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ID Date Author Typedown Category Subject
  8613   Wed May 22 11:09:33 2013 JamieSummaryCDSWeird DAC bit flipping at half integer output values

After querying CDS folks about this issue, I got some responses that indicated the problems was likely limit-cycle oscillations due to zero-padding of the data when upsampling.  Tobin ran some Matlab tests to confirm this issue.

Starting in RCG 2.5 there is a new "no_zero_pad=1" cdsParameters option turns zero padding OFF.  I tried enabling this option c1scy to see how the behavior changed.  Sure enough, the 32 kHz oscillations mostly went away.  There are no oscillations for outputs held at the half-count value, and the oscillations around the half-count transitions went away as well.

The only thing I could see is a bit of oscillation when converging on a constant half-count value that went away after a couple of milliseconds:


So we might consider adding the no_zero_pad=1 option to all of our coil driver outputs, which might eliminate the need to add notches at the Nyquist in the analog anti-image filters

  8614   Wed May 22 11:21:28 2013 KojiSummaryCDSWeird DAC bit flipping at half integer output values

Is this limit cycle caused by the residual of the digital AI filtering at the half sampling freq and that his the threshold?
Or is this some nonlinear effect? If this is a linear effect associated with the zero-padding, the absolute
value of the DC may affect the amplitude of the oscillation. (Or equivalently the range of the DC where we get this oscillation.)

Anyway, it seems that we should use no-zero-padding.

You pointed out the ringdown of the digital AI filter in the sample-hold case (i.e. no-zero-padding case).
How does it look like in the conventional zero-padding case?

  8615   Wed May 22 11:35:06 2013 JamieSummaryCDSWeird DAC bit flipping at half integer output values


Is this limit cycle caused by the residual of the digital AI filtering at the half sampling freq and that his the threshold?
Or is this some nonlinear effect? If this is a linear effect associated with the zero-padding, the absolute
value of the DC may affect the amplitude of the oscillation. (Or equivalently the range of the DC where we get this oscillation.)

This is a good question.  We may be able to test if it's a linear effect if we have enough DAC range to get the oscillation to be more than a single sample.


You pointed out the ringdown of the digital AI filter in the sample-hold case (i.e. no-zero-padding case).
How does it look like in the conventional zero-padding case?

 In the zero-pad case the oscillation just continues indefinitely at the half-count value, so it never dies out (at least as far as I can tell).

  8616   Wed May 22 15:08:37 2013 KojiSummaryCDSWeird DAC bit flipping at half integer output values

It seems that the effect is from the (linear) residual fluctuation of the digital AI filter for the zero-padded signal.

Namely, if we give the larger constant number, we get more oscillation.

Attachment 1: Screenshot.png
  8624   Thu May 23 01:27:11 2013 ManasaSummaryLSCXarm beat note search continues

Towards finding the x-arm beat note:

The green would not lock to a maximum GTRX this morning. In the course of aligning the green stably to the X arm, somewhere down the line, the input pointing got messed up (reasons unknown). To set this right, Koji tried to lock the Yarm with POY DC but it wouldn't work. The transmon for Y had to be set up temporarily and the Y arm was locked with TRY. This restored the input pointing and the arms locked with transmission TRX/TRY > 0.9 counts. The transmon path along the Y arm was then re-configured as mentioned in Annalisa's elog.

I still had trouble getting the X-green locked in TEM00 (similar situation mentioned by Jenne in elog). The arm cavity mirrors were tweaked to get the green to resonate in TEM00 but it wouldn't stay locked when the temperature of the x-end NPRO was changed. Koji helped recover missing links to filters for the ALS_X_SLOW servo from the archives. Enabling the filters helped keep the green locking stable for laser temperature changes (which corresponds to 'offset' change in ALS_X_SLOW servo screen).

PSL green alignment was checked once again and the X-end laser temperature was scanned trying to find the beatnote. RFMON from the beatbox was connected to the spectrum analyzer. I have scanned through the whole range of offset but have not been able to find the beat note yet.

The search will continue tomorrow

  8626   Thu May 23 10:24:23 2013 JamieSummaryCDSc1scy model continues to run at the hairy edge

c1scy, the controller model at the Y END, is still running very long, typically at 55/60 microseconds, or ~92% of it's cycle.  It's currently showing a recorded max cycle time (since last restart or reset) of 60, which means that it has actually hit it's limit sometime in the very recent past.  This is obviously not good, since it's going to inject big glitches into ETMY.

c1scy is actually running a lot less code than c1scx, but c1scx caps out it's load at about 46 us.  This indicates to me that it must be some hardware configuration setting in the c1iscey computer.

I'll try to look into this more as soon as I can.

  8629   Thu May 23 13:14:34 2013 KojiSummaryLSCXarm beat note search continues

We should consider to hook up the temperature monitors of the NPROs to the ADCs.

  8631   Thu May 23 17:51:39 2013 KojiSummaryLSCMy usual locking procedure

For purpose of the automation and my record, I summarized my locking procedure as a chart.

Attachment 1: PRMI_locking_procedure.pdf
PRMI_locking_procedure.pdf PRMI_locking_procedure.pdf
  8686   Thu Jun 6 15:46:10 2013 Max HortonSummaryGeneral Smart UPS 2200 Batteries Replaced

Replaced the batteries successfully in the control room.  We just had to switch the clips from the old batteries to the new one, which we didn't know was possible until now.

  8694   Tue Jun 11 22:16:56 2013 ManasaSummaryGreen LockingALS for X arm

I discussed with Yuta about the ALS servo and phase tracker and found that there was a lot of information lying around from last year but there aren't any clear elogs on how to enable ALS and obtain IR resonance.


Guide to enabling the ALS servo and find IR resonance:

The steps will explain in detail how to ressurrect the ALS servo for green X-arm and find IR resonance using ALS. The medm screens are very confusing right now.


(i) Finding the beat note

1. Get the IR to flash in TEM00 for the arm and lock it by enabling LSC (Locking the arm to IR keeps the arm cavity mirrors stable so that you can scan the temperature of the X-end laser to find the beat note).

2. Steer the X-green into the arm cavity such that the arm cavity locks in TEM00 for green as well. At this point you should also have the X-green reaching the PSL table.

3. Align the PSL doubled green (PSL-green) and the X-green in near-field (at the camera) and far-field (letting the beams to propagate beyond the Green-TRX PD).

