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  11423   Fri Jul 17 02:46:07 2015 IgnacioUpdateGeneralNew huddle test data for Wilcoxon 731A results

On Thursday, new huddle test data for the Wilcoxon 731A was aquired by Eric. 

The difference between this new data and the previous data, is:

1) We used three accelerometers instead of six this time around.

2) We used a foam box, and clamped cables on the experimental set up as shown in the previous elog, http://nodus.ligo.caltech.edu:8080/40m/11389

I have analyzed the new data. Here I present my results.

The following plot shows the ASD's for the three accelerometers raw outputs as well as their error signals computed using the three cornered hat method,

As before, I computed the mean for the output signals of the accelerometers above as well as their mean self noise to get the following plot


Now, below I compare the new results with the results that I got from the old data, 

Did the enclosure and cable clamping do much? Not really, according to the computed three hat results. Also, notice how much better, even if its a small improvement, we get from using six accelerometers and calculating their self noise by the six cornered hat method.


Now, I moved on to analyzing the same data with Wiener Filtering.

Here are again, the raw outputs, and the self noises of each individual accelerometer calculated using Wiener filtering,

The accelerometer in the Y direction is show a kind of funky signal at low frequncies. Why? Anyways, I calculated the mean of the above signals as I did for the three cornered hat method above to get the following, I also show the means of the signals computed with the old data using wiener filtering,

Is the enclosure really doing much? The Wiener filter that I applied to the huddle test old data gave me a much better, by an order of magnitude better self noise curve. Keep in mind that this was using SIX accelerometers, not THREE as we did this time. I want to REDO the huddle test for the WIlcoxon accelerometers using SIX accelerometers with the improved experimental setup to see what I get.

Finally, I compare the computed self noises above with what the manufacturer gives,


As I expected, the self noise using six accelerometers and Wiener filtering is the best I could work out. The three cornered hat method works out pretty well from 1 to 10 Hz, but the noise is just too much anywhere higher than 10 Hz. The enclosed, clamped, 3 accelerometer wiener filter result is an order of magnitude worse than the six accelerometer wiener filtered result, and two orders of magnitude worse than the three cornered hat method in the 1 to 10 Hz frequency band. 

As I stated, I think we must performed the huddle test with SIX accelerometers and see what kind of results we get.

  11424   Fri Jul 17 04:56:37 2015 IgnacioUpdateGeneralMCL Wiener filtering + FIR to IIR conversion using vectfit


We took data for the mode cleaner a while ago, June 30th I believe. This data contained signals from the six accelerometers and the three seismometers. In here I have only focused on the seimometer signals as witnesses in order to construct Wiener filters for each of the three seismometer signals (x,y,z) and for the combined seismometers signal. The following plot showing the ASD's shows the results,

 Wiener filtering works beautifully for the seismometers. Note that subtraction is best when we use all three seismometers as the witnesses in the Wiener filter calculation, as can be clearly seen in the first plot above.

Now, I used vectfit to conver the Wiener FIR filters for each seismometer to their IIR versions. The following are the bode plots for the IIR filters,

For the x-direction seismometer,


For the y-direction seismometer



And for the z-direction seismometer,

 The IIR filters were computed using 5 zeros and 5 poles using vectfit. That was the maximum number of poles that I could use wihtout running into trouble with matrices being almost singular in Matlab. I still need to figure out how to deal with this issue in more detail as fitting the y-seismometer was a bit problematic. I think having a greater number of poles will make the fitting a bit easier.

  11425   Sat Jul 18 06:12:07 2015 IgnacioUpdateGeneralMCL Wiener filtering + FIR to IIR conversion using vectfit (Update)

(updateAfter Eric gave me feedback on my previous elog post, I went back and fixed some of the silly stuff I stated.

First of all, I have come to realized that it makes zero sense to plot the ASD's of the mode cleaner against the seismometer noise. These measurements are not only quite different, but elementary, they posess different units. I have focused my attention to the MCL being Wiener filtered with the three siesmometer signals. 

One of the major improvements that I make in the following analysis is,

1) Prefiltering; a band pass filter from 1 to 5 Hz, in order to emphasize subtraction of the bump shown in the figure below.

2) I have used vectfit exclusively in the 1 to ~5 Hz range, in order to model the FIR filter properly, as in, the kind of subtraction that we care about. Limiting myself to the 1 - 5 Hz range has allowed me to play freeley with the number of poles, hence being able to fit the FIIR filter properly with an IIR rational transfer function properly,

The resulting ASD's are shown below, in blue we show the raw MCL output, in blac the Wiener filter (FIR) result, and finally in black, the resultant data being filtered with the calculated IIR Wiener filter.


