To design a new resonant EOM box I started reviewing the prototype that I've built.

As a part of reviewing I checked an important thing that I haven't carefully done so far :

I compared the measured input impedance with that of predicted from a circuit model. I found that they show a good agreement.

So I am now confident that we can predict / design a new circuit performance.

* * * (input impedance) * * *

 Performance of a resonant circuit is close related to its input impedance and hence, in other words, determined by the input impedance.

Therefore an investigation of input impedance is a way to check the performance of a circuit. That's why I always use impedance for checking the circuit.

The plot below is a comparison of input impedance for the measured one and one predicted from a model. They show a good agreement.

(Note that the input impedance is supposed to have 50 Ohm peaks at 11, 29.5 and 55 MHz.)

 
* * * (circuit model) * * *

To make the things simpler I assume the following three conditions in my model:

 1. inductor's loss is dominated by its DC resistance (DCR)

 2. capacitor's loss is characterized only by Q-value

 3. Transformer's loss is dominated by DCR and its leakage inductance

All the parameters are quoted from either datasheet or my measurement. The model I am using is depicted in the schematic below.

Basically the Q-vaules for the capacitors that I used are quite low. I think higher Q capacitors will improve the performance and bring them to more 50 Ohm.

Background:
  Yesterday, I said I will use ZHL-32A for amplifying beat note signal, but as Koji pointed out, ZHL-32A is for medium high power.
  So I changed my mind to use ZFL-1000LN instead. ZFL-1000LN is a low noise RF amp whose maximum power is 3dBm.
  Also, we included a splitter in our consideration.

What I did:
1. Set up a new setup. ZFL-1000LN has a gain of +24dB at 80MHz and splitter ZFRSC-42 has a loss of -6dB. So;

beat note signal -> ZFL-1000LN -> ZFL-1000LN -> ZFRSC-42 => SR620 and VCO

2. Measured frequency-output relation. When the input signal was 80MHz -48dBm, the output was -8.7dBm. For other frequencies;
       60MHz  -3.3dBm
       70MHz  -5.7dBm
       80MHz  -8.7dBm
       90MHz  -5.5dBm
      100MHz  -3.5dBm
  So, we can see frequency up to >100MHz by SR620 using this setup.

3. Checked harmonics peak levels of the output using an RF spectrum analyzer. When the input signal was 80MHz -48dBm, the height of the peaks were;
     80MHz -8.8dBm
    160MHz -30dBm
    240MHz -42dBm
  Other peaks were smaller than the 3rd harmonics. Also, RF PD that detects beat note signal has a cut-off frequency at around 100MHz. So, we don't need to worry about wave transformation for this setup.

Yes. I corrected my previous elog.

Current status:

• There is a single Acromag ADC unit installed in 1X4
• It is presently hooked up to the PSL NPRO diagnostic connector channels
• I had (re)-started the acquisiton of these channels on August 16 - but for reasons unknown, the tmux session that was supposed to be running the EPICS server on megatron seems to have died on August 22 (judging by the trend plot of these channels, see Attachment #1)
• I had not set up an upstart job that restarts the server automatically in such an event. I manually restarted it for now, following the same procedure as linked in my previous elog.
• While I was at it, I also took the opportunity to edit the Acromag channel names to something more appropriate - all channels previously prefixed with C1:ACRO- have now been prefixed with C1:PSL-

Plan of action:

1. Hardware - we have, in the lab, in addition to the installed ADC unit
   • 3x 8 channel differential input ADC units
   • 2x 8 channel differential output DAC units
   • 1x 16 channel BIO unit
   • 2U chassis + connectors + breakout boards + other misc hardware that I think Johannes and Lydia procured with the original plan to replace the EX slow controls.
   • Some relevant elogs: Panel designs, breakout design, sketch for proposed layout, preliminary channel list.
     So on the hardware side, it would seem that we have everything we need to go ahead with replacing the EX slow controls with an Acromag system, although Johannes probably knows more about our state of readiness from a hardware PoV.
2. Software
   • We probably want to get a dedicated machine that will handle the EPICS channel serving for the Acromag system
   • Have to figure out the networking arrangement for such a machine
   • Have to figure out how to set up the EPICS server protocol in such a way that if it drops for whatever reason, it is automatically restarted

http://www.supermicro.com/products/system/1U/5015/SYS-5015A-H.cfm?typ=H

This is the machine that Larry suggested when I asked him for his opinion on a low workload rack-mount unit. It only has an atom processor, but I don't think it needs anything particularly powerful under the hood. He said that we will likely be able to let us borrow one of his for a couple days to see if it's up to the task. The dual ethernet is a nice touch, maybe we can keep the communication between the server and the DAQ units on their separate local network.

