GPIB<->WIFI on Agilent Network Analyzer 4395A was broken.
The connection was fixed by replacing and configuring the LINKSYS bridge.

=======

Kiwamu and I have identified that the LINKSYS bridge was guilty.

I knew that we had another one in the bathroom, I configured it.

HOW TO CONFIGURE IT

• You need a host with 192.168.1.*.
• Connect the host and the LINKSYS directly
• Open http://192.168.1.226/
• Select 40MARS and infrastructure mode
• Register it in the MAC filter of the 40MARS (see wiki and use your head)

The new unit works fine.

I checked the malfunctioning unit and the configuration was the same as the others.

The bad one detected the existence of 40MARS during the configuration, but it does not establish
the connection in the actual use. I am afraid that something is broken or some setting is lost
during the power supply shutdown.

EOM TEMPMON and HEATER DRIVEMON have been hooked up to the following channels.

C1:IOO-EOM_TEMPMON
C1:IOO-EOM_HEATER_DRIVEMON 

What a fragile circuit...

I found some of the resistors popped up from the board because of the tension by the Pomona grabbers.
I tried to fix it based on the schematic (photo) and the board photo.

Now stochmon for 11MHz and 55MHz is running. The calibration / noise measurement are going to be post later...

Here is a drawing of where the monitors are coming from:

 Since we can't put current into the ADC, the heater drivemon is measuring the input of the OP27, which is related to the amount of current sent to the heater.

Jenne: The point you indicate for the heater monitor is a virtual ground--it will be driven to zero by the circuit if it's functioning properly; the readout should be done at the input pin (2, I think) to the BUF634.

Koji: This is odd, as I made a point of not attaching any clips directly to resistors for exactly this reason. I was also careful to trim resistor/capacitor leads so that they were not towering over the breadboard and prone to bending (with the exception of the gain-setting resistor of the AD620, which was changed at the last minute). At the end of the day, it is a breadboard circuit with Pomona "readout", so it's not going to be truly resilient until I put it on a protoboard. Another thing: I think the small Pomona clips are absolutely terrible, since they slip off with piconewtons of tension; I could not find any more regular clips, so I used them against my better judgment.

Those clips for the readouts were the ones who popped out.
When I have restored the connections, I checked the schematic and the heater drive mon is clipped on the output side of the OP27.

I left the HEPA at the 50% level @5AM, Nov 24

I modified elogd.c as shown below in order not to allow to display all of the entries at once by specifying page number "0".

After this modification, elog seems to have survived 66 times of attacks by googlebots.

==============================

rossa:src>pwd
/cvs/cds/caltech/elog/elog-2.8.0/src

rossa:src>diff elogd.c_orig elogd.c
19912a19913,19917
>
>    /* KA */
>    if (page_n<1)
>      page_n = 1;
>


I calculated the F2A filters for the input mode cleaner optics as described in T010140-01-D eq (4). On Ranas recommendation I added an s/ ( w_0 * Q ) term to the numerator.

The used values are:

w_0 = 2pi / s
h= 0.0009
D= 2.46957E-2
Q=10

I put theses filters into C1:SUS-MC1_TO_COIL_1_1 to _4_1 . For convenience split in Z and P. Well it doesn't work. After a few seconds the optic begins to swing wildly.

Tried the wiener filter with the TF from p.5900

Tried it out with the TFs from p.5900:

Adding a filter element that compensates the acutator TF makes the MC lose lock.

Woo. Pretty crazy. The numerators should only be ~10% larger than the denominator below 1 Hz. Let's try again.

We are now trying to understand why the coherence between SUS-X_SUSPOS_IN1 and SUS-X_SUSPOS_OUT is lost below 1 Hz for X = MC1, MC2, MC3, BS, ITMX, ITMY, ETMX, ETMY, SRM. It is OKEY only for PRM but the different filteres are used there. For PRM - 30:0.0 and Bounce Roll, for all others - 30:0.0 and Cheby. The transfer functions between these two signals plotted in foton and fft tools are also not the same.