Now, in the following plots I show the IIR Wiener filters for each of the three seismometers, 

X Seismometer,

For the Y seismometer,

and for the Z seismometer,


The matlab code for this work is attached: code.zip

  11426   Sat Jul 18 14:55:33 2015 jamieUpdateGeneralall front ends back up and running

After some surgery yesterday the front ends are all back up and running:

  • Eric found that one of the DAC cards in the c1sus front end was not being properly initialized (with the new RCG code).  Turned out that it was an older version DAC, with a daughter board on top of a PCIe board.  We suspected that there was some compatibility issue with that version of the card, so Eric pulled an unused card from c1ioo to replace the one in c1sus.  That worked and now c1sus is running happily.
  • Eric put the old DAC card into c1ioo, but it didn't like it and was having trouble booting.  I removed the card and c1ioo came up fine on it's own.
  • After all front end were back up and running, all RFM connections were dead.  I tracked this down to the RFM switch being off, because the power cable was not fully seated.  This probably happened when Steve was cleaning up the 1X4/5 racks.  I re-powered the RFM switch and all the RFM connections came back on-line
  • All receivers of Dolphin (DIS) "PCIE" IPC signals from c1ioo where throwing errors.  I tracked this down to the Dolphin cable going to c1ioo being plugged in to the wrong port on the c1ioo dolphin card.  I unplugged it and plugged it into the correct port, which of course caused all front end modules using dolphin to crash.  Once I restarted all those models, everything is back:

  11430   Mon Jul 20 11:57:17 2015 ericqUpdateGeneralArm Locking recovered

The interferometer is warming up!

I had some issues locking the IMC at first. It turned out that the MC3 side OSEM signal wasn't getting to the ADC. A satellite box sqush fixed it. 

I touched up the PMC alignment; the best I could do is 0.75V, probably due to the AOM being in place. 

I haven't touched the WFS offsets, but the current ones seem to be doing ok. I'll touch them up tonight when the seismic activity has calmed. 

I made some changes to the state of the PZT/PC crossover gain in the mcdown script, resulting in the IMC catching lock quicker. 

Thankfully, the tip tilt pointing stayed good during the upgrade. I barely had to touch the ETM alignment to lock the arms. ETMX is showing some errant motion, though... 

  11431   Mon Jul 20 16:45:15 2015 Max IsiConfigurationGeneralSummary page c1sus.ini error corrected

Bad syntax errors in the c1sus.ini config file were causing the summary pages to crash: a plot type had not been indicated for plots 5 and 6, so I've made these "timeseries."
In the future, please remember to always specify a plot type, e.g.:




       C1:SUS-ITMY_SUSPIT_INMON.mean timeseries

By the way, the pages will continue to be unavailable while I transfer them to the new shared account.

  11432   Tue Jul 21 05:17:09 2015 IgnacioUpdateGeneralMore clear accelerometer huddle tests results

I generated the following plots from the two sets of huddle test data we have for the accelerometers. 

Old data: 6 accelerometers, no cables clamped, no box, 55 mins worth of data.

New data: 3 accelerometers, cables clamped, foam box put on placed and completely sealed, 20 mins worth of data.

I made sure to use the same Impuse response time (6 sec) and sampling frequency (256 Hz), as well as every other parameter for the calculations.



Top left: The resultant self noise curve using the new data, there is definitely and improvement in the 0.5-2 Hz band. 

Top right: Resultant self noise using the old data, for the first set of three accelerometers.

Bottom left: Old data result for the remaining three accelerometers.

Bottom right: Old data result, using all six accelerometers as witnesses instead.

  11433   Tue Jul 21 21:25:18 2015 Max IsiUpdateGeneral40m LDAS account

A shared LIGO Data Grid (LDG) account was created for use by the 40m lab. The purpose of this account is to provide access to the LSC computer cluster resources for 40m-specific projects that may benefit from increased computational power and are not linked to any user in particular (e.g. the summary pages).

For further information, please see https://wiki-40m.ligo.caltech.edu/40mLDASaccount

  11434   Tue Jul 21 21:33:22 2015 Max IsiUpdateGeneralSummary pages moved to 40m LDAS account

The summary pages are now generated from the new 40m LDAS account. The nodus URL (https://nodus.ligo.caltech.edu:30889/detcharsummary/) is the same and there are no changes to the way the configuration files work. However, the location on LDAS has changed to https://ldas-jobs.ligo.caltech.edu/~40m/summary/ and the config files are no longer version-controlled on the LDAS side (this was redundant, as they are under VCS in nodus).

I have posted a more detailed description of the summary page workflow, as well as instructions to run your own jobs and other technical minutiae, on the wiki: https://wiki-40m.ligo.caltech.edu/DailySummaryHelp

  11436   Wed Jul 22 15:09:40 2015 ericqUpdateGeneralIMC work

The other night, I spent some time with the mode cleaner. 

First, I made some model changes to the MC_TRANS part of c1mcs.mdl. Specifically, I brought in the userapps QPD part that we are using for the transmon and oplev QPDs. My main motivation for doing so was to have FMs for the pitch and yaw values, to be able to set offsets. Up until now, we have used a QPD centering servo in conjunction with the WFS, but the center of the QPD is not perfectly aligned to represent the center of MC2. Using offsets at the servo isn't really practical, since there are integrators. 

I then spent some time manually aligning the mode cleaner mirrors with WFS off, followed by centering the in-lock MC REFL beam on the WFS QPDs, and setting the WFS and MC_TRANS offsets. (I updated the WFS offset script, and made one for MC_TRANS in scripts/MC/WFS. They now use averaging instead of servoing to zero, a la LSC PD offset script). 

The resultant intracavity power and RIN was an improvement over the older offsets. (RMS RIN went down by half, I think.)

Since Monday, the autolocker seems to be having some trouble. At first, I suspected the changes I made weren't so hot after all, but I've now noticed a pattern. Often when I come to manually lock the mode cleaner due to a long unlocked period, I find that the sliders are not in the state specified by the mcdown script. Furthermore, it's not the same channels every time; sometimes the servo gain is left high, sometimes the boosts are left on. I fear that some of the caput commands are failing to execute. Ugh. 

