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  17547   Tue Apr 18 19:29:43 2023 yutaUpdateBHDLO phase noise measurements in ITMX single bounce, MICH and FPMI

[Anchal, Yuta]

We have repeated LO phase noise measurement done in elog 40m/17511.
Method we took was the same, but this time, we used (1+G)*[C1:HPC-LO_PHASE_IN1]/[optical gain] to estimate the free-running noise, instead of using [C1:HPC-LO_PHASE_OUT] multiplied by LO1 actuator gain.
We confirmed that both method agrees down to ~ 10 Hz (at lower frequencies, OLTF measurement is not robust; we used interpolated measured OLTF (Attachment #1) for compensation).
Below is the summary of optical gains etc measured today.
Filter gains were adjusted to have UGF of 50 Hz for all.

LO_PHASE lock in ITMX single bounce
        Demod phase  Optical gain     filter gain
BH55_Q  -102.7 deg    6.9e9 counts/m  -0.34
BH44_Q  -5.7 deg     1.3e10 counts/m  -0.17

        Demod phase  Optical gain     filter gain
BH55_Q  -72.6 deg    8.7e8 counts/m   -4.4
BH44_Q  -27.6 deg    8.8e8 counts/m   -2.2

        Demod phase  Optical gain     filter gain
BH55_Q  24.2 deg     3.7e9 counts/m   -0.67
BH44_Q  2 deg        5.3e8 counts/m   -4.4
  (An order of magnitude smaller than elog 40m/17511)

The values are consistent with elog 40m/17511, except for BH44 in FPMI.
It took sometime to robustly rock LO_PHASE with BH44_Q in FPMI today.
After some alignment, offset tuning and demod phase tuning, it finally worked.
Demod phase of BH44 was tuned to have more DC signal when LO_PHASE was locked with BH55_Q, considering that BH55 and BH44 are orthogonal.
It actually created BH44_I having more amplitude (some noise?) than BH44_Q, but BH44_Q was more coherent to LO_PHASE fringe in BH55_Q.
It might be related to why we are not dark noise limited for BH44_Q, while BH55_Q is dark noise limited in FPMI, and why we cannot lock FPMI BHD with BH44.

Attachment 1: Screenshot_2023-04-18_19-48-11.png
Attachment 2: BH555_BH44_LO_Phase_Control_Noise_Budgets.pdf
BH555_BH44_LO_Phase_Control_Noise_Budgets.pdf BH555_BH44_LO_Phase_Control_Noise_Budgets.pdf BH555_BH44_LO_Phase_Control_Noise_Budgets.pdf
Attachment 3: BH55_BH44_LO_Phase_Control_Noise_Budgets.zip
Attachment 4: BH44_LO_Phase_Noise.pdf
  17549   Wed Apr 19 11:35:20 2023 YehonathanUpdateBHDPRMI estimated noise budget

First, simple stuff. We estimate the noise budget with total input and output noises. Later, we will break it down (ADC, DAC, whitening, dewhitening noises etc.):

We take the dark noise of AS55, REFL11 and make sure that the whitening and "unwhitening" software filters are on (attachment 1)

To convert cts to Watts we use the values from previous MICH noise budgeting for AS55:

PD_responsivity = 1e3*0.8 #V/W
ADC_TF = 3276.8 #cts/V
demod_gain = 2 #6.77 #According to https://wiki-40m.ligo.caltech.edu/Electronics/LSC_demoddulators
whitening_gain = 10**(24/20) #24 dB

We are not sure why the demod gain was chosen to be 2 and not 6.77 as in the Wiki, maybe it was chosen to match the measurements back then. The demod gain for AS55 was actually measured to be 2.4 in elog 16961.

For now, for lack of time, we use the PD responsivity and demod gain of REFL11 from the wiki:

PD_responsivity = 4.08e3*0.8 #V/W
ADC_TF = 3276.8 #cts/V
demod_gain = 4.74 #According to https://wiki-40m.ligo.caltech.edu/Electronics/LSC_demoddulators
whitening_gain = 10**(18/20) #18 dB

Using the Finesse model for PRMI (should push to git) we calculate the sensing matrix (attachment 3). We turn off the HOMs as it gives us strange results for now.

We take the output noise that was measured at the output of the BS coil driver measured in elog 16960.

Attachment 2 shows the estimated PRMI noise budget. Notice that the dark noise contribution is an order of magnitude better than MICH (elog 16984) due to PRG.

Attachment 1: PRMI_input_noise_spectrum.pdf
Attachment 2: Quickl_PRMI_noise_budget.pdf
Attachment 3: PRMI_sensing_matrix.pdf
  17560   Mon Apr 24 19:11:20 2023 KojiSummaryBHDLO/MI(DARM) signal strength comparison between the configurations

Yuta and I had a discussion last week about the signal strength between the configurations. Here are some naive calculations.
=== Please check the result with a more precise simulation ===

Michelson: Homodyne (HD) phase signal @44MHz is obtained from the combination of LO11xAS55 and LO CAxAS44. SBs at AS rely on the Schnupp asymmetry, the signal is weaker than the one with a single bounce beam from an ITM.

PRMI Carrier resonant:
- Despite the non-resonant condition of the sidebands, the HD phase signal @44MHz is expected to be significantly stronger (~x300) compared with the MI due to the resonance of the carrier and the 44MHz sidebands (the 2nd-order SBs of 11 and 55) in the PRC. Thus, the LO CAxAS44 term dominates the signal.
- The MICH signal @55MHz is enhanced by the resonant carrier by a factor of ~5.5, in spite of the non-resonant 55MHz SBs.
- The MICH signal @BHD is enhanced by the resonant carrier by a factor of ~300. This is the comparable phase sensitivity to PRFPMI case.

PRMI Sideband resonant:
- Despite the non-resonant condition of the carrier, the HD phase signal @44MHz is expected to be even stronger (~x400) compared with the MI due to the resonance of the 11MHz and 55MHz sidebands in the PRC. Thus, the LO11xAS55 term dominates the signal.
- The level of the MICH signal @55MHz is expected to be comparable to the one with PRMI carrier resonant as the resonant condition for the CA and 55MHz SBs are interchanged.
- The MICH signal @BHD is expected to be negligibly small due to non-resonance of the carrier.

PRFPMI: Now the carrier and the 11 and 55MHz sidebands are resonant.
- The HD phase signal @44MHz is expected to be the same level as the SB resonant PRMI, and the LO11xAS55 term dominates the signal.
- The level of the MICH sensitivity @AS 55MHz shows x300 of the MICH signal of the MI and x50 of the MICH with PRMI.
- The MICH signal @BHD is going to be the same level as the one with PRMI Carrier resonant.
The DARM signal shows up at the dark port signal enhanced by x300 from the MICH level due to the finesse of the arms.

Simple assumptions
1) PRM has a transmission of TPRM = 0.05
2) PRG is limited by the transmission of PR2 (TPR2=0.02 per bounce).
    If the IFO is lossless, PRG is 25 (i.e. theoretical maximum). In reality, the IFO loss is 2~3% -> PRG is ~15.
    The asymmetry of 30mm has a negligible effect.
3) For the anti-resonant fields, APRG is ~TPRM/4 = 0.0125
4) Arm finesse is 450. Therefore the phase enhancement factor N is ~300.
5) Modulation depth is ~0.1. J0=1, J1=0.05, J2=0.00125
6) Sideband leakage by the asymmetry is ɑ=l_asym wm / c = 0.008 for 11MHz and 5ɑ for 55MHz.