4. Check cabling of the RF beat PD.

5. Change the X-laser temperature by sweeping the offset (C1: ALS-SLOW_SERVO2_OFFSET) in steps of 10.

6. Find the beat note and tune the alignment at the beat PD to maximize the beatnote amplitude. Disable LSC for X arm.


(ii) The GREEN HORNET explained

'Input signal conditioning' block takes I and Q signals after the delay frequency discriminator (DFD) in the beat box and these signals pass through C1ALS_BEATX_FINE filter banks. The output signal then enters the phase rotation matrix of the phase tracker. The phase tracker gives 'PHASE_OUT' which is the error signal that is fed to the ETM servo filter module (DOF filters)  through the 'Input matrix' in the medm. 

An offset can also be fed to the phase tracker which will scan the beat frequency (used to find IR resonance).


(iii) Scripts

1. easyALS.py - This runs from 'ON plus' or 'ON minus' buttons in the C1ALS_COMPACT. 

The script clears history of 'fine_phase' filter module and increases gain of the servo in steps ('ON plus' for positive gain and 'ON minus' for negative gain).

2. findIRresonance.py - This runs from 'IRres' button in the C1ALS_COMPACT.

It adds offset to the phase tracker in steps which scans the beat frequency to find IR resonance.

P.S. Check the scripts before enabling the servo so that the right filter modules are being turned ON. Using the wrong set of filter modules can kick the ETM.


X arm ALS progress:

I found the beat note and got ALS to work reasonably for the Xarm without kicking the ETM. I did this by manually toggling buttons and changing gains. The scripts need editing.

To do:

Modify the scripts to work as we want them to.

The ALS medm is SSSOOOO confusing. It definitely needs to be fixed (remove all unwanted parts of the screen that existed 'pre-phase tracker').

Find IR resonance.

  8703   Thu Jun 13 22:31:12 2013 ManasaSummaryGreen LockingX arm ALS

Stabilized ALS and beat frequency sweep realized.


1. Enable appropriate filter modules and set appropriate servo gains.

Servo module

Filters Gain
C1:ALS-XARM FM4 FM5 -0.25
C1:ALS-ETMX - 1.0

2. Clear history of C1:ALS-BEATX_FINE_PHASE

3. Enable the servo loop. I had set limits on the servo loop and ramp time for gain switching so that I don't kick the ETMY hard.
Gains were decided such that the error signal C1:ALS-BEATX_FINE_PHASE_OUT was minimized.

4. Beat frequency sweep is realized by stepping up on C1:ALS-BEATX_FINE_OFFSET_OFFSET (from 0 to 2100 in this case).

Video1 shows the difference that can be seen at the RF spectrum analyzer when ALS is enabled.

Video2 shows the beat frequency sweep as seen on the spectrum analyzer.

I could not get 'getdata' to work as I wanted. So I have attached the error signal trend before and after the ALS servo loop is enabled.

Thank you Jenne for helping retrieve more sensible data!

More info:
The beat note is very strong and we can clearly see its harmonics as well. Attached is the picture showing the several harmonics.
Peak frequency(MHz)    Power(dBm)
 47                                    -2.77
 93.5                                -27.56
 139                                 -32.75
 185.4                              -45.64
 231.9                              -57.10
 278.4                              -59.42

To do:
1. Obtain IR resonance.
2. Check the digital anti-whitening filter after the beatbox.
3. The effect of the harmonics should be figured out.
4. Write scripts to enable ALS and findIRresonance.

Attachment 1: IMG_0659.JPG
Attachment 2: ALS_stabilized_13June2013.png
  8708   Fri Jun 14 07:06:19 2013 KojiSummaryGreen LockingX arm ALS

It's nice that we are now able to scan the cavity again. We got close to PRMI+one arm one step further.
The calibration of the scan frequency and the evaluation of the in-loop/out-of-loop error signal in terms of (Hz/rtHz) would be necessary.

The beat amplitude looks actually huge aIthough I don't know where you are monitoring.
Talk to Jamie to figure out how much the signal should be at the monitoring point.
If it is more than we are supposed to have, put an attenuator somewhere.

  8717   Tue Jun 18 10:37:00 2013 SteveSummaryGeneralnew laser pointers

  Red-green laser pointers added to the depleted stock of 2011

The two pointers output measured 4.4 mW green and 2 mW red


  8738   Mon Jun 24 16:06:17 2013 ManasaSummaryGreen LockingALS model

 I am working on the basic ALS servo model. The simulink model for the same is attached. The loop is not yet complete (I'm still debugging it) ; but this is just an update of where I am right now.

Attached is the simulink and matlab file. 






Attachment 1: elog.zip
  8752   Wed Jun 26 01:30:31 2013 ranaSummaryPEMVariation in 10-30 Hz seismic RMS

For quite a while (no one knows how long), we've seen fluctuations in the 10-30 Hz seismic motion. This shows up as the purple trace on the seismic BLRMS on the wall projector.

The second plot shows that this is not only a periodic increase in the usual 29.5 Hz HVAC peak, but also an anomolous 32.2 Hz peak. Probably some malfunctioning machinery - maybe in the 40m or maybe on the roof.

Attachment 1: gur1z_rms.pdf
Attachment 2: gur1z.pdf
  8776   Thu Jun 27 22:52:38 2013 Rana, Gabriele, FrancescoSummaryComputer Scripts / ProgramsLIGO-DV installed

I installed ligoDV in the /ligo/apps/ligoDV/

Now, by pointing the tool at the local NDS2 server (megatron:31200) you can access the recent local data (raw, trends, etc.)

by running /ligo/apps/ligoDV/ligodv from the command line.

Attachment 1: ldv.png
  8795   Wed Jul 3 11:07:17 2013 AlexSummary Photodetector Characterization

 [Alex, Koji]

We characterized Koji's BBPD MOD for REFL165 (see attachment).

First, we calibrated the Agilent 4395 Network Analyzer (NA) to account for differences in cable features between the Ref PD and Test PD connections. This was done using the 'Cal' softkey on the NA. 

Then we performed transimpedance measurements for the test PD and reference PD relative to the RF output of the NA and relative to each other (see 2nd attachment. Note that the NA's RF output is split and sent to both the IR Laser and the NA's Ref input).