  11440   Thu Jul 23 20:54:42 2015 JessicaUpdateGeneralALS Delay Line Box

The front panels for the ALS delay line box came in last week. Some of the holes for the screws were slightly misaligned, so I filed those and everything is now put together. I just need to test both front panels to determine if the SMAs should be isolated or not.


Koji had also suggested making the holes in the front and back panel conical recesses so that flat head screws could be used and would counteract the anodization of the panel and avoid the SMAs being isolated. I think if we did that then conductivity would be ensured throughout the panel and also through the rest of the box. I also think one way we could test this before drilling conical recesses would be to test both front panels now, as one has isolated SMAs and one has conductive SMAs. If the anodization of the panel isolated the SMA regardless, we could potentially figure this out by testing both panels. But, would it also be that it is possible that the isolation of the SMA itself does not matter and so this test would tell us nothing? Is there a better way to test if the SMAs are being isolated or not? Or would this be more time consuming than just drilling conical recesses as a preventative measure?

  11441   Thu Jul 23 20:57:15 2015 JessicaSummaryGeneralApplying Pre-filter to data before IIR Wiener Filtering

I updated my bandpass filter and have included the bode plot below in Figure 1. It is a fourth order elliptic bandpass filter with a passband ripple of 1dB and a stopband attenuation of 30 dB. It emphasizes the area between 3 and 40 Hz.

Below, I applied this filter to the huddle test data. The results from this were only slightly better in the targeted region than when no pre-filter was applied. 

When I pre-filtered the mode cleaner data and then used an IIR wiener filter, I found that the results did not differ much from the data that was not pre-filtered. I'm not sure yet if I'm targeting the right region of this data with my bandpass filter, and will be looking more into choosing a better region. Also, I am only using certain regions of ff when calculating the transfer function, and need to optimize that region also. I uploaded the code I used to make these plots to github.

  11442   Thu Jul 23 21:12:14 2015 IgnacioUpdateGeneralNewer accelerometer huddle test data + detrending

In the last post concerning the self noise of the accelerometers, I mentioned the differences between the two data sets I was playing with. In order to give a more concrete analysis of the accelerometers self noise, we came to the conclusion that data taking time should be the same.

The plots below show the analysis for the following two datasets:

Old Data:  6 accelerometers, no cables clamped, no box, 55 mins worth of data.

Newer data: 3 accelerometers, cables clamped, foam box put on placed and completely sealed, 57.66 mins worth of data, (we had 20 mins of data in the previous data set).

Filter parameters were kept the same in all calculations, the only change that was added to the analysis was the detrending of the signals using the detrend function on Matlab, this improved the results as the plots show. I also plotted the error bars for the Wiener filtered result for reference as well as the manufactures claimed self noise.


After detrending the data and taking a longer dataset we can see the improvement brought upon by the foam box in the low frequency band of 0.5 - 10 Hz, as shown in the bottom left plot. There is a lot of noise that needs to be cancelled out from 10 Hz and on, which brings to our attention the plot on the bottom right corner. This plot uses the old data but uses all six accelerometers as witnesses, it also improved overall after having detrended the data, but what is peculiar about this plot is the fact that it manages to mitigate the higher frequency 10 - ~100 Hz band noise. 


  11444   Fri Jul 24 18:12:52 2015 Max IsiUpdateGeneralData missing

For the past couple of days, the summary pages have shown minute trend data disappear at 12:00 UTC (05:00 AM local time). This seems to be the case for all channels that we plot, see e.g. https://nodus.ligo.caltech.edu:30889/detcharsummary/day/20150724/ioo/. Using Dataviewer, Koji has checked that indeed the frames seem to have disappeared from disk. The data come back at 24 UTC (5pm local). Any ideas why this might be?

  11449   Tue Jul 28 05:00:03 2015 IgnacioUpdateGeneralSeismometer cans

I've have been talking a little bit with Steve about the seismometer enclosures.

We want to improve on the current stainless steel cans that cover the two Guralps at the end of the arms. In order to do this, we want to cover the interior of the cans with copper foil to improve the thermal conductivity of the enclosure to better control the temperature inside it. Ideally, we would want to copper plate the cans, but cost and difficulty has been an issue.

I have done some rough calculations and it seems that we need a copper layer of thickness being about a third that of the stainless steel can. This happens to be around 0.5-0.6 mm since we have 16 gauge (~1.6 mm) stainless steel cans. 

After wrapping the cans interior with copper, we will insulate them with foam in order to improve its thermal inertia. We want to probably use the same foam that Megan has been using for her seismometer enclosure. I have yet to think about a heater, but something similar to Megans resistor thing would work only smaller. I would be placed inside the can, right on the center of its bottom in order to ditribute heat evenly.


  11450   Tue Jul 28 09:31:35 2015 IgnacioUpdateGeneralNewest accelerometer huddle test

I downloaded new accelerometer huddle test data from last night and analyzed it. This new data set is ~55 mins and uses the same Wiener filter parameters as previous huddle test analysis, the main difference being six accelerometers used in the Wiener filter and the improved experimental set up.

After computing the ASD for the self noise for each of the six accelerometers, (being witnessed by the remaining five), we get,

Now computing the mean of the above signals and the corresponding error bars gives the following result,

Comparing to prevoius huddle tests, I can note two trends on the Wiener subtraction:

1) When using six accelerometers, the subtraction above ~8 Hz drastically improves.

