I can definitely see it on the BS and LVEA mics, though it's a bit hard to hear. There's a lot of ambient noise - I don't know if they're near HVACs or cleanrooms, or if it's the way that the signal is conditioned, or my headphones just have bad lowrange.

I don't see anything in DARM (second plot). If anyone wants to try coherence or anything else more sophisticated, the motorcycle sounds peaks at 1121972165 and extends 15 seconds on a side, though I think maybe the engine is idling for a minute before that.

I've heard two ETMY saturations announced while I've been here, the most recent one at ~17:24 UTC. I also see several large, 1 minute drops in the inspiral range over the course of this lock stretch. Suspecting that all of these gltiches are ETMY saturations, I've trended the saturation channel (H1:FEC-98_ACCUM_OVERFLOW) over the pas 10 hours (starting at 17:25:44) and I see that there are plenty.

Sadly, we *still* can't trend DMT channels in dataviewer (I would love it if someone told me I'm wrong), so I can't quickly put the inspiral range on the same trend plot to see if they're roughly coincident.

To aide in the offline study, I attach the channel map for each OSEM / ESD DAC channel from the Simulink front-end model. Recall you can find out where all of these OSEMs / QUADRANTs I mention are physically by looking at E1000617. Also recall, there are two EPICs channels for saturations one can look at for each DAC channel, the "instantaneous" and accumulative. The instantaneous channels are 
${IFO}:FEC-${DCUID}_DAC_OVERFLOW_${CARDNUM}_${CHANNELNUM}
${IFO}:FEC-${DCUID}_DAC_OVERFLOW_ACC_${CARDNUM}_${CHANNELNUM}

I cite the accumulative channels below.

H1:FEC-98_DAC_OVERFLOW_ACC_0_0 = M0/TOP F1
H1:FEC-98_DAC_OVERFLOW_ACC_0_1 = M0/TOP F2
H1:FEC-98_DAC_OVERFLOW_ACC_0_2 = M0/TOP F3
H1:FEC-98_DAC_OVERFLOW_ACC_0_3 = M0/TOP SD
H1:FEC-98_DAC_OVERFLOW_ACC_0_4 = M0/TOP LF
H1:FEC-98_DAC_OVERFLOW_ACC_0_5 = M0/TOP RT

H1:FEC-98_DAC_OVERFLOW_ACC_0_6 = R0/TOP LF
H1:FEC-98_DAC_OVERFLOW_ACC_0_7 = R0/TOP RT
H1:FEC-98_DAC_OVERFLOW_ACC_1_0 = R0/TOP F1
H1:FEC-98_DAC_OVERFLOW_ACC_1_1 = R0/TOP F2
H1:FEC-98_DAC_OVERFLOW_ACC_1_2 = R0/TOP F3
H1:FEC-98_DAC_OVERFLOW_ACC_1_3 = R0/TOP F4

H1:FEC-98_DAC_OVERFLOW_ACC_1_4 = L1/UIM UL
H1:FEC-98_DAC_OVERFLOW_ACC_1_5 = L1/UIM LL
H1:FEC-98_DAC_OVERFLOW_ACC_1_6 = L1/UIM UR
H1:FEC-98_DAC_OVERFLOW_ACC_1_7 = L1/UIM UR

H1:FEC-98_DAC_OVERFLOW_ACC_2_0 = L2/PUM UL
H1:FEC-98_DAC_OVERFLOW_ACC_2_1 = L2/PUM LL
H1:FEC-98_DAC_OVERFLOW_ACC_2_2 = L2/PUM UR
H1:FEC-98_DAC_OVERFLOW_ACC_2_3 = L2/PUM LR

H1:FEC-98_DAC_OVERFLOW_ACC_3_0  = L3/TST ESD Bias
H1:FEC-98_DAC_OVERFLOW_ACC_3_1  = L3/TST ESD UR
H1:FEC-98_DAC_OVERFLOW_ACC_3_2  = L3/TST ESD LR
H1:FEC-98_DAC_OVERFLOW_ACC_3_3  = L3/TST ESD UL
H1:FEC-98_DAC_OVERFLOW_ACC_3_1  = L3/TST ESD LL
(not the "odd" ordering of the TOP and ESD channels, which are different from "normal" OSEM stages.)