Single Bounce

The numbers are power transmission to each port
   Carrier              11MHz                    55MHz
TPRM TPR2 = 1.0e-3   J1^2 TPRM TPR2 = 2.5e-6  J1^2 TPRM TPR2 = 2.5e-6
AS TPRM/4    = 1.3e-2   J1^2 TPRM/4    = 3.1e-5  J1^2 TPRM/4    = 3.1e-5

LO phase @44MHz: LO 11 x AS 55 = Sqrt(2.5e-6 * 3.1e-5) = 8.8e-6


   Carrier               11MHz                     55MHz                      44MHz
TPRM TPR2 = 1.0e-3    J1^2 TPRM TPR2 = 2.5e-6   J1^2 TPRM TPR2   = 2.5e-6
AS TPRM ε^2  = 0.05 ε^2  ɑ^2 J1^2 TPRM  = 8.0e-9   25 ɑ^2 J1^2 TPRM = 2.0e-7  16 ɑ^2 J1^4 TPRM = 3.2e-10

LO phase @44MHz: LO 11 x AS 55 = Sqrt(2.5e-6 * 2.0e-7)  = 7.1e-7
                 LO CA x AS 44 = Sqrt(1.0e-3 * 3.2e-10) = 5.7e-7

AS MICH  @55MHz: AS CA x AS 55 = Sqrt(0.05 * 2.0e-7) ε  = 1.0e-4 ε
AS MICH  @BHD:  LO CA x AS CA = Sqrt(1.0e-3 * 0.05) ε  = 7.1e-3 ε

PRMI (Carrier Resonant)

   Carrier              11MHz                     55MHz                      44MHz
LO PRG TPR2 = 0.3       J1^2 APRG TPR2 = 2.5e-7   J1^2 APRG TPR2   = 2.5e-7  J1^4 PRG TPR2 = 1.9e-6
AS PRG ε^2  = 15 ε^2    ɑ^2 J1^2 APRG  = 8.0e-10  25 ɑ^2 J1^2 APRG = 2.0e-8  16 ɑ^2 J1^4 PRG = 9.6e-8

LO phase @44MHz: LO 11 x AS 55 = Sqrt(2.5e-7 * 2.0e-8)  = 7.1e-8
                 LO CA x AS 44 = Sqrt(0.3 * 9.6e-8)     = 1.7e-4
AS MICH  @55MHz: AS CA x AS 55 = Sqrt(15 * 2.0e-8) ε    = 5.5e-4 ε

AS MICH  @BHD:  LO CA x AS CA = Sqrt(0.3 * 15) ε       = 2.1 ε

PRMI (Sideband Resonant)

   Carrier               11MHz                     55MHz                      44MHz
LO APRG TPR2 = 1e-4      J1^2 PRG TPR2 = 7.5e-4    J1^2 PRG TPR2   = 7.5e-4  J1^4 APRG TPR2 = 6.3e-10
AS APRG ε^2  = 5e-3 ε^2  ɑ^2 J1^2 PRG  = 2.4e-6    25 ɑ^2 J1^2 PRG = 6.0e-5  16 ɑ^2 J1^4 APRG = 3.2e-11

LO phase @44MHz: LO 11 x AS 55 = Sqrt(7.5e-4 * 6.0e-5)  = 2.1e-4
                 LO CA x AS 44 = Sqrt(1e-4 * 3.2e-11)   = 5.7e-8
AS MICH  @55MHz: AS CA x AS 55 = Sqrt(5e-3 * 6.0e-5) ε  = 5.5e-4 ε

AS MICH  @BHD:  LO CA x AS CA = Sqrt(1e-4 * 5e-3) ε    = 7.1e-4 ε


   Carrier             11MHz                     55MHz                      44MHz
LO PRG TPR2 = 0.3      J1^2 PRG TPR2 = 7.5e-4    J1^2 PRG TPR2   = 7.5e-4   J1^4 APRG TPR2 = 6.3e-10
AS PRG ε^2  = 15 ε^2   ɑ^2 J1^2 PRG  = 2.4e-6    25 ɑ^2 J1^2 PRG = 6.0e-5   16 ɑ^2 J1^4 APRG = 3.2e-11

LO phase @44MHz: LO 11 x AS 55 = Sqrt(7.5e-4 * 6.0e-5)  = 2.1e-4
                 LO CA x AS 44 = Sqrt(0.3 * 3.2e-11)    = 3.1e-6
AS MICH  @55MHz: AS CA x AS 55 = Sqrt(15 * 6.0e-5) ε    = 3.0e-2
ε  ==> DARM@55MHz 9.0 ε
AS MICH  @BHD:  LO CA x AS CA = Sqrt(0.3 * 15) ε       = 2.1 ε     ==> DARM@BHD   6.3e2 ε

  17563   Tue Apr 25 21:21:03 2023 YehonathanUpdateBHDDewhitening noises

{Mayank, Paco, Yehonathan}

Dewhitening noise curves were taken using SR785+SR560 for the PRMI noise budget. One representative channel was measured at each board, suspensions were tripped before work was done. The input pins to the dewhitening boards were shorted using an exposed ribbon cable.

At each board, the measurement was taken with and without dewhitening filter on. The toggling of the dewhitening filter was done by turning on and off the SimDW filters at the coil filter screen of each suspension.

Attachment 1 summarizes the results.

ITMX dewhitening noise is much higher than the rest.

ITMY measurement turned out to be bogus since we mostly measured dark noise. The reason we made the gain so low in that measurement is that it was saturating the SR560 whenever we used gain>1.

Attachment 1: De-whitening_noises.pdf
  17564   Wed Apr 26 09:37:10 2023 PacoUpdateBHDIQ demod board gains for REFL11 and AS55

We measured the IQ demodulation board gains for REFL11 and AS55.

To do this, we replaced the PD input on the demod board with an RF signal at near the nominal frequencies of 11.066195 MHz and 55.330975 MHz using a Marconi 2024A identical to the one which sources the PM sidebands in our PSL. Even though we matched the modulation frequencies we found the two marconis were in practice offset by ~ 3 Hz. After tuning the frequency around a bit, we managed to get them to within 450 mHz.


We started with REFL11 IQ demod board. After sourcing 11.066198 MHz into the PD input port, we took the I and Q outputs and looked at them using an osciloscope. We measured the Vpp levels on both as well as the Marconi output. The resulting levels were

  • Source = 44.4 mVpp, I = 8.8 mVpp and Q = 10.8 mVpp ==> Gains are therefore 0.19 and 0.24. The amplitude gain of this board is sqrt(0.19 ** 2 + 0.24 ** 2) = 0.153. This is in stark disagreement with the wiki. Has the wiki finally failed us?


We then moved on to AS55 IQ demod board. After sourcing 55.330975 MHz* into the PD input port, we took the I and Q outputs and looked at them using an osciloscope. We measured the Vpp levels on both as well as the Marconi output. The resulting levels were

  • Source = 16.8 mVpp, I = 50.8 mVpp and Q = 56.3 mVpp ==> Gains are therefore estimated to be 3.3 and 3.7. The amplitude gain of this board is sqrt(3.3**2 + 3.7**2) = 4.74. This is in slight contrast with the previously measured gain of 2.8, but we think a factor of 2 may have been misplaced in either calculation since one typically estimates AMP = 2 * sqrt(I**2 + Q**2).