We'd like to setup the recording of the PSL diagnostic connector Acromag channels in a more robust way - the objective is to assess the long term performance of the Acromag DAQ system, glitch rates etc. At the Wednesday meeting, Rana suggested using c1ioo to run the IOC processes - the advantage being that c1ioo has the systemd utility, which seems to be pretty reliable in starting up various processes in the event of the computer being rebooted for whatever reason. Jamie pointed out that this may not be the best approach however - because all the FEs get the list of services to run from their common shared drive mount point, it may be that in the event of a power failure for example, all of them try and start the IOC processes, which is presumably undesirable. Furthermore, Johannes reported the necessity for the procServ utility to be able to run the modbusIOC process in the background - this utility is not available on any of the FEs currently, and I didn't want to futz around with trying to install it.

One alternative is to connect the PSL Acromag also to the Supermicro computer Johannes has set up at the Xend - it currently has systemd setup to run the modbusIOC, so it has all the utilities necessary. Or else, we could use optimus, which has systemd, and all the EPICS dependencies required. I feel less wary of trying to install procServ on optimus too. Thoughts?

Rga scan of day 231 since pumpdown pd66-m-d231

m stands for maglev pumping speed, vacuum normal condition of valves,

cc4 cold cathode gauge at the rga location,

cc1 is real ifo pressure from the 24" tube at the pumpspool,

PEM-count temp: vac envelope temp at the top of IOO chamber

We did our first ringdown measurement on the Y arm. First we tried to keep the arm locked in green during the ringdown, but for some reason it was not possible to get the cavity locked in green. So we decided to do the first measurement with infrared locked only.

For the measurement we had to change the LSC model to acquire the C1:LSC-TRY_OUT_DQ at higher sampling frequency. We changed the sampling frequencies of C1:LSC-{TRX,TRY}_OUT_DQ from 2048Hz to 16384Hz.

The measurement was done at GPS 1027289507. The ringdown curve looks very clean, but there seem to be two time constants involved. The first half of the curve is influenced by the shutter speed, then curvature is changing sign and the ringdown is likely taking over. We will try to fit a curve to the ringdown part, but it would certainly be better to have a faster shutter and record a more complete ringdown.

Is this the step response of the single pole low pass???
It should have an exponential decay, shouldn't it? So it should be easier to comprehend the result with a log scale for vertical axis...

I think you need a fast shutter. It is not necessary to be an actual shutter but you can use faster thing
which can shut the light. Like PMC or IMC actuators.

Another point is that you may like to have a witness channel like the MC transmission to subtract other effect.

Let's see if the ripples observed in the MC ringdown can be due to tilt motion of the mirrors.

The time it takes to produce a phase shift corresponding to N multiples of 2*pi is given by:

t = sqrt(2*N*lambda/(L*omega_T^2*(alpha_1+alpha_2)))

L is the length of the MC (something like 13m), and alpha_1, alpha_2 are the DC tilt angles of the two mirrors "shooting into the long arms of the MC" produced by the MC control with respect to the mechanical equilibrium position. omega_T is the tilt eigenfrequency of the three mirrors (assumed to be identical). lambda = 1.064e-6m;

The time it takes from N=1 to N=2 (the first observable ripple) is given by: tau1 = 0.6/omega_T*sqrt(lambda/L/(alpha_1+alpha_2))

The time it takes from N=2 to N=3 is given by: tau2 = 0.77*tau1

etc

First, we also see in the measurement that later ripples are shorter than early ripples consistent with some accelerated effect. The predicted ripple durations tau seem to be a bit too high though. The measurements show something like a first 14us and a late 8us ripple. It depends somewhat on the initial tilt angles that I don't know really.

