prepared the REFL165 PD for the 4" optical height. The actual issue was the power supply for the PD.
We soldered wires between the PD and the RF PD interface break-out board. Then the PD interface
cable for the old REFL165 (iLIGO style) was connected.
At the REFL port, most of the light is rejected by the first beam splitter (R=90%?). We attenuated the beam by a factor of 10
using an ND filter. The new PD showed the DC output of ~10V. This corresponds to the photocurrent of 5mA.
(cf. the shot-noise intercept current is ~1mA)
The output of the REFL165 PD was checked with the RF spectrum analyzer. It was a bit surprising but we had a forest of
RF signals betwen 11MHz and 178MHz. We tried to use a high-pass filter with fc=100MHz (SPH-100) but still the rejection
was not enough. We ended up with using SPH-150 (fc=150MHz).
- Whitening / Demodulation phase
Then we connected the RF output to the SMA cable to the LSC rack. We immediately saw the nice signals from REFL165I/Q
channels, namely sensible structure of pendulum resonances (1/3/16Hz peaks) and floor level.
The whitening level was changed from 21dB to 45dB (max). The DC offsets in the I/Q channels (of the order of 2000~4000)
were removed by the ./LSC/LSCoffset script.
Firstly we locked the PRMI with the usual signals (REFL33I and AS55Q).
The demodulation phase was roughtly tuned (1deg precision) such that the Q phase signal is minimized,
assuming most of the signal is coming from PRCL. Our choise is 74deg.
In this configuration, PRCL shows same quality of signal as our prefered PRCL (i.e. REFL33I) in the amplitude and the sign.
We switched to the REFL165 signal by handing off at the input matrix. The input matrix element for REFL165_I was gradually
increasded up to 0.8 while the element for REFL33I was gradually reduced to 0. We did the same for REFL165_Q with the element of 0.2.
Now we tried locking with REFL165I/Q from the beginning. Once the alignment is adjusted, the lock was immediately obtained
only with REFL165I/Q. Today we did not adjusted the ASC stuff (OPLEVs and PRM ASC) so the lock was not long (<1min). Particularly
ITMX poiting kept drifting and it made the lock difficult. We should check the oplev setup carefully.
- LSC summary
Signal source: REFL165I (74deg) / Whitening gain 45dB
Normalization sqrt(POP110I x 0.1) / Trigger POP110I 100up 3down
Servo: input matrix 0.80 -> PRCL Servo FM3/4/5 Always ON G=+2.50
Actuator: output matrix 1.00 -> PRM
Signal source: REFL165Q (74deg) / Whitening gain 45dB
Normalization sqrt(POP110I x 10.0) / Trigger POP110I 100up 3down
Servo: input matrix 0.20 -> MICH Servo FM4/5 Always On G=-40
Actuator output matrix -1.00 -> ITMX / +1.00 -> ITMY
- Refine the PRM asc servo (AC coupled)
- Align oplevs
- ITMX oplev is drifting quickly (~1min time scale)
This is an update on the situation as far as PZT installation is concerned. I measured the required cable (PZT driver board to PZT) lengths for the X and Y ends as well as the PSL table once again, with the help of a 3m long BNC cable, just to make sure we had the lengths right. The quoted cable lengths include a meter tolerance. The PZTs themselves have cable lengths of 1.5m, though I have assumed that this will be used on the tables themselves. The inventory status is as follows.
I also did a preliminary check on the driver boards, mainly to check for continuity. Some minor modifications have been made to this board from the schematic shown here (using jumper wires soldered on the top-side of the PCB). I will have to do a more comprehensive check to make sure the board as such is functioning as we expect it to. The plan for this is to first check the board without the high-voltage power supply (using an expansion card to hook it up to a eurocrate). Once it has been verified that the board is getting powered, I will connect the high-voltage supply and a test PZT to the board to do both a check of the board as well as a preliminary calibration of the PZTs.