* Note that in the second test, we didn't match up the frequency, which caused I and Q outputs to have significant gains (instead of just I).

  17565   Wed Apr 26 11:27:49 2023 PacoSummaryBHDLO/MI(DARM) signal strength comparison between the configurations with finesse

I'm checking Koji + Yuta's not-so-naive calculations using finesse.

  Michelson PRMI carrier PRMI sideband PRFPMI
max(BH44) [W/m] 0.61 @ 90 deg 235.76 @ 90 deg    
max(BH55) [W/m] 4.55 @ 0 deg 1539.67 @ 0 deg    
max(BHD_DIFF) [W/m] 35550 10656140    

PRMI Carrier resonant:
- The HD phase signal @44 MHz is estimated to be 386.5 times stronger.
- The MICH signal @BHD_DIFF is estimated to be enhanced by a factor of 299.75.

PRMI Sideband resonant:
- The HD phase signal @44MHz is estimated to be () stronger.
- The MICH signal @BHD_DIFF is estimated to be suppressed by a factor of

PRFPMI: Now the carrier and the 11 and 55MHz sidebands are resonant.
- The HD phase signal @44MHz is estimated to be ().
- The MICH signal @BHD_DIFF is estimated to be the same level as the one with PRMI Carrier resonant.

  17567   Wed Apr 26 12:59:42 2023 YehonathanUpdateBHDUpdated noise budget with output electronics

I included the output electronic noises into the PRMI carrier noise budget (attachment 1).

The coil driver noise was calculated using the Johnson noises of the coil driver resistor:

PRM 430 ohm

BS 100 ohm

ITMX/Y 400 ohm

For the dewhitening noises I use the measurements from yesterday. As expected fro yesterday's measurements, the ITMX dewhitening noise is dominating. For the coil driver gain I use the recently measured actuation calibration (elog   17522 ) to extract it. I find that these gain values:

PRM 1.009

BS 1.333

ITMX/Y 0.24

For the DAC noise I assume 1uV/sqrtHz and use the simDW filters from the coil outputs MEDM screens as the DW filters TFs.


1. Break down input noises.

2. Measure how much light is reaching REFL11 to correct the sensing matrix and get the right shot noise.

Attachment 1: Quickl_PRMI_noise_budget.pdf
  17570   Fri Apr 28 18:40:49 2023 YehonathanUpdateBHDUpdated noise budget with some input electronic noises

{Mayank, Yehonathan}

Yesterday, we measured AS55 and REFL11 dark noises at the IQ demod boards outputs (attachment 1) using SR560+SR785 setup.

We also measured the whitening board noise of REFL11 using an improvised adapter (picture will come later). The measurement result is shown in attachment 2. Didn't have time to measure the whitening noise for AS55

Also, after realizing the Finesse model doesn't account for the REFL port attenuation I measure how much DC power at the REFL11 PD to be 0.8mW by aligning PRM and misaligning the rest of the optics.

For some reason, the power before the attenuation is only ~ 360mW. The Finesse model predicts around 700mW. Where is the rest of the light going?

I added the PDs Dark noises (using the recently measured IQ demod gains) and shot noise to the PRMI carrier noise budget (attachment 3). ADC and whitening noises coming soon.

Measurements and PRMI noise budget notebooks were uploaded to the 40m git.

Attachment 1: PDIQ_Demod_noises.pdf
Attachment 2: Whitening_noises.pdf
Attachment 3: Quick_PRMI_noise_budget.pdf
  17579   Wed May 3 12:11:52 2023 YehonathanUpdateBHDUpdated noise budget with measured noise and OLTF

{Paco, Yehonathan, Yuta}

Paco and Yuta locked PRMI carrier and I took the MICH OLTF measurement (attachment 1).

I downloaded 300secs of C1:LSC-MICH_IN1_DQ from when the PRMI was locked yesterday and calibrated it with the OLTF. I plot it together with the noise budget (attachment 2).

Attachment 1: PRMI_carrier_MICH_OLTF.pdf
Attachment 2: Quick_PRMI_noise_budget.pdf
  17582   Wed May 3 18:40:50 2023 YehonathanUpdateBHDWhitening noises measurements

{Mayank, Yehonathan}

We measured the noise at the WF1 (REFL11) and WF2 (AS55) boards at the LSC rack with and without whitening filter. We switch the filter on and off by switching off and on the unwhitening in the PDs filter bank.

Attachment 1 shows the measurements.

Attachment 2 shows the ratio between the noise with and without whitening filter. I also plot the inverse of the unwhitening MEDM filter (all the unWhite filters were the same). I tune the gain of that filter to match the ratio of the AS55 whitening noises.

This is because I couldn't match the ratio of the REFL11 noises.

Moreover, the overall gain doesn't make sense to me. AS55 whitening has a gain of 24db and REFL11 has a gain of 18db. I'm not entirely sure where these values should show up. Also seems like REFL11 whitening has more gain than AS55 whitening. Will have to investigate more tomorrow.

Attachment 1: Whitening_noises.pdf
Attachment 2: Whitening_noises_on_off_ratios.pdf
  17584   Mon May 8 17:05:30 2023 YehonathanUpdateBHDWhitening TF measurements

{Mayank, Yehonathan}

We measured today the TFs of the whitening boards. We measured in particular REFL11 I/Q and AS55 I/Q channels using SR785.

There seems to be an issue with turning on whitening gain bigger than 18dB. In all our measurements, when the whitening filter was off the TF was flat and had the right gain. However, when we turned the whitening on, the measured TFs for gains higher than 18 dB would like exactly like as if the whitening gain was 18 dB. This happened in all channels that were measured and across two separate whitening filter boards.

Also, it was hard to measure both low and high-frequency parts of the TFs when the gain was high. The gain difference should be normally 40 dB but for higher gains it seems smaller. We verified that at higher gain level the high-frequency response was dependant on the ecxitation level meaning we had some saturation there.


Attachment 1: Whitening_TFs_REFL11_I.pdf
Attachment 2: Whitening_TFs_REFL11_Q.pdf
Attachment 3: Whitening_TFs_AS55_I.pdf
Attachment 4: Whitening_TFs_AS55_Q.pdf
  17585   Tue May 9 11:32:04 2023 YehonathanUpdateBHDWhitening TF measurements

We forgot to take a reference TF measurement by looping the SR785 on itself using the same BNC cables used for the actual measurement. I took this measurement today (attachment 1). As can be seen, there is a significant delay in the SR785 + cables themselves.

I also retook some measurements on the AS5_I whitening channel for various gains. Being careful with the excitation level and the channel range on the SR785 to avoid saturation I was also able to see low-frequency gains higher than 18dB so that problem is gone too. The results are shown in attachment 2 with the reference phase subtracted from the measurements.

Attachment 1: Reference_TF.pdf
Attachment 2: Whitening_TFs_AS55_I.pdf
  17588   Wed May 10 11:49:34 2023 YehonathanUpdateBHDUpdated PRMI AS55+REFL11 noise budget

I added input noises and angle to length coupling to the noise budget.