Next, we made DC measurements of the outputs of the photodetectors to estimate the photocurrent distribution of the transimpedance setup (like the 2nd attachment, but with the outputs of the PDs going to a multimeter). By photocurrent distribution, we mean how the beamsplitter and respective quantum efficiencies/generalized impedance/etc. of the PDs influence how much current flows through each PD at with a DC input.

Finally, we measured the output noise as a function of photocurrent (like the 2nd attachment, but with a lightbulb instead of the IR Laser). Input voltages for the lightbulb ranged from 0mV to 6V. Data was downloaded from the NA using netgpibdata from the scripts directory. Analysis is currently in progress; graphs to come soon.


Attachment 1: BBPD_PCB.pdf
Attachment 2: transimpedance_measurement.pdf
  8797   Wed Jul 3 14:33:46 2013 KojiSummaryLSCTest result for the REFL165 photodetector

P.1 Circuit diagram

Added components are indicated by red symbols.

- The diode on the board is HAMAMATSU S3399. It is a Si PIN diode with φ3.0 mm.

- Based on prototype version of aLIGO BBPD D1002969-v8 (although the board says v7, It is v8.)

- The input impedance of the MAR-6SM amplifier (50Ohm) provides the transimpedance.

- The first notch (Lres and Cresa/b) is actually not notch but a LF rejection with DC block.

- The second and third notches are tuned to 11MHz and 55MHz.

- Another notch is implemented between the RF amps. The 33MHz signal is weak so I expected
to have no saturation at the first amplifier.

- As you see from the DC path, the transimpedance of the DC path is 2k V/A. If this is too high,
  we need to replace R9 and R11 at the same time. TP1 is providing +10V such that the total
  reverse bias becomes 25V without bringing a special power supply.

P.2 Transimpedance

The transimpedance is measured with an amplitude modulated diode laser.

The transimpedance is 1k V/A ish. It is already at the edge of the bandwidth.
If we need more transimpedance at 165MHz, we should replace
the PD with FFD-100 (I have one) and apply 100V of reverse bias.

P.3 Current noise spectrum

The measured dark noise voltage spectrum was converted to the equivalent current noise at the diode.

The measured transimpedance is ~1.2kV/A.
The reduction of the transimpedance above 100MHz has been seen as 165MHz is already at the edge of the bandwidth.
If we need more transimpedance at 165MHz, we should replace the diode with FFD-100 (I have one) and apply 100V of reverse bias.

P.4 Shot-noise intercept current

Shot-noise intercept current was measured with a white light from a light bulb.
This measurement suggests the shot-noise intercept current of 1mA, and transimpedance of 1.5kV/A.

Attachment 1: REFL165_response_130702.pdf
REFL165_response_130702.pdf REFL165_response_130702.pdf REFL165_response_130702.pdf REFL165_response_130702.pdf
  8816   Tue Jul 9 23:27:17 2013 KojiSummaryLSCMICH: ITMX/Y <=> PRM/BS

The MICH actuation with PRM/BS was investigated again.

(ITMX -1 / ITMY +1) is equivalent to (PRM -0.267 and BS +0.50).

- PRMIsb was locked with REFL33I&AS55Q.

- Using the locking module in the LSC model, actuate ITMX (-1) and ITMY (+1) at 580.1Hz. Note that the notch filters in the MICH/PRCL servos were on.

- Look at the peak in the AS55Q spectrum. Tune the BS element in the output matrix of the lock-in to minimize the peak height.
=> The peak was minimized at BS = -0.50.

- Look at the peak in the REFL33I spectrum. Tune the PRM element in the output matrix of the lock-in to minimize the peak height.
=> The peak was minimized at PRM = +0.267

- These measurement leads to the conclusion mentioned above.

  8882   Fri Jul 19 22:35:06 2013 KojiSummaryLSCVarious Arm signal (Yarm)

The StripTool plot attached below shows various arm signals measured with the Y arm cavity swept using ALS.

Yellow: TRY

Blue: ALS additive OFFSET to the error signal

Red: Raw PDH error signal (POY11I)

Purple: Linearized PDH error (POY11/TRY)

Green: 1/Sqrt(TRY)-5 (No normalization)

Inverse Sqrt of the TRY had been implemented when this LSC controller was first coded.
It is confirmed that the calculation is working correctly.

Attachment 1: various_arm_signal.png
  8885   Fri Jul 19 23:35:52 2013 KojiSummaryLSCTRY DC locking

The Y arm was locked with the TRY DC signal.

The handing off process is too complicated because there is no path from ALS to the LSC error.

 The TRY DC error signal & the gain determination

- The error signal was produced by the operation 1/SQRT(TRY) - OFFSET. The initial offset was -5.

- The sign of the TRY DC error signal depends on which side of the resonance the arm is.
  By looking at the strip chart, I determined that the sign is opposite of the ALS.
  The ALS had the gain of -25, so the TRY control gain was to be positive.

- From the strip chart on the previous entry , the slope difference between the PDH error and the TRY DC error was x500.
  The arm control with POY11 PDH had the gain of 0.2. So the target gain for the TRY DC was determined to be +100.

Handing off

- The arm was stabilized by ALS. The ALS gain was -25 with FM2/3/5/6/7/10

- YARM configuration: no trigger / no FM trigger / gain =+0 / FM5 ON / OFFSET -5

- Start handing off:
  YARM: Turned up the gain to +50

- ALS: Turned off FM6/7

- YARM: Turned on FM6/7

- ALS: Turned off FM2

- YARM: Turned on FM4

- ALS: Turned off FM3/10

- YARM: Turned on FM2/3/8/9 ON

- ALS: Reduced the gain to -15

- YARM: Increased the gain to +70

- ALS: Reduced the gain to 0

- YARM: Increased the gain to +100


Changing the offset

The offset of -5 gave the TRY of <0.1.

The detuning was reduced by giving the offset of -4. TRY went up to ~.1

The offset of -3 made TRY 0.13

The offset of -2 made TRY 0.25

The offset of -1.5 made TRY 0.4. And the arm could not be held by this error signal anymore.



Attachment 1: TRY_locking.png
  8887   Mon Jul 22 03:10:41 2013 ranaSummaryloreAngel of the Y End Table?

 Trying to take an image or movie of the ETMY Transmon cam, we got instead this attached image.

I think it is just some scattered green light, but others in the control room think that it is a message from somewhere or someone...

Attachment 1: asdasd.jpg
  8888   Mon Jul 22 06:58:17 2013 LisaSummaryloreAngel of the Y End Table?


