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ID Date Authorup Type Category Subject
  2239   Wed Nov 11 16:18:57 2009 AlbertoUpdateABSLWorking on the AP table

Quote:

I've opened the AP table and I'm working on it.

I re-aligned the Faraday on the AP table. I also aligned the beam to the periscope on the PSL and all the other optics along the beam path.  Now I have a nice NPRO beam at the PLL which overlaps with the PSL beam. The alignment has to be further improved because I see no beat yet.

I wonder if the all the tinkering on the PSL laser done recently to revive the power has changed the PSL NPRO temperature and so its frequency. That could also explain why the beat doesn't show up at the same temperature of the NPRO as I used to operate it. Although I scanned the NPRO temperature +/- 2 deg and didn't see the beat. So maybe the misalignment is the casue.

Not feeling very well right now. I need to go home for a while.

AP table closed at the moment.

NPRO shutter closed

  2249   Thu Nov 12 10:45:02 2009 AlbertoUpdatePSLAbandoned Frequency Generator

This morning I found a frequency generator connected to something on the PSL table sitting on the blue step next to the sliding doors.

Is anyone using it? Has it been forgotten there? If that's the case, can the interested person please take care of removing it?

  2250   Thu Nov 12 10:45:36 2009 AlbertoUpdateABSLWorking on the AP table

I've opened the AP table and I'm working on it.

Also auxiliary NPRO turned on and mechanical shutter opened.

  2252   Thu Nov 12 11:34:38 2009 AlbertoUpdateABSLWorking on the AP table

Quote:

Yes it did.

For long time, the crystal temperature C1:PSL-126MOPA_LTMP was 43~46deg. Now it is 34deg. Try ~10deg lower temperature.

Quote:

I wonder if the all the tinkering on the PSL laser done recently to revive the power have changed the PSL NPRO temperature and so its frequency. That could also explain why the beat doesn't show up at the same temperature of the NPRO as I used to operate it. Although I scanned the NPRO temperature +/- 2 deg and didn't see the beat.

 

 Beat found at 30MHz with auxiliary NPRO temperature of 37.19 degrees, vs. ~48 deg as it used to be.

The beat is small (-70dBm). PLL alignment has to be improved.

  2253   Thu Nov 12 12:50:35 2009 AlbertoUpdateComputersStochMon calibrated channels added to the data trend

I added the StochMon calibrated channels to the data trend by including the following channel names in the C0EDCU.ini file:

[C1:IOO-RFAMPD_33MHZ_CAL]
[C1:IOO-RFAMPD_133MHZ_CAL]
[C1:IOO-RFAMPD_166MHZ_CAL]
[C1:IOO-RFAMPD_199MHZ_CAL]

Before saving the changes I committed C0EDCU.ini to the svn.

Then I restarted the frame builder so now the new channels can be monitored and trended.

  2254   Thu Nov 12 12:51:45 2009 AlbertoUpdateABSLWorking on the AP table

Quote:

I've opened the AP table and I'm working on it.

Also auxiliary NPRO turned on and mechanical shutter opened.

AP table and aux NPRO shutter just closed.

  2256   Thu Nov 12 16:13:05 2009 AlbertoUpdatePSLMC Trans Offset

On Rana's suggestion I checked the MC transmission QPD (C1:IOO-MC_TRANS_SUM). I found that the readout is almost zero when the MC is unlocked.

I unlocked the Mode Cleaner turning off the LSC control and disabling the autolocker. The QPD reads 0.014. It seems that there is no offset.

I also checked with the IR card around the photodetector and I didn't see any stray beam.

  2257   Thu Nov 12 16:53:59 2009 AlbertoUpdateABSLWorking on the AP table

Quote:

Quote:

Yes it did.

For long time, the crystal temperature C1:PSL-126MOPA_LTMP was 43~46deg. Now it is 34deg. Try ~10deg lower temperature.

Quote:

I wonder if the all the tinkering on the PSL laser done recently to revive the power have changed the PSL NPRO temperature and so its frequency. That could also explain why the beat doesn't show up at the same temperature of the NPRO as I used to operate it. Although I scanned the NPRO temperature +/- 2 deg and didn't see the beat.

 

 Beat found at 30MHz with auxiliary NPRO temperature of 37.19 degrees, vs. ~48 deg as it used to be.