If we switch off all the filters between these 2 signals, than the coherence is one. If one of the filters is switched on, everything is also fine. But if there are several present, than they filter the signal in unexpected way.

Moreover it seems that the coherence is dependent on the input signal. The coherence is better with local dumping than without.

 We have done the following on the c1sus and c1lsc computers : provided excitation, let the signal pass through filters 30:0.0 and Cheby and plotted the coherence between in and out signals.

c1sus computer - coherence is corrupted

c1lsc computer - coherence is not corrupted

 New RFAM mon calibration

It seems as if someone was looking into this on Wednesday, but as there's no elog, I think probably not.

Tonight we noticed that, in fact, the watchdogs don't work for any of the corner optics (I confirmed that they do work for the ETMs).

Whether the switch for the coil drivers is enabled or disabled, the voltage monitor on the coil drivers responds to the digital signals.

I tried restarting the c1susaux process, hitting reset on the crate, and also keying the crate. The +5V light on the front of the crate is flickering somewhat, but I'm not sure if this is new or not since the power outage. The next step is to track the Xycom signal from the card over to the coil driver to find where the signal is failing to happen.

Since its not working for any of the corner optics, I suspect the crate and not the cards. If that's the issue this will be a painful fix. We are sort of assuming that this is due to the power outage, but in fact, I cannot tell when the last time was that someone rigorously verified the working of these switches. [

I][B]We had better get ready for upgrading our SLOW controls, Jamie.[/B][/I]

[Rana, Den, Mirko]

It seems you can shoot yourself in the foot if your filter modules are too complex.

Den discovered this when looking into the C1:SUS-MC?_SUSPOS filter module named Cheby, consisting of cheby1("LowPass",6,1,12)cheby1("LowPass",2,0.1,3)gain(1.13501) by noticing that the coherence between input and output of the filter is low.

Cheby filter:

This is most likely due to the filter spanning more than the 16 orders of precision that the double data type spans.

The coherence is fine when one splits the filter in two, giving every cheby1 filter its own module. The coherence is also fine when you use the Cheby filter in a 2kHz system, although the freq. response looks very odd

Black: 16kHz, Red 2kHz (yes the filter was converted correctly, no text file editing there)

The problem occurs on c1lsc as well as c1sus computer.

Looking into the foton files actually points to a precision problem, with the huge range of scale covered in there:

C1:MCS 16kHz (Cheby: Original filter with low coherence. CHbyTST & ChebyTST: Original filter split amongst two filter modules)
################################################################################
### SUS_MC3_LSC                                                              ###
################################################################################
# DESIGN   SUS_MC3_LSC 0 zpk([0],[30],0.333333,"n")
# DESIGN   SUS_MC3_LSC 1 cheby1("LowPass",6,1,12)
# DESIGN   SUS_MC3_LSC 2 cheby1("LowPass",2,0.1,3)gain(1.13501) \
#                       
# DESIGN   SUS_MC3_LSC 3 cheby1("LowPass",2,0.1,3)gain(1.13501)cheby1("LowPass",6,1,12)
# DESIGN   SUS_MC3_LSC 4 ellip("BandStop",4,1,40,16.1,16.9)ellip("BandStop",4,1,40,23.7,24.5)gain(1.25871)
###                                                                          ###
SUS_MC3_LSC 0 12 1  32768      0 30:0.0          9.942903833923793  -0.9885608209680459   0.0000000000000000  -1.0000000000000000   0.0000000000000000
SUS_MC3_LSC 1 21 3      0      0 CHbyTST     9.095012702673064e-18  -1.9978637592754149   0.9978663974923444   2.0000000000000000   1.0000000000000000
                                                                 -1.9984258494490537   0.9984376515442090   2.0000000000000000   1.0000000000000000
                                                                 -1.9994068831713223   0.9994278587363880   2.0000000000000000   1.0000000000000000
SUS_MC3_LSC 2 12 1  32768      0 ChebyTST    1.228759186937126e-06  -1.9972699801052749   0.9972743606395355   2.0000000000000000   1.0000000000000000
SUS_MC3_LSC 3 12 4  32768      0 Cheby       1.117558041371939e-23  -1.9972699801052749   0.9972743606395355   2.0000000000000000   1.0000000000000000
                                                                 -1.9978637592754149   0.9978663974923444   2.0000000000000000   1.0000000000000000
                                                                 -1.9984258494490537   0.9984376515442090   2.0000000000000000   1.0000000000000000
                                                                 -1.9994068831713223   0.9994278587363880   2.0000000000000000   1.0000000000000000
SUS_MC3_LSC 4 12 8  32768      0 BounceRoll     0.9991466189294013  -1.9996634951844035   0.9997010181703262  -1.9999611719719754   0.9999999999999997
                                                                 -1.9999303040590390   0.9999684339228864  -1.9999605309876360   0.9999999999999999
                                                                 -1.9999248796830529   0.9999668732412945  -1.9999594299327190   1.0000000000000002
                                                                 -1.9996385459838455   0.9996812069238987  -1.9999587601905868   1.0000000000000000
                                                                 -1.9996161812709703   0.9996978939989944  -1.9999163485656493   0.9999999999999999
                                                                 -1.9998855694973159   0.9999681878303275  -1.9999154056705493   0.9999999999999998
                                                                 -1.9998788577090287   0.9999671193335300  -1.9999137972442669   1.0000000000000000
                                                                 -1.9995951159123118   0.9996843310430819  -1.9999128255920269   1.0000000000000000

C1:OAF 2kHz
###############################################################################
### YARM_IN                                                                  ###
################################################################################
# DESIGN   YARM_IN 0 zpk([0],[30],0.333333,"n")
# DESIGN   YARM_IN 3 cheby1("LowPass",6,1,12)cheby1("LowPass",2,0.1,3)gain(1.13501)
# DESIGN   YARM_IN 4 ellip("BandStop",4,1,40,16.1,16.9)ellip("BandStop",4,1,40,23.7,24.5)gain(1.25871)
# DESIGN   YARM_IN 8 cheby1("LowPass",6,1,12)cheby1("LowPass",2,0.1,3)gain(1.13501)zpk([],[10],1,"n")
###                                                                          ###
YARM_IN  0 12 1   4096      0 30:0.0           9.56649943398763  -0.9119509539166185   0.0000000000000000  -1.0000000000000000   0.0000000000000000
YARM_IN  3 12 4   4096      0 Cheby       1.829878084970283e-16  -1.9828889048300398   0.9830565293861987   2.0000000000000000   1.0000000000000000
                                                                 -1.9868188576622443   0.9875701115261976   2.0000000000000000   1.0000000000000000
                                                                 -1.9940934073784453   0.9954330165532327   2.0000000000000000   1.0000000000000000
                                                                 -1.9781245722853238   0.9784022621062476   2.0000000000000000   1.0000000000000000

 [Rana, Mirko]

I redid this calculation. The idea behind it is to get rid on any pitch that is introduced by applying longitudinal feedback to the mirrors. This coupling happens because the center of percussion for pitch , which is identical with the point where the wires lift off of the mirror, is above the center of mass.

With the same values as before, just less faulty math and Q = 2 instead of 10 we end up with the following filters:

For the lower coils (red), compared to corresponding preexisting BS filters (black):

The upper coils' TF is just mirrored at the 0dB magnitude axis, and have a corresponding frequency response.

I switched the F2a filters on for all MC mirrors. For convenience they are split into F2aZeros and F2aPoles. Everything seems fine. The F2a filters seem to be off for ( all ?) other mirrors.

We replaced the complicated Cheby filter module with three separate filter modules. Probably the filter doesn't need to be so complicated, but rather not change too many things at once. The new filter modules are called:
Ch1, Ch2, Ch3 and are in filter module 3,9, and 10 of the C1:SUS-MC?_SUSPOS filters. The coherence with these filters is fine. Someone should look into the possibility of simplifying these filters.