To this end, I need something to track the spot position as I apply varying voltage to the PZT. QPDs are an option, the alternative being some PSDs I found. The problem with the latter is that the interfaces to the PSD (there are 3) all seem to be damaged (according to the labels on two of them). I tried connecting a PSD to the third interface (OT301 Precision Position Sensing Amplifier), and hooked it up to an oscilloscope. I then shone a laser pointer on the psd, and moved it around a little to see if the signals on the oscilloscope made sense. They didn't on this first try, though this may be because the sensing amplifier is not calibrated. I will try this again. If I can get one of the PSDs to work, mount it on a test optical table and calibrate it. The plan is then to use this PSD to track the position of the reflected beam off a mirror mounted on a PZT (temporarily, using double sided tape) that is driven by feeding small-amplitude signals to the driver board via a function generator.
The LEMO connector on the PZTs have the part number LEMO.FFS.00, while the male SMB connectors on the board have the part number PE4177 (Pasternack)
Plan of Action:
The wiring scheme has been modified a little, I am uploading an updated one here. In the earlier version, I had mistaken the monitor channels as points from which to log data, while they are really just for debugging. I have also revised the coaxial cable type used (RG316 as opposed to RG174) and the SMB connector (female rather than male).
After familiarizing myself with Altium, I drew up the attached schematic for the ISS to be used in the CTN experiment. The filename includes 'abbott-switch' as I am using an Altium component (the switch, in particular), that he created. The MAX333A actually has 20 pins on a single component, but the distributed component that he created is useful for drawing uncluttered schematics. I won't be using all of the pins on this switch, but for completeness, I have included the 3rd and 4th portion of the full component in the upper right hand corner.
Currently, the schematic includes the voltage reference (AD586), a LP filter for the reference signal, the differential amplifier stage to obtain the error signal and then finally all of the filter stages. The schematic does not include the RMS detection and subsequent triggering of each filter stage. The TRIGGER 1 signal is a user input (essentially the on button) while the TRIGGER 2 signal will flip the second switch when the RMS noise has decreased sufficiently after the first filter stage has been turned on.
PCB layouts will be done once I understand that part of Altium
NOTE THAT I HAVE DELETED ELOG 8798 AS IT WAS A DUPLICATE OF THIS ONE.
I wanted this elog to be in reply to a previous one and I couldn't figure out how to change that in an elog I already submitted.
P.1 Circuit diagram
Added components are indicated by red symbols.
- The diode on the board is HAMAMATSU S3399. It is a Si PIN diode with φ3.0 mm.
- Based on prototype version of aLIGO BBPD D1002969-v8 (although the board says v7, It is v8.)
- The input impedance of the MAR-6SM amplifier (50Ohm) provides the transimpedance.
- The first notch (Lres and Cresa/b) is actually not notch but a LF rejection with DC block.
- The second and third notches are tuned to 11MHz and 55MHz.
- Another notch is implemented between the RF amps. The 33MHz signal is weak so I expected
to have no saturation at the first amplifier.
- As you see from the DC path, the transimpedance of the DC path is 2k V/A. If this is too high,
we need to replace R9 and R11 at the same time. TP1 is providing +10V such that the total
reverse bias becomes 25V without bringing a special power supply.
The transimpedance is measured with an amplitude modulated diode laser.
The transimpedance is 1k V/A ish. It is already at the edge of the bandwidth.
If we need more transimpedance at 165MHz, we should replace
the PD with FFD-100 (I have one) and apply 100V of reverse bias.
P.3 Current noise spectrum
The measured dark noise voltage spectrum was converted to the equivalent current noise at the diode.
The measured transimpedance is ~1.2kV/A.
The reduction of the transimpedance above 100MHz has been seen as 165MHz is already at the edge of the bandwidth.
If we need more transimpedance at 165MHz, we should replace the diode with FFD-100 (I have one) and apply 100V of reverse bias.
P.4 Shot-noise intercept current
Shot-noise intercept current was measured with a white light from a light bulb.
This measurement suggests the shot-noise intercept current of 1mA, and transimpedance of 1.5kV/A.
We characterized Koji's BBPD MOD for REFL165 (see attachment).
First, we calibrated the Agilent 4395 Network Analyzer (NA) to account for differences in cable features between the Ref PD and Test PD connections. This was done using the 'Cal' softkey on the NA.
Then we performed transimpedance measurements for the test PD and reference PD relative to the RF output of the NA and relative to each other (see 2nd attachment. Note that the NA's RF output is split and sent to both the IR Laser and the NA's Ref input).