 Trying to take an image or movie of the ETMY Transmon cam, we got instead this attached image.

I think it is just some scattered green light, but others in the control room think that it is a message from somewhere or someone...

 It is not an angel, it is clearly a four leaf clover (also known as "quadrifoglio"). It is very rare, it brings good luck!

Attachment 1: image.jpg
  8905   Tue Jul 23 13:29:58 2013 KojiSummaryGeneral 

record of the initial state

Attachment 1: initial_state_130723.png
  8987   Thu Aug 8 18:43:12 2013 SujanSummaryPEMOptimally subtracting signals from two seismometers.

An exercise of optimally subtracting one seismometer signal by another using weiner filters was done. Results have been summarized document attached.

Attachment 1: Results.pdf
  8988   Thu Aug 8 18:47:41 2013 SujanSummaryPEMUsing weiner filters for subtracting signals MC_L and GUR2_X

I used MC_L signal from the Mode Cleaner as the desired signal with GUR2_X as witness signals. I observed good subtraction where coherence is high. But there was noise added in other frequency bands. I am not sure how to avoid that.

Please find attached documents that contains relevant plots.

Attachment 1: Results.zip
  9004   Tue Aug 13 11:40:19 2013 Alex ColeSummaryElectronicsRFPD Demod Filter Frequency Response Measurement

 For the RF PD Frequency Response Measurement project, we get each PD signal from the "PD RF Mon" output of each demodulator board corresponding to our PD under test. Therefore we can't neglect the frequency response of various filters inside the demodulator board. I used our Agilent 4395 Network Analyzer to gather frequency response data for each demodulator board being considered for the RFPD frequency response project (AS55, REFL11, REFL33, REFL55, REFL165, POX11, POP22, POP110).

The NA swept over a frequency range of 1-500 MHz. Data was collected using NWAG4395A (from the netgpibdata directory). It should be noted that the command line options -a 16 -x 15 (averaging=16 and excitation amplitude=15 dBm[the max]), in addition to the usual command line options described in the help file, were used to minimize noise. 

The data is located in /users/alex.cole. The file names are in the format [PDNAME]DemodFilt_1000000.dat (e.g. REFL11DemodFilt_1000000.dat). Results for POP110 are shown below.

Attachment 1: photo_(3).JPG
Attachment 2: test.jpg
  9009   Tue Aug 13 21:49:32 2013 KojiSummaryGeneralTesting new AG4395A network analyzer

New AG4395, sn MY41101114  for West Bridge Labs was delivered. For the test purpose it is at the 40m now.

I made a series of tests in order to find anything broken.

Network analyzer test

- RF out / Rch test

RF out directly connected to R input channel.
The received power at the R-ch was measured while the output was swept from 10Hz to 500MHz.

The RF power was changed from -50dBm to +15dBm with +10dBm increment (but the last one).

The attenuator setting was changed from 50dB to 0dB.

=> The configured output power was properly detected by the R channel.

=> RF output is producing the signal properly. R-ch is detecting the produced signal properly.

- Ach/Bch test

Same test as above for Ach and Bch 

=> Same result as above

=> A-ch and B-ch are detecting the produced signal properly.

- Transfer function test

Connect a power splitter to the RF out. Detect the split signals by R-ch and A-ch

=> Measurement is at around 0dB +/- 1dB up to 500MHz.

Same measurement for B-ch

=> Same result

=> A/R and B/R indicates proper transfer function measurements.

- Calibration

RF out was split in to two. One was connected to R-ch. The other was connected to A-ch.
The thru response calibration was run.

=> The thru calibration was performed properly. 

- Practical tranfer function measurements.

In the above calibration setup, various RF filters were inserted in the Ach path.

The measured data was extracted via GPIB connection.

=> Practical transfer function measurements were performed.

=> GPIB connectivity was confirmed


External reference test

- External 10MHz reference from an SRS frequency counter was connected to Ext Ref In

=> Ext Ref indicator on the screen appeard

=> The internal oscillator seemed to be locked to the external reference in



Spectrum analyzer test

- Measured the signals from DS345 by R/A/B ch

Sinusoidal signal (1V) swept from 10MHz to 30Mhz

=> Corresponding moving peak was detected in each case

- Noise level measurement

R/A/B channels were terminated. The attenuation at each port was set to 0dB.

Frequency span was changed between 500MHz, 10MHz, 100kHz, 1kHz.

=> Noise level of ~10nV/rtHz between 0.1-500MHz was confirmed. All R/A/B channels have the same performance.

Attachment 1: AG4395A_noise.pdf
  9010   Tue Aug 13 22:21:12 2013 KojiSummaryGeneralMinicircuit Filter TFs (AG4395A test)

As a part of the network analyzer test in the previous entry, the transfer functions of Mini-Circuits filters we have at the 40m were measured.

<<List of the filters>>

- LPF (SMA): SLP1.9, SLP5, SLP21.4, SLP30, SLP50, SLP100, SLP150, SLP750
- LPF (BNC): BLP1.9, BLP2_5, BLP5, BLP30
- BPF (SMA): SBP10.7, SBP21.4, SBP70
- HPF (SMA): SHP25, SHP100, SHP150, SHP200, SHP500


Attachment 1: Minicircuit_LPF.pdf
Attachment 2: Minicircuit_BPF.pdf
Attachment 3: Minicircuit_HPF.pdf
Attachment 4: 130813.zip
  9012   Thu Aug 15 01:51:50 2013 KojiSummaryGeneralRFM<->Dolphin bridge distributed to c1rfm and c1mcs

Since the RFM-Dolphin bridges for the ASX model was added to the c1rfm model, c1rfm kept timing-out from the single sample time of 60us.

The model had 19 dolphin accesses, 21 RFM accesses, and 9 shared memory (SHM) accesses.

At the beginning 2 RFM and 2 SHM accesses were moved to c1sus (i.e. they were mistakenly placed on c1rfm).
But this actually made the c1sus model timed out. So the model was reverted.

The current configuration is that the WFS related bridges were accommdated in the c1mcs model.
This made the timing of c1rfm ~40us. So it is safe now.
On the other hand, the c1mcs model has the time consumption of ~59us. This is marginal now.

We need to understand why any RFM access takes such huge delay.