I added ADC and whitening filters noise contributions. The ADC noise is assumed to be 1uV/sqrtHz and the whitening noises were measured before in elog 17582. I use the measured whitening filter (elog   17584 ) to get the signal referred noise and calibrate.

The angle-to-length coupling is computed by taking the suppressed OpLev noise spectra of ITMX, ITMY, and BS and converting them to length noise by using the recently measured coupling coefficients in ELOG   17583 

Attachment 1: Quick_PRMI_noise_budget.pdf
  17590   Thu May 11 12:05:24 2023 ranaUpdateBHDUpdated PRMI AS55+REFL11 noise budget

Is the A2L coming from the optical lever feedback? If so, we can make a 30 Hz ELP to cut it off by 60 Hz.

  17600   Wed May 24 13:19:28 2023 PacoUpdateBHDBH44 and BH55 dc transimpedance modified

We lowered the BH44 and BH55 DC transimpedances to ~ 50 V/A

[Paco, Yuta]


When locking the homodyne phase angle using BH44_Q or BH55_Q error signals, we notice the orthogonal quadrature (BH44_I, BH55_I) sometimes appears too noisy. The origin of this useless signal is not known, but we have recently attenuated these beams by placing ND filters before the two RFPDs to avoid saturation effects which become obvious when we lock PRMI. We decided to investigate further by the following tests:

  • Remove ND filters and lower the DC transimpedances to ~ 50 V/A
  • Check for scattering from suspended optics, e.g. by injecting a line at ITM PIT/YAW and look at the BH44/BH55 demodulated spectra
  • Check for PRCL sensing by BH44/BH55, e.g. by measuring the transfer function and/or running a simulation in finesse.
  • Check the RF spectra for the signals entering the IQ demod boards (including the 44 and 55 MHz LOs).

DC transimpedance modifications

The first thing we did was change the DC transimpedances of both RFPDs. After removing them from the table, we checked the schematics for 40m RFPDs on the wiki. The DC transimpedance for these gold RFPDs (D980454-v1-C) is estimated as (R22*(1+R13/R23), where these resistors are located around the follower and non-inverting amplifier stages along the DC output traces. After opening the two RFPDs and taking photos of the circuits before any changes (Attachment #1-2), we estimated the DC transimpedances from the measured values for R22, R23 and R13 and summarized them below:

Before R13 R22 R23 Est. DC transimpedance
BH44 8.2 kOhm 10.4 Ohm 99.9 Ohm ~ 864.05 V/A
BH55 99.9 kOhm 12.6 Ohm 102.7 Ohm ~ 12.26 kV/A

The changes were made on R13 (photos in Attachments #2-3) and the final values summarized below:

Before R13 R22 R23 Est. DC transimpedance
BH44 402.4 Ohm 10.4 Ohm 99.9 Ohm ~ 52.29 V/A
BH55 309.5 Ohm 12.6 Ohm 102.7 Ohm

~ 50.57 V/A

All changes have been summarized and recorded in the wiki. The ND filters were set to 0.04 (minimum attenuation) and RFPDs reinstalled.

Next steps:

Continue investigating these items:

  • Remove ND filters and lower the DC transimpedances to ~ 50 V/A
  • Check for scattering from suspended optics, e.g. by injecting a line at ITM PIT/YAW and look at the BH44/BH55 demodulated spectra
  • Check for PRCL sensing by BH44/BH55, e.g. by measuring the transfer function and/or running a simulation in finesse.
  • Check the RF spectra for the signals entering the IQ demod boards (including the 44 and 55 MHz LOs).
Attachment 1: PXL_20230524_191008053~2.jpg
Attachment 2: PXL_20230524_192525594~2.jpg
Attachment 3: PXL_20230524_193122794~2.jpg
Attachment 4: PXL_20230524_194225616~2.jpg
  17601   Wed May 24 17:36:25 2023 PacoUpdateBHDBH44_I content and PRC alignment

BH44 is sensitive to PRC alignment noise

[Paco, Yuta]

We investigated the content of BH44 demodulated signals under PRMI configuration. We had a few ideas of what was being sensed by BH44_I but we wanted to test this. Attachment #1 shows a timeseries screenshot of the DCPDs and BH44 error signals during PRMI lock stretch. It is pretty clear how BH44_I is sensing the same as REFLDC. To understand what REFLDC is sensitive to, we locked PRY (this is like having a lossy PRC) and looked at REFLDC, and BH44 error signals again. When PRY is aligned nicely, BH44 error signals show clean LO fringes and we could lock LO_PHASE stably (Attachment #2). Dithering the PRM YAW at 0.5 Hz (amplitude of 150 counts) is sensed by the REFLDC output, so we can attribute its fluctuations to the PRC misalignment (Attachment #3). Now we saw that the zero crossing of the homodyne phase angle changes following REFLDC, and LO_PHASE could not be locked stably. These suggest that alignment of PRC is sensed by BH44, and we might need alignment control to stably lock LO_PHASE in PRMI.
To get the idea of what is causing alignment fluctuations of PRC, we checked the spectrum of SUSPIT/YAW of PRM, PR2, PR3, BS, ITMX, and ITMY. It was not clear what is causing REFLDC fluctuations. (But we found that ITMX and ITMY has huge bounce mode at 16.2 Hz; see Attachment #4).

 - Check FINESSE to see what BH44 sees. PRCL? PRG?
 - Commission REFL WFS for alignment control of PRC?
 - Commission dither loops (add option to demodulate PRCL, modulate PR2 and PR3) for alignment control of PRC?
 - Check RF spectrum of BH44 and RF LO for 44 MHz (sidebands other than 44 MHz might be contaminating the signal).
 - Check ITMY scattering. Dither ITMY in YAW and check BH44.
 - Move on to PRMI sideband BHD

Attachment 1: Screenshot_2023-05-24_17-38-22_PRMI_REFLDCvsBH44.png
Attachment 2: Screenshot_2023-05-24_17-40-58_PRY_REFLDCvsBH44.png
Attachment 3: Screenshot_2023-05-24_17-44-49_PRY_REFLDCvsBH44_PRM0.5Hz.png
Attachment 4: Screenshot_2023-05-24_17-46-13_ITMSBOUNCE.png
  17607   Wed May 31 10:23:40 2023 YehonathanUpdateBHDSensing matrix model

I calculated the sensing matrix for PRMI carrier using the Finesse model (git updated) using MAXTEM=2. PRG is calculated to be 11.14, consistent with observations.

LO Phase is chosen such that it maximizes MICH signal on BHD_DIFF.

The RFPDs were assumed to have a demodulation angle that maximizes the signal they are intended to sense (using MAXTEM=2).

That is,

BH44/55 maximized for HPC

REFL11 maximized for PRCL

AS55 maximized for MICH

Values are in uW/nm

REFL11_I 1.9e-2


7.6e-2 4.0e-2 0

Some interesting numbers here. First, BHD_SUM is sensitive to MICH. It's not surprising because PRM reflects the MICH signal into POP.

Also interesting, BHD_SUM is super sensitivef to PRCL. Much more than REFL11. We can use it to enhance the PRCL lock.

Unfortunately, although BH44/55 are sensitive to HPC (LO phase), they are swamped by MICH and PRCL. This issue needs to be addressed in order to gain robust LO Phase locking in PRMI.