Next, we made DC measurements of the outputs of the photodetectors to estimate the photocurrent distribution of the transimpedance setup (like the 2nd attachment, but with the outputs of the PDs going to a multimeter). By photocurrent distribution, we mean how the beamsplitter and respective quantum efficiencies/generalized impedance/etc. of the PDs influence how much current flows through each PD at with a DC input.
Finally, we measured the output noise as a function of photocurrent (like the 2nd attachment, but with a lightbulb instead of the IR Laser). Input voltages for the lightbulb ranged from 0mV to 6V. Data was downloaded from the NA using netgpibdata from the scripts directory. Analysis is currently in progress; graphs to come soon.
I found WFS had been left disabled from sometime yesterday. I don't see anyone mentioning when and why they had turned OFF the WFS servo.
I aligned MC and turned ON the WFS servo. MC is back.
I realized that I cannot open the attached plots. I'll fix them tomorrow.
[Koji, Annalisa, Manasa]
Today we worked on the ALS servo stabilization for the Y arm.
First step: find the beat note
The beat note was found following the usual steps:
Beat note amplitude = -27 dBm @ 50 MHz
PSL temperature = 31.54 degC
Laser Offset on the slow servo2 = -11011
In the GREEN HORNET we did the following changes for the Y arm:
Input Signal Conditioning
On the C1ALS-BEATY_FINE screen the same antiwhitening filters of the C1ALS-BEATX_FINE have been reproduced. At moment, only the FM3 [10:1] is enabled.
On the C1ALS-BEATY_FINE_PHASE screen the gain was set at 3600, since the amplitude of the Q signal after the Phase rotator (BEATY_FINE_Q_ERR) was about 30. To set this value we made a proportion with respect to a previous optimized value, where the amplitude was 100 and the gain was set to 1200.
In order to stabilize the beat frequency, we started enabling the FM5 [1000:1] filter in the C1ALS_YARM panel, and then we started increasing the gain first in small steps (0.1), in order to understand which sign the gain should have without kicking the mirror.
We measured the Power Spectrum of the C1:ALS-BEATY_FINE_PHASE_OUT in-loop signal while varying the gain of the C1ALS_YARM servo filter.
Eventually, we enabled the following filters:
Gain = -30.
Koji expects the UGF of the loop to be around 100-ish Hz, and he also expected the small bump around 300-400 Hz.
Then we realized that the channel we were measuring was not calibrated in unit of Hz, so we took again the measurement looking at the channel C1:ALS-BEATY_FINE_PHASE_OUT_HZ. In this case, we didn't observe any bump. Maybe the beat frequency was slightly changed from the previous measurement and the all servo shape was also different. The final value of the gain was set at -8.
The Y axis unit is missing (bad me!). It's in deg/sqrt(Hz) for the first plot and Hz/sqrt(Hz) for the second one.
While attempting to develop a somewhat accurate noise budget for the 40m, I reasoned that while the shape of the transfer function for the ISS is important, the degree to which we can 'tune' it to a particular experiment/application is limited.
Beyond that, we're sort of limited by the desired high and low frequency behavior as well as the general principle that more electronics = more noise so we probably don't want more than 3 or 4 filter stages, if that. Additionally, the ISS can be over-engineered so that it suppresses the laser noise to levels well below other fundamental noise sources over the important regime ~10 - 10^3 Hz without particular regard to a noise budget.
The design I propose is very similar to a previous design, with a few adjustments. It consists of 3 filter stages that easily be modified to increase gain for higher frequencies if it is known/determined that the laser being stabilized has a lot of high frequency noise.
Stage 1: Basic LP Filter + Establish UGF (each stage 'turning on' will not change the UGF), Stage 2: Integrator with zero @ 10 kHz, Stage 3: Optional extra gain if necessary
With the full TF given by,
As usual we consider the noise caused by the servo itself. Noise analysis in LISO is done with a 1 V input excitation.
This servo should function sufficiently for the 40m.
Here is the Sensing Matrix movie (sorry for the iffy quality - my movies usually come out better than this):
This is the sensing matrix for the sideband locked on PRMI, bringing the Xarm into resonance from anti-resonance, in 20 equally-spaced steps. You can see the microscopic ETMX offset (units of meters) in the title of the figures.
I was surprised to see some of the 'jumps' in the sensing matrix that happen near the end, when the arm is almost in resonance. I'm in the process of making movies of the error signals as the Xarm is brought into resonance. I'll have to post those in the morning, since they're taking a long time to produce and save, however when I looked at a few, there is some weird stuff going on as we get close to resonance, even with the 3f signals.