I've written some gwpy code to find ADC/DAC overflows and turn them into DQ segments: github link. It needs gwpy and has to run on a cluster so it has access to the data. If you want to use it in the control room, and gwpy has been installed there, I can easily convert it to use NDS.

To use it on the cluster, do
source ~detchar/opt/gwpysoft/etc/gwpy-user-env.sh
python make_overflow_dq_triggers.py -i H1 -c H1-omc-lsc-etm.txt -s 1121940832 -e 'lalapps_tconvert now'

The config file is attached, as is the code.

The times when the ETMY L3 DACs overflowed in this lock are below. I can scan them to see how big of a glitch they made.

 1121942076.7500 1121942077.0000
 1121950991.2500 1121950991.3750
 1121951661.9375 1121951662.0625
 1121953931.1250 1121953931.2500
 1121955356.8125 1121955356.9375
 1121957517.1875 1121957517.3125
 1121963083.7500 1121963083.8750
 1121966658.3125 1121966658.6250
 1121969119.5625 1121969119.7500

I've made some Omega scans. Here's a link to the directory: LHO webserver

The SNRs of the resulting glitches range from 200 to 3000. The biggest of these are about as bad as the beamtube cleaning glitches. We plan to make some veto flags for overflows like this, but obviously it's best to fix them.

See below for the coherence report.

Minute trends seem to have about a 2 hour delay getting to ldas.
Because of the difference in range of the 2 channels I had to make 2 plots but the drop in range does seem to coincide with the overflow.

I'm not sure if DMT now has access to H1:DMT-SNSH_EFFECTIVE_RANGE_MPC but that data is available via NDS2

I think that evan meant to say he increased the gain for CHARD by 20 dB by engaging FM1

Jeff pointed out that I should leave an instruction on how to kill the code since I left it running on the Ops computer. About 30 minutes after lock loss go to the terminal that has the TCS code running (the only terminal that refreshes itself every second or so), simply kill it by Ctrl+C. Do it repeatedly until the code is killed. I'd wait 30 minutes to allow the spherical power to decrese all the way to the bottom. This way I know the code was actually working and the data make sense.  

Hang, Evan

We measured the input-referred voltage noise of the summing node and common-mode boards.

• We terminated the input of the SNB that receives REFL9Q (INA2). INA1 was disabled. On the CMB, IN1 was enabled with -22 dB, and IN2 was disabled. The 40 Hz / 4 kHz boost was engaged. The fast gain was 7 dB.
• We measured the noise at the output of the CMB fast output.
• We then took the TF from SNB INA2 to CMB fast out. This is sufficient to get the input referred noise.

According to this estimate, the CARM loop is not shot noise limited; rather, at 1 kHz the noise is about a factor of 3 in ASD above shot noise.

I looked back at the CARM sensing noise data I took (on 12 Aug) using the new gain distribution: 0 dB SNB gain, −13 dB CMB common gain, 0 dB CMB fast gain, and 107 ct/ct digital MCL gain.

[For comparison, the old CARM gain distribution was 0 dB SNB gain, −20 dB CMB common gain, 7 dB CMB fast gain, and 240 ct/ct digital MCL gain.]

☞ For those looking for a message in this alog: something about the current frequency noise budgeting doesn't hang together. The projection based on the CARM sensing noise and the measured CARM-to-DARM coupling TF suggests a CARM-induced DCPD sum noise which is higher than what can be supported by coherence measurements.

☞ Second attachment: As expected, the noise (referred to the input of the SNB) is lower; at 40 Hz, it is about 350 nV/Hz^1/2. However, we are not really shot-noise (or dark-noise) limited anywhere.

☞ Third attachment: I am also including the CARM-to-DARM coupling TF from a few weeks ago. This TF was taken by injecting into the CARM excitation point and measuring the response in OMC DCPD sum, using the old CARM gain distribution. Then I referred this TF to the SNB input by multiplying by the SNB gain (0 dB), the CMB common gain (−20 dB), and the CMB common boost (40 Hz pole, 4 kHz zero, ac gain of 1).

