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ID Date Author Type Categoryup Subject
  7054   Mon Jul 30 22:52:51 2012 YaakovUpdateSTACISGeophone calibration

Tonight I looked at the signal from a geophone and accelerometer side by side, in order to see if they show the same ground motion and if the sensitivity factor I am using to convert from V to m/s is right. This is plotted below, along with the current estimates for accelerometer and geophone noise:

sensor_comp.bmp

sensor_comp.fig

From this it is pretty clear that at least one of the sensitivity factors (V/m/s) I am using is wrong (the noise levels are much lower than the ground motion, so they can't account for the difference). I suspect it is the geophone one, because Wilcoxon provided these sensitivities for each individual accelerometer, but I was just using the number I found in online specs for the geophones.

The reason the online value is wrong is probably because of the value of the shunt resistor, a resistor that just goes across the top of the geophone (its purpose is to provide damping, by Lenz's Law). The specs assume a value of 380 Ohm, but I measured the one in the STACIS to be about 1.85 kOhm.

Assuming the accelerometer signal is correct, I multiplied the geophone signal by different factors to try to get an idea of what the true calibration factor is, and found that a value of 0.25 (m/s)/V gives decent agreement at higher frequencies (below 10 Hz the sensitivity drops off, according to the online specs). This is shown below:

sensor_comp2.bmp

sensor_comp2.fig

Above, the geophone noise was recalculated with the new sensitivity and assuming that both geophones in the noise measurement had the same sensitivity. I took the transfer function of two geophones side by side to see if their gains were dramatically different; this plot is shown below. The coherence is only good for a small band, but looking at that band the gain is approximately unity, implying very roughly that the sensitivity of each is approximately the same. The lack of coherence is strange, and I'm not sure what the cause is. Even using the shaker near the geophones only improved the coherence slightly.

2_geo_gain.bmp2_geo_coherence.bmp

Attachment 2: sensor_comp2.bmp
  7058   Tue Jul 31 15:24:53 2012 YaakovUpdateSTACISOpen loop gains and block diagram

First, a quick note on the PZT I thought I killed- it was most likely something in the high voltage amplifier that broke, since I put the amplifier in another STACIS with a working y-axis PZT and it still didn't work properly. Conclusion: something in the y-axis amplifier circuitry is broken, not the PZT itself.

Today I retook the open loop gains in the X and Z axes (Y axis out of commission for now, see above). With the loop open, I input a swept sine signal from 0.1 to 100 Hz, and measure the output of the geophones. This way all the transfer function that are present in the closed loop are present here as well: the transfer functions of the physical STACIS, the geophone pre-amplifier circuit, the high-voltage amplifier, and the PZT actuators.

Here is a block diagram showing what I am measuring, with the various transfer functions in blue boxes (the measurement is their product):

 stacis_block.bmp

x_OL.bmpz_OL.bmp

z_OL.fig

x_OL.fig

These open loop gains show there is gain of at least 10x from 2 to 80 Hz in the z-axis and 2 to 60 Hz in the x-axis. This is the region I was seeing isolation in when I switched to closed loop, which is consistent. These measurements were with all the pots in the geophone preamplifier set very low, so more gain (and thus isolation) is hypothetically possible if I find a way to stop the horizontal axes from becoming unstable at higher gains. There is unity gain at around 0.5 Hz and 100 Hz for the z-axis, but the phase is nowhere near 180 deg. at these points so there shouldn't be instability due to this. The peak at around 15 Hz is consistent with old records of the STACIS open loop gain.

  7061   Tue Jul 31 19:34:55 2012 KojiUpdateSTACISOpen loop gains and block diagram

With your definition of the open loop gain, G=+1 is the condition to have singularity in a closed loop transfer function 1/(1-G).

But this is not the sole criteria of the loop stability.
Basically, the closed loop transfer function should not have "unphysical" pole.
For more about loop instability, you should refer stability criteria in literature such as Nyquist's stability criterion.

Both of the X and Z loops look unstable with the current gain.

  7068   Wed Aug 1 11:54:59 2012 YaakovSummarySTACISGeophone calibration and open loop gains

This week I've looked into finding an accurate sensitivity for the geophones in the STACIS. I found that when placing a geophone and accelerometer side by side, and using the sensitivity values I had from spec sheets, the readings were very different (see eLog 7054: http://nodus.ligo.caltech.edu:8080/40m/7054).

I cut the shunt resistor off one of the STACIS geos and found it to be 4000 Ohm, which is one of the standard values for this geophone model. When it is connected to the geophone the net resistance is 2000 Ohm (I took a more careful measurement, I took the geophone out). Then the internal coil resistance should be 4000 Ohm, if they are connected in parallel. However, the geophone spec sheet does not have a sensitivity value for this exact scenario, so I'll have to find a different way to determine the calibration (maybe by putting it next to a seismometer with a known sensitivity). So I know for sure that the sensitivity value I was originally using is wrong, because it assumed an internal coil resistance of 380 Ohm, but I have to check if the value I found by forcing the geophones to agree with the accelerometers (eLog 7054 --> 0.25 (m/s)/V) is correct.