The modeling phone call is in the morning, but if anyone who is not regularly on the call has thoughts, I'm all ears.
[Koji, Annalisa, Gautam]
Annalisa noticed that over the weekend the Y-arm green PDH was locked to a sideband, despite not having changed anything on the PDH box (the sign switch was left as it was). On friday, we tried turning on and off some of the filters on the slow servo (C1ALS_Y_SLOW) which may have changed something but this warranted further investigation. We initially thought that the demodulation phase was not at the optimal value, and decided to try introducing some capacitances in the path from the function generator to the LO input on the universal PDH box. We modelled the circuit and determined that significant phase change was introduced by capacitances between 1nF and 100nF, so we picked out some capacitors (WIMA FKP) and set up a breadboard on which to try these out.
After some trial and error, Koji dropped by and felt that the loop was optimized for the old laser, the various loop parameters had not been tweaked since the new laser was installed. The following parameters had to be optimized for the new laser;
The setup was as follows:
The PDH error signal did not have very well-defined features, so Koji tweaked the LO frequency and the modulation depth till we got a reasonably well-defined PDH signal. Then we turned the excitation off and locked the cavity to green. The servo gain was then optimized by reducing oscillations in the error signal. Eventually, we settled on values for the Servo Gain, LO frequency and modulation depth such that the UGF was ~20kHz (determined by looking at the frequency of oscillation of the error signal on an Oscilloscope), and the PDH signal had well-defined features (while the cavity was unlocked). The current parameters are
We then proceeded to find the optimal demodulation phase by simulating the circuit with various capacitances between the function generator and the PDH box (circuit diagram and plots attached). The simulation seemed to suggest that there was no need to introduce any additional capacitance in this path (introducing a 1nF capacitance added a phase-lag of ~90 degrees-this was confirmed as the error-signal amplitude decreased drastically when we hooked up a 1nF capacitor on our makeshift breadboard). In the current configuration, the LO is connected directly to the PDH box.
Now that we are reasonably confident that the loop parameters are optimal, we need to stabilise the C1ALS_Y_SLOW loop to stabilise the beat note itself. Appropriate filters need to be added to this servo.
Circuit Diagram: 50 ohm input impedance on the source, 50 ohm output impedance seen on the PDH box, capacitance varied between 1nF and 100nF in steps.
Plots for various capacitances: Gold-green trace (largest amplitude) direct from LO, other traces at input to PDH box.
I have modeled the PRMI sensing matrix as I bring the Xarm into resonance. In optickle, I have the PRMI on sideband resonance, the ETMY is artificially set to have a transmission of 1, and the ETMX has it's nominal transmission of 15ppm. I start with the ETMX's microscopic position set to lambda/4 (antiresonant for IR in the arm), and take several steps until the ETMX's microscopic position is 0 (resonant for IR in the arm).
Modeled sensing matrix, units = W/m, Offset = 2.66e-07, phase in degrees
MICH Mag MICH Phase PRCL Mag PRCL Phase
AS55 3.348E+04 142.248 5.111E+03 70.571
POX11 3.968E+01 -66.492 1.215E+04 54.312
REFL11 3.231E+05 24.309 9.829E+07 144.311
REFL165 9.946E+03 -159.540 4.540E+05 -64.710
REFL33 1.963E+04 -168.530 1.573E+06 -2.744
REFL55 1.160E+06 -6.755 5.429E+07 86.895
Modeled sensing matrix, units = W/m, Offset = 0, phase in degrees
MICH Mag MICH Phase PRCL Mag PRCL Phase
AS55 1.647E+06 57.353 3.676E+06 -81.916
POX11 3.927E+02 -118.791 2.578E+04 -102.158
REFL11 7.035E+05 61.203 1.039E+08 167.149
REFL165 1.602E+04 -144.586 5.971E+05 -49.802
REFL33 2.157E+04 171.658 1.940E+06 -9.133
REFL55 1.822E+06 7.762 6.900E+07 101.906
For REFL55, the MICH magnitude increases by a factor of 1.6, while the PRCL magnitude increases by 1.3 . The MICH phase changes by 15 degrees, while the PRCL phase also changes by 15 degrees. Just eye-balling (rather than calculating), the other REFL PDs look to have similar-ish magnitude and phase changes. Certainly none of them are different by orders of magnitude.