2) When using three accelerometers, there is better cancellation in the 1-5 Hz region, see http://nodus.ligo.caltech.edu:8080/40m/11442. This might have to do with how much more closer the accelerometers are to each other? 

  11451   Tue Jul 28 14:58:59 2015 SteveUpdateGeneraldo not place anything on optical table tops

angrySpecially heavy items: old analoge scope or hardware loaded boxes......etc

 The table cover section holding crossbars are not evenly spaced.no

You have to center each cover section on the cross bar so it is supported on both sides !


I will clean up on this table tomorrow



  11454   Tue Jul 28 16:42:25 2015 SteveUpdateGeneralJamies entry was deleted

Sorry Jamie, I accidentally deleted your elog entry #11453

  11455   Tue Jul 28 17:07:45 2015 JamieUpdateGeneralData missing

For the past couple of days, the summary pages have shown minute trend data disappear at 12:00 UTC (05:00 AM local time). This seems to be the case for all channels that we plot, see e.g. https://nodus.ligo.caltech.edu:30889/detcharsummary/day/20150724/ioo/. Using Dataviewer, Koji has checked that indeed the frames seem to have disappeared from disk. The data come back at 24 UTC (5pm local). Any ideas why this might be?

Possible explanations:

  • The data transfers to LDAS had been shut off while we were doing the DAQ debugging. I don't know if they have been turned back on.  Unlikely this is the problem since you would probably see no data at all if this were the case.
  • wiper script parameters might have been changed to store less of the trend data for some reason.
  • Frame size is different and therefore wiper script parameters need to be adjusted.
  • Steve deleted it all.
  • ...
  11456   Tue Jul 28 20:42:50 2015 JessicaSummaryGeneralNew Seismometer Data Coherence

I was looking at the new seismometer data and plotted the coherence between the different arms of C1:PEM_GUR1 and C1:PEM_GUR2. There was not much coherence in the X arms, Y arms, or Z arms of each seismometer, but there were within the x and y arms of the seismometer.

I think the area we should focus on with filtering is lower ranges, between 0.01 and 0.1, because that it where coherence is most clearly high. It is higher in high frequencies but also incredibly noisy, meaning it probably wouldn't be good to try to filter there. 

  11459   Wed Jul 29 14:32:01 2015 SteveUpdateGeneralHow not to solder





Koji and Steve,

The result: bad Guralp x-arm cable.

I will swap the short cables tomorrow at the base.


Short 46" long cables at the base plates were swapped. Their solderings looked horrible.

This cable actually worked at 5-5-2015

Bad cable at ETMY station now.  The new cable should be a little bit longer ~52"

Koji could pull out easily 11 of the wires  from their socket.

  11471   Thu Jul 30 18:58:36 2015 JessicaUpdateGeneralALS Delay Line Box Front Panel Testing

I tested both of the front panels (conductive and isolated SMAs) with the ALS Delay Line Box by driving extremely close frequencies through the cables. By doing this, we would expect that a spike would show up in the PSD if there was crosstalk between the cables. 

In the plots below, for the conductive panel, the frequencies used were

               X Arm:  22.329 MHz                        Y Arm: 22.3291 MHz        

For the isolated panel, the frequencies were

              X Arm: 22.294 MHz                         Y Arm: 22.2943 MHz    

This gives a difference of 100 Hz for the conductive panel and 300 Hz for the isolated panel. Focusing on these areas of the PSD, it can be seen that in the Y Arm cable there is a very clear spike within 30 Hz of these differences when frequencies are being driven through both cables as opposed to the signal being in only the Y Arm. In the X Arms, the noise in general is higher when both cables are on, but there is no distinct spike at the expected frequencies. This indicates that some sort of crosstalk is probably happening due to the strong spikes in the Y Arm cables.          


  11477   Mon Aug 3 18:19:09 2015 JessicaUpdateGeneralAnodization of front panels accounted for

Previously, I had gotten the same results for the conductive and the isolated front panels. Today, I sanded off the anodized part on the back of the conductive front panel. I checked afterwards with a mulitmeter to ensure that it was indeed conductive through all the SMA connectors. 

I drove a frequency of 29.359 Hz through the X Arm cable and 29.3592 Hz through the Y Arm cable, giving a difference of 200 Hz. Previously, there would only be a spike in the Y Arm at the difference, while the X Arm did not change if the Y arm was on or off. Now that the panel is fully conductive, a spike can also be seen in the X arm, indicating that crosstalk may possibly be happening with this panel, now that the spike corresponds to both the X arm and Y arm. These results are only after one set of data. Tomorrow I'll take two more sets of data with this panel and do a more in depth comparison of these results to what had been previously seen.  

  11484   Thu Aug 6 11:45:01 2015 JessicaUpdateGeneralALS Delay Line front panel testing

Koji had suggested that I sync up the two function generators to ensure that they have the same base frequency and so that crosstalk will actually appear at the expected frequency. After syncing up the two function generators, I drove the following frequencies through each cable:

Conductive SMAs:

     X: 29.537 MHz           Y: 29.5372 MHz

Isolated SMAs:

     X: 29.545 MHz           Y: 29.5452 MHz

Each time, the difference between the frequencies was 200 Hz, so if there was crosstalk, a spike should appear in the PSDs at 200 Hz when frequencies are being driven through both cables simulataneously, but not when just one is on. We very clearly see a spike at 200 Hz in both the X arm and the Y arm with the conductive SMAs, indicating crosstalk. For the front panel with isolated SMAs, we see a spike at 200 Hz when both frequencies are on, but it is much less pronounced than with the conductive SMAs. It seems as though there will be crosstalk using either panel, just less with the isolated SMAs. 