I've also been looking again at the open loop gains of the STACIS (see eLog 7058: http://nodus.ligo.caltech.edu:8080/40m/7058). Attached is what TMC, which makes the STACIS, says it should look like (with a 4000 lb load on the STACIS). Today I am taking the open loop gains into higher frequencies to get a better comparison, but the plots look quite similar to what I have so far. So if it is an unstable open loop gain, then it's at least not new.

Attachment 1: 08011201.pdf
08011201.pdf 08011201.pdf
  7109   Tue Aug 7 21:34:50 2012 YaakovUpdateSTACISMore noise data

Yesterday I plugged the geophone and accelerometer output into the ADC, rather than the SR785, so I could collect for longer and take more data at once.

As per Rana's suggestion, I am also now taking the geophone output after the first op-amp in the circuitry following the geophone (a low-noise op-amp, OPA227). It acts as a buffer so I'm not just measuring other local noise sources (which explains why the geophone noise curve sort of matched the SR785 noise curve in my old plots).

With these changes, I remeasured the accelerometer and geophone noises as well as collected an ASD of a geophone sitting on the STACIS in open loop operation. I also looked up the noise specs for the various op-amps in the geophone pre-amp and high voltage board; everything I found, I added in quadrature to come up with an approximate op-amp noise value for the STACIS. All of this is plotted below:

budget.bmpbudget.fig

I left the y-axis in V/rtHz instead of converting it to m/s/rtHz so that the op-amp noise could be compared to the other noises. All sensor data was taken with the sensors horizontal (noise data taken in granite and foam).

The accelerometer and geophone noise still appear to be similar, and the op-amp noise, at least according to specs, is low compared to the other noises. This implies there's not much to gain from switching the geophones with accelerometers nor with swapping out the op-amps for lower-noise components (unless the ones I couldn't find specs for were high-noise, though it seems like mainly low-noise components were used). 

  7112   Tue Aug 7 23:33:44 2012 ranaUpdateSTACISMore noise data

Looks like you're just measuring the ADC noise. You should add ADC noise to your plot. To compare the geophones with the accelerometers, you have to correct for the preamp gain and plot them both in the same units.

To get above the ADC noise you can use an SR560 preamp. (AC Coupled, G = 100)

  7118   Wed Aug 8 11:47:52 2012 YaakovSummarySTACISWeekly summary

As Rana pointed out (http://nodus.ligo.caltech.edu:8080/40m/7112), the geophone/accelerometer noise lines from my last eLog (http://nodus.ligo.caltech.edu:8080/40m/7109) were dominated by ADC noise. I checked this today by terminating the ADC channels with 50 Ohm terminators and measuring the noise. The ADC noise line is included on the plot below, and it is clearly dominating the sensor noise data.

budget_with_adc.pngbudget_with_adc.fig

I set the accelerometer gain to 100, and will hook up the geophones to the SR560 pre-amp today- this should put both signals above the ADC noise, and I can calculate the sensor noises without the ADC noise being significant.

I have also begun to make some progress in understanding the pre-amp circuitry, and I will post a schematic when I've sketched it all.

Another issue that seems increasingly relevant to me is the power supply to the high voltage amplifier. It appears to go into the high voltage board from the power supply, then into the geophone pre-amp, then back into the high voltage board (see block diagram below). I tested this by inputting a signal after the pre-amp, with the geophones disconnected- the signal only drives the PZT if the pre-amp is plugged in, so the power that returns from the pre-amp must be powering some chips on the high voltage amplifier.

 

Power flow through the STACIS :

power_diagram.png

This is somewhat inconvenient, because it means if I want to provide external feedback (with accelerometers, for example) or actuation (such as feedforward), which I want to input after the geophone pre-amp, the pre-amp still needs to be plugged in for the high voltage amplifier to work and drive the PZTs.  I am cataloging all of the pins on the high voltage amplifier and pre-amp so I can figure out how to reroute the power and cut out the geophone pre-amp entirely if necessary. I'll include a pin diagram with the pre-amp circuit sketch.

  7148   Fri Aug 10 18:11:55 2012 YaakovUpdateSTACISCorrected noise budget, plan for external actuation

I hope you're not all tired of the STACIs noise budgets, because I have another one! Here, the main difference is my modeling of the geophone sensitivity according to a predicted physical model for the system (just a damped oscillator) instead of trying to fit it to the accelerometer motion signal with more arbitrary functions.

The result of this calibration is shown below (accel and geo signals taken for 5 minutes at the same time, in granite and foam):

sensor_comp.pngsensor_comp.fig

The m/s/V sensitivity function I am using is g*[(w^2-2idww(0)-w(0)^2)/w^2], where g (the high freq. m/s/V sensitivity) was 2.5*10^-5 and d (damping) was set to 2.

Now, the recalculated noise plot looks like this:

noise_budget_8-10.pngnoise_budget_8-10.fig

The accel. specs I took from the Wilcoxon spec sheet, and the geo specs I found in https://dcc.ligo.org/public/0028/T950046/000/T950046-00.pdf, a LIGO document about the STACIS. The geo noise was measured for the STACIS geo and their pre-amp, while I was using the SR560 as the pre-amp. If anything, my noise should be lower, since the SR560 noise spec is lower than what I estimated for the STACIS geophone pre-amp, so I'm not sure about that order of magnitude difference between the experimental and expected geo noise. A sign that my noise values are at least reasonable is that the geophone noise flattens out above the geophone's resonant frequency (4.5 Hz), as Jan pointed out it should.