The beat is small (-70dBm). PLL alignment has to be improved.

 PLL alignment improved. Beat amplitude = -10dBm. Good enough.

DC readouts at the PLL photodiode:

V_NPRO = -4.44V

V_PSL = -3.76V

The NPRO beam is attenuated by a N.D.=1 attenuator just before going to the photodiode.

Something strange happened at the last. Right before -10dBm, the amplitude of the beat was about -33dBm. Then I was checking the two interfering beams with the IR card and saw that they overlapped quite well. I then turned my head back to the spectrum analyzer and suddenly the beat was at -10dBm. Not only, but a bunch of new peaks had appeared on the spectrum. Either I inadvertently hit the PD moving it to a better position or something else happened.

Like if someone was making some other modulation on the beam or the modulation depth of the PSL's sidebands had gone up.

  2261   Thu Nov 12 18:10:27 2009 AlbertoUpdateABSLPLL Locked

I locked the PLL and made some first measuremtns of the spectrum of the error signal. I'll post them later.

I closed the shutter of the NPRO.

  2271   Sun Nov 15 18:42:10 2009 AlbertoUpdateLockingInterferometer fully locked for 3331 seconds

This afternoon, I tried to lock the interferometer again after a few days.

After a couple of failed attempts, and relocks of the MZ, the interferometer stayed locked continuously for about 50 minutes, with arm power of about 92.

I just wanted to check the status of the interferometer so I didn't do any particular measurement in the meantime.

  2302   Thu Nov 19 16:04:48 2009 AlbertoConfigurationelogElog debugging output - Down time programmed today to make changes

We want the elog process to run in verbose mode so that we can see what's going. The idea is to track the events that trigger the elog crashes.

Following an entry on the Elog Help Forum, I added this line to the elog starting script start-elog-nodus:

./elogd -p 8080 -c /cvs/cds/caltech/elog/elog-2.7.5/elogd.cfg -D -v > elogd.log 2>&1

which replaces the old one without the part with the -v argument.

The -v argument should make the verbose output to be written into a file called elogd.log in the same directory as the elog's on Nodus.

I haven't restarted the elog yet because someone might be using it. I'm planning to do it later on today.

So be aware that:

We'll be restarting the elog today at 6.00pm PT. During this time the elog might not be accessible for a few minutes.

  2303   Thu Nov 19 18:49:55 2009 AlbertoConfigurationelogElog debugging output - Down time programmed today to make changes

Quote:

We want the elog process to run in verbose mode so that we can see what's going. The idea is to track the events that trigger the elog crashes.

Following an entry on the Elog Help Forum, I added this line to the elog starting script start-elog-nodus:

./elogd -p 8080 -c /cvs/cds/caltech/elog/elog-2.7.5/elogd.cfg -D -v > elogd.log 2>&1

which replaces the old one without the part with the -v argument.

The -v argument should make the verbose output to be written into a file called elogd.log in the same directory as the elog's on Nodus.

I haven't restarted the elog yet because someone might be using it. I'm planning to do it later on today.

So be aware that:

We'll be restarting the elog today at 6.00pm PT. During this time the elog might not be accessible for a few minutes.

 I tried applying the changes but they didn't work. It seems that nodus doesn't like the command syntax.

I have to go through the problem...

The elog is up again.

  2308   Fri Nov 20 13:54:45 2009 AlbertoOmnistructureEnvironmentNew Paper and Cardboard Recycling Bins Introduced to the 40m

The 40m produces a large amount of paper and cardboard waste. It would be worth it if we disposed those kind of garbages for recycling.

I set up two new garbage bins in the lab: one in the control rooms that adds up to the can/bottle recycling bin, and one other one in the office area, next to the printer for general paper disposal.

People in the lab are strongly invited to make use of the two new garbage bins and recycle their paper and cardboard waste.

Boxes can be larger than the garbage bin, so I'd recommend people to crash them before throwing them into the bin.

DSC_1030.JPG

DSC_1031.JPG

  2321   Tue Nov 24 14:33:22 2009 AlbertoUpdateABSLworking on the AP table

I'm working on the AP table. I also opened the auxiliary NPRO shutter. The auxiliary beam is on its path on the AP table and PSL table.