  11486   Mon Aug 10 11:57:45 2015 ericqUpdateGeneralIMC work

Often when I come to manually lock the mode cleaner due to a long unlocked period, I find that the sliders are not in the state specified by the mcdown script. Furthermore, it's not the same channels every time; sometimes the servo gain is left high, sometimes the boosts are left on. I fear that some of the caput commands are failing to execute. Ugh. 

This continues to happen. I believe the network latency boogeyman is to blame. 

There was a long unlocked period because the enable switch for the MC servo fast path (FASTSW) was left off. Running the mcdown script fixed this, but included the error message:

Channel connect timed out: 'C1:IOO-MC_REFL_GAIN' not found.
CA Client Library: Ignored duplicate create channel response from CA server?

which means the IN1 gain didn't get touched. A second pass of the script produced no errors. 

I'm thinking of adding some logic that if the autolocker has failed to lock for some period (5 minutes?), it should rerun mcdown. 

  11491   Tue Aug 11 10:13:32 2015 JessicaUpdateGeneralConductive SMAs seem to work best

After testing both the Conductive and Isolated front panels on the ALS delay line box using the actual beatbox and comparing this to the previous setup, I found that the conductive SMAs improved crosstalk the most. Also, as the old cables were 30m and the new ones are 50m, Eric gave me a conversion factor to apply to the new cables to normalize the comparison.

I used an amplitude of 1.41 Vpp and drove the following frequencies through each cable:
      X: 30.019 MHz          Y: 30.019203 MHz

which gave a difference of 203 Hz. 

In the first figure, it can be seen that, for the old setup with the 30m cables, in both cables there is a spike at 203 Hz with an amplitude of above 4 m/s^2/sqrt(Hz). When the 50m cables were measured in the box with the conductive front panel, the amplitude drops at 203 Hz by a factor of around 3. I also compared the isolated front panel with the old setup, and found that the isolated front panel worse by a factor of just over 2 than the old setup. Therefore, I think that using the conductive front panel for the ALS Delay Line box will reduce noise and crosstalk between the cables the most. 

  11494   Tue Aug 11 16:13:28 2015 EveUpdateGeneralGaussianity tests

I’m working on a code to determine the Gaussianity of a PSD.



It can be difficult to distinguish between GW events and non-Gaussian noise, especially in burst searches. By characterizing noise Gaussianity, we can better recognize noise patterns and distinguish between GW events and noise.


What I did:

I analyzed an hour of S5 L1 data. First, I plotted a timeseries, just to see what I was working with. Then, I produced a PSD (technically, an ASD) for the timeseries using Welch’s method in Python.


I split the data segment into smaller time-chunks and then produced a PSD for each chunk. All PSDs were superimposed in one plot. Here’s a plot for 201 time-chunks of equal length:

For a specific frequency, I can view the spread in PSD value through the production of a histogram.



I’ve made histograms displaying varying PSD values for the 201 PSD plot at 100 Hz, 500 Hz, and 1kHz.

For Gaussian noise, an exponential decay plot is expected. I will continue this analysis by following the statistical method in Ando et al. 2003 to calculate specific values indicative of the Gaussianity of various distributions. I’ll then look at different periods of time in the S5 L1 data to find periods of time suggesting non-Gaussian behavior.

  11509   Fri Aug 14 23:49:34 2015 KojiSummaryGeneralB&K Shaker fixed

I fixed a shaker that was claimed to be broken. I had to cut the rubber membrane to open the head.

Once it was opened, the cause of the trouble was obvious. The soldering joint could not put up with the motion of the head.

It is interesting to see that the spring has the damping layer between the metal sheets.

After the repair the DC resistance was measured. It was 1.9Ohm. The side of the shaker chassis said "3.5Ohm, Max 15VA". So it can take more than 4A (wow).

I gave 2A DC from the bench top supply and turn the current on and off. I could confirm the head was moving.

I'll claim the use of this shaker for the seismometer development.

  11511   Sun Aug 16 23:26:40 2015 EveUpdateGeneralGaussianity tests

I've continued to work on my Gaussianity tests for S5 L1 data. 

Following the statistical measure in Ando et al. (2003), I've calculated the Laguerre coefficient, c2, for all frequencies present in my S5 L1 PSD as a metric of Gaussianity. When c2 is zero, the distribution is Gaussian. A positive c2 corresponds to glitchy noise, while a negative c2 suggests stationary noise.

Below is a plot displaying variation in c2 for this PSD:

By observing the c2 value and histogram of distribution of various PSD values at a given frequency, we can elucidate statistical differences in the Gaussian nature of noise at that frequency which are unclear in the standard PSD.

  11624   Mon Sep 21 00:51:36 2015 ranaUpdateGeneralop340m, autoburt cron =? megatron

I modified the perl script which does our hourly autoburt so that it can run on megatron instead of op340m (old Solaris machine). Nothing major, just some path stuff. That was the last function of op340m that I know of, so after a week of watching this we ought to be able to power it off and send it to e-waste.

Seems to work so far. It complains about some models that aren't running but mostly it reports successful snapshot taking based on the .req files.