The sensor noise (either accel. or geo.) is the dominating signal below 1 Hz in the STACIS platform measurement, which then limits the closed loop performance at those frequencies. Since the noises I am finding are looking reasonable, I think it's fair to definitively state that accelerometers will not significantly help at low frequencies (there may be at most a factor of 2 lower noise below 1 Hz for the accel., but I need more data to say for sure).

The plan right now is to concentrate on using the STACIS as actuators, perhaps with seismometers on the ground and a feedforward signal sent into the high voltage amplifier.

I took the transfer function of the high voltage board itself (no pre-amp included) by driving the PZTs with a swept sine and measuring the accelerometer response (which I am now fairly confident is calibrated correctly). The input point was the signal IN on the extender board, but with the geophones disconnected from the pre-amp.

hv_bode.pnghv_bode.fig

I took the coherence at just a few single frequencies (you can't do coherence measurements in swept sine mode on the SR785) to make sure I was really driving the PZTs, and it was near 1 (998, 999.9, etc) at the frequencies at which I drove. Without the extra notches at 1 Hz (which may be real, it's coherent there too), it looks like a 2-pole high pass filter (goes from -180 to 180 deg, approx. an f^2 dependence). This transfer function should be taken into account by the feedforward algorithm.

The current plan is to make a box with a switch that allows geophone feedback and/or external signals into the high voltage amplifier. It would act sort of like the extender card, except more compact so it could fit into the STACIS. It also would have the advantage of not having to reroute the power, since those lines from the pre-amp could all still be connected (see eLog 7118: http://nodus.ligo.caltech.edu:8080/40m/7118).

  7166   Mon Aug 13 21:47:30 2012 YaakovUpdateSTACISTwo changes to STACIS noise budget

In eLog 7148 (http://nodus.ligo.caltech.edu:8080/40m/7148), Koji pointed out that the op-amp and SR560 noise values (which I took from specs and then multiplied by the geophone calibration factor to get m/s/rtHz) were waaay too low. My error was an extra multiplication factor in the plotting script.

The other change was recalculating the ADC noise by splitting a signal into two ADC channels and subtracting the time series (then taking the PSD and converting to m/s/rtHz). It compares well to the value I got by terminating the ADC channels, which was the ADC noise line in my last eLog.

Both these changes are included in the below plot:

noise_budget_8-13.bmpnoise_budget_8-13.fig

Attachment 1: noise_budget_8-13.bmp
  7190   Wed Aug 15 11:40:15 2012 YaakovSummarySTACISWeekly Summary

This week I've been focusing mainly on two things: 1) Designing a port for the STACIS that will allow external actuation and/or local feedback and 2) Investigating the seismic differential motion along the interferometer arms.

The circuit for the port is just a signal summing junction (in case we want to do feedforward and feedback at the same time) with BNC inputs for the external signal and switches that allow you to turn the external signal or feedback signal on/off. I'll test this on a breadboard and post the schematic if it works. I looked at the noise of the geophone pre-amp and DAC, which would be the feedback and external signal sources, respectively. According to Rolf Bork, the DAC noise is 700 nV/rtHz, and I measured the pre-amp board's minimum noise level at 20*10^-6 V/rtHz (which seems quite high). Both these noises are higher than the op-amp noise for my circuit (I'm considering the op-amp LT1012), which according to the specs is 30 nV/rtHz. This confirms that my circuit will not be the limiting noise source

Along with Den, I calibrated the seismometers in the lab and measured the displacement differential arm motion (see eLog 7186: http://nodus.ligo.caltech.edu:8080/40m/7186). I'm trying to find a transfer function for the seismic stacks (and pendulum, but that's simpler) so I can calculate the differential motion in the chamber. After doing this offline, I'll make new channels in the PEM to look at the ground and chamber differential motion along the arms online.

I also am looking at the noise of the geophones with their shunt resistor (4k resistor across the coil) removed, to see if it improves the noise at low frequencies. My motivation for this was that the geophone specs show a better V/m/s sensitivity at low frequencies when the shunt resistor is removed, so the actual signal may become larger than the internal noise at these frequencies.

  7210   Thu Aug 16 20:18:39 2012 YaakovUpdateSTACISInput for feedforward/feedback in the STACIS

Below is the bottom view of the geophone preamplifier and controller for the STACIS. It slides into the upper part of the STACIS, under the blue platform. The geophone signal goes in the bottom left, gets amplified, filtered, and otherwise pampered, and goes out from the bottom right. From there it goes on to the high voltage amplifier, and finally to the PZT stacks. Below right is a closer view of the output port for the preamplifier, top and bottom.

SAM_0256.JPGSAM_0259.JPGSAM_0258.JPG

I suggest de-soldering and bending up the pins that carry the geophone signal (so the signals don't go directly to the high voltage amplifier), and adding the circuit below between the preamp and amplifier. The preamp connector is still attached to the high voltage amplifier connector in this setup, only the geophone signal pins are disconnected.

x-chip.png

More on the circuit and its placement:

The first op-amp is a summing junction, and the second is just a unity gain inverter so that signal doesn't go into the high voltage amplifier inverted. I tested this with the breadboard, and it seems to work fine (amplitudes of two signals add, no obvious distortion). The switches allow you to choose local feedback, external feedforward, or both.