  2324   Tue Nov 24 19:16:02 2009 AlbertoUpdateABSLworking on the AP table

Quote:

I'm working on the AP table. I also opened the auxiliary NPRO shutter. The auxiliary beam is on its path on the AP table and PSL table.

 Closing the AP table and the NPRO shutter now.

  2326   Wed Nov 25 08:43:08 2009 AlbertoUpdateABSLWorking on the AP table

I'm working on the AP table. I also opened the auxiliary NPRO shutter. The auxiliary beam is on its path on the AP table and PSL table.

  2328   Wed Nov 25 10:20:47 2009 AlbertoUpdateABSLAbsL PLL not able to lock

Last night something happened on the beat between the PSL beam and the auxiliary NPRO beam, that spoiled the quality of the beating I had before. As a result the PLL has become unable to lock the two lasers.

The amplitude of the beat at the spectrum analyzer has gone down to -40 dBm from -10 that it was earlier. The frequency has also become more unstable so that now it can be seen writhing within tens of KHz.

Meanwhile the power of the single beams at the PLL photodiode hasn't changed, suggesting that the alignment of the two beam didn't change much.

Changes in the efficiency of the beating between the two beams are not unusual. Although that typically affects only the amplitude of the beat and wouldn't explain why also its frequency has become unstable. Tuning the alignment of the PLL optics usually brings the amplitude back, but it was uneffective today.

It looks like something changed in either one of the two beams. In particular the frequency of one of the two lasers has become less stable.

Another strange thing that I've been observing is that the amplitude of the beat goes down (several dBm) as the beat frequency is pushed below 50 MHz. Under 10 MHz it even gets to about -60 dBm.

I noticed the change yesterday evening at about 6pm, while I was taking measurements of the PLL open loop tranfer function and everything was fine. I don't know whether it is just a coincidence or it is somehow related to this, but Jenne and Sanjit had then just rebooted the frame builder.

  2329   Wed Nov 25 11:02:54 2009 AlbertoUpdateABSLAbsL PLL not able to lock

Quote:

Last night something happened on the beat between the PSL beam and the auxiliary NPRO beam, that spoiled the quality of the beating I had before. As a result the PLL has become unable to lock the two lasers.

The amplitude of the beat at the spectrum analyzer has gone down to -40 dBm from -10 that it was earlier. The frequency has also become more unstable so that now it can be seen writhing within tens of KHz.

Meanwhile the power of the single beams at the PLL photodiode hasn't changed, suggesting that the alignment of the two beam didn't change much.

Changes in the efficiency of the beating between the two beams are not unusual. Although that typically affects only the amplitude of the beat and wouldn't explain why also its frequency has become unstable. Tuning the alignment of the PLL optics usually brings the amplitude back, but it was uneffective today.

It looks like something changed in either one of the two beams. In particular the frequency of one of the two lasers has become less stable.

Another strange thing that I've been observing is that the amplitude of the beat goes down (several dBm) as the beat frequency is pushed below 50 MHz. Under 10 MHz it even gets to about -60 dBm.

I noticed the change yesterday evening at about 6pm, while I was taking measurements of the PLL open loop tranfer function and everything was fine. I don't know whether it is just a coincidence or it is somehow related to this, but Jenne and Sanjit had then just rebooted the frame builder.

 I confirm what I said earlier. The amplitude of the beat is -10 dBm at 300MHz. It goes down at lower frequencies. In particular it gets to-60 dBm below 20 MHz. For some strange reason that I couldn't explain the beating efficiency has become poorer at low frequencies.

  2334   Wed Nov 25 15:42:27 2009 AlbertoUpdateABSLWorking on the AP table

Quote:

I'm working on the AP table. I also opened the auxiliary NPRO shutter. The auxiliary beam is on its path on the AP table and PSL table.

 NPRO shutter closed

  2337   Wed Nov 25 20:14:58 2009 AlbertoUpdateABSLAbsL PLL not able to lock: problem fixed

Quote:

Last night something happened on the beat between the PSL beam and the auxiliary NPRO beam, that spoiled the quality of the beating I had before. As a result the PLL has become unable to lock the two lasers.

The amplitude of the beat at the spectrum analyzer has gone down to -40 dBm from -10 that it was earlier. The frequency has also become more unstable so that now it can be seen writhing within tens of KHz.

Meanwhile the power of the single beams at the PLL photodiode hasn't changed, suggesting that the alignment of the two beam didn't change much.