I've restarted the NDS2 process on Megatron so that we can use it for getting past data and eventually from outside the 40m.
1) from /home/controls/nds2 (which is not a good place for programs to run) I ran nds2-megatron/start-nds2
2) this is just a script that runs the binary from /usr/bin/ and then leaves a log file in ~/nds2/log/
3) I tested with DTT that I could access megatron:31200 and get data that way.
There is a script in usr/bin called nds2_nightly which seems to be the thing we should run by cron to get the channel list to get updated, but I' m not sure. Let's see if we can get an ELOG entry about how this works.
Then we want Jamie to allow some kind of tunneling so that the 40m data can be accessed from outside, etc.
I have done the following:
* installed the nds2-client in /ligo/apps/nds2-client
* moved the nds2 configuration directories to /ligo/apps/nds2/nds2-megatron
* set up a cron job to update the channel list every morning at 5 am. The cron line is:
15 5 * * * /usr/bin/nds2_nightly /ligo/apps/nds2/channel-tracker /ligo/apps/nds2/nds2-megatron
cron will send an email each time the channel list changes, at which point you will have to restart the server with:
* restarted nds2 with updated channel lists.
I have set the cron job up to restart the nds2 server automatically if the channel list changes. The only change is that the cron command was changes to /ligo/apps/nds2/nds2-megatron/test-restart.
I'm working on developing a full noise budget for the 40m. To that end, I'll use measurements from the GUR1 seismometer to characterize seismic noise. Without any unit calibration, I found the following spectrum,
To extract useful information from this data, I first used the calibration from "/users/Templates/Seismic-Spectra_121213.xml" to obtain the spectrum in [m / s / sqrt(Hz)].
calibrated_data = raw_data * 3.8e-09
I then divided each point in the power spectrum by the frequency of said point to obtain [m / sqrt(Hz)]. I don't think we can simply divide the whole spectrum by 40 meters to obtain [RIN / sqrt(Hz)], although that was my immediate intuition. Having power spectra of all the major noise contributions in units of [RIN / sqrt(Hz)] would make designing an appropriate filtering servo fairly straightforward.
I found the south end emergency doors not latched completely. There was a ~ 3/8" vertical gap from top to bottom.
Please pull or push doors harder if they not catch fully.
As mentioned in elog 8770, I wanted to give the POX beam a little more clearance from the pick-off mirror steering the outcoming oplev beam. I tweaked the position of this mirror a little this morning, re-centred the spot, and checked the loop transfer function once again. These were really close to those I measured last night (UGF for pitch ~8Hz, for yaw ~7Hz), reported in elog 8777, so I did not have to change the loop gains for either pitch or yaw. Plots attached.
There is no sensible REFL165 PD in the lab. I am supposed to prepare a new version of REFL165 using prototype BBPD.
I'm not sure what's going on today but we're seeing ~80% packet loss on the 40MARS wireless network. This is obviously causing big problems for all of our wirelessly connected machines. The wired network seems to be fine.
I've tried power cycling the wireless router but it didn't seem to help. Not sure what's going on, or how it got this way. Investigating...
Mike and Christian brought over a Mac laptop for surf Alex.
They power cycled the wireless router of 40Marsh and labtops are working. Seeing 75-80% signals on all 3 Dell lab top sisters at both end of the lab
[Lisa, Rana, Jenne]
Lisa asked to see a model of the PRMI sensing matrix with REFL165 included, in the hopes that it wouldn't be as degenerate as REFL33.
The conclusion, immediately after looking at this, is that I should make sure the REFL beam is nicely aligned onto the REFL165 PD (Koji did some tests, swapping out the REFL165 resonant PD with a broadband PD, and I don't remember if he aligned beam back onto the REFL165 PD). Then, I need to measure the PRMI sensing matrix, including REFL165. Hopefully, it is similar to the model, and we can use it as our 3f diode for locking.
Rana had the epiphany that I didn't have any antiwhitening for my POP QPD. Ooops.