The geo input will be wires from the preamp (soldered to where the pins used to go), and the external input will be BNC cables, with the source probably a DAC. The output will go to the bent up pins that used to be connected to the preamp (they go into the high voltage amplifier). This circuit can sit outside of the STACIS- there is a place to feed wires in and out right near where the preamplifier sits. For power, it can use the STACIS preamp supply, which is +/- 15V. The resistors I used in the breadboard test were 10 kOhm, and the op-amp I used was LT1012 (whose noise should be less than either input, see eLog 7190).

This is visually represented below, with the preamp pin diagram corresponding to the soldering points with the preamp upside down (top right picture):

SAM_0266.JPGSAM_0265.JPG

 

  7231   Sun Aug 19 19:56:20 2012 YaakovUpdateSTACISSTACIS signal box made

I made the signal box as described in eLog 7210. It adds the geophone signal and an external signal.

It has six switches, for x, y, and z signals from both an external and local (geophone) source. The x signals add if both x switches are flipped down (and the same for the other directions). For example, if you want to feed in only an external signal in the x direction, flip down the external x direction switch (it's labeled on the box), leaving all others flipped up.

The x, y, and z outputs are wired to the pins from the preamplifier that go to the high voltage board. These I disconnected from the preamplifier by cutting at their base (there are spare connectors if this wants to be undone, or, a wire can just be soldered from the pin to its old spot on the board). The power (plus/minus) and ground are wired to the respective pins from the geophone preamplifier (naturally, the STACIS must be turned on for the box to work since the box shares its power source). Below, the front (switches and geophone/external inputs) and back (power, ground, outputs) of the box are shown:

SAM_0276.JPGSAM_0277.JPG

The preamplifier can plug into its regular connectors- the x,y,and z signals will all be redirected to the signal box with these modifications. The box sits outside the STACIS, there is room to feed the wires out from underneath the STACIS platform.

SAM_0275.JPG

NOTE: The geophone z switch is a little different than the others, just make sure it's flipped all the way down if you want that signal to be seen in the z output.

 

  7258   Thu Aug 23 15:42:48 2012 ranaUpdateSTACISSTACIS signal box made

 

 I found this entry in the old 40m ilog which describes the STACIS performance. It shows that even though the STACIS is bad for the differential arm motion below 3 Hz. It has quite a big and positive effect at 10-30 Hz. The OSEMs show a bigger effect than what the single arm does. I think this is because the single arm is limited by the MC frequency noise above 10 Hz.

We should figure out how to turn on the STACIS but set the lower UGF to be ~5 Hz.

Attachment 1: vsanni-1107222997.pdf
vsanni-1107222997.pdf
  34   Wed Oct 31 08:33:54 2007 ranaProblem FixedSUSVent measurements
There was a power outage during the day yesterday; whoever was around should post something here about the
exact times. Andrey and David and Tobin got the computers back up - there were some hiccups which you can
read about in David's forthcoming elog entry.

We restarted a few of the locking scripts on op340m: FSSSlowServo, MCautolocker. Along with the updates
to the cold restart procedures we have to put an entry in there for op340m and a list of what scripts
to restart.

David tuned up the FSS Slow PID parameters a little; he and Andrey will log some entry about the proper
PID recipe very soon. We tested the new settings and the step response looks good.

We got the MC locking with no fuss. The 5.6 EQ in San Francisco tripped all of the watchdogs and I upped
the trip levels to keep them OK. We should hound Rob relentlessly to put the watchdog rampdown.pl into
the crontab for op340m.
  66   Tue Nov 6 09:45:22 2007 steveSummarySUSvent sus trend
The mc optics dragwippings were done by locking optics by eq stops and rotating-moving
cages so access were good. This technic worked well with mc1 & mc2
MC3 osems were reoriented only.
Attachment 1: ventsustrend.jpg
ventsustrend.jpg
  70   Tue Nov 6 15:37:34 2007 robConfigurationSUSrampdown script
/cvs/cds/caltech/scripts/SUS/rampdown.pl is now in the crontab for op340m, running every half-hour at 15&45. It checks the suspension watchdog trip levels, and reduces them by 20 if they are above 150.
  91   Sun Nov 11 21:05:55 2007 ranaHowToSUSMC Touching or not
I wrote a script: SUS/freeswing-mc.csh, which gives the MC mirrors the appropriate kicks
needed to make a measurement of the free swinging peaks in the way that Sonia did.
#!/bin/csh

set ifo = C1
set sus = ${ifo}:SUS-

foreach opt (MC1 MC2 MC3)

  set c = `ezcaread -n ${sus}${opt}_PD_MAX_VAR`
  ezcastep ${sus}${opt}_PD_MAX_VAR +300

  ezcaswitch ${sus}${opt}_ULCOIL OFFSET ON
  ezcawrite ${sus}${opt}_ULCOIL_OFFSET 30000
  sleep 1
  ezcawrite ${sus}${opt}_ULCOIL_OFFSET 0
  sleep 1
  ezcawrite ${sus}${opt}_ULCOIL_OFFSET 30000
  sleep 1
  ezcawrite ${sus}${opt}_LATCH_OFF 0