  9021   Sun Aug 18 16:04:07 2013 ranaSummaryCDSFB lights all RED: mxstream restart

Sun Aug 18 15:52:50 2013

Found the FB lights (C1:FEC-NN_FB_NET_STATUS and C1:DAQ-DC0_C1XXX_STATUS) RED for everything on the CDS_FE_STATUS screen.

I used the (! mxstream restart) button ro restart the mxstreams. Everything is green now.

PMC was out of lock- relocked it and the IMC locked itself as did the X & Y arms on IR. X was already green locked.

Attachment 1: IFO-Trend.png
  9022   Sun Aug 18 17:56:16 2013 ranaSummaryCDSMEDM Screen CPU Usages

I noticed at LLO (?) that the LSC screen there uses up ~25-30% of the CPU time on a single core for the control room iMac workstations - this seems excessive.

Here is an accounting of CPU usage percentages for some of our screens:


Screen Name CPU (%)

These were measured using the program 'glances' on rosalba. MEDM running with only the sitemap used up 0.9% of a CPU. With the screens running, the fluctuation from sample to sample could be ~ +/- 0.5%. While the LSC screen seems to be the biggest pig, it is only big in comparison to small pigs. Certainly this pig has gotten bigger after getting sent to Louisiana.

Attachment 1: obama1404_666531c.jpg
  9042   Tue Aug 20 16:23:41 2013 ranaSummaryGeneral/home/cds nearly full

/home/cds is >98% full - below are some of the usage numbers:

controls@rosalba:/users/OLD 0$ du -h --max-depth=1
42M    ./katrin
1.5M    ./ben
2.4M    ./sanjit
569M    ./waldman
328M    ./sonia
3.6G    ./lsinger
44M    ./dbusby
105M    ./dbarron
21M    ./manuel
709M    ./yaakov
46M    ./rodionov
240M    ./ishwita
2.7G    ./clara
56M    ./gopal
290M    ./mashaB
87M    ./varvella
5.6M    ./Sascha
2.9G    ./ryan
190M    ./nancy
3.5G    ./john
269M    ./elizabeth.davison
165M    ./jweiner
460K    ./mjones
49M    ./stephanie
52M    ./mohana
56M    ./noriyasu
38M    ./mjenson
76M    ./sballmer
224M    ./kirk
812K    ./bonnie
33M    ./janosch
16M    ./kevin
122M    ./dblair
2.6G    ./mirko
389M    ./keenan
195M    ./tf
150M    ./littlezach
193M    ./jmiller
1.8G    ./ting
131M    ./dmalling
842M    ./sharmila
1.4G    ./caryn
12G    ./rward
4.1M    ./jay
443M    ./emintun
184M    ./katharine
76K    ./nick
804K    ./nicole.ing
14M    ./jenny
542M    ./vsanni
45M    ./peter
7.8G    ./miyakawa
4.8M    ./channa
4.0K    ./frank
9.9G    ./razib
35M    ./amin
361M    ./sharon
62M    ./bram
3.9M    ./volodya
7.9M    ./larisa
301M    ./sasha
33M    ./eric.hendries
18M    ./vuk
101M    ./huan
1.8M    ./sonali
453M    ./megan
43M    ./Royal
5.4G    ./ayaka
19M    ./mott
518M    ./justing
501M    ./avi
173M    ./kakeru
3.9G    ./alberto
41M    ./paul.fulda
59M    ./elena
67G    .

controls@rosalba:/opt/rtcds/userapps 0$ du -h --max-depth=1
1.4G    ./tags
13M    ./trunk.bak
40K    ./.svn
3.0G    ./trunk
174M    ./trunk.bak2
4.2G    ./branches
8.7G    .

linux1:cds>nice du -h --max-depth=1
du: `./llo/chans/daq/archive': Permission denied
du: `./llo/chans/daq/old': Permission denied
707M    ./llo
9.7M    ./mit~
752K    ./raidwebFirmware
462M    ./epics
2.1G    ./tmp
1.5G    ./gds
76M    ./project
9.1G    ./ligo
449G    ./rtcds
3.3G    ./apps
20K    ./.kde
512K    ./cdscfg
1.4M    ./.Trash-controls
5.8M    ./scripts
20K    ./.TemporaryItems
964G    ./caltech
71M    ./bin
16K    ./.Trash-1001
4.5G    ./rtapps
564M    ./src
11M    ./vw
3.8M    ./dvSave
460M    ./lho
1.2G    ./data
1.5T    .

  9044   Wed Aug 21 00:18:03 2013 MasayukiSummaryGreen LockingX-arm PDH OLTF measurement

[Manasa Masayuki]
Today we measured the openloop transfer function of the PDH green lock of the x-arm.

Edit //manasa// The excitation was given from SR785 source. SR560 was used as the summing node at the PDH servo box output where the loop was broken to measure the OLTF. The SR785 was used to measure the frequency response (CH2/CH1; CH1 A SR560 output and CH2 A PDH servo output) in sweptsine mode.

We measured with two different servo gain. We started with the servo gain of 3 and at that gain the UGF was 1.5 kHz and the phase margin was 50 degree. After that we increase the servo gain to 5.5 and at that gain the UGF was 6.2 kHz and the phase margin was 55 degree. In all the measurement we use the source amplitude of 1.0 mV for all frequencies (from 100 Hz to 100 kHz). We could not increase the gain and also the source amplitude any more because the green was kicked out of lock.

Next work list
1. In the earlier measurements we found the UGF of the PDH green lock of the x-arm as 10 kHz and the phase margin as 45 degree, so we will investigate what has changed from these measurements.elog 4490

2. We will measure the power spectrum of the error signal and the feedback signal.

3. We will calibrate the above signals to compare with ALS out of loop noise.

netgpib was taking forever to transfer data. So the measurements are just photos of the display.

attachment1 - servo gain 3


attachment2 - servo gain 5.5


  9045   Wed Aug 21 17:42:03 2013 ranaSummaryGeneral/home/cds nearly full

One of the reasons that our disk is getting full is due to the scripts_archive directory. A backup script runs on op340m and makes a tar.bz2 file of the scripts directory and puts it in scripts_archive every morning at 6 AM.

On Oct 7, 2011, Koji fixed this script to point at our new scripts directory instead of the old /cvs/cds/caltech/scripts directory. Since then, however, no one has fixed the exclude file to NOT back up the junk that's in that directory. Its a 1.6 GB directory so its full of it.