In any case, the short ripple times could also be explained if the tilt motions start a little earlier than the ringdown, or the tilt motion starts with some small initial velocity. The next step will be to program a little ringdown simulation that includes mirror tilts and see what kind of tilt motion would produce the ripples exactly as we observe them (or maybe tilt motion cannot produce ripples as observed).

Isn't it just a ringing of the intracavity power as you shifted the laser frequency abruptly?

Hmm. I don't know what ringing really is. Ok, let's assume it has to do with the pump... I don't see how the pump laser could produce these ripples. They have large amplitudes and so I always suspected something happening to the intracavity field. Therefore I was looking for effects that would change resonance conditions of the intracavity field during ringdown. Tilt motion seemed to be one explanation to me, but it may be a bit too slow (not sure yet). Longitudinal mirror motion is certainly too slow. What else could there be?

Laser frequency shift = longitudinal motion of the mirrors

Ringing: http://www.opticsinfobase.org/ol/abstract.cfm?uri=ol-20-24-2463

Ok, so the whole idea that mirror motion can explain the ripples is nonsense. At least, when you think off the ringdown with "pump off". The phase shifts that I tried to estimate from longitudinal and tilt mirror motion are defined against a non-existing reference. So I guess that I have to click on the link that Koji posted...

Just to mention, for the tilt phase shift (yes, there is one, but the exact expression has two more factors in the equation I posted), it does not matter, which mirror tilts. So even for a lower bound on the ripple time, my equation was incorrect. It should have the sum over all three initial tilt angles not only the two "shooting into the long arms" of the MC.

On Monday evening, I ran this command: trianglewave C1:IOO-MC_REFL_OFFSET 0 4 120 600;ezcawrite C1:IOO-MC_REFL_OFFSET 1.76

which I thought (from the syntax help) would move that offset slider with a period of 120 seconds for 600 seconds. In actuality, the last argument is the

run time in number of periods. So the offset slider has been changing by 8 Vpp for most of the last day. Oops. The attached image shows what effect

this had in the MC transmitted power (not negligible). This would also make the locking pretty difficult.

In the second plot you can see the zoom in view for ~30 minutes. During the first part, the MCWFS are on and there are large fluctuations

in the transmitted power as the WFS offset changes. This implies that the large TEM00 carrier offset we induce with the slider couples into

the WFS signals because of imbalances in the quadrant gains - we need someone to balance the RF gains in the WFS quadrants by injecting

an AM laser signal and adjusting the digital gains.

Since there is still a modulation of the MC RFPD DC with the WFS on, we can use this to optimize the REFL OFFSET slider. The third plot

shows a 8 minute second trend of this. Looks like the slider offset of zero would be pretty good.

Physical plan is cleaning our roof and gutters today.

It rained hard yesterday. We have not had this strong downpoor for years. We got 0.7" and the roof did not leak.

I lowered room 101 thermostat setting from 74F to 72F

And I raised it back to 73F. The thermometers on the wall show 74-75F as the actual room temp. The dial on the temperature controller is not calibrated.

Since Rosalba wanted to update ~500 packages, I let it do it. This, of course, stopped the X server from running. I downloaded and installed the newest Nvidia driver and its mostly OK.

The main problem with the auto-update on our workstations is that we've updated some packages by hand; i.e. not using the standard CentOS yum. So that means that the auto-update doesn't work right. From now on, if you want to install a fancier package than what CentOS distributes, you should commit to handle the system maintenance for these workstations for the future. Its not that we can't have new programs, we just have to pay the price.

At 23:45 PST, I also started a slow triangle wave on the AOM drive amplitude. This is to see if there's a response in the FSS-FAST which might imply a coupling from intensity noise to frequency noise via absorbed power and the dn/dT effect in the coatings.

Its a 93 second period triangle modulating the RC power from 100% down to 50%.

This morning I installed Ubuntu 10.04 on rosalba.  This is the same version that is running on pianosa.  The two machines should be identically configured, although rosalba may be missing some apt-getable packages.

I rebooted rossa and the X sever has stalled.

For some reason, rossa's Xdisplay won't start up anymore. This happened right after the UPS reset. Koji and I tried ~1.5 hours of debugging, got nowhere.