  ezcawrite ${sus}${opt}_ULCOIL_OFFSET 0
  ezcaswitch ${sus}${opt}_ULCOIL OFFSET OFF

  ezcawrite ${sus}${opt}_PD_MAX_VAR $c

end

echo
date
echo

It basically ups the watchdog threshold, wacks it around at the pendulum frequency, and then disables the
optic so that there are no electronic forces applied to it besides the bias. The date command at the end
is so that you know when to start your DTT or mDV or lalapps code or whatever.
  122   Mon Nov 26 10:17:31 2007 steveOmnistructureSUSetmy sus damping restored
20 days plot is showing etmy loosing damping 4 times.
I zoomed in with each event. Three of them could of been triggered
by garbage loading just outside. However attachment 2 plot demonstrating that small earthquake or seismic event
did not tripped etmy damping.
The fourth event was preceded by a 4-5 hrs of continous rise of the rms motion at C1:SUS-ETMY_LLPD_VAR
Attachment 1: etmyrms20d.jpg
etmyrms20d.jpg
Attachment 2: etmyrmseq.jpg
etmyrmseq.jpg
  133   Wed Nov 28 17:15:26 2007 ranaConfigurationSUSETMY damping / watchdogs
Steve has noted that ETMY was often tripping its watchdog. I saw this again today.

So I checked the damping settings. Someone had set the SIDE gain to +1. The gain which gives
it a Q of ~10 is +10. I set the SIDE gain to +20. I checked and the ETMX gain is -16 so now
they're at least similar. I have updated the snapshot to reflect the new value.

Hopefully now it will be more well behaved.
  148   Fri Nov 30 19:29:14 2007 ranaConfigurationSUSnew screen
Andrey is working on a new screen to show us the drift of the optics by alarming on
their osem values. You can find it under SUS as 'Drift Mon' from the site map.

To aid in this I ran the following csh commands which effect all optics:
foreach opt (ETMX ETMY ITMX ITMY MC1 MC2 MC3 BS PRM SRM)
  foreach dof (POS PIT YAW)
     ezcawrite C1:SUS-${opt}_SUS${dof}_INMON.PREC 0
  end
end

This should make the DOF readouts more readable.
  176   Thu Dec 6 19:19:47 2007 AndreyConfigurationSUSSuspension damping Gain was restored

Suspension damping gain was disabled for some reason (all the indicators in the most right part of the screen C1SUS_ETMX.adl were red), it is now restored.
  213   Wed Dec 26 15:00:06 2007 ranaUpdateSUSETMY tripping
Steve mentioned to me that ETMY is still tripping more than ETMX. The attached DV plot
shows the trend of the watchdog sensors; essentially the RMS fluctuations of the shadow
sensors. (note** DV can make PNG format plots directly which are much better than JPG
when making plots and much smaller than PS or PDF when plotting lots of points).
Attachment 1: etm.png
etm.png
  214   Wed Dec 26 15:12:48 2007 ranaUpdateSUSETMY tripping
It turned out that the ETMY POS damping gain was set to 1.0 while the ETMX had 3.8.

I put both ETMs to a POS gain of 4 and then also set the PIT, YAW and SIDE gains for
ETMY. Let's see if its more stable now.

In the next week or so Andrey should have perfected his damping gain setting technique
and the numbers should be set more scientifically.
  216   Thu Dec 27 13:08:04 2007 ranaUpdateSUSETMY tripping
Here's a trend from the last 2 days of ETMX and ETMY. You can see that the damping gain increase
has made them now act much more alike. Problem fixed.
Attachment 1: Untitled.png
Untitled.png
  220   Thu Jan 3 08:53:55 2008 steveUpdateSUSetmy vs etmx
Rana have corrected sus gain damping setting of ETMY 8 days ago

gain settings: pos, pit, yaw & sd
etmx: 4,2,2,& -16
etmy: 4,2,2,& 50
Attachment 1: sus.jpg
sus.jpg
  222   Thu Jan 3 09:55:11 2008 steveUpdateSUSetmy sus damping restored
ETMY watch dog was lost at midnight
Attachment 1: etmy12h.jpg
etmy12h.jpg
  225   Fri Jan 4 08:42:03 2008 steveUpdateSUSetmy trips again
ETMY sus damping tripped at 6am this morning
It was reset. We should put an accelerometer to the south end to see
the garbage dumping effect.
Attachment 1: etmy20m.jpg
etmy20m.jpg
Attachment 2: etmy120s.jpg
etmy120s.jpg
Attachment 3: etmysenV.jpg
etmysenV.jpg
  226   Mon Jan 7 09:01:39 2008 steveUpdateSUSBS sus damping restored
The BS sus damping was lost at 8am Sunday morning.
Attachment 1: bssdl.jpg
bssdl.jpg
  232   Thu Jan 10 10:38:02 2008 steveUpdateSUSetmy damping restored
The IST building onstruction has really started yesterday and continuing today with big heavy ground breaking
machinary. The MC is holding lock and the suspentions are hanging on.

ETMY does not like this.