It would be good to check for numerical problems in other filters!

[Rana, Mirko]

I tried out the virtual pendulum idea today. The idea is to compensate the physical pendulum via the control system, and then add a virtual pendulum formed in the control system. We know the actuator TF from p. 5900 and apply its inverse to the C1:SUS-MC?_SUSPOS filters. Also we add an pendulum Q=3 with a resonance frequency of 0.1Hz to the POS control loops.

The result is pretty awesome!

1. Black: Standard config. Wfs on. New Cheby filter in place ( p. 6031 )
2. Red: With virtual pendulum. Extra eliptic LP filter @ 2.5Hz

Filter shape:

This is stable for 5-10minutes, at which point it falls out of lock, swinging in yaw.

What I did:

    I have changed the c1ioo model such that the signals which are demodulated in the WFS lockin (the SIG inputs) are now picked up just after the input matrix.  This permits us to put a notch filter at the excitation frequency into the WFS servo filterbanks and thus prevent the excitation of all the actuators when we wish to excite just one of them. 

The Problem:

    I had followed the procedure of determining the TF coefs between actuators (MC1,2,3 P and Y ) and sensors (WFS1, 2 and MC2Trans P and Y)  and found the output matrix by inverting this TF coef matrix. However these matrices, once substituted for the heuristically determined matrices were always unsuccessful in keeping the WFS servo lock.  The reason appeared to be that when the loops are closed the exitation of one actuator led to the excitation of all actuators through the cross couplings in the output matrix.    In order to prevent this we need a notch filter in the servo filter banks.   But then we will not be able to see the sensor response after the servo filters since the response at 10Hz would be blocked from reaching the lockins.  So I shifted the point at which we sample the sensor response to a point before the WFS servo filters. 

The solution:

a) shift the point where the lockin input signals are picked up in the c1ioo model.

b) retune the lockin servo phases to minimise Q phase

c) edit the WFS lockin scripts to ensure that the 10Hz notch is turned on

d) measure the TF coefs and compute the -1*inverse

e) plug it into the output matrix and tweak the gains to ensure a stable lock

f) examine cross talk by comparing the expected TF in each loop with the expected loop TF.

Current state:

  I have completed steps a to e above.  The loops are stable and the error signal is suppressed (see attached pdf files)

To be done:

  The open loop transfer function has to be compared with expected OLTF to be sure we have minimised cross talk.

c1sus has been shutdown so that the optics dont bang around.  This is because the watch dogs are not working.

 Could be that what we're seeing is the noise floor of the Direct Form II filter structure (see Matt's 2008 elog) which shows an example (also see G0900928-v1 ).

The AM transfer function of the Y end laser has been measured again, but using the frequency-doubled laser this time.

Here is the latest plot of the AM transfer function. The Y-axis is calibrated to RIN (Relative Intensity Noise) / V.

IFBW (which corresponds to a frequency resolution) was set to 100 Hz and the data was averaged about 40 times in a frequency range of 100 kHz - 400 kHz.

Also the zipped data is attached.

It is obvious that out current modulation frequency of 179 kHz (178850 Hz) is not at any of the notches.

It could potentially introduce some amount of the offset to the PDH signal, which allows the audio frequency AM noise to couple into the PDH signal.

Currently I am measuring how much offset we have had because of the mismatched modulation frequency and how much the offset can be reduced by tuning the modulation frequency.

 I've checked foton files for small numbers. There are several other filters besides "Cheby" that are presented with small numbers. For example, "BTW0.01" in the LOCKING_Q, LOCKING_I modules,  "SeisDaytime"  in the SUP_MC3_SP_NOISE and others. The output of the commands is presented below.