  17608   Wed May 31 12:08:07 2023 ranaUpdateBHDSensing matrix model

it is great to see a sensing matrix without 900 digits of precision!

for choosing what sensor to use, we don't necessarily care about W/m, but more like the equivalent noise of the sensor in m/rtHz, taking into account the real noise floor. In that case, we would possibly rotate the demod phase to maximize the SNR rather than maximize the S or minimize the N.

  17673   Fri Jul 7 20:34:43 2023 HirokiSummaryBHDBHD alignment has been restored

[Yuta, Hiroki]

BHD alignment has been restored

We aligned the AS beam (reflection of ITMX) and LO beam and maximized the fringing of the BHD differential signal (Attachment 1).
We used LO1, SR2 and AS4 for the alignment and the result parameters are shown in Attachment 2.

Procedure log of BHD alignment

Alignment of LO beam:

  • ETMY, ETMX and ITMY were misalinged during this BHD alignment
  • Misaligned SR2 to have only the LO beam in BHD DCPDs
  • Tuned LO1 so that the LO beam comes to the previous position in the video

Alignment of AS beam:

  • Restored SR2
  • Tuned AS4 so that the AS beam comes to the position of LO beam
  • Repeated the followings for the pitch and the yaw until the fringing was maximized:
    • Misaligned AS beam using SR2
    • Restore the alignment of AS beam using AS4
    • If the fringing gets worse, it means that you moved SR2 in the wrong direction. Move the SR2 in the opposite direction next and repeat the procedures above.
    • If the fringing gets better, it means that you moved SR2 in the correct direction. Continue the procedures above.
Attachment 1: Screenshot_2023-07-07_20-27-31_BHDalignment_monitors.png
Attachment 2: Screenshot_2023-07-07_20-29-14_BHDalignment_IFO.png
Attachment 3: BHDcamera.jpg
  17703   Thu Jul 20 17:28:03 2023 KojiUpdateBHDBHD Platform OMC cables

Dean made the OMC cables for the BHD Platform. They are going through the C&B process.

From left to right: QPD cable, PZT cable with Picomotor etc, DCPD cables

Attachment 1: image001.png
  17715   Wed Jul 26 00:30:16 2023 HirokiUpdateBHDMode-matching breadboard for BHD OMCs

Currently, I'm constructing the mode-matching telescope on a breadboard for the alignment of two OMCs for BHD.

What I did on July 25th:

  • Constructed the input optical system before the fiber collimator (Attachment  1).
  • Measured the mode-matching efficiency to the fiber collimator: 0.878 +/- 0.006


  • Fix the end of the fiber on the mode-matching breadboard.
  • Arrange two lenses to match the output beam with the OMC eigen mode (Horizontal: 489.6 um, Vertical: 490.5 um)
Attachment 1: InputSystem.jpg
  17722   Thu Jul 27 03:39:57 2023 HirokiUpdateBHDMode-matching breadboard for BHD OMCs

I almost finished constructing the mode-matching breadboard today.

What I did on July 26th:

  • Constructed the mode-matching telescope on a breadboard (Attachment  1).
    • Height of optical axis: 3.5" (from the bottom of the breadboard)
    • Used two lenses of f = 200 mm @ ~6 cm and ~24 cm from the surface of the collimator mount
      (Used JamMt to obtain the solution)
    • Tuned the position of the two lenses monitoring the resulting beam waist so that the waist becomes ~ 500 um
      (OMC eigen mode: 489.6 um (horizontal), 490.5 um (veritical))


  • Measure the dimensions of the resulting mode-matching telescope
  • Measure the beam profile of the resulting beam
  • Estimate the upper limit of the mode-matching efficiency to the OMC


Output beam profile from collimator:
I measured the beam profile of the output from the collimator (Attachment 2).

Beam waist X: 44.3 +/- 0.5 um
Beam waist Y: 46.1 +/- 0.6 um
Waist position X (from the front surface of the collimator mount): 1.64 +/- 0.04 cm
Waist position Y (from the front surface of the collimator mount): 1.70 +/- 0.05 cm

I found that the resulting beam is not collimated but focused.
The model number is not written on the collimator so I was not able to find its specification.

Attachment 1: ModeMatchingTelescopeBreadboard.jpg
Attachment 2: BeamProfileFromCollimator.pdf
  17732   Fri Jul 28 22:43:26 2023 JCUpdateBHDBHD Platform Preparation.

BHD Platform has been washed and set to dry over the weekend

Yesterday, I began to wipe down the BHD platform in the C&B lab. While I was cleaning, I wanted to be very particulate of how clean it was here because of how long it was sitting in Don’s office. There was dust that was built up in the crevasses of the underside of the platform and it was be difficult to get out. I spent ~30 min clean and I felt like I was better off washing the entire piece. 

I contacted Maty and this morning we decided to place the platform inside the Machine Washer. We had to remove the 2 basket and shelves in order to fit the Platform inside. We decided to stand the platform vertically as shown in Attachment #1 and hold in place using Zipties. After a few soft tugs on the platform, Matt and I agreed that it was pretty secure. We started the parts washer and ran it for 10 minutes. The Machine washer was set to use water at 120°F. 

After the machine washer was done, Maty removed the platform from the machine and we were rinsed of using water. 

What’s next ? 

We agreed to leave the platform to dry over the weekend. This will set us back a day, but we did not want to insert to platform to be baked while it was still wet. We left the platform under the vent to dry over the weekend.

Attachment 1: IMG_6212.jpeg
Attachment 2: IMG_6213.jpeg
Attachment 3: IMG_6214.jpeg
  17735   Mon Jul 31 15:34:56 2023 JCUpdateBHDBHD Platform Preparation.

[Maty, JC]
This morning, Maty and I proceeded to work on the BHD Platform work. We rinsed off the BHD platform one more time with water and placed onto the work bench. Here, we wiped down using IPA and removed a ton of the metal shavings from the platform. (Attachment #2 & #3 ) The threads in the platform had a ton of shaving, but we were able to get majority, if not all, off the part. 

Next, we garbed up and prepared the large tub for the BHD Platform. The tub contained 107 L of water, so we added 1000 mL of Liquinox into the tub. The Platform was a bit too wide, so we had to put it in at an angle. We used a beaker to pour the solution over all of the part. Along with this, we used the Sonicating probe to clean the threads. ( Attachment #3 ) We did this for the entire part and then drained the tub. 

I lifted and placed the platform into the blue machine parts washer to rinse off the part. We went thread by thread to make sure all of the Liquinox was rinsed off of the part, this to ~30 minutes. ( Attachment #4 )After rinsing the part off, we brought it over to the clean room flow bench. Here, Maty placed large clothes under to platform. She then went through each hole of the platform with the TopGun to remove the loose excess water. ( Attachement #5 )

We have stopped here and are leaving the BHD Platform to dry overnight. We will insert the BHD Platform into the Large Air Bake Oven TOMORROW! We plan to have it ready by the end of the week. 


Attachment 1: IMG_6233.jpeg
Attachment 2: IMG_6234.jpeg
Attachment 3: IMG_6235.jpeg
Attachment 4: IMG_6236.jpeg
Attachment 5: IMG_6237.jpeg
  17737   Mon Jul 31 16:04:54 2023 JCUpdateBHDBHD Platform Preparation.