Changes in the efficiency of the beating between the two beams are not unusual. Although that typically affects only the amplitude of the beat and wouldn't explain why also its frequency has become unstable. Tuning the alignment of the PLL optics usually brings the amplitude back, but it was uneffective today.

It looks like something changed in either one of the two beams. In particular the frequency of one of the two lasers has become less stable.

Another strange thing that I've been observing is that the amplitude of the beat goes down (several dBm) as the beat frequency is pushed below 50 MHz. Under 10 MHz it even gets to about -60 dBm.

I noticed the change yesterday evening at about 6pm, while I was taking measurements of the PLL open loop tranfer function and everything was fine. I don't know whether it is just a coincidence or it is somehow related to this, but Jenne and Sanjit had then just rebooted the frame builder.

 

Problem found. Inspecting with Koji we found that there was a broken SMA-to-BNC connector in the BNC cable from the photodiode.

  2338   Wed Nov 25 20:24:49 2009 AlbertoUpdateABSLPLL Open Loop Gain Measured

I measured the open loop gain of the PLL in the AbsL experiment.

I repeated the measurement twice: one with gain knob on the universal PDH box g=3.0; the second measurement with g=6.0

The UGF were 60 KHz and 100 KHz, respectively.

That means that one turn of the knob equals to about +10 dB.

Attachment 1: 2009-09-25_OLgain_g3png.png
2009-09-25_OLgain_g3png.png
Attachment 2: 2009-09-25_OLgain_g6png.png
2009-09-25_OLgain_g6png.png
  2339   Wed Nov 25 20:28:17 2009 AlbertoUpdateABSLStopped working on the AbsL

I closed the shutter of the NPRO for the night.

  2345   Mon Nov 30 10:28:47 2009 AlbertoAoGall down cond.sea of red

Quote:

Came in, found all front-ends down.

 

Keyed a bunch of crates, no luck:

Requesting coeff update at 0x40f220 w/size of 0x1e44
No response from EPICS 

Powered off/restarted c1dcuepics.  Still no luck.

Powered off megatron.  Success!  Ok, maybe it wasn't megatron.  I also did c1susvme1 and c1susvme2 at this time.

 

BURT restored to Nov 26, 8:00am

 

But everything is still red on the C0_DAQ_RFMNETWORK.adl screen, even though the front-ends are running and synced with the LSC.  I think this means the framebuilder or the DAQ controller is the one in trouble--I keyed the crates with DAQCTRL and DAQAWG a couple of times, with no luck, so it's probably fb40m.    I'm leaving it this way--we can deal with it tomorrow.

 I found the red sea when I came in this morning.

I tried several things.

  1. ssh into fb40m: connection refused
  2. telnet fb40m 8087: didn't respond
  3. shutdown fb40m by physically pushing the power button: it worked and the FB came back to life but still with a red light on the MEDM DAQ_DETAIL screen;
  4. powercycled fb40m AND C0DAQCTRL: no improvement
  5. shutdown fb40m, C0DAQCTRL, C1DCUEPICS and pushed the reset button on the RF network crate; then I restarted the computers in this order: fb40m, C1DCUEPICS, C0DAQCTRL: it worked: they came back to life and the lights eventually turned green on the MEDM montior screen

I'm now going to restart the single front -ends and burtgooey them if necessary.

  2346   Mon Nov 30 11:29:40 2009 AlbertoAoGall down cond.sea of red

Quote:

Quote:

Came in, found all front-ends down.

 

Keyed a bunch of crates, no luck:

Requesting coeff update at 0x40f220 w/size of 0x1e44
No response from EPICS 

Powered off/restarted c1dcuepics.  Still no luck.

Powered off megatron.  Success!  Ok, maybe it wasn't megatron.  I also did c1susvme1 and c1susvme2 at this time.

 

BURT restored to Nov 26, 8:00am

 

But everything is still red on the C0_DAQ_RFMNETWORK.adl screen, even though the front-ends are running and synced with the LSC.  I think this means the framebuilder or the DAQ controller is the one in trouble--I keyed the crates with DAQCTRL and DAQAWG a couple of times, with no luck, so it's probably fb40m.    I'm leaving it this way--we can deal with it tomorrow.

 I found the red sea when I came in this morning.

I tried several things.