>chans

>cat C1???.txt | grep e-23

SUP_MC3_SP_Y_NOISE 2 12 4  16384      0 SeisDaytime    4.3736847644382e-23    -1.99994247406600     0.99994247737496    -0.00000000000000    -1.00000000000000

SUP_MC3_SP_YAW_NOISE 2 21 4      0      0 SeisDaytime    4.3736847644382e-23    -1.99994247406600     0.99994247737496    -0.00000000000000    -1.00000000000000

SUP_MC3_SP_ROLL_NOISE 2 21 4      0      0 SeisDaytime    4.3736847644382e-23    -1.99994247406600     0.99994247737496    -0.00000000000000    -1.00000000000000

SUP_MC3_SP_PIT_NOISE 2 21 4      0      0 SeisDaytime    4.3736847644382e-23    -1.99994247406600     0.99994247737496    -0.00000000000000    -1.00000000000000

SUP_MC2_SP_Y_NOISE 2 12 4  16384      0 SeisDaytime    4.3736847644382e-23    -1.99994247406600     0.99994247737496    -0.00000000000000    -1.00000000000000

SUP_MC2_SP_YAW_NOISE 2 21 4      0      0 SeisDaytime    4.3736847644382e-23    -1.99994247406600     0.99994247737496    -0.00000000000000    -1.00000000000000

SUP_MC2_SP_ROLL_NOISE 2 21 4      0      0 SeisDaytime    4.3736847644382e-23    -1.99994247406600     0.99994247737496    -0.00000000000000    -1.00000000000000

SUP_MC2_SP_PIT_NOISE 2 21 4      0      0 SeisDaytime    4.3736847644382e-23    -1.99994247406600     0.99994247737496    -0.00000000000000    -1.00000000000000

SUP_MC1_SP_Y_NOISE 2 12 4  16384      0 SeisDaytime    4.3736847644382e-23    -1.99994247406600     0.99994247737496    -0.00000000000000    -1.00000000000000

SUP_MC1_SP_YAW_NOISE 2 21 4      0      0 SeisDaytime    4.3736847644382e-23    -1.99994247406600     0.99994247737496    -0.00000000000000    -1.00000000000000

SUP_MC1_SP_ROLL_NOISE 2 21 4      0      0 SeisDaytime    4.3736847644382e-23    -1.99994247406600     0.99994247737496    -0.00000000000000    -1.00000000000000

SUP_MC1_SP_PIT_NOISE 2 21 4      0      0 SeisDaytime    4.3736847644382e-23    -1.99994247406600     0.99994247737496    -0.00000000000000    -1.00000000000000

SUS_MC3_SUSYAW 3 12 4  32768      0 Cheby       1.117558041371939e-23  -1.9972699801052749   0.9972743606395355   2.0000000000000000   1.0000000000000000

SUS_MC3_SUSSIDE 3 12 4  32768      0 Cheby       1.117558041371939e-23  -1.9972699801052749   0.9972743606395355   2.0000000000000000   1.0000000000000000

SUS_MC3_SUSPOS 3 12 4  32768      0 Cheby       1.117558041371939e-23  -1.9972699801052749   0.9972743606395355   2.0000000000000000   1.0000000000000000

SUS_MC3_SUSPIT 3 12 4  32768      0 Cheby       1.117558041371939e-23  -1.9972699801052749   0.9972743606395355   2.0000000000000000   1.0000000000000000

SUS_MC3_LSC 3 12 4  32768      0 Cheby       1.117558041371939e-23  -1.9972699801052749   0.9972743606395355   2.0000000000000000   1.0000000000000000

SUS_MC2_SUSYAW 3 12 4  32768      0 Cheby       1.117558041371939e-23  -1.9972699801052749   0.9972743606395355   2.0000000000000000   1.0000000000000000

SUS_MC2_SUSSIDE 3 12 4  32768      0 Cheby       1.117558041371939e-23  -1.9972699801052749   0.9972743606395355   2.0000000000000000   1.0000000000000000

SUS_MC2_SUSPOS 3 12 4  32768      0 Cheby       1.117558041371939e-23  -1.9978637592754149   0.9978663974923444   2.0000000000000000   1.0000000000000000