I began to prepare the temporary clean room where we will be putting together the BHD Platform Assembly - D2100085. I wiped down the table with the Acetone and IPA multiple times. After this, I used Mylar sheets to use as the cleanroom walls. I slit the sheet into separate pieces to allow easy access and held these sheets up by using Kapton tape. Next, I connected the HEPA booth to an extension cord which was plugged into the Wall outlet of 1X3. 


Attachment 1: IMG_6209.jpeg
  17739   Tue Aug 1 02:51:46 2023 HirokiSummaryBHDMode-matching breadboard for BHD OMCs

Mode-matching breadboard has been constructed

I have constructed the mode-matching breadboard for aligning the BHD OMCs.
I also measured the profile of the resulting beam:

Beam waist X: 496 +/- 2 um
Beam waist Y: 504 +/- 3 um
Waist position X (from the front surface of the collimator mount): 224 +/- 1 cm
Waist position Y (from the front surface of the collimator mount): 236 +/- 2 cm

Maximum mode-matching efficiency to OMC: 99.78 +/- 0.07 % (if the waist of the OMC eigen mode is place at 230 cm)
(OMC eigen mode: 489.6 um (horizontal), 490.5 um (veritical))

The details are shown in the following attachments:

  • Attachment 1: Current configuration and summary of beam profile
  • Attachment 2: Resulting beam profile
  • Attachment 3: Photo of mode-matching bread board
Attachment 1: MMTBBdrawing.pdf
Attachment 2: ResultingBeamProfile.pdf
Attachment 3: MMTBBphoto.jpg
  17745   Wed Aug 2 10:33:53 2023 JCUpdateBHDBHD Platform Preparation.

BHD platform is estimated to stop baking by the end of the day. We are following the LIGO Procedure and baking at 150°C By tomorrow morning, I will have the platform out of the Air Bake Oven.

· I have began to prepare the smaller components for the assembly for baking. I am trying to get all of these components cleaned and together by the end of next week.


Attachment 1: Screenshot_2023-08-02_at_10.32.10_AM.png
  17807   Thu Aug 24 02:54:19 2023 KojiUpdateBHDOMC Interface Aligner / BHD OFI arrangement

OMC Interface Aligner - (It's upside down...)

BHD OFI arrangement

Attachment 1: Screenshot_2023-08-24_at_02.50.23.png
Attachment 2: Screenshot_2023-08-24_at_02.51.53.png
Attachment 3: Screenshot_2023-08-24_at_02.52.32.png
  17811   Fri Aug 25 20:27:33 2023 KojiUpdateBHDOMC Interface Aligner

A bit improved the design of OMC Interface Aligner

The idea is...The OMC I/F aligner covers the OMC for aligning the kinematic mounts (3 pairs of a V-groove and a ball) on the OMC. This makes the kinematic mount of two OMCs identical.

However, the OMC kinematic mount can't be adjusted because all the fasteners of the kinematic mounts are hidden by their counterparts.
We can copy the alignment of the OMC to the aligner, but the opposite is not possible.

Attachment 1: Screenshot_2023-08-25_at_20.26.46.png
  17814   Tue Aug 29 02:02:51 2023 KojiUpdateBHDBHD Prep Status

Ready / Soon Ready
- BHD OMC Cables ready
- OMC#1 / OMC#4 ready
- BHD Platform parts being cleaned
- Assembly area HEPA being built
=> We will be soon ready to assemble BHD Platform and test with the OMC

In progress
- OMC locking setup (Moku)
- Connectors being attached to the BHD Platform actuators (picos & rotation stage)
- BHD Platform OFI parts drawing/procurement

- 40m BHD Electronics (BHD Adapter / DCPD TIA / Actuator driver I/F)

Other vent items
- In-vac ribbon cable holder (JC)

- Connector holder

- Scattered light control

- Pre-vent work
    * ASS recovery / extension

    * ETMX tuning
    * Vertex Eletronics upgrade
    * Fix PZT amps / PZT
    * Acromag

- Vent work items
    * New PR2
    * Alignment

  13   Thu Oct 25 00:01:21 2007 ranaSoftware InstallationCDSGEO DV => LIGO DV
Martin Hewitson of GEO600 fame has modified the cool GEO DV
to work with the LIGO NDS system with some NDS advice from Rolf (who's over in Germany this week).

I've moved it onto the 40m CDS system and installed it on the AdhikariLab computer named 'django'. It worked immediately.

I modified the main .m file to include the 40m's NDS server. When you run it you have to include the path to the NDS
client written by Ben Johnson.

The attached is a screenshot of it working on a Mac; it looks as cool on Linux.

Its installed in /cvs/cds/caltech/apps/ligoDV/. In matlab you navigate to that directory and then
type addpath('/cvs/cds/caltech/apps/linux/UNIX_NDS_Client_beta2/') to add the NDS client.
On the Solaris machines, type type addpath('/cvs/cds/caltech/apps/solaris9/UNIX_NDS_Client_beta2/') instead.

Then type ligoDV to start it up. Then click away and have fun.

In the example I've selected
and plotted its specgram.

Big grin
Attachment 1: Picture_1.png
  28   Mon Oct 29 23:25:42 2007 tobinSoftware InstallationCDSframes mounted
I mounted the frames directory on mafalda and linux3. It's intentionally not listed in the /etc/fstab so that an fb crash won't prevent the controls machines from booting. The command to mount the frames directory is:

mount fb40m:/frames/frames /frames
  144   Fri Nov 30 11:22:22 2007 ajwSummaryCDSGEO DV => LIGO DV

Martin Hewitson of GEO600 fame has modified the cool GEO DV
to work with the LIGO NDS system with some NDS advice from Rolf (who's over in Germany this week).

I've moved it onto the 40m CDS system and installed it on the AdhikariLab computer named 'django'. It worked immediately.

I modified the main .m file to include the 40m's NDS server. When you run it you have to include the path to the NDS
client written by Ben Johnson.

The attached is a screenshot of it working on a Mac; it looks as cool on Linux.

Its installed in /cvs/cds/caltech/apps/ligoDV/. In matlab you navigate to that directory and then
type addpath('/cvs/cds/caltech/apps/linux/UNIX_NDS_Client_beta2/') to add the NDS client.
On the Solaris machines, type type addpath('/cvs/cds/caltech/apps/solaris9/UNIX_NDS_Client_beta2/') instead.

Then type ligoDV to start it up. Then click away and have fun.

In the example I've selected
and plotted its specgram.

Big grin

Download and installation instructions, as well as a few examples for use
can be found here (typical lsc username and password):

  170   Wed Dec 5 19:25:07 2007 ranaDAQCDSDMF
I made a database file on C1AUX called dmf.db. It has 9 DMF EPICS channels which are also trended
so that one can now write data to those channels from a DMF Monitor and the data will be records.

New channels:

I added these to C1AUX because it doesn't do much and can be booted without having much effect.
(it controls Mech Shutters, Video, and Illuminators. It used to also do the EO Shutter but I
removed that from its startup.cmd and it will no longer load those records).
  270   Fri Jan 25 21:36:40 2008 ranaUpdateCDSmDV / channel issues
Fri Jan 25 21:30:00 2008

As it turns out, the residual problem with the mDV stuff was not to do with our button pushing episode but instead fallout from the 'turning off of the computers' during the water leak caused by the rain and construction.