  1. ssh into fb40m: connection refused
  2. telnet fb40m 8087: didn't respond
  3. shutdown fb40m by physically pushing the power button: it worked and the FB came back to life but still with a red light on the MEDM DAQ_DETAIL screen;
  4. powercycled fb40m AND C0DAQCTRL: no improvement
  5. shutdown fb40m, C0DAQCTRL, C1DCUEPICS and pushed the reset button on the RF network crate; then I restarted the computers in this order: fb40m, C1DCUEPICS, C0DAQCTRL: it worked: they came back to life and the lights eventually turned green on the MEDM montior screen

I'm now going to restart the single front -ends and burtgooey them if necessary.

Everything is back on.

Restarted all the front ends. As usual c1susvme2 was stubborn  but eventually it came up.

I burt-restored all the front-ends to Nov 26 at 8am.

The mode cleaner is locked.

  2350   Thu Dec 3 15:55:24 2009 AlbertoAoGLSCRF AM Stabilizer Output Power

Today I measured the max output power at the EOM output of one of the RF AM Stabilizers that we use to control the modulation depth. I needed to know that number for the designing of the new RF system.

When the EPICS slider of the 166 MHz modulation depth is at 0 the modulation depth is max (the slider's values are reversed : 0 is max, 5 is min; it is also 0 for any value above 5, sepite it range from 0 to 10).

I measured 9.5V from the EOM output, that is 32 dBm on a 50 Ohm impedance.

  2365   Tue Dec 8 10:20:33 2009 AlbertoDAQComputersBootfest succesfully completed

Alberto, Kiwamu, Koji,

this morning we found the RFM network and all the front-ends down.

To fix the problem, we first tried a soft strategy, that is, we tried to restart CODAQCTRL and C1DCUEPICS alone, but it didn't work.

We then went for a big bootfest. We first powered off fb40m, C1DCUEPICS, CODAQCTRL, reset the RFM Network switch. Then we rebooted them in the same order in which we turned them off.

Then we power cycled and restarted all the front-ends.

Finally we restored all the burt snapshots to Monday Dec 7th at 20:00.

  2376   Thu Dec 10 08:40:12 2009 AlbertoUpdateComputersFronte-ends down

I found all the front-ends, except for C1SUSVME1 and C0DCU1 down this morning. DAQAWG shows up green on the C0DAQ_DETAIL screen but it is on a "bad" satus.

I'll go for a big boot fest.

  2378   Thu Dec 10 08:50:33 2009 AlbertoUpdateComputersFronte-ends down

Quote:

I found all the front-ends, except for C1SUSVME1 and C0DCU1 down this morning. DAQAWG shows up green on the C0DAQ_DETAIL screen but it is on a "bad" satus.

I'll go for a big boot fest.

Since I wanted to single out the faulting system when these situations occur, I tried to reboot the computers one by one.

1) I reset the RFM Network by pushing the reset button on the bypass switch on the 1Y7 rack. Then I tried to bring C1SOSVME up by power-cycling and restarting it as in the procedure in the wiki. I repeated a second time but it didn't work. At some point of the restarting process I get the error message "No response from EPICS".
2) I also tried rebooting only C1DCUEPICS but it didn't work: I kept having the same response when restarting C1SOSVME
3) I tried to reboot C0DAQCTRL and C1DCU1 by power cycling their crate; power-cycled and restarted C1SOSVME. Nada. Same response from C1SOSVME.
4) I restarted the framebuilder;  power-cycled and restarted C1SOSVME. Nothing. Same response from C1SOSVME.
5) I restarted the framebuilder, then rebooted C0DAQCTRL and C1DCU, then power-cycled and restarted C1SOSVME. Niente. Same response from C1SOSVME.
 
Then I did the so called "Nuclear Option", the only solution that so far has proven to work in these circumstances. I executed the steps in the order they are listed, waiting for each step to be completed before passing to the next one.
0) Switch off: the frame builder, the C0DAQCTRL and C1DCU crate, C1DCUEPICS
1) turn on the frame builder
2) reset of the RFM Network switch on 1Y7 (although, it's not sure whether this step is really necessary; but it's costless)
3) turn on C1DCUEPICS
4) turn on the C0DAQCTRL and C1DCU crate
5) power-cycle and restart the single front-ends
6) burt-restore all the snapshots
 
When I tried to restart C1SOSVME by power-cycling it I still got the same response: "No response from EPICS". But I then reset C1SUSVME1 and C1SUSVME2 I was able to restart C1SOSVME.
 