SUS-MC2_LLPD_VAR monitor is a good indicator of seismic activity on this 12 days plot
Attachment 1: etmysus.jpg
etmysus.jpg
Attachment 2: sustrend16d.jpg
sustrend16d.jpg
  233   Thu Jan 10 12:08:23 2008 steveUpdateSUSwhy did the BS move?
Attachment 1: bshopped.jpg
bshopped.jpg
  235   Thu Jan 10 15:04:04 2008 steveUpdateSUSilluminator light effect on BS position
The bs chamber illuminator light was turned on this morning and left on.
Earlier on Rana noticed that the bs moved.
I follwed up to see what happened. I turned off oplev servo and tried to recenter on oplev pd
by adjusting pitch and yaw biases. It did not move. I looked at suspention and realized that the
illuminator was still on. I turned it off and to my amazement the the AP spot started flashing
Attachment 1: bssusilum.jpg
bssusilum.jpg
  237   Mon Jan 14 14:41:09 2008 steveUpdateSUSetmy sus damping restored & mz relocked
Tree days trend of MZ HV drift is typical these days.
So as the etmy sus inability to hold damping for longer then 2-3 days.
Attachment 1: etmysus&mzhvtrend.jpg
etmysus&mzhvtrend.jpg
  242   Wed Jan 16 18:24:41 2008 ranaUpdateSUSETMY Watchdog
Because Steve keeps complaining about ETMY, I looked at some minute trend to see if there was something exotic happening at that time. It looks like there is some tremendous seismic activity to make it happen.

The trend shows that there is nothing special happening on the ETMX accelerometer or the ETMX suspension. At the same time, however, there is a huge jump in the ETMY sensors and therefore the watchdog signal. Whenever the watchdog value goes above 140, it trips.

After Andrey moves some accelerometers over to the Y end we can see the effect more directly.
Attachment 1: A.pdf
A.pdf
  256   Wed Jan 23 12:31:36 2008 AndreySummarySUSDissapointing Results of XARM optimization (PDF-file)

I attach a PDF-file which summarizes briefly the results of measurements/calculations of Q-factors for ITMX mass as a function of suspension damping gain,

and this file contains the results of measurements of RMS peaks on the values of suspension gains of ITMX and ETMX (see ELOG entries from December 2007, specifically #202, #199, #194)),
but now those dependences are plotted in Q-ITMX and Q_ETMX axes.

Unfortunately, there are no clear narrow areas of minimum in those dependences (that explains the sad title of this ELOG entry).

The attached pdf-file can be shown as a short presentation for a wall during our Wednesday meeting.
Attachment 1: Sad_Results_XARM.pdf
Sad_Results_XARM.pdf Sad_Results_XARM.pdf Sad_Results_XARM.pdf Sad_Results_XARM.pdf Sad_Results_XARM.pdf Sad_Results_XARM.pdf Sad_Results_XARM.pdf Sad_Results_XARM.pdf
  260   Thu Jan 24 20:03:40 2008 AndreyConfigurationSUSChanges to Dataviewer channels (XARM)

1) Good news. I added a chanel "C1:SUS-ETMX_POS" to Dataviewer.

I followed the instructions from WIKI-40:

modify the file "C1SUS_EX.ini" in /cvs/cds/caltech/chans/daq,
then telnet to fb40m,
then "click the appropriate blue button on the DAQ MEDM screen".

So, I can now read a signal from the channel "C1:SUS-ETMX_POS" in Dataviewer,

and this allows me to measure Q-factors of ETMX this evening (make similar work for what I did on Tuesday for ITMX).


2) BAD NEWS. While "clicking the appropriate blue button" on the DAQ MEDM screen,
namely CODAQ_DETAIL,adl screen, I obviously clicked some blue button that I should not have clicked,
and as a result the signal in Dataviewer from the channel "C1:SUS-ITMX_POS" has disappeared (it is now a straight line).


Description of what has happened and of my wrong actions:
I had two channels opened in Dataviewer simultaneously (both "C1:SUS-ETMX_POS" and "C1:SUS-ITMX_POS"),
and after clicking some blue button on CODAQ_DETAIL,adl screen, the signal from "C1:SUS-ITMX_POS" became
a straight line,
while signal from "C1:SUS_ETMX_POS" continued to be a random noise.

I was scared that I made worse for the channels and for Dataviewer, and I started clicking random blue buttons chaotically hoping that it will restore the signal from "C1:SUS-ITMX_POS". Random clicking on arbitrary blue buttons did not return the signal.

As the channel "C1:SUS-ETMX_POS" works normally, I will be measuring Q-factors of ETMX tonight,
but it is obvious that someone else (Rana, Robert,Steve?) needs to restore the correct settings for "C1:SUS-ITMX_POS".

Moreover, as I was clicking chaotically all the blue buttons on CODAQ_DETAIL,adl screen, someone else (Rana, Robert, Steve?) will need to check somehow that I did not destroy signals from some other channels.

I apologize for the negative consequences of my channel adding,

but Rana asked me in the very beginning in September to let others know if I spoil something, so that others would be aware of it and could fix the problem.