I've deleted a bunch of junk from the scripts directory: this directory is for scripts, not for your personal home movies or junk data files. Put those in your USER directory. Put temporary data files in /tmp/. I've also added a few more patterns to the exclude file so that less .mpg, .png, .pdf, .dat, etc get stored every day. The new daily .tar.bz2 file wil be ~25 MB instead of 770 MB.

(also fixed the backup script to use 'env' to setup the perl environment and removed the hard-coded path to tar)

  9047   Wed Aug 21 19:37:25 2013 MasayukiSummaryGreen LockingX-arm PDH OLTF measurement

[Manasa, Masyauki]

Today we measured OLTF of PDH green lock of x-arm again. In the previous measurement the excitation signal was injected at the PDH servo box output(elog 9044), but in this measurement we changed the injection point to the RFPD mixer output (just before the servo input).

We measured the OLTF with the servo gain of 6.5 and source amplitude of 5 mV for all frequency band. The measured UGF was 11 kHz and the phase margin was 48 degree.

Next that measurement, we tried to measure the power spectrum density of the error signal and feedback signal. But the alignment was not so good, so we aligned the green light injection point. Tomorrow we will continue the alignment and will measure the PSD.

attatchment1 - OLTF of PDH green lock with servo gain of 6.5


  9054   Thu Aug 22 20:25:28 2013 MasayukiSummaryGreen LockingY-arm PDH OLTF measurement

[Manasa, Masayuki]
We measured the the openloop transfer function of the PDH green lock of the y-arm.The measurement setup was same as yesterday's measurement.elog 9047

In this measurement, the servo gain was 7 and the source amplitude for the excitation was 1 mV. As you can see in below figure, the measured UGF was 15 kHz and the phase margin was 45 degree.

attatchment1 - OLTF with servo gain of 7


  9089   Fri Aug 30 01:01:28 2013 rana, nicSummaryComputer Scripts / ProgramsaLIGO Noise Budget code installed and running

Chris Wipf has been developing a new Noise Budget code that allows us to use our existing Simulink models to handle all of the noise transfer functions. This is mainly by being clever about avoiding the numerical pitfalls that we encounter when doing linearization of Simulink models (e.g. linmod or linmod2).


In this model, the optical plant is done with analytic TFs using the formulae from the Sigg Frequency Response doc. The big Orange block has just the DAC and some simple pendulum TFs. The upper section contains the simulated digital system: input matrix, digital filter TFs, and output matrix. The digital filters are just based on my memory of iLIGO. The CARM path is made to be fast to approximate the high gain of the Common Mode servo. Without this high gain the PRC optical plant is unstable due to the right half plane zeros. This simple model is used just so that we could see the NB work on a multi-loop system. For the next steps of getting it to work for the 40m, we will use the Optickle TFs instead of analytic functions and also load the digital filters directly from the FOTON files. For the LLO DRMI, we'll add some simplified version of the SUS Simulink models for triples and quads.


Yesterday, Nic and I took my old iLIGO IFOmodel.mdl Simulink model and added the new NB hooks that allowed us to use the new code. The screenshot below is from a run of this code:

1) Figure 1 shows the DARM Noise budget. So far we have included shot noise in DARM, CARM, MICH, & PRC. Radiation pressure noise on the ITMs and ETMs. Coating thermal noise on all mirrors.

2) Figure 2 shows the breakdown of how each of the shot noises at each port couple to the DARM readout. The RED trace is the AS port DC readout shot noise. The GREEN trace is the MICH shot noise feeding through the MICH loop and being mostly cancelled by the scalar MICHdamp feedforward path.

3) Figure 3 shows that we've set the coating thermal noise to be equal on all 4 TMs.

4) Figure 78754 is a set of Bode plots of the open loop gains of the 4 LSC loops (inferred from the closed loop TF). Also plotted is the residual MICH2DARM TF (with the MICHdamp cancellation path ON).

5) Figure 9911123 are the step responses of the LSC loops: step inserted at the error point and response measured just after the excitation point.

The editor window on the left shows how simple the NB code is to use once the Simulink model has had all the hooks added to it.

Attachment 1: NBplots.png
  9123   Wed Sep 11 23:34:37 2013 MasayukiSummaryGreen LockingALS locking in both arms

[manasa, masayuki]

We locked the XARM and YARM with using ALS control loop and we succeeded to lock stably both arms. The performance of the ALS was tested with a measurement of the calibrated error signal. (attachment 1)

- red and blue : the in-loop noise of ALS of each arm.

- green and purple:Stability of the beat-note frequency with the MC and the arm freely running.


In the high frequency region, YARM has larger noise than XARM, and these noises were not there in previous measurements by Koji and Manasa (elog8865). You can see that in both of in-loop noise and free running noise. These noises may be caused by the Green PDH servo or hte phase tracker servo or any other electrical staff. We will start noise budget of these servo.

At higher frequency than UGF of ASL control loop, the loop does not suppress the noises at all, but the inloop and free running noise are not equivalent. I have no idea about that so far.




Attachment 1: noise.pdf
  9124   Wed Sep 11 23:43:10 2013 KojiSummaryGreen LockingALS locking in both arms

What was the beat freq for each arm?
The HF noise level depends on the frequency of the beat note.
As the BBPD has the freq dependent noise level. (See this entry)

  9125   Thu Sep 12 00:07:26 2013 MasayukiSummaryGreen LockingALS locking in both arms


What was the beat freq for each arm?
The HF noise level depends on the frequency of the beat note.
As the BBPD has the freq dependent noise level. (See this entry)

 I'm not sure about the actual number of the beat frequency, but the beat frequency was almost same in both arms. And I took this measurement sometimes with slightly different beat frequency but the noise level didn't change so much.

  9147   Fri Sep 20 20:14:52 2013 ranaSummaryGeneral/home/cds nearly full


One of the reasons that our disk is getting full is due to the scripts_archive directory. A backup script runs on op340m and makes a tar.bz2 file of the scripts directory and puts it in scripts_archive every morning at 6 AM.

On Oct 7, 2011, Koji fixed this script to point at our new scripts directory instead of the old /cvs/cds/caltech/scripts directory. Since then, however, no one has fixed the exclude file to NOT back up the junk that's in that directory. Its a 1.6 GB directory so its full of it.