It turned out that while I was checking the efficacy of the steps of the Grand Reboot to single out the crucial one, I was getting fooled by C1SOSVME's status. C1SOSVME was stuck, hanging on C1SUSVME1 and C1SUSVME2.
 
So the Nuclear option is still unproven as the only working procedure. It might be not necessary.
 
Maybe restating BOTH RFM switches, the one in 1Y7 and the one in 1Y6, would be sufficient. Or maybe just power-cycling the C0DAQCTRL and C1DCU1 is sufficient. This has to be confirmed next time we incur on the same problem.
  2384   Thu Dec 10 13:10:25 2009 AlbertoConfigurationLSC166 LO Disconnected

I temporarily disconnected the Heliax cable that brings the 166MHz LO to the LSC rack.

I'm doing a couple of measurement and I'll put it back in as soon as I'm done.

  2389   Thu Dec 10 17:05:21 2009 AlbertoConfigurationLSC166 MHz LO SMA-to-Heliax connection repaired

I replaced the SMA end connector for the 166 MHZ Local Oscillator signal that goes to the back of the flange in the 1Y2 rack. The connector had got damaged after it twisted when I was tigheting the N connector of the Heliax cable on the front panel.

  2393   Thu Dec 10 18:31:44 2009 AlbertoConfigurationLSC166 LO Disconnected

Quote:

I temporarily disconnected the Heliax cable that brings the 166MHz LO to the LSC rack.

I'm doing a couple of measurement and I'll put it back in as soon as I'm done.

 These are the losses I measured on a RG-174 cable for the two frequencies that we're planning to use in the Upgrade:

@11MHz Loss=0.22dBm/meter

@55MHz Loss=0.41dBm/meter

(The cable was 2.07m long. The input signal was +10dBm and the output voltages at the oscilloscope where: Vpk-pk(11MHz)=1.90V, Vpk-pk(11MHz)=1.82V )

  2396   Fri Dec 11 11:42:26 2009 AlbertoConfigurationLSC166 LO Disconnected

Quote:

They must not be dBm, must be dB

Quote:

Quote:

I temporarily disconnected the Heliax cable that brings the 166MHz LO to the LSC rack.

I'm doing a couple of measurement and I'll put it back in as soon as I'm done.

 These are the losses I measured on a RG-174 cable for the two frequencies that we're planning to use in the Upgrade:

@11MHz Loss=0.22dBm/meter

@55MHz Loss=0.41dBm/meter

(The cable was 2.07m long. The input signal was +10dBm and the output voltages at the oscilloscope where: Vpk-pk(11MHz)=1.90V, Vpk-pk(11MHz)=1.82V )

 

I apologize for the lack of correctness on the units in yesterday's elog entry, but I wasn't very sharp last night.

I repeated the measurement today, this time also making sure that I had a 50ohm input impedance set in the scope. These the results for the losses.

RG-174 Cable 0.053 dB/m @ 11MHz  0.155 dB/m @ 55 MHz

 I also measured the losses in the Heliax cable going from the 166 MHz LO to the LSC rack:

166MHz LO Heliax 0.378 dB @ 11MHz  1.084 dB @ 55 MHz

 

  2397   Fri Dec 11 13:18:17 2009 AlbertoConfigurationVACpumpdown has started

Quote:

Oplev positions before and after drag wiped arm TMs as of yesterday. Slow-mode pumpdown has started with 3/4 turn opened  RV1 valve at 8am today.

 I'm leaving the lab now for less than 2 hours. I should be back in time for when the pumping is finished so that I can measure the finesse again.

  2402   Fri Dec 11 19:51:13 2009 AlbertoConfigurationLSC166 LO Disconnected

Quote:

 

 Seems like very strange cable loss numbers. The Heliax is lossier than the RG-174? I wonder how these compare with the specs in the cable catalog?

In my last entry there was a typo for the measurement of the Heliax at 55 MHz. I corrected it. It was 1.084 dB instead of 1.084 dB/m.
For the Heliax I don't have the measurement of the loss per meter since I don't know the cable actual length.
 