"bricked" is to mean that it has the functionality of a brick and can be tossed. But rossa seems to have just gotten some software config corruption. I spent a couple hours reinstalling SL7 today as per my previous elog notes and the X display seems to work as before.

i.e. it was fine with the default setup, except for the ole "X chrashes if the mouse goes to left side of screen". As before, I

1. blacklisted the nouvaeu driver (which is used by default)
2. download the NVIDIA driver as per the link
3. run its installation from the no-X terminal

left side of screen is safe again

This time I installed SL7.6 and followed the K Thorne wiki. But its having trouble installing cds-root because it can't find root.

This is to facilitate running of scripts like the CDS reboot script, mx_stream restart, etc, from rossa, without being pwd prompted every time, whereas previously it was only possible from pianosa. I added the public key of rossa to FB and the RT FE servers. I suppose I could add it to the Acromag servers too, but I haven't yet.

Summary:

SnapPy scripts made to work on Pianosa.

Details:

Of course rossa was the only machine in the lab that could run the python scripts to interface with the GigE camera. And it is totally bricked now. Lame.

So I installed several packages. The key was to install pypylon - if you go to the basler webpage, pypylon1.4.0 does not offer python2.7 support for x86_64 architecture, so I installed pypylon1.3.0. Here are the relevant lines from the changelog:

Camera server is running on a tmux session on pianosa. But it keeps throwing up some gstreamer warnings/errors, and periodically (~every 20 mins) crashes. Kruthi tells me that this behavior was seen on Rossa as well, so whatever the problem is, doesn't seem to be because I missed out on installing some packages on pianosa. Moreover, if the server is in fact running, I am able to take a snapshot - but the camera client does not run.

Now same as pianosa and rosalba.  I'll upgrade allegra on Friday.

**** Deleted
apps/emacs
apps/linux64/firefoxold
apps/linux64/comsol      (old v. 3.5)

* running up2date on rossa

* rossa needs to be able move windows between monitors: Xinerama?

* there are permissions problems: controls on rossa can't
make and delete directories made by 'controls' elsewhere.
Some sort of user# or group issue?

The controls group is user id 500 by default on most new machines. Unfortunately, the user ID used across the already existing machines is 1001. One method of doing this switch is in this elog.  You can also do the change of the controls ID by becoming root and using the graphical command system-config-users.  This will  let you change the user ID and group ID for controls to 1001.  This graphical interface also lets you change the login shell.

Unfortunately, I had some minor difficulty and I ended up removing the old controls and creating a new controls account with the correct values and using tcsh.  The .cshrc file has been recreated to source cshrc.40m.  The controls account now has correct permissions, although some of the preferences such as background will need to be reset.

 Xinerama support has been enabled on rossa using nvidia-settings.

I wiped out the old CentOS install on rossa and installed CentOS 5.5 on there. The DVDs are on a spindle in the control room; there were 2 iso's, but I only needed the first to install most things.

It still needs to get all of the usual stuff (java, flash, nvidia) installed as well as setting up the .cshrc and the NFS mount of /cvs/cds. The userID and groupID are set to 1001 as before. Whoever

sees Sanjit first should steer him towards this elog entry.

I found Sanjit's instructions for doing the Nvidia settings too complicated and so I followed these instructions from Facebook:

http://www.facebook.com/notes/centos-howtos/installing-nvidia-display-drivers-on-centos-55/399295987425

After installations, the monitors were autodetected and the Xinerama effect is working.

Simple steps (but don't try these on a working computer without getting some experience on a spare one, you may find it difficult to restore the system if something goes wrong):

1. download the appropriate driver from NVIDIA website for this computer
   
   • we did: NVIDIA GeForce 310 64bit Linux, version: 256.53, release date 2010.08.31
2. keep/move the driver in /root (use "sudo" or "su")
3. reboot the computer in "single user" mode
   • in the GRUB screen edit the boot command by pressing the appropriate key listed in the screen
   • in the boot command-line put " single" in the end (no other change is normally needed), don't save
   • press ENTER and the system will reboot to a root shell (# prompt)
4. cd /root
5. run the NVIDIA driver script
6. exit the shell (ctrl-d), let the system reboot
   • it should flash (mostly green) "nvidia" screen before starting X
   • in case of problems run system-config-display and revert to vesa driver
7. login as "root" and run "nvidia-settings" from command line or GUI menu to add/configure display

Why are we running CentOS 4.8 instead of 5.5 ?    What runs at LLO?     What runs in Downs?