I've deleted a bunch of junk from the scripts directory: this directory is for scripts, not for your personal home movies or junk data files. Put those in your USER directory. Put temporary data files in /tmp/. I've also added a few more patterns to the exclude file so that less .mpg, .png, .pdf, .dat, etc get stored every day. The new daily .tar.bz2 file wil be ~25 MB instead of 770 MB.

(also fixed the backup script to use 'env' to setup the perl environment and removed the hard-coded path to tar)

 OUr disk was getting full again. Turned out my "fix" to 25 MB was only a fix to 250 MB. Since we were getting disk full warnings on our Ubuntu workstations, I deleted some COMSOL.dmg files from users/zach/ and then started deleting every other tarball from the scripts_archive directory. ~221 GB are now free. Still need to fix the exclude file for scripts better.

  9156   Tue Sep 24 20:43:45 2013 masayukiSummarySUSoptical levers centering

I centered optical levers of ITMX,BS,ETMY. I also change the position of optical levers of ITMX, ETMY, ITMY, BS on Friday night(9/21), of ITMX, ETMY, BS on Monday night. Both are around 6:00 ~ 7:00.But centering on Monday was totally wrong, because I centered with not good IFO alignment.

The attachment is the 5 days trend of the opt lev of ITMX. First gap is alignment on Friday and Second gap is the alignment on Monday. Now I centered after  locking the FPMI.

The attachment 2 is the last 6 hours data.  The gap on 9/25 00:00 and 1:30(UTC)  is because the alignment of the cavity and the last gap is because of  centering of the optical lever.

Attachment 1: Screenshot-Untitled_Window.png
Attachment 2: Screenshot-Untitled_Window-1.png
  9158   Wed Sep 25 08:11:01 2013 MasayukiSummaryLSCLSC calibration screen


  The real time calibration system is not correct in high frequency.

The attachment are the plot of two free running noise. Blue curve is the plot of noise calibrated with OLTF. Green one is the just fft analysed signal of the real time calibration system output. You can see the ripple in high frequency region in green curve. That is because the anti-aliasing filter and digital anti-aliasing filter. I assume the sensitivity of MI as constant but Rana mentioned that we should take these filters into account.

modeled OLTF and sensitivity H
 I put the AA filter and DAA filter effects into matlab calibration script. The attachment 2 is the modeled sensitivity of the MICH. You can find each filter properties in  elog#8555 (analog AA filter) and in elog#3961. I estimate the H gain by measuring the fringe. The attachment 3 is the plot of fringe and I averaged with green points. The actual number is 3.48e7 count/m

attachment 2: the sensitivitiy of MICH


 attachment 3: fringe of the MICH


I modeled OLTF with this H and the fitted into the measurement data. That is in attachment 4. In this OLTF I also included the DAI filter and AI filter, and ' sample and hold circuit' of DAC TF . These are  mentioned in two references. Additionally I added the time delay 309.6 us.  Yuta mentioned that in C1SUS has 125us time delay. In MICH control we have also C1LSC , so I think this time delay is reasonable. I compensated the error signal with these OLTF and MICH sensitivity.

attachment 4: OLTF of the MICH control


You can see that the ripple is gone in blue curve and after 5 kHz the curve is flat.

Next step

I'm trying to put the inverted AA filter and DAA filter in C1CAL_INCV servo. But the ploblem is the difference of sampling frequency, so I couldn't fix yet. One possibility is putting approximated filter. I hope I will find some good way to design these filters.



Other thing

I esitimated the FPMI noise propagated from the residual noise of IR PDH control of both ARMS. I will summarize and write these staff in this afternoon.

Attachment 1: plot.pdf
  9161   Wed Sep 25 23:15:11 2013 MasayukiSummaryGreen LockingFPMI noise caused by ARM locking
I measured some error signal, OLTFs and responses for FPMI noise estimation. Especially we are interested in the noise from in-loop noise of ALS Green PDH control. The strategy and
1) Purpose
 Estimation of the FPMI phase shift noise caused by in-loop noise of Green PDH control. 
2) What we should figure out
 For that estimation we have to figure out the transfer function from the cavity length change to the phase shift which is measured by MICH.
3) Strategy
 I attached the block diagram of  our interferometer. Our goal is to find the transfer function H_L-l and to calibrate the out of loop noise of interferometer with that TF and error signal of the PDH control.
 H,A and F mean the sensitivity, actuator response and servo filter for each control loop. L_xarm is the disturbance of the cavity length and l- is the differencial motion of the interferometer
We can get this H_L-l from measurement of the response from calibrated ETM actuation to the MICH error signal. You can get the formula for calculating H_L-l with simple calculation and that is
             1 + G_mich       1 + G_xarm      V_mi  
H_L-l = ---------------  -----------------  ------------
              H_mich             A_etmx         V_excetm
where the each G is OLTF and V_mi/Vexcetm is the response from the ETM actuation to the MICH error signal.
And then  the FPMI noise in the unit of meter / rHz is
N_fpmi = l_dis + ------------ Vx
This second term is what we are interested in.
To estimate these noises
i) We can calibrate the actuators of  ITMX, ITMY and BS with using the MICH as sensor. So we can calibrate the arm error signals by  excitation of arm length using ITMs actuator.
ii) If we know the TFs of arms, we can calibrate the ETMX and ETMY actuators.
iii) We should know the response from ETMX or ETMY actuating to error signal of mich.
iv) Also we should calibrate the error signal of MICH in FPMI locking(H_mich). We can do that by exciting the BS.

Then we can estimate the noises.

In next entry, I will write about measurement.