We looked at the schematic for the Pentek Generic board (pdf), and saw that it has a Zero @ 15Hz, and Poles @ 150Hz and 1500Hz, times 2 stages. We determined from the TF that I posted that probably both stages are engaged, so I made an antiwhitening filter consisting of the inverse (so, 2 poles at 15Hz, 2 zeros at 150Hz and 2 zeros at 1500Hz). [Rana points out that for this low frequency system we may not want to include the 1500Hz compensation, since it is probably just enhancing ADC noise]. The ASC system worked really well, really easily, after that.
Another note though, the AA stage of the Pentek Generic boards have 4 poles at 800Hz, which are not compensated.
Rana also added a 60Hz comb to the filter bank with the AntiWhitening, since the QPD has an unfortunately large amount of 60Hz noise. Also, the 60Hz lowpass in the ASC loop was engaged for both pitch and yaw.
Rana, Lisa and Manasa also found that the ASC system was *more* stable with the PRM oplev ON.
So, the ASC locking situation is:
PRM oplev loops on.
AS-POP_QPD_[PIT/YAW] filter banks with FM1, FM6 on.
ASC-PRCL_[PIT/YAW] filter banks with FM1, FM5, FM6 and FM9 on.
ASC-PRCL_YAW_GAIN = -0.040
ASC-PRCL_PIT_GAIN = +0.030
(No triggering yet).
The ASC Up and Down scripts (which are called from the buttons on the ASC screen) have all of these gain settings, although they assume for now that all the filters are already on.
Here's a screenshot of the power spectra showing the angular motion suppression. The PDF is attached so you can zoom in and see some details. The dashed lines are the "PRMI locked, ASC off" case, and the solid lines are the "PRMI locked, ASC on" case. You can see that according to the QPD, we do an excellent job suppressing both the pitch and yaw motion (although better for yaw), but there isn't a huge effect on POPDC or POP110I. While we could probably do better if we had a 2 QPD system with the QPDs at differet gouy phases, this seems to be good enough that we can keep the PRMI locked ~indefinitely.
I would like to compile the ASC model, so that I can implement triggering. For tonight, we did not have the ASC engaged during our PRMI+Xarm tests (see Manasa's elog), but I think it'll make things a little easier if we can get the ASC going automatically.
X arm stabilized using ALS while PRMI stayed locked
[Rana, Lisa, Jenne, Manasa]
Time series : ALS enabled at t = 0 and disabled at t = 95s
What we did:
1. Jenne will elog about ASC (POP QPD) updates.
2. Found the beat note between Xarm green and PSL green.
3. Stabilized arm fluctuation by enabling ALS servo.
4. Scanned the arm for carrier resonance by ramping on the offset and set the offset such that we had IR resonating (TRX fluctuated between 0.1 and 0.8 counts).
5. Disabled the ALS servo and locked PRMI using AS55 for MICH and REFL33 for PRCL.
6. Enabled ALS.
Enabling ALS to detune the arm out of resonance kept PRMI locked (currently for a span of few tens of seconds). However we could not see PRMI locked as stably compared to when the arms are misaligned. Everytime the offset was set IR to resonate, the PRMI was kicked out of lock.
Also there is some leakage at the arm transmission when PRMI was locked. The leakage was visible at ETMX transmission as flashes in different higher order modes indicating the not-so sufficient ALS stability. The leakage sets an offset at TRX measuring 0.01-0.05 counts.
To do list:
The ALS_OFFSETTER1 has to be calibrated in FSR. We were giving random offsets to do the offset scan.
Installed a filter before ETMXT camera to remove the refl green. (Note to myself: The filter needs to go on a better mount/adapter).
I moved the old matlab directory from /cvs/cds/caltech/apps/linux64/matlab_o to /cvs/cds/caltech/apps/linux64/matlab_oo
and moved the previously current matlab dir from /cvs/cds/caltech/apps/linux64/matlab to /cvs/cds/caltech/apps/linux64/matlab_o.
And have installed the new Matlab 2013a into /cvs/cds/caltech/apps/linux64/matlab.
Since I'm not sure how well the new Matlab/Simulink plays with the CDS RCG, I've left the old one and we can easily revert by renaming directories.
Be careful with this. If Matlab starts re-saving models in a new file format that is unreadable by the RCG, then we won't be able to rebuild models until we do an svn revert. Or the bigger danger, that the RCG *thinks* it reads the file and generates code that does something unexpected.