Unfortunately, it seems that its only doing the new target directory, so its missing all of our old VME machines which still use the /cvs/cds/caltech/target area.

But I think Gautam and Jamie and Aidan have volunteered to start our slow controls upgrade by moving the EX slow controls to Acromag and into the new target area. We ought to modify the CRON to point at the old directory for now, but its a temporary fix hopefully.

  11626   Mon Sep 21 11:40:30 2015 ericqUpdateGeneralMegatron maitenence

The MC autolocker and FSSslow scripts weren't running on Megtron. These were started by running the following commands on megatron:

sudo initctl start MCautolocker
sudo initctl start FSSslow

The new autoburt cronjob was failing because the .cron file was not executable (fixed by chmod +x burtnew.cron), and the new perl script didn't use the full path for ifconfig. Similarly, the simulink webview updating script was failing because the full path for matlab wasn't being given. Both of these fixes have been tested and commited to SVN. 

In general, cron scripts can be a real pain, since the cron process doesn't run our .bashrc, and so doesn't know about updates to $PATH, or other environment vairables that get updated through /ligo/cdscfg/workstationrc.sh, which is called by .bashrc. So something that manually works fine in the terminal may not play out as expected when run by cron.

  11635   Tue Sep 22 16:52:36 2015 ericqSummaryGeneralRandom Notes

Some things bouncing around my head that haven't made it to ELOG yet:

  • Last week, Rana and I were investigating excess power line noise coming from the DFD demodulation. We put transformers on the green beat signals where they arrive at the LSC rack, to avoid connecting their signal ground from the PSL table to the LSC rack ground. This didn't help; it's unclear what the culprit is; maybe the demod board power board?
  • Lately, when the interferometer loses lock, the Y arm will not lock on POY, or even flash its IR resonance. for a little while. The green beam can be locked, the X arm can be locked, and no excess angular noise is evident from glancing at the oplev XY plots. Mysterious.  
  • Sometimes, when writing new values to the C1LSC SDF table, the c1lscepics process dies (though the write is successful). This is highly annoying. This may have been adressed in some slightly newer RCG code. 
  • C1OAF is running with a big red NO SYNC message on its GDS screen. C1LSC has shown this too, but I think only when the SDF/epics crash happens. 
  • C1OAF also doesn't seem to properly load the "safe" SDF table when starting up, and errantly puts ones in every element in the static FF matrix. Be careful when restarting OAF!
  11650   Tue Sep 29 19:38:09 2015 gautamUpdateGeneralFOL fiber box revamp

The new 2x2 fiber couplers arrived today so Eric gave me an overview on the changes to be made to the existing configuration of the FOL fiber box. I removed the box from the table after ensuring that the PDs were powered OFF and removing and capping all fiber leads on the front panel. Here is a summary of the changes made.

  • On-Off positions for the rocker switches corrected - these switches for the power to the PDs were installed such that the "1" position was OFF. I flipped both the switches such that the "1" position now corresponds to ON (see Attachment #1).
  • All the couplers/beam combiners/splitters were initially removed. 
  • I then re-configured the layout as per the schematic (Attachment #2). I only needed to use one of the 4 new 2x2 couplers ordered. I think the 1x2 couplers are appropriate for mixing the PSL and AUX beams, as if we use a 2x2 coupler, half of the mixed light goes nowhere? Indeed, if we had one more such coupler, we could do away with the 2x2 coupler I am now using to divide the PSL light into two. 
  • The spec-sheets on the inside of the top cover were updated to reflect the new hardware (Attachment #3).
  • The old hardware from the box that was not used, along with their spec-sheets, are stored temporarily in a Thorlabs lab snacks box (all the fibers have been capped).
  • The finished layout is shown in Attachment #4.

I then ran a quick check to see what the power levels were at the input to the PDs, using the fiber coupled power meter. However, I found that there was no light in the fiber marked "PSL light in" (the power meter read out "Sig. Low"). The X arm Aux light had an input power of 1.12 mW, which after the various coupling losses etc went down to 63 uW just before the PD. The corresponding figures for the Y arm are 200 uW and 2.2 uW. I am not too sure of how the AUX light is coupled into fibers so I am not trying to tweak the alignment to see if I get more power. 

  11652   Wed Sep 30 13:07:13 2015 gautamUpdateGeneralFOL fiber box revamp

Eric pointed out that the 1x2 couplers that were used in the previous arrangement and which I recycled, were in fact NOT appropriate - they are not 50-50 couplers but 90-10 couplers, which explains the measured power levels I quoted here.

I switched out these for a pair of the newly arrived 2x2 couplers, and have also replaced the datasheets on the inside of the top cover. I then redid the power level measurements, and got some sensible values this time (see Attachment #1 for revised layout and measured power levels, numbers in red are powers for PSL light, numbers in green are for AUX laser light, and all numbers are in mW). I did find that the 90-10 splitter in the PSL+Y path was not working (though the one in the PSL+X path seems to be working fine), and hence, have not quoted power levels at the output of these splitters. For now, I guess we can bypass the splitters and take the PSL+AUX light from the 2x2 couplers directly to the PDs.