Again, I apologize and hope that the problem is not very serious.
  265   Fri Jan 25 10:14:35 2008 robConfigurationSUSChanges to Dataviewer channels (XARM)

Quote:

2) BAD NEWS. While "clicking the appropriate blue button" on the DAQ MEDM screen,
namely CODAQ_DETAIL,adl screen, I obviously clicked some blue button that I should not have clicked,
and as a result the signal in Dataviewer from the channel "C1:SUS-ITMX_POS" has disappeared (it is now a straight line).


Description of what has happened and of my wrong actions:
I had two channels opened in Dataviewer simultaneously (both "C1:SUS-ETMX_POS" and "C1:SUS-ITMX_POS"),
and after clicking some blue button on CODAQ_DETAIL,adl screen, the signal from "C1:SUS-ITMX_POS" became
a straight line,
while signal from "C1:SUS_ETMX_POS" continued to be a random noise.

I was scared that I made worse for the channels and for Dataviewer, and I started clicking random blue buttons chaotically hoping that it will restore the signal from "C1:SUS-ITMX_POS". Random clicking on arbitrary blue buttons did not return the signal.

As the channel "C1:SUS-ETMX_POS" works normally, I will be measuring Q-factors of ETMX tonight,
but it is obvious that someone else (Rana, Robert,Steve?) needs to restore the correct settings for "C1:SUS-ITMX_POS".

Moreover, as I was clicking chaotically all the blue buttons on CODAQ_DETAIL,adl screen, someone else (Rana, Robert, Steve?) will need to check somehow that I did not destroy signals from some other channels.

I apologize for the negative consequences of my channel adding,

but Rana asked me in the very beginning in September to let others know if I spoil something, so that others would be aware of it and could fix the problem.


I eventually resolved the situation by restarting the c1susvme1 processor, which had somehow got confused by the clicking random blue buttons chaotically. The data acquisition should be working again.
  286   Wed Jan 30 13:09:55 2008 AndreyUpdateSUSNew results for XARM (pdf)

See attachments: pdf-presentation with plots in "true" axes Q_ETMX and Q_ITMX, and seismic backgound measurement.

Results that were shown a week ago turned out to be not sad at all!
Attachment 1: New_Results_XARM.pdf
New_Results_XARM.pdf New_Results_XARM.pdf New_Results_XARM.pdf New_Results_XARM.pdf New_Results_XARM.pdf New_Results_XARM.pdf New_Results_XARM.pdf New_Results_XARM.pdf
Attachment 2: Accel-Seismic_10AM.pdf
Accel-Seismic_10AM.pdf
  305   Sat Feb 9 13:32:07 2008 JohnSummarySUSAll watchdogs tripped
When I arrived this afternoon the watchdogs had tripped on all optics. I reset them and enabled the coil currents.

I had to adjust the alignment of the mode cleaner to get it to lock.
  306   Sun Feb 10 20:47:01 2008 AlanSummarySUSAll watchdogs tripped
A moderate earthquake occurred at 11:12:06 PM (PST) on Friday, February 8, 2008.
The magnitude 5.1 event occurred 21 km (13 miles) NW of Guadalupe Victoria, Baja California, Mexico.
http://quake.wr.usgs.gov/recenteqs/Quakes/ci14346868.html
  323   Tue Feb 19 15:21:47 2008 AndreyUpdateSUSEarthquake tripped watchdogs in ETMY, ITMY

According to the web-page http://earthquake.usgs.gov/eqcenter/recenteqsus/Quakes/ci14351140.php ,

there was a 5.0 earthquake in northern Baja California in Mexico at 02.41PM earlier today.

This earthquake made an effect on our watchdogs for ETMY and ITMY (their currents exceeded maximal values).
Watchdogs for ITMY are now restored back,
and it is taking more time for a "side degree" for ETMY to calm down,
it is still (40 minutes after the kick) swinging a lot with amplitude ~ 200mV.
  404   Wed Mar 26 13:41:53 2008 AndreyHowToSUSModification of ''C1DRIFT_MONITOR''
I learned how to modify the drift-monitor in MEDM so that values on it change colors from green to yellow to red depending how much is the fluctuatioin (deviation) of the value from its mean nominal value.

In order to do this, I used the following eight commands:

tdswrite CHANNEL_NAME.HIHI VALUE
tdswrite CHANNEL_NAME.HIGH VALUE
tdswrite CHANNEL_NAME.LOW VALUE
tdswrite CHANNEL_NAME.LOLO VALUE
tdswrite CHANNEL_NAME.HHSV 2
tdswrite CHANNEL_NAME HSV 1
tdswrite CHANNEL_NAME LSV 1
tdswrite CHANNEL_NAME LLSV 2

where CHANNEL_MAME is the name of the channel the value of which is indicated on the MEDM screen C1DRIFT_MONITOR, for example
C1:SUS-MC1_SUSPOS_INMON, and VALUE is numerical value that I assigned to the channel parameters.

By now I modified nine mode-cleaner channels (POS, PITCH and YAW channels for MC1, MC2 and MC3) and 6 channels for ITMX and ITMY.

Note that as we have problems this week with computer C1SUSVM, namely ''c1susvme2'' is not working, indicators for MC2 in the drift-monitor do not change colors today although they should.

In order to judge which values should be established as reasonable deviations from the average nominal values, I was looking into Dataviewer trends for the channels that are in the drift-monitor.