Of course this all may be an attempt to drive home the point that we need an RCG test suite.
With rana's input, I changed the ITMx oplev servo gains given the beam path had been changed. The pitch gain was changed from 36 to 30, while the yaw gain was changed from -25 to -40. Transfer function plots attached. The UGF is ~8Hz for pitch and ~7Hz for yaw.
I had to change the envelope amplitudes in the templates for both pitch and yaw to improve the coherence. Above 3Hz, I multiplied the template presets by 10, and below 3Hz, I multiplied these by 25.
I installed ligoDV in the /ligo/apps/ligoDV/
Now, by pointing the tool at the local NDS2 server (megatron:31200) you can access the recent local data (raw, trends, etc.)
by running /ligo/apps/ligoDV/ligodv from the command line.
The keyboard on Pianosa workstation has been flaky for the last several days at least. Today, it was having troubles mounting the linux1 file system and was hanging on boot.
People in the control room emailed Jamie and then grew afraid of the computer. Annalisa suggested that we put garlic on it since was clearly possessed.
Typing 'dmesg' at the command prompt, I found that there were thousands of messages like these:
[ 3148.181956] usb 2-1.2: new high speed USB device number 68 using ehci_hcd
[ 3149.773883] usb 2-1.2: USB disconnect, device number 68
[ 3150.228900] usb 2-1.2: new high speed USB device number 69 using ehci_hcd
[ 3152.076544] usb 2-1.2: USB disconnect, device number 69
[ 3152.787391] usb 2-1.2: new high speed USB device number 70 using ehci_hcd
[ 3154.123331] usb 2-1.2: USB disconnect, device number 70
[ 3154.578459] usb 2-1.2: new high speed USB device number 71 using ehci_hcd
So I replaced the existing Dell keyboard with an older Dell keyboard and the bad messages have stopped. No garlic was used.
Its an increase in the microseismic peak. Don't know what its due to though.
Measured frequency noise is ~10Hz/rtHz @100Hz.
Measure the out-of-loop noise of Xarm ALS:
1. The X-arm was locked for IR using PDH error signal.
2. 'CLEAR HISTORY' of the phase tracker filters.
3. Measured the power spectrum of the phase tracker output. I have used the newly created calibrated channel "PHASE_OUT_DQ. So the phase tracker output now reads in Hz.
The measurement was done with beat note frequency at ~40MHz. The flat noise level of 10Hz/rtHz from 20-100Hz (in plot 2) is not good. We should investigate as to what sets this noise level. The spike at 60Hz is because the 60Hz frequency comb filter was not enabled.
I plan to the following to get a clearer outlook
1. Connecting the beat box to an RF source and measure the noise levels for a range of frequency inputs to the beatbox.
2. Measure the noise at C1:ALS-BEATX_FINE_I_IN1 (before the antiwhitening filters) and check whether the new whitening filters has done anything good with respect to minimizing the DAQ noise.
As I showed in [elog 8759], measuring the transfer function of my prototype servo was difficult due to physical limitations of either some portion of the construction or even the SR785 itself. To get around this, I tried using lower input excitation amplitudes, but ran into problems with noise.
Finding a TF consistent with theoretical predictions made by LISO was easy enough when I simply measured the TF of each of the two filter stages individually and then multiplied them to obtain the TF for the full servo. I still noticed some amount of gain limitation for 100 mV and 10 mV inputs, although I only had to lower the input to 5 mV to avoid this and thus did not see significant amounts of noise as I did with a 1 mV input. The individual transfer functions for each stage are shown below. Note that the SR785 has an upper cutoff frequency of 100 kHz so I could analyze the TF beyond this frequency. Additionally, the limited Gain Bandwidth Product of OP27 op-amps (used in the prototype) causes the magnitude and phase to drop off for f > 10^5 Hz approximately. The actual servo will use AD829 op-amps which have a much larger GBWP.
The measured TFs above are very close to ideal and agree quite well with theoretical predictions. Based on the [circuit schematics],
Indeed, this is exactly what we can see from the above two TFs. We can also multiply the magnitudes and add the phases (full_phase = phase1 + phase2 - 180) to find the TF for the full servo and compare that to the ideal TF produced by LISO,
And we find exceptionally consistent transfer functions, which speaks to the functionality of my prototype
As such, I'll proceed with designing this servo in Altium (most of which will be learning how to use the software)
Note that all TFs were taken using the netgpibdata python module. Measurement parameters were entered remotely using the TFSR785.py function (via control room computers) and following the examples on the 40m Wiki.