SUS_MC2_SUSPIT 3 12 4  32768      0 Cheby       1.117558041371939e-23  -1.9972699801052749   0.9972743606395355   2.0000000000000000   1.0000000000000000

SUS_MC1_SUSYAW 3 12 4  32768      0 Cheby       1.117558041371939e-23  -1.9972699801052749   0.9972743606395355   2.0000000000000000   1.0000000000000000

SUS_MC1_SUSSIDE 3 12 4  32768      0 Cheby       1.117558041371939e-23  -1.9972699801052749   0.9972743606395355   2.0000000000000000   1.0000000000000000

SUS_MC1_SUSPIT 3 12 4  32768      0 Cheby       1.117558041371939e-23  -1.9972699801052749   0.9972743606395355   2.0000000000000000   1.0000000000000000

SUS_SRM_SUSYAW 3 12 4  32768      0 Cheby         1.1175580413719e-23    -1.99726998010527     0.99727436063954     2.00000000000000     1.00000000000000

SUS_SRM_SUSPOS 3 12 4  32768      0 Cheby         1.1175580413719e-23    -1.99726998010527     0.99727436063954     2.00000000000000     1.00000000000000

SUS_SRM_SUSPIT 3 12 4  32768      0 Cheby         1.1175580413719e-23    -1.99726998010527     0.99727436063954     2.00000000000000     1.00000000000000

SUS_PRM_SUSYAW 3 12 4  32768      0 Cheby         1.1175580413719e-23    -1.99726998010527     0.99727436063954     2.00000000000000     1.00000000000000

SUS_PRM_SUSPOS 3 12 4  32768      0 Cheby         1.1175580413719e-23    -1.99726998010527     0.99727436063954     2.00000000000000     1.00000000000000

SUS_PRM_SUSPIT 3 12 4  32768      0 Cheby         1.1175580413719e-23    -1.99726998010527     0.99727436063954     2.00000000000000     1.00000000000000

SUS_ETMX_SUSYAW 3 12 4  32768      0 Cheby       1.117558041371939e-23  -1.9972699801052749   0.9972743606395355   2.0000000000000000   1.0000000000000000

SUS_ETMX_SUSSIDE 3 12 4  32768      0 Cheby       1.117558041371939e-23  -1.9972699801052749   0.9972743606395355   2.0000000000000000   1.0000000000000000

SUS_ETMX_SUSPOS 3 12 4  32768      0 Cheby       1.117558041371939e-23  -1.9972699801052749   0.9972743606395355   2.0000000000000000   1.0000000000000000

SUS_ETMX_SUSPIT 3 12 4  32768      0 Cheby       1.117558041371939e-23  -1.9972699801052749   0.9972743606395355   2.0000000000000000   1.0000000000000000

SUS_ETMX_LOCKIN1_I 5 21 2      0      0 BTW0.01     1.351815922494362e-23  -1.9999929139431329   0.9999929139578397   2.0000000000000000   1.0000000000000000

SUS_ETMX_LOCKIN1_Q 5 21 2      0      0 BTW0.01     1.351815922494362e-23  -1.9999929139431329   0.9999929139578397   2.0000000000000000   1.0000000000000000

SUS_ETMX_LOCKIN2_I 5 21 2      0      0 BTW0.01     1.351815922494362e-23  -1.9999929139431329   0.9999929139578397   2.0000000000000000   1.0000000000000000

SUS_ETMX_LOCKIN2_Q 5 21 2      0      0 BTW0.01     1.351815922494362e-23  -1.9999929139431329   0.9999929139578397   2.0000000000000000   1.0000000000000000

SUS_ETMY_SUSYAW 3 12 4  32768      0 Cheby       1.117558041371939e-23  -1.9972699801052749   0.9972743606395355   2.0000000000000000   1.0000000000000000

SUS_ETMY_SUSSIDE 3 12 4  32768      0 Cheby       1.117558041371939e-23  -1.9972699801052749   0.9972743606395355   2.0000000000000000   1.0000000000000000