In the future indicators for channels ETMX and ETMY, BS, PRM, SRM should be modified in complete analogy with what I did already for MC and for ITM. So, I have modified 3*5 = 15 channels, and 3*5 = 15 channels are left for the future.

Note that (as far as I understand) instead of commands "tdswrite" it is absolutely legitimate to use commands "ezcawrite".
  425   Fri Apr 18 16:02:58 2008 alexUpdateSUSend station sus front-end bug fix
installed and started new susEtmx.o and susEtmy.o to fix a problem with ETMY optical lever variables.
  426   Fri Apr 18 16:27:04 2008 robUpdateSUSend station sus front-end bug fix

Quote:
installed and started new susEtmx.o and susEtmy.o to fix a problem with ETMY optical lever variables.


But where is the code?
  431   Sun Apr 20 23:39:57 2008 ranaSummarySUSMC1 electronics busted
I spent some time trying to fix the utter programming fiasco which was our MCWFS diagonalization script.

However, it still didn't work. Loops unstable. Using the matrix in the screen snapshot is OK, however.

Finally, I realized from looking at the imaginary part of the output matrix that there was something
wrong with the MC1 drive. The attached JPG shows TFs from pit-drives of the MC mirrors to WFS1.

MC1 & MC3 are supposed to have 28 elliptic low pass filters in hardware for dewhitening. The MC2
hardware is different and so we have given it a software 28 Hz ELP to compensate. But it looks like
MC1 doesn't have the low pass (no phase lag). I tried switching its COIL FM10 filters to make it
switch but no luck.

We'll have to engage the filters to make the McWFS work right and to get the MC noise down. This
needs someone to go check out the hardware I think.

I have turned the gain way down and this has stabilized the MC REFL signal as you can see from the StripTool screen.
Attachment 1: mcwfs.jpg
mcwfs.jpg
  435   Tue Apr 22 10:59:24 2008 robUpdateSUSMC1 electronics busted

Quote:
I spent some time trying to fix the utter programming fiasco which was our MCWFS diagonalization script.

However, it still didn't work. Loops unstable. Using the matrix in the screen snapshot is OK, however.

Finally, I realized from looking at the imaginary part of the output matrix that there was something
wrong with the MC1 drive. The attached JPG shows TFs from pit-drives of the MC mirrors to WFS1.

MC1 & MC3 are supposed to have 28 elliptic low pass filters in hardware for dewhitening. The MC2
hardware is different and so we have given it a software 28 Hz ELP to compensate. But it looks like
MC1 doesn't have the low pass (no phase lag). I tried switching its COIL FM10 filters to make it
switch but no luck.

We'll have to engage the filters to make the McWFS work right and to get the MC noise down. This
needs someone to go check out the hardware I think.

I have turned the gain way down and this has stabilized the MC REFL signal as you can see from the StripTool screen.


This was just because the XYCOM was set to switch the "dewhites" based on FM9 rather than FM10. To check whether the hardware ellipDW filters were engaged, I drove MC1 & MC3 in position (using the MCL bank), and looked at the transfer functions MC2_MCL/MC1_MCL and MC2_MCL/MC3_MCL. This method uses the mode cleaner length servo to enable a relatively clear transfer function measurement of the ellipDW, modulo the loop gain of MCL and the fact that it's really hard to measure an ELP cascaded with a suspension. The hardware and the switching appear to be working fine.

It's now set up such that the hardware is ENGAGED when the coil FM10 filters are OFF, and I deleted all the FM10 filters from the coils of MC1 and MC3. Since we don't switch these filters on and off regularly, I see no need to waste precious SUS processor power on filters that just calculate "1".
  436   Tue Apr 22 16:17:48 2008 robUpdateSUSend station sus front-end bug fix

Quote:
installed and started new susEtmx.o and susEtmy.o to fix a problem with ETMY optical lever variables.


What Alex means is that the EPICS values for the ETMY optical levers were being clobbered in the RFM. The calculations were being done correctly in the FE, so the DAQ/testpoints were working--it was just the EPICS/RFM communication via c1losepics that was bugged. This was a result of the recent SUS code changes to accept inputs from the ASS for adaptive feedforward.
  462   Thu May 1 08:31:51 2008 steveUpdateSUSearthquake trips etmy & mc1
Earthquake at Lake Isabel magnitude 4.4 at 1am today shakes the 40m
ETMY and MC1 watchdogs tripped.
Sus damping restored.
  472   Fri May 9 08:40:24 2008 steveUpdateSUSETMY sus damping restored
ETMY lost damping at 19:10 last night.
There was no seismic event than.
Sus damping was restored this morning.
  474   Tue May 13 10:15:52 2008 steveUpdateSUSrestored damping of BS & PRM
I think our janitor was cleaning too heavy handedly.
The BS and PRM sus damping were lost.
They were restored.
  485   Sun May 18 18:44:48 2008 ranaSummarySUSOptical Lever SUM Trend - 80 days
I used the OL-Trend.xml dataviewer template to make this plot. Looks like the ETMY optical lever
slowly degraded over the last few months and then finally died 10 days ago. Would someone please
replace this laser and tune the lens position to minimize the spot size on the quad?
Attachment 1: e.pdf
e.pdf
ELOG V3.1.3-