Jenne just aligned the X arm and I got a chance to check the status of the POX beam coming out of the chamber. Turned the Oplev servo off so that the red beam could be blocked, turned all the lights off, and had a look at the beam in the vicinity of the mirror steering the Oplev-out beam to the QPD with an IR view-card. The beam is right now about half a centimeter from the pitch knob of the said mirror, so its not getting clipped at the moment. But perhaps the offending mirror can be repositioned slightly, along with the Oplev QPD such that more clearance is given to the POX beam. I will work this out with Steve tomorrow morning.
Could be that this is OK, but it doesn't yet make sense to me. Can you please explain in words how this manages to apply the calibration rather than just add an extra gain to the phase tracking loop?
The calibration is applied by adding an extra gain. But, I missed the point that I should be doing this outside the phase-tracking loop....my BAD .
So I modified the model such that the calibration is done without disturbing the phase tracking loop.
Right now, epics input 'PHASE_OUT_CALIB' accepts the calibration and we get the calibrated phase tracker output converted from deg to Hz at 'PHASE_OUT_HZ'. I have also made it a DAQ channel to be used with dataviewer and dtt.
medm screens have been modified to accommodate these additions to the phase tracker screen. I used Yuta's phase tracker calibration data in elog to set PHASE_OUT_CALIB in the medm screens.
Y arm beat note found!
The green transmission on the PSL reads about 500 cts, and the transmitted power is about 50 uW.
(the second peak on the screen in the picture is the 29 MHz of the MC)
Last night before dinner, I copied over the ASC yaw servo filters to the ASC pitch filter bank. Using ASC gain of +0.001, I was getting the ~250Hz oscillations that Rana and I had seen with yaw.
Rana pointed out to me that my measured TF of the yaw loop doesn't look right up in the several hundred Hz region:
As you can see on the right side, which is all of the PRCL ASC yaw filter banks, multiplied by a simulated pendulum filter, the magnitude should just keep decreasing. However, on the measured plot on the left, you can see that I have a little gain hump. I'm not sure what this is from yet.
All of us in the control room / desk area heard a sudden whoosh of air a few minutes ago. It kind of sounded like a pressure washer or something. We determined that the northmost nitrogen bottle outside the front door was letting out all its gas.
It's a gazillion degrees outside (okay, only 91F, according to a google of "Caltech Weather"), and those bottles are in direct sun all day.
We are leaving the bottle as-is, since it seems like its has finished, and nothing else is happening.
Particle counts were measured inside the PSL enclosure at 40VAC variac setting.
Directly under HEPAs, on the east half of the optical table : 0.3 micron 20 particles / cu ft, 0.5 micron 0 p / cu ft, 0.7 micron 0 p / cu /ft
Away from the HEPAs, on the west edge of the op table: 0.3 micron 960 particles / cu ft, 0.5 micron 50 p / cu ft, 0.7 micron 20 p / cu ft
We may want to increase the RPM a little bit.
Checked our counters against recently calibrated Met One GT-526:
#1 is right on, #2 measured 25% less (it will go for calibration)
Flow bench at the south end : zero particle for all 3 sizes
IOO chamber particle logging measures 0.5 and 1 micron. Chamber opening limit is set to 10,000 particles max of 0.5 micron
At 10,000 p of 0.5 micron means ~100,000 - 180,000 p of 0.3 micron
We may have to lower the limit.
The BLRMS are totally crazy today! I'm not sure what the story is, since it's been this way all day (so it's not an earthquake, because things eventually settle down after EQs). It doesn't seem like anything is up with the seismometer, since the regular raw seismic time series and spectrum don't look particularly different from normal. I'm not sure what's going on, but it's only in the mid-frequency BLRMS (30mHz to 1Hz).
Here are some 2 day plots:
I'm still seeing some problems with this - some laptops are losing and not recovering any connection. What's to be done next? New router?
We had the same problem yesterday. However the Vacuum Dedicated laptop worked with fewer disconnects. Christian is coming over this after noon to look at this issue.
This happened a few weeks ago and it recovered misteriously. Jamie did not understand it.