SUS_ETMY_SUSPOS 3 12 4  32768      0 Cheby       1.117558041371939e-23  -1.9972699801052749   0.9972743606395355   2.0000000000000000   1.0000000000000000

SUS_ETMY_SUSPIT 3 12 4  32768      0 Cheby       1.117558041371939e-23  -1.9972699801052749   0.9972743606395355   2.0000000000000000   1.0000000000000000

SUS_PIT_NOISE_FILT 2 21 4      0      0 SeisDaytime    4.3736847644382e-23    -1.99994247406600     0.99994247737496    -0.00000000000000    -1.00000000000000

SUS_ROLL_NOISE_FILT 2 21 4      0      0 SeisDaytime    4.3736847644382e-23    -1.99994247406600     0.99994247737496    -0.00000000000000    -1.00000000000000

SUS_YAW_NOISE_FILT 2 21 4      0      0 SeisDaytime    4.3736847644382e-23    -1.99994247406600     0.99994247737496    -0.00000000000000    -1.00000000000000

SUS_Y_NOISE_FILT 2 12 4  16384      0 SeisDaytime    4.3736847644382e-23    -1.99994247406600     0.99994247737496    -0.00000000000000    -1.00000000000000

SUS_PIT_NOISE_FILT 2 21 4      0      0 SeisDaytime    4.3736847644382e-23    -1.99994247406600     0.99994247737496    -0.00000000000000    -1.00000000000000

SUS_ROLL_NOISE_FILT 2 21 4      0      0 SeisDaytime    4.3736847644382e-23    -1.99994247406600     0.99994247737496    -0.00000000000000    -1.00000000000000

SUS_YAW_NOISE_FILT 2 21 4      0      0 SeisDaytime    4.3736847644382e-23    -1.99994247406600     0.99994247737496    -0.00000000000000    -1.00000000000000

SUS_Y_NOISE_FILT 2 12 4  16384      0 SeisDaytime    4.3736847644382e-23    -1.99994247406600     0.99994247737496    -0.00000000000000    -1.00000000000000

BS_LOCKIN2_Q 5 21 2      0      0 BTW0.01     1.351815922494362e-23  -1.9999929139431329   0.9999929139578397   2.0000000000000000   1.0000000000000000

BS_LOCKIN2_I 5 21 2      0      0 BTW0.01     1.351815922494362e-23  -1.9999929139431329   0.9999929139578397   2.0000000000000000   1.0000000000000000

BS_LOCKIN1_Q 5 21 2      0      0 BTW0.01     1.351815922494362e-23  -1.9999929139431329   0.9999929139578397   2.0000000000000000   1.0000000000000000

BS_LOCKIN1_I 5 21 2      0      0 BTW0.01     1.351815922494362e-23  -1.9999929139431329   0.9999929139578397   2.0000000000000000   1.0000000000000000

BS_SUSPIT 3 12 4  32768      0 Cheby       1.117558041371939e-23  -1.9972699801052749   0.9972743606395355   2.0000000000000000   1.0000000000000000

BS_SUSPOS 3 12 4  32768      0 Cheby       1.117558041371939e-23  -1.9972699801052749   0.9972743606395355   2.0000000000000000   1.0000000000000000

BS_SUSSIDE 3 12 4  32768      0 Cheby       1.117558041371939e-23  -1.9972699801052749   0.9972743606395355   2.0000000000000000   1.0000000000000000

BS_SUSYAW 3 12 4  32768      0 Cheby       1.117558041371939e-23  -1.9972699801052749   0.9972743606395355   2.0000000000000000   1.0000000000000000

ITMX_LOCKIN2_Q 5 21 2      0      0 BTW0.01     1.351815922494362e-23  -1.9999929139431329   0.9999929139578397   2.0000000000000000   1.0000000000000000

ITMX_LOCKIN2_I 5 21 2      0      0 BTW0.01     1.351815922494362e-23  -1.9999929139431329   0.9999929139578397   2.0000000000000000   1.0000000000000000