The /frames partition from fb0 (the FrameBuilder) is not mounted to the control machines via vfstab; it does not remount on bootup. I originally did this because Ben Johnson and Dave Barker had warned me that during a power outage, fb0 may not come up right away. This could make the control room machines hang up for awhile. I elected to have the mount be by hand.

So the thing to do is to put the mount command into the cold start procedures (Andrey). Its in an old elog entry of mine from Feb '07.
  278   Sun Jan 27 21:44:48 2008 ranaUpdateCDSSeismic BLRMS on Matlab
I wrote a matlab script to produce band limited RMS trends from our accelerometers. It mimics the code written
by Ed Daw which makes the seismic FOMs at the sites.

Here's how it works:
  • Use mDV to get data by reading directly from frames.
  • Use the Matlab pwelch function to produce a power spectrum of the channels.
  • Use the Matlab find function and rms.m to get the RMS in user-defined frequency bands.
  • Makes a tdswrite command string which writes all the values to EPICS channels.
  • The EPICS channels are just a list of simple names in a database file.
  • The channel names are (will be) added to the C0EDCU.ini file so that its all trended.

The code is in the mDV/extra/C1 directory; its ~20 lines of code (excluding comments and spaces).

Next up is to add more DMF trend channels to the database and upgrade the code to use a .conf file
instead of hardcoded channel names. We should also evaluate if the bands I used are appropriate for the 40m;
I just used Ed's choices (0.1-0.3, 0.3-1, 1-3, 3-10, and 10-30 Hz).

In the medium term, we should make this compiled (like what RW did with the linetracker), and explore if we
want it to write values faster than 1/minute.
Attachment 1: seisBLRMS.m
% Seismic BLRMS Monitor
% RA 08-01-26

% 0 for no messages, 1 for debugging
debug_flag = 1;

% ------------ Build channel list
... 82 more lines ...
  356   Tue Mar 4 19:14:09 2008 ranaConfigurationCDSTDS & SVN
Matt, Rob, Rana

Today we added the TDS software to the 40m SVN repo.

First we rationalized things by deleting all the old TDS directories and taking
the tds_mevans dir and making it be the main one (apps/linux/tds).

We also deleted all of the TDS directories in the project area. It is now very
likely that several scripts will not work.
We're going to have the teething
problems of repointing everything to the nominal paths (in the apps areas).

Finally we did:
svn import tds https://40m.ligo.caltech.edu/svn/40m/tds --username rana

to stick it in. To check it out do:
svn checkout https://40m.ligo.caltech.edu/svn/40m/tds --username rana

We'll get a couple of the O'Reilly SVN books as well to supplement our verion control knowledge.
Unitl then you can use the SVN cheat sheets available at:
  383   Sun Mar 16 17:03:32 2008 robConfigurationCDSASS code change

I've updated the ass.mdl file in the directory:


to get us started in the adaptive PEM noise subtraction.

After several iterations of remote help from Alex, the code compiles and runs, receives signals from the LSC, PEM, and MC2, and communicates with the suspension controllers. I've also adapted the .par file from the code generator, but haven't got the testpoints working with the new ASS code. There are no MEDM screens yet, and Matt's adaptive filter code has not been installed (there's a matrix as a placeholder).

Putting in the adaptive code should be simple, building the MEDM screens tedious, and getting the testpoints working uncertain. I noticed that the new testpoint.par file starts at a different channel number than the previous (working) version, which is strange. I probably have a script somewhere to change all these numbers by a constant offset, but I don't know if that's the actual problem--maybe stuff just needs to be rebooted.

The code receives as input the first 24 channels from the PEM ADCU, the eight suspension control signals from the LSC, and the output of the MCL filter from MC2. It outputs to the MCL filter input of each suspension (except MC2).
  394   Sat Mar 22 22:39:02 2008 mevansSummaryCDSDirect Form 2 filters are bad
Here I show a comparison between the filter algorithm currently used in LIGO (Direct Form II), and an alternative algorithm designed to reduce numerical noise. The input signal is

x = sin(2 * pi * t) + 1e-9 * sin(2 * pi * (fs / 4) * t);

where fs = 16384 is the sample rate. The filter is a 4th order notch at 1Hz (f_poles = f_zeros = 1Hz, Q_poles = 1, Q_zeros = 1e6). It is clear that the DF2 algorithm produces a noise floor that is, for this simple filter, 1e-11 / rtHz smaller than the input drive amplitude (see plots). That should probably be scary given how many second-order-sections we run our signals through. The low-noise form does a somewhat better job. The low-noise algorithm has the same memory and computational requirements as DF2, and our CDS guys have the code in hand. I suggest we start testing soon.

(The code is included below. You will need my Matlab library to run the top level test script.)
Attachment 1: low-noise_filtering.png
Attachment 2: low-noise_zoom.png
Attachment 3: FiltRT.zip
  459   Tue Apr 29 21:09:12 2008 ranaDAQCDSFE Filters
These are new FE filters for downsampling and upsampling. We will be going from native hardware sampling rates of 64k down to 32k, 16k, and 2k.

The attached plot shows these filters. They are 3dB ripple, 40 dB stopband, 4th order elliptic filters in which I have moved the zeros around
into good places (e.g. to the Nyquist frequency).

I'm also attaching the .txt file containg the filter coefficients and the design strings. The filters are called x2, x4, and x32, for the
D2, D4, and D32 downsampling, respectively.
Attachment 1: fefilters.jpg
Attachment 2: fefilters.txt
# Computer generated file: DO NOT EDIT
### ULYAW                                                                    ###
... 28 more lines ...
  1782   Thu Jul 23 07:34:45 2009 AidanUpdateCDSAdded C2 MEDM screens to 40m SVN.


See Adhikari eLOG entry: http://nodus.ligo.caltech.edu:8080/AdhikariLab/194

  1801   Tue Jul 28 18:32:21 2009 KojiUpdateCDSRCG work

Peter and Koji,

We are constructing a setup for the new 40m CDS using Realtime Code Generator (RCG).
We are trying to put simulated suspensions and test suspension controllers on a different processors of megatron
in order to create a virtual control feedback loop. Those CDS processes are communicating
each other via a shared memory, not via a reflective memory for now.

After some struggles with tremendous helps of Alex, we succeeded to have the communication between the two processes.
Also we succeeded to make the ADC/DAC cards recognized by megatoron, using the PCI express extension card replaced by Jay.
(This card runs multi PCI-X cards on the I/O chasis.)

Next steps:
- Establish a firewall between the 40m network and megatron (Remember this)
- Make DTT and other tools available at megatron
- Try virtual feedback control loops and characterize the performance
- Enable reflective memory functionalities on megatron
- Construct a hybrid system by the old/new CDSs
- Controllability tests using an interferometer

o Each cdsIPC should have a correct shared memory address spaced by 8 bytes. (i.e. 0x1000, 0x1008, 0x1010, ...)

Note on MEDM
o At the initial state, garbage (e.g. NaN) can be running all around the feedback loops. They are invisible as MEDM shows them as  "0.0000".
To escape from this state, we needed to disconnect all the feedback, say, by turning off the filters.

Note on I/O chasis
o We needed to pull all of the power plugs from megatron and the I/O chasis once so that we can activate
the PCI-e - PCI-X extension card. When it is succeeded, all (~30) LEDs turn to green.