  9162   Wed Sep 25 23:59:29 2013 MasayukiSummaryGreen LockingFPMI noise caused by ARM locking


Measurement with ARMs

i) By locking the MICH with AS55Q signal I measured the actuator response of ITMX ITMY BS for calibration of each actuator. This measurement was done at the same time with elog#9158. The actuator response was
BS : 2.2347e-8 / f^2 [m/count]

ITMX: 5.0843e-9 /f^2 [m/count]

ITMY: 4.9677e-9 / f^2 [m/count]

ii)By locking the Arms for IR with POX,POY. I measured the OLTF and the response from ITM actuation to POX and POY signal. Attachment 1,2 are the plots of fitted OLTF , the measured OLTF, and residual function (model - measure)/model and the attachment 3,4 are the response of each arm. I fitted the three parameters. Those are the gain, time-delay and cavitypole. Each fitted parameter is
timedelay:-282.09 usec, cavity pole : 2872.0 Hz
timedelay:-283.84 usec, cavity pole : 2939.9 Hz
The cavity pole seems higher than privious measurement (In 2009). Actually the residual function are increase at the higher frequency region than 1kHz, so I guess the fitting is not so good.One possibility is that in the region where cavity pole effect increase we has not much data.
With fitted OLTF and actuator response I calibrated the H_xarm and H_yarm.
Hxarm : 2.9796 e11 [count / m]
Hyarm : 6.1394 e11 [count / m]
iii) After that I measured the response from ETM actuation to POX and POY signal to calibrate the ETM actuator. The response of each actuator is
ETMX:1.2040e-8 / f^2 [m/count]

ETMY:1.4262e-8 / f^2 [m/count]
iv) I calibrated the error signal with OLTF and Hxarm,Hyarm. The result is in Attachment 5

 In high frequency region there is the difference between xarm and yarm. These difference are already there in error signal. I'm not sure where these noise comes from. We will make measurement with Green PDH from tomorrow, so  we can also check with those measurement.

In other region the two noises are very close and also very similar to the plot of the seismic motion in the control room (attached on the front of TV screen).

Attachment 1: XARM_OLTF.pdf
Attachment 2: YARM_OLTF.pdf
Attachment 3: XARM_ITMXresponse.png
Attachment 4: YARM_ITMYresponse.png
Attachment 5: free_running.pdf
  9163   Thu Sep 26 01:49:28 2013 MasayukiSummaryGreen LockingFPMI noise caused by ARM locking


 Measurement with FPMI

i)By locking the FPMI with AS55Q and arms using POX,POY we measured  the OLTF on AS55Q, the response from BS actuation to error signal on AS55Q  for H_mich. The fitted,  measured OLTF and the residual function is in attachment1. I fitted two parameters and they are time-delay and the gain. The time delay is -275 usec. The time delay in three different control are almost same. The response from BS to AS55Q is in attachment 2.

With these two measuremets, I calclated the H_mich in FPMI. This H_mich should be different from simple MI because the cavity  refrectivity is different from the front mirror. Acrually it changed and the value was
Hmich = 4.4026e7

ii) I excited the ETMX and ETMY and measure the response from actuation to the error signal of MICH on AS55Q. The response is in attachment 3 and 4. from these result I calculated the H_L-l by using the formula as I mentioned. The value was
H_Lx-l = 175.7650 (XARM)
H_Ly-l = 169.8451 (YARM)

iii) I measured the error signal of MICH and XARM and YARM and with measured H_L-l, I estimated the FPMI noise caused by ARM locking. You can see in the higher frequency region than 10 Hz is dominated by noise caused by ARM control in-loop noises. 150 Hz and 220Hz are the UGF of each arms, so the two peaks are caused by arm control. You can see the small difference between FPMI noise and  noise from arms. There are two possibilities, one is that these measurement is not same time measurement so they should have small difference. and  other possibility is the error of the caliculation. But I think it doesn't look so bad estimation.


Next step

We will do same measurement with lock the arms the ALS system on tomorrow. Then we will check the PDH servo or other noise source and investigate the ALS system

Attachment 1: MICH_OLTF.pdf
Attachment 2: BS-RS55Q.png
Attachment 3: ETMX-RS55.png
Attachment 4: ETMY-RS55.png
Attachment 5: plot.pdf
  9182   Tue Oct 1 14:12:22 2013 ranaSummaryCDSsvndumpfilter on linux1 makes NFS slow

 Yesterday and this morning's slow NFS disk access was caused by 'svndumpfilter' being run at linux1 to carve out the Noise Budget directory. It is being moved to another server; I think the disk access is back to normal speed now.

  9184   Tue Oct 1 19:42:19 2013 ranaSummaryCDSmegatron upgrade

Max and I started upgrading megatron to Ubuntu 12.NN today. We were having some troubles with getting latest python code to run to support the Summary pages stuff.

Its also a nice test to see what CDS tools fail on there, before we upgrade the workstations to Ubuntu 12.

Since its Linux, none of the usual upgrading commands worked, but after an hour or so of reading forums we were able to delete some packages and all the 3rd party packages and get the upgrade to go ahead. We'll have to re-install the LSC, GDS, LAL repos to get it back into shape and get NDS2 working. The upgrade is running in a 'screen' command on there.

Wed Oct 02 14:50:16 2013 

Update #1: The upgrade asks a couple dozen questions so it doesn't proceed by itself. I've been checking in to the 'screen' every couple hours to type in 'Yes' to let it keep going.

Update #2: It finished a few hours ago:

controls@megatron:~ 0$ uname -a
Linux megatron 3.2.0-54-generic #82-Ubuntu SMP Tue Sep 10 20:08:42 UTC 2013 x86_64 x86_64 x86_64 GNU/Linux
controls@megatron:~ 0$ date
Wed Oct  2 18:33:41 PDT 2013

  9191   Thu Oct 3 02:43:34 2013 rana, jenneSummaryLSCPRMI: comparison of 1f and 3f signals w/ calibration

The attached plot shows the spectra of all the REFL signals with the PRMI SB lock.

We excited the ITMY_LSC with 3000 counts. We used the Masayuki calibration of ITMY (5 nm / count * (1/f^2)) to estimate this peak in the REFL spectra.

To correctly scale the REFL spectra we account for the fact that the DTT BW was "0.187 Hz" and we turn off the "Bin" radio box before measuring the peak height with the cursor.

Since the ITMY motion is 3000 * 5e-9 / (580.1 Hz)^2 = 44.6 pm_peak, we want the DTT spectrum of the REFL spectra to report that too.

i.e. to convert from peak height to meters_peak, we use this formula:

meters_peak = peak_height * sqrt(BW) * sqrt(2)

I *think* that since the line shows up in multiple bins of the PSD, we should probably integrate a ~0.5 Hz band around the peak, but not sure. Need to check calibration by examining the time series, but this is pretty close.

Mystery: why are the REFL_I 3f signals nearly as good in SNR as the 1f signals? The modelling shows that the optical gain should be ~30-100x less. Can it be that our 1f electronics are that bad?

Bonus: notice how we have cleverly used the comb of bounce frequencies around the calibration line to determine that REFL11 is clipping!

Attachment 1: REFL_signals_CalLinesLinedUp.pdf
ELOG V3.1.3-