  11654   Wed Sep 30 15:44:06 2015 SteveUpdateGeneralSun Fire X4600

Gautam and Steve,

The decommissioned server from LDAS is retired to the 40m   with 32 cores and 128GB of memory in rack 1X7   http://docs.oracle.com/cd/E19121-01/sf.x4600/

  11670   Tue Oct 6 16:56:40 2015 gautamUpdateGeneralFOL fiber box revamp

[gautam, ericq]

We had a look at the IR beat (PSL+Xarm) today using the new FOL fiber box, and compared it to the green beat signal for the same combination. We first switched out the green Y beat input into the RF amplifiers on the PSL table with the PSL+Xarm IR beat input (so in all the plots, the BEATY channels really correspond to the IR beat for PSL+X). The IR and green beat notes were found without much difficulty, and we compared the beat signal PSDs for the green and IR signals (see Attachment #1 - arms were locked to green and the X slow control was turned on). The pink trace (labeled REF1) corresponds to the green beat signal, and was in good agreement with an earlier reference trace Eric had saved for the same signal. The teal trace (labeled REF0) corresponds to the the IR beat signal monitored simultaneously. 

We then went back to the PSL table to check the amplitude of the signal from the broadband fiber PDs using the Agilent network analyzer. An initial measurement yielded a beat note (@~50MHz) at ~-22dbm (17mV rms). We figured that by bypassing the 90-10 splitter in this path, we could get a stronger signal. But after switching out the fiber connections we found that the signal amplitude had fallen to ~-27dbm (10mV rms). As per my earlier measurements here, we expect ~600uW of light on the PD, and a quick calculation suggested the signal should be more like 60mV, so we used the fiber power meter to check the power levels after each of the couplers again. We then found that the fiber connector on the front panel of the box for the PSL input wasnt ideal (the laser power after the first 50-50 coupler was only ~250 uW, though the input was ~1.2  mW). The power after the first coupler also fluctuated unpredictably (<100 uW to 350 uW) in response to slightly tightening/loosening the fiber connections on the front panel. I then switched the PSL input to one of the two unused fiber connectors on the front panel (meant for the 10% of the beat signal for the DC readout), and found that this input behaved much better, with ~450 uW of power available after the first 50-50 coupler. The power going into the beat PD was also measured to be ~550uW, closer to what was expected. The beat signal peak now was ~-14dbm (~30mV rms).

We then once again repeated the comparison between green and IR beat signals - but while in the control room, I noticed that the beat signal amplitude on the network analyzer in the control room was fluctuating by nearly 1.5 divisions on the vertical scale - not sure what the reason for this is. A look at the PSD of the IR beat with higher power incident on the PD was also not encouraging (see blue trace in Attachment #1), it seems to have gotten worse in the 10-30 Hz range. We also looked at the coherence between the beat spectrum and the beat note amplitude in order to look for any linear coupling between the two, but from Attachment #2, we cannot explain the disparity between the green and IR beat spectra. This warrants further investigation.

Everything on the PSL table has now been restored to the configurations before these investigations (i.e. the Y+PSL green beat cable has been reconnected to the RF amplifier, and both green beat PDs have been powered back ON. The fiber PDs are powered OFF) 

  11689   Wed Oct 14 16:53:22 2015 KojiUpdateGeneralNon inverting buffer for SR560

Eric needed a buffer to drive low input impedance (~130Ohm) of his pomona box, I quickly made a non-iverting buffer with G=+10. The DC power is obtained from the back of SR560. It uses 1.02K and 9.09K
to have the gain of ~10. The chip is OP27. In fact this limits the output swing to be +/-5V for the load resistance of 130Ohm. Eric thinks this is enough. If we need more, we need to swap the chip.

As SR560s tend to saturate too quickly, it would be very useful to have this kind of kit in all the labs
once it is packed in a box.

  11725   Mon Nov 2 17:39:01 2015 KojiFrogsGeneralDRFPMI celebration


  11750   Tue Nov 10 19:25:42 2015 gautamUpdateGeneralFS725 Rubidium reference

In the last few days, with Koji's help, I have recovered both the FS725 Rubidium references from W. Bridge, one from the ATF lab, and one from the CTN lab. Both are back at the 40m at the moment.

However, the one that was recovered from the ATF lab is no longer locking to the Rubidium reference frequency, although it was locked at the time we disconnected it from the ATF lab. I emailed the support staff at SRS, who seem to think that either the internal oscillator has drifted too far, or the Rb lamp is dead. Either ways, it needs to be repaired. They suggested that I run a check by issuing some serial commands to the unit to determine which of these is actually the problem, but I've been having some trouble setting up the serial link - I will try this again tomorrow. I'm also having trouble generating an RMA number that is needed to start the repair/maintenance process, but I've emailed SRS support again and hope to hear back from them soon. 

The other FS725, recovered from the CTN lab earlier today, seems to work fine and is locked to the Rb reference at the moment. I plan to redo the calibration of the phase tracker with an 'absolute' frequency reference with the help of the FS725 and out GPS timing unit tomorrow. Once that is done, the working unit can be returned to the CTN lab. 

  11751   Wed Nov 11 11:41:42 2015 gautamUpdateGeneralLong cable laid out for 1pps signal

In order to synchronise the FS725 Rb clock with our GPS timing signals, I laid out a longish cable running from 1X7 to the IOO rack via the overhead cable guide. There was a T-connector attached to the 1pps output of the GPS timing unit, with one of the outputs unused - I have connected one end of the cable I laid out to this output, with the other end going to the 1pps input of the FS725. I am now waiting for the FS725 to sync to the external reference, before running the calibration of the phase tracker once again using the same method detailed here, using the 10MHz output from the FS725 to serve as a reference for the Fluke RF signal generator...