Except for that, I checked the values I found on the Internet.
My measurements for the RG-174 seem comparable to the loss specified in the catalog (here): 6.6dB in 100ft @ 55 MHz, that is 0.22 dB/m, that compare with 0.155 dB/m that I measured.

I did the measurement on a 4.33 meter long cable with SMA connectors at the ends.

  2413   Mon Dec 14 14:16:14 2009 AlbertoUpdateTreasureLOCKSTARS

Quote:

Good job guys. What I did was saying "I don't know", "Maybe", and "Ants...".

Now you can proceed to measurements for the visibility and the cavity pole! 

Quote:

[Jenne, Kiwamu, Koji]

We got the IFO back up and running!  After all of our aligning, we even managed to get both arms locked simultaneously.  

 I'm going to do it right now.

  2415   Mon Dec 14 19:33:04 2009 AlbertoUpdateGeneralArm Cavity Poles measured again after cleaning the optics last week

Last week we vented and we cleaned the main optics of the arm cavities.

I measured the frequency of the cavity poles for both the arm cavities to see how they changed (see previous elog entry 2226). These the results:

fp_X = 1616 +/- 14 Hz

fp_Y = 1590 +/- 4 Hz

The error is the statistical error that I got with the Matlab NonLinearLeastSquare fitting function.
 
I calculated the cavity pole frequencies by measuring the transfer function between a photodiode located at the end of the arms (either X or Y) and another photodiode placed after the mode cleaner. Both diodes where Thorlabs PDA255.
(Last time, I had measured that the pair of diode had a flat calibration).
 
With the SR785 I measured the transfer function by exciting the OMC_ISS_EXC input cable.
For both arms I set to 1V the excitation amplitude. I repeated the measurements for different excitation amplitudes without observing any changes.
I then fitted the data with the NonLinearLeastSquare function of matlab. The script I wrote to do that is attached to this entry in a compressed file.
The files also contains the PDF with the output plots and the data from both set of measurements performed before and after the cleaning.
The data is commented in a file called measurements.log.
 
In the end I disabled again the test switch on the ISS MEDM screen.
I disconnected the excitation cable from the OMC_ISS_EXC input cable.
I removed the photodiode that measured the Mode Cleaner transmission from the PSL clearing the way for the beam to get back to its path to the RFAM photodiode.
Attachment 1: XarmTF01_fit.pdf
XarmTF01_fit.pdf
Attachment 2: YarmTF01_fit.pdf
YarmTF01_fit.pdf
Attachment 3: ArmCavityFinesseMeasurment.tar.gz
  2418   Tue Dec 15 05:29:31 2009 AlbertoUpdateGeneralArm Cavity Poles measured again after cleaning the optics last week

 

 The Y arm cavity pole moved down by 130 Hz, whereas the X arm moved by only 34 Hz. I wonder if that is because Kiwamu spent much more time on cleaning ITMY than on any other optic.

  2420   Tue Dec 15 21:39:34 2009 AlbertoUpdateABSLbrief summary of this afternoon's measurements
I took measurements of the open loop gain of the AbsL PLL with the old Universal PDH Box.
I Also measured the filter shape of both the new and the old PDH box.
I'm going to plot the results in a nice form tomorrow morning.
For who's interested, the PLL UGF was at 10KHz.
 
I can't lock the PLL with the new PDH box. Measuring its filter's shape, as suggested by Koji, I found out that it differs from the old one. That despite the fact that the two boxes should share the same circuit schematic. O,r at least, that is what it looks like from the schematics in the DCC.
I need to understand whether that is intentional and, if that was the case, what kind of use  Rich Abbott designed it for.
 
Tomorrow I'm going to post in the elog the filter's transfer functions too.
 
Before leaving the lab I closed the auxiliary laser's mechanical shutter.
  2421   Wed Dec 16 11:21:20 2009 AlbertoUpdateABSLUniversal PDH Box Servo Filters
Yesterday I measured the shape of the servo filter of both the old and the new Universal PDH boxes.
Here they are compared.

NewandOlfFilterTF.png

The way the filter's transfer function has been measured is by a swept sine between the "SERVO INPUT" and the "PIEZO DRIVE OUTPUT" connection on the box front panel. The spectrum analyzer used for the measurement is the SR785 and the source amplitude is set at 0.1V.