This gives a coupling which is flat at 1.0×10⁻² mA/V, transitioning to 1/f² around 250 Hz. Or, to say it in some more meaningful units:

• Assuming a REFL9Q demodulation coefficient of 2900 V/W, this implies a flat power coupling of 3.4×10⁻⁶ mA/W above 250 Hz, rising like 1/f² below that.
• Assuming a CARM optical gain of 13 W/Hz and an optical pole of 0.48 Hz, this implies a 1/f frequency coupling above 250 Hz, a 1/f³ coupling below 250 Hz, and an overall magnitude of 6.2×10⁻⁵ mA/Hz at 1 kHz.
• Stated in terms of phase coupling (Stefan's favorite), the magnitude of the CARM optical plant is 6.2 W/rad above the cavity pole, which implies a flat phase coupling of 6.2×10⁻² mA/rad above 250 Hz, rising like 1/f² below that.

☞ Synthesis of the above: based on the measurements described above, at 40 Hz we expect a coupling into the DCPD sum of 350 nV/Hz^1/2 × 0.4 mA/V = 1.4×10⁻⁷ mA/Hz^1/2, which is very close to the overall DCPD sum noise of 3.2×10⁻⁷ mA/Hz^1/2.

But what is wrong with this picture? If 1.4/3.2 = 44 % of the DCPD sum noise comes from CARM sensing noise, we should expect a coherence of 0.44² = 0.19 between the DCPD sum and the CARM error point.

☞ First attachment: The coherence between the CARM error point and the DCPD sum is <0.01 around 40 Hz. Now, it is almost certainly the case that not all of the CARM error point noise is captured by LSC-REFL_SERVO_ERR, since this channel is picked off in the middle of the CMB rather than the end. Conservatively, if we suppose that LSC-REFL_SERVO_ERR contains only dark noise and shot noise, this amounts to 180 nV/Hz^1/2 of noise at 40 Hz referred to the SNB error point, or 0.72×10⁻⁷ mA/Hz^1/2 referred to the DCPD sum. This would imply a coherence of 0.05 or so.

☞ What is going on here?: Four possibilities I can think of are:

• I've overestimated the sensing noise.
• I've overestimated the CARM-to-DARM coupling TF.
• I've made an algebra mistake somewhere.
• LSC-REFL_SERVO_ERR is corrupted by noise that is not in the CARM loop.

☞ A word about noise budgeting: In my noise budget, there was a bug in my interpolating code for the CARM-to-DARM TF, making the projection too low below 100 Hz. With the corrected TF, the projected CARM noise is much higher and begins to explain the mystery noise from 30 to 150 Hz. However, given that the above measurements don't really hang together, this is highly speculative.

According to the CMB schematic and the vertex cable layout, the CARM error point monitor goes through some unity-gain op-amps and then directly into the ADC. So I don't think we have much chance of seeing the 180 nV/Hz^1/2 of shot/dark noise above the 4 µV/Hz^1/2 of the ADC.

According to the CMB schematic and the vertex cable layout, the CARM error point monitor goes a gain of 200 V/V and then directly into the ADC. So the 180 nV/Hz^1/2 of shot/dark noise appears as 36 µV/Hz^1/2 at the ADC. But as Daniel pointed out, this should be heavily suppressed by the loop. For comparison, the ADC's voltage noise is 4 µV/Hz^1/2.

For the sake of curiosity, I'm attaching the latest noise budget with the corrected CARM-to-DARM coupling TF. However, I note again that this level of frequency noise coupling is not supported by the required amount of coherence in any of our digitally acquired channels. Additionally, this level of frequency noise coupling is not seen at Livingston, although they've done a better job of TCS tuning than we have. I would not be surprised to find out that this coupling is somehow an overestimate.

Adding DetChar, SEI, and SYS Tags and an ASD.

For the record, the reference trace is 10 AVGs and the Live trace is 25 AVGs. Not sure why we're using this crazy weird template that doesn't display the number of averages, but I'll pick another battle.

Intent bit was turned off around 2015-07-26 02:24:00 Z in order to save the lock from 1 Hz pitch instability. I turned up the dHard pitch gain by a factor of 2.

1 hour of dHard pitch error signal is attached. The gain was turned up near the end.

Yes, it appears this feature is broken, at least in swept sine mode.

I pushed the abort button around 06:20:00 Z (around the 10 second mark in the attachment). The excitation continues at full strength until the last second. Then, as far as I can tell, there is some slightly different waveform being written to the excitation channel for about a second. Then the excitation stops abruptly, causing a lockloss.