  11767   Mon Nov 16 16:18:34 2015 gautamUpdateGeneralwater leak along Y-arm?

A Caltech maintenance staff dropped by at around noon today, and told me that he had seen a small puddle of water on the other side of the door along the Y-arm that is kept locked (about 10m from the end-table, on the south side of the arm). He suspected a leak in the lab. Koji and I went down to the said door and observed that there was indeed a small puddle of water accumulated there. There isn't any obvious source of a leak on our side of the door, although the walls tiles in the area suggest that there could be a leak in one of the pipes running through the wall/under the floor. In any case, the leak doesn't seem too dramatic, and we have decided to consult Steve as to what is to be done about this once he is back on Wednesday.

  11771   Tue Nov 17 10:06:53 2015 SteveUpdateGeneralwater leak in east arm

A Caltech maintenance staff dropped by at around noon today, and told me that he had seen a small puddle of water on the other side of the door along the Y-arm that is kept locked (about 10m from the end-table, on the south side of the arm). He suspected a leak in the lab. Koji and I went down to the said door and observed that there was indeed a small puddle of water accumulated there. There isn't any obvious source of a leak on our side of the door, although the walls tiles in the area suggest that there could be a leak in one of the pipes running through the wall/under the floor. In any case, the leak doesn't seem too dramatic, and we have decided to consult Steve as to what is to be done about this once he is back on Wednesday.

The leak was found inside the wall. Fortunately the plumbers were able to access it from CES room 108

This has been leaking for sometimes. The damaged wall area is about 18 ft long and 1 ft high.

  11788   Thu Nov 19 14:50:34 2015 Max IsiUpdateGeneralNew 2D histogram plot for summary pages

A new type of plot is now available for use in the summary pages, based on EricQ's 2D histogram plots (elog 11210). I have added an example of this to the SandBox tab (https://nodus.ligo.caltech.edu:30889/detcharsummary/day/20151119/sandbox/). The usage is straighforwad: the name to be used in config files is histogram2d; the first channel corresponds to the x-axis and the second one to the y-axis; the options accepted are the same as numpy.histogram2d and pyploy.pcolormesh (besides plot limits, titles, etc.). The default colormap is inferno_r and the shading is flat.

  11830   Tue Dec 1 10:52:52 2015 SteveUpdateGeneralDataviewer

Dataviewer x axis end is not there.

On ( 2600 days) longer plots it is missing 8 moths and on (100 days) shorther plot it is missing 1 month.

  11834   Tue Dec 1 17:26:14 2015 KojiUpdateGeneralMegatron maitenence

SLOWDC servo was dead. I followed EricQ's instruction.

  11835   Tue Dec 1 20:20:16 2015 KojiUpdateGeneralMegatron maitenence

MC Autolocker got stack somewhere. I had to go to megatron and kill MC Autolocker.

init relaunched the autolocker automatically, and now it started properly.

  11867   Wed Dec 9 18:45:58 2015 KojiSummaryGeneralNetwork Topology Check

[Eric Q, Gautam, Koji]

We went through the network connections to produce the mapping of the instruments.
Gautam summarized the notes into a spread sheet. See attachments.

We didn't find any irregular connections except for the connection of NETMGR port of c1ioo to Martian Network.
This cable was removed.

  11884   Tue Dec 15 18:08:22 2015 Max IsiUpdateGeneralSummary archive cleaning cron job

I have added a new cron job in pcdev1 at CIT using the 40m shared account. This will run the /home/40m/DetectorChar/bin/cleanarchive script one minute past midnight on the first of every month. The script removes GWsumm archive files older than 1 month old.

  11898   Tue Dec 22 16:44:03 2015 gautamUpdateGeneralFS725 Rubidium reference - REPAIRED

However, the one that was recovered from the ATF lab is no longer locking to the Rubidium reference frequency, although it was locked at the time we disconnected it from the ATF lab. I emailed the support staff at SRS, who seem to think that either the internal oscillator has drifted too far, or the Rb lamp is dead. Either ways, it needs to be repaired. They suggested that I run a check by issuing some serial commands to the unit to determine which of these is actually the problem, but I've been having some trouble setting up the serial link - I will try this again tomorrow.

The Rubidium standard we had sent in for repair and recalibration has come back. I checked the following:

  • Powered the unit on - it was locked to the internal rubidium reference within a few minutes as prescribed in the manual.
  • After it had locked to the internal reference, I checked that it was able to lock to an external 1pps reference from our GPS timing unit- this too was achieved within a few minutes as prescribed in the manualyes

However, I am still having trouble setting up a serial communications link with the FS725 with a USB-serial adaptor - I've tried with a Raspberry Pi and my Mac (using screen to try and connect), and also using one of the old Windows laptops lying around on which I was able to install the native software supplied by SRS (still using the USB-serial adaptor to establish connection though). Could it be that the unit is incompatible with the USB-serial adaptor? I had specifically indicated in the repair request that this was also a problem. In any case, this doesn't seem to be crucial, though it would have been nice for diagnostics purposes in the future...

I've stored the repaired FS725 inside the electronics cabinet (marked "Eletronics Modules") for now (the other unit was returned to Antonio in W. Bridge some weeks ago). 

  11902   Sat Dec 26 10:34:43 2015 SteveUpdateGeneraltoday

PMC locked manually and PRM sus damping restored.

ELOG V3.1.3-