The two transfer functions are clearly different. In particular the old one looks like a simple integrator, whereas the new one already includes some sort of boost.

That probably explains why the new one is unable to lock the PLL. Indeed what the PLL needs, at least to acquire lock, is an 1/f filter.

I thought the two boxes were almost identical, at least in the filter shapes. Also the two schematics available in the DCC coincide.

Attachment 1: NewandOlfFilterTF.png
NewandOlfFilterTF.png
  2422   Wed Dec 16 11:46:25 2009 AlbertoUpdateABSLAbsl PLL Open Loop Gain

Yesterday I measured the Open Loop Gain of the PLL in the absolute length experiment. The servo I used was that of the old Universal PDH box.

The OLG looks like this:

OldBoxOLTF.png

The UGF is at 10 KHz.

  2427   Thu Dec 17 09:30:08 2009 AlbertoHowToComputersNodus sluggish

The elog has been quite slow for the last two days. The cause is nodus, that has been slowing down the access to it.

I looked at the list of the running processes on nodus by typing the command prstat, which is the equivalent for Solaris of the Linux "top". I didn't see any particular process that might be absorbing too many resources.

I remember Rana fixing the same problem in the past but couldn't find his elog entry about that. Maybe we should just restart nodus, unless someone has some other suggestion.

  2428   Thu Dec 17 17:13:50 2009 AlbertoOmnistructureEnvironmentSTACIS stuff
One of the electronics benches is currently occupied by the STACIS equipment.
We need that table If no one is working on the STACIS anymore, it should be removed from there.
  2429   Thu Dec 17 19:03:14 2009 AlbertoHowToComputersNodus sluggish

Quote:

The elog has been quite slow for the last two days. The cause is nodus, that has been slowing down the access to it.

I looked at the list of the running processes on nodus by typing the command prstat, which is the equivalent for Solaris of the Linux "top". I didn't see any particular process that might be absorbing too many resources.

I remember Rana fixing the same problem in the past but couldn't find his elog entry about that. Maybe we should just restart nodus, unless someone has some other suggestion.

 Problem solved. Nodus and the elog are running fine. It's just that the elog takes some time to make a preview of complex pdf attachments, like those in Kiwamu's entry 2405.

  2459   Mon Dec 28 15:19:19 2009 AlbertoUpdateComputersBurtrestored to Dec 26 at 20:00

Since it wasn't sure whether all the front-ends had been restored after the bootfest, I burtrestored everything to Dec 26 at 20:00.

Always keep in mind that to burtrestore c1dcuepics, the snapshot file has to be modified by hand by moving the last quote up to the line before the last.

  2460   Mon Dec 28 15:34:14 2009 AlbertoUpdateABSLWorking on the AP table

I opened the auxiliary laser's shutter.

I'm currently working on the AP table.

  2461   Mon Dec 28 18:35:27 2009 AlbertoUpdateABSLWorking on the AP table

Quote:

I opened the auxiliary laser's shutter.

I'm currently working on the AP table.

 I finished working on the table.

I closed the AUX NPRO's shutter.

  2467   Wed Dec 30 10:58:48 2009 AlbertoUpdateGeneralAll watchdogs tripped this morning

This morning I found all the watchdogs had tripped during the night.

I restored them all.

I can't damp ITMX. I noticed that its driving matrix is all 1s and -1s as the the right values had been lost in some previous burtrestoring.

  2476   Tue Jan 5 09:18:38 2010 AlbertoOmnistructureElectronicsUniversal PDH Box Stored in the RF Cabinet

FYI: I stored the Universal PDH boxes in the RF cabiner in the Y arm.

  2479   Tue Jan 5 13:23:45 2010 AlbertoOmnistructureEnvironmentturning page

In the lab there are lots of old posters with outdated autocad drawings, or printouts with schematics of old electronics hanging on the walls.

Can we get rid of those and start giving the lab a fresh and modern look?

  2485   Fri Jan 8 10:03:04 2010 AlbertoOmnistructureLSCSPOB shutter was closed

This morning I found that there was no light on the SPOB PD. I went looking at the photodetector and I found that the shutter in front of it was closed.

I switched the shutter driver from n.c. to n.o. which had the effect of opening it.

I guess we inadvertently closed the shutter with Rana when last week we were tinkering with the ITMY  camera.

ELOG V3.1.3-