  2045   Fri Oct 2 18:04:45 2009 robUpdateCDSDTT no good for OMC channels

I took the output of the OMC DAC and plugged it directly into an OMC ADC channel to see if I could isolate the OMC DAC weirdness I'd been seeing.  It looks like it may have something to do with DTT specifically.

Attachment 1 is a DTT transfer function of a BNC cable and some connectors (plus of course the AI and AA filters in the OMC system).  It looks like this on both linux and solaris.

Attachment 2 is a transfer function using sweepTDS (in mDV), which uses TDS tools as the driver for interfacing with testpoints and DAQ channels. 

Attachment 3 is a triggered time series, taken with DTT, of the same channels as used in the transfer functions, during a transfer function.  I think this shows that the problem lies not with awg or tpman, but with how DTT is computing transfer functions. 


I've tried soft reboots of the c1omc, which didn't work.   Since the TDS version appears to work, I suspect the problem may actually be with DTT.

Attachment 1: omc_dac_dtt.png
Attachment 2: omc_dac_sweepTDS.png
Attachment 3: omc_dac_dtt_ts.png
  2173   Tue Nov 3 12:47:01 2009 KojiConfigurationCDS1Y9 Rack configuration update

For the CDS upgrade preparation I put and moved those stuff at the rack 1Y9:

Placed 1Y9-12 ADC to DB44/37 Adapter LIGO D080397

Placed 1Y9-14 DAC to IDC Adapter LIGO D080303

Moved the ethernet switch from 1Y9-16 to 1Y9-24

Wiki has also been updated.

  2181   Thu Nov 5 16:24:59 2009 KojiUpdateCDSETMY CDS test stuff

Joe, Peter, Jay, Koji, Rana

We put the new CDS stuff at Y end 1Y9 rack.


  • megatron
  • wireless router
  • IO chasis (black)
  • Extention cable (between megatron & IO chasis)
  • 1 ADC card
  • 1 DAC card
  • 1 BIO card
  • The adapter box for ADC
  • The adapter box for DAC
  • The adapter box for BIO
  • 2x IDC-DB37 cable for the ADC box - AA chasis
  • 1x IDC cable for the DAC box - Pentek
  • 1x DB cable for the BIO box
  • 1x +/-15V cable for the BIO box
  2233   Wed Nov 11 01:33:52 2009 peteUpdateCDSRCG ETMY code update

 I've added the side coil to the model controller and plant, and the oplev quad to the model controller and plant.  After the megatron wipe, the code now lives in /home/controls/cds/advLigo/src/epics/simLink.  The files are mdc.mdl (controller) and mdp.mdl (plant).  These RCG modules go at 16K with no decimation (no_oversampling=1 in the cdsParameters block) so hopefully will work with the old (16K) timing.

I've loaded many of the filters, there are some eft to do.  These filters are simply copied from the current frontend.  

Next I will port to the SUS module (which talks to the IO chassis).  This means channel names will match with the current system, which will be important when we plug in the RFM.

  2243   Wed Nov 11 20:46:07 2009 peteUpdateCDSRCG ETMY phase I update

The .mdl code for the mdc and mdp development modules is finished.  These modules need more filters, and testing.  Probably the most interesting piece left to do is putting in the gains and filters for the oplev model in mdp.  It might be OK to simply ignore oplevs and first test damping of the real optic without them.   However, it shouldn't be hard to get decent numbers for oplevs, add them to the mdp (plant) module, and make sure the mdc/mdp pair is stable.  In mdp, the oplev path starts with the SUSPIT and SUSYAW signals. Kakeru recently completed calibration of the oplevs from oplev cts to radians:   1403  .  From this work we should find the conversion factors from PIT and YAW to oplev counts, without making any new measurements.  (The measurements wouldn't be hard either, if we can't simply pull numbers from a document.)  These factors can be added to mdp as appropriate gains.

I've also copied mdc to a new module, which I've named "sas" to address fears of channel name collisions in the short term, and replaced the cpu-to-cpu connections with ADC and DAC connections.  sas can be the guy for the phase I ETMY test.  When we're happy with mdc/mdp, we hopefully can take the mdc filter file from chans, replace all the "MDC" strings with "SAS", and use it.

  2259   Thu Nov 12 17:24:29 2009 Koji, Joe, PeterConfigurationCDSETMY CDS test started

We started the test of the new CDS system at ETMY.

The plan is as follows:
We do the ETMY test from 9:30 to 15:00 at ETMY from Nov 12~17. This disables the ETMY during this period.
From 15:00 of the each day, we restore the ETMY configuration and confirm the ETMY work properly.

Today we connected megatron to the existing AA/AI modules via designated I/F boxes. The status of the test was already reported by the other entry.

During the test, c1iscey was kept running. We disabled the ETMY actuation by WatchDog. We did not touch the RFM network.

After the test we disconnected our cables and restored the connection to ICS110B and the AI/AA boards.

The WatchDog switches were released.

The lock of the ETMY was confirmed. The full interferometer was aligned one by one. Left in the full configuration with LA=off.

  2471   Sun Jan 3 08:23:39 2010 ranaConfigurationCDSautoburt.pl 'fixed' for post 2009 years

Tobin & Keith pointed out in the LLO ilog that there was a code bug in the autoburt.pl script for autoburts.

I edited the autoburt.pl script so that it will work from now until 2099 (by which time we may no longer be using this version of perl):

nodus:autoburt>diff autoburt.pl~ autoburt.pl
<     $thisyear = "200".$timestamp[5];
>     $thisyear = "20".$timestamp[5];

The autoburt has not been working ever since 11PM on New Year's eve.

I ran it by hand and it seems to run fine. I noticed along the way that it was running on op340m (our old Sun Blade 150 machine). The autoburt.pl was pointing at /cvs/cds/bin/perl

which is Perl v5.0. I changed it to use '/usr/bin/env' and now points at '/usr/bin/perl' which is perl 5.8. It runs fine with the new perl:

op340m:scripts>time perl /cvs/cds/scripts/autoburt.pl >> /cvs/cds/caltech/logs/autoburtlog.log
5.37u 6.29s 2:13.41 8.7%

Also ran correctly, via cron, at 9AM.

  2640   Thu Feb 25 15:49:05 2010 AlbertoAoGCDSNew IO Chassis for the new CDS
Yesterday Kiwamu and I went to Downs to take all the available parts of the IO chassis that Gary and I had put together over there.
We've got only 3 of the 5 that we need for the Upgrade. The other 2 are currently being used for some other purpose in Downs labs.
I'm not sure about what each chassis has supposed to contain. They all also look different from each other.
Anyway, it looks like there should be a sort of motherboard and an IO Chassis Interface Board (DCC# D0902029) in each of them. The IO Chassis Interface Board is just a board with a bunch of PCI slots.
This is what the 3 chassis that we've got yesterday have:
Chassis 1
- 1 very big "motherboard"
- power supply
Chassis 2
- small motherboard
- IO Interface Board (DCC# D0902029)
- power supply
Chassis n.3
- "Dolpjin" motherboard
- IO Interface Board
- power supply
Apparently 2 of these 3 chassis are still missing their IO interface boards,
Also all chassis are still missing all the connections to powering, fans, LEDs, power and reset buttons. It's not clear how these connections should be. Gary didn't know it either.
ELOG V3.1.3-