In an effort to make a second usable workstation, I did the following (remotely) on rossa today (not necessarily in this order, I wasn't maintaining a live log so I forgot):

1. Fixed /etc/resolv.conf, so that the other martian machines can be found.
2. Copied over .bashrc file, and the appropriate lines from /etc/fstab from pianosa to rossa.
3. Ran sudo apt install nfs-common. Then ran sudo mount -a to get /cvs/cds mounted.
4. Made symlinks for /users and /opt/rtcds , and /ligo. All of these are used by various environment-setting scripts and I chose to preserve the structure, though why we need so many symlinks, I don't know...
5. Set up the shell variable $NDSSERVER using export NDSSERVER=fb:8088. I'm not sure how, but I believe DTT, awggui etc use this on startup to get the channel list (any
6. Followed instructions from Erik von Reis at LHO to install the cds workstation packages and dependencies. Worked like a charm 🎃! 
7. As a test, I plotted the accelerometer spectra in DTT, see Attachment #1. I also launched foton from inside awggui, and confirmed that the sample rate is inherited and I could designate a filter. But I haven't yet run the noise injection to test it, I'll do that the next time I'm in the lab.
8. Also checked that medm, StripTool and ndscope, and anaconda python all seem to work 👍🏾.

So, in summary, rossa is now all set up for use during lock acquisition. However, until this machine has undergone a few months of testing, we should freeze the pianosa config and not mess with it.

Note that this version of the "crtools" is rather new. Please, use them and if there is an issue, report the errors! I am going to occassionally try lock acquisition using rossa. 

maybe we should make a "dd" copy of pianosa in case rossa has issues and someone destroys pianosa by accidentally spilling coffee on it.

Formatted and re-installing OS on rossa for the 3rd or 4th time this year. I suggest that whoever is installing software and adjusting video settings please stop.

If you feel you need to tinker deeply, use ottavia or zita and then be prepared to show up and fix it.

While I was moving the UPS around, the network lights went out for Rossa, so I may have damaged the network interface or cable. Debugging continues.

Got the network to work again just by unplugging the power cord and letting it sit for awhile. But corrupted OS by trying to install Nvidia drivers.

https://www.advancedclustering.com/act_kb/installing-nvidia-drivers-rhel-centos-7/

back on new Rossa from Xi computing

1. switched to using Display Port for video; this works. The DVi, HDMI, VGA ports are connected to the motherboard rather than the video card, so they are not active.
2. runs super slow w/ SL 7.6; maybe some service is running after startup?
3. install repos and update according to LLO CDS wiki
4. add controls user and group according to LLO wiki
5. remove gstreamer ugly because it breaks yum update
6. run 'yum update --skip-broken' because GDS doesn't work
7. turn off old selinux stuff
8. modify fstab to get NFS

Next:

1. finish mounting
2. xfce
3. figure out why the LLO install instructions can't install any CDS software (e.g. root, DTT, etc)

Update: Sun Nov 3 18:08:48 2019

1. moved the SL7 fresh install repos back into etc/yum.repos.d/. The LLO instructions has me remove them, but the LLO supplied repos are no good for standard apps. After putting these back was able to install standard apps (terminator, root, diaggui)
2. copied over /etc/fstab lines from pianosa sothat the NFS mounts work correctly
3. added symlinks so that the NFS dirs mount in the right dirs
4. symlink libsasl2.so.3 -> libsasl2.so.2 and now DTT runs and can get data now and in the past
5. install XFCE
6. sitemap / MEDM works
7.  Did "sudo ln -s /usr/lib64/libXm.so.4 /usr/lib64/libXm.so.3" to enable StripTool.

Update: Fri Nov 15 00:00:26 2019:

1. random hanging of machine while doing various window moving or workspace switching
2. turned off power management in XFCE
3. turned off power management on monitor
4. disabled SELINUX
5. firewalld was already off
6. installed most, pdftk, htop, glances, qtgrace, lesstif
7. dataviewer now works and QTgrace is much nicer than XMGrace