ITMX_LOCKIN1_Q 5 21 2      0      0 BTW0.01     1.351815922494362e-23  -1.9999929139431329   0.9999929139578397   2.0000000000000000   1.0000000000000000

ITMX_LOCKIN1_I 5 21 2      0      0 BTW0.01     1.351815922494362e-23  -1.9999929139431329   0.9999929139578397   2.0000000000000000   1.0000000000000000

ITMX_SUSPIT 3 12 4  32768      0 Cheby       1.117558041371939e-23  -1.9972699801052749   0.9972743606395355   2.0000000000000000   1.0000000000000000

ITMX_SUSPOS 3 12 4  32768      0 Cheby       1.117558041371939e-23  -1.9972699801052749   0.9972743606395355   2.0000000000000000   1.0000000000000000

ITMX_SUSSIDE 3 12 4  32768      0 Cheby       1.117558041371939e-23  -1.9972699801052749   0.9972743606395355   2.0000000000000000   1.0000000000000000

ITMX_SUSYAW 3 12 4  32768      0 Cheby       1.117558041371939e-23  -1.9972699801052749   0.9972743606395355   2.0000000000000000   1.0000000000000000

ITMY_LOCKIN2_Q 5 21 2      0      0 BTW0.01     1.351815922494362e-23  -1.9999929139431329   0.9999929139578397   2.0000000000000000   1.0000000000000000

ITMY_LOCKIN2_I 5 21 2      0      0 BTW0.01     1.351815922494362e-23  -1.9999929139431329   0.9999929139578397   2.0000000000000000   1.0000000000000000

ITMY_LOCKIN1_Q 5 21 2      0      0 BTW0.01     1.351815922494362e-23  -1.9999929139431329   0.9999929139578397   2.0000000000000000   1.0000000000000000

ITMY_LOCKIN1_I 5 21 2      0      0 BTW0.01     1.351815922494362e-23  -1.9999929139431329   0.9999929139578397   2.0000000000000000   1.0000000000000000

ITMY_SUSPIT 3 12 4  32768      0 Cheby       1.117558041371939e-23  -1.9972699801052749   0.9972743606395355   2.0000000000000000   1.0000000000000000

ITMY_SUSPOS 3 12 4  32768      0 Cheby       1.117558041371939e-23  -1.9972699801052749   0.9972743606395355   2.0000000000000000   1.0000000000000000

ITMY_SUSSIDE 3 12 4  32768      0 Cheby       1.117558041371939e-23  -1.9972699801052749   0.9972743606395355   2.0000000000000000   1.0000000000000000

ITMY_SUSYAW 3 21 4      0      0 Cheby       1.117558041371939e-23  -1.9972699801052749   0.9972743606395355   2.0000000000000000   1.0000000000000000

PRM_LOCKIN2_Q 5 21 2      0      0 BTW0.01     1.351815922494362e-23  -1.9999929139431329   0.9999929139578397   2.0000000000000000   1.0000000000000000

PRM_LOCKIN2_I 5 21 2      0      0 BTW0.01     1.351815922494362e-23  -1.9999929139431329   0.9999929139578397   2.0000000000000000   1.0000000000000000

PRM_SUSPIT 3 12 4  32768      0 Cheby       1.117558041371939e-23  -1.9972699801052749   0.9972743606395355   2.0000000000000000   1.0000000000000000

PRM_SUSPOS 3 12 4  32768      0 Cheby       1.117558041371939e-23  -1.9972699801052749   0.9972743606395355   2.0000000000000000   1.0000000000000000

PRM_SUSSIDE 3 12 4  32768      0 Cheby       1.117558041371939e-23  -1.9972699801052749   0.9972743606395355   2.0000000000000000   1.0000000000000000

PRM_SUSYAW 3 12 4  32768      0 Cheby       1.117558041371939e-23  -1.9972699801052749   0.9972743606395355   2.0000000000000000   1.0000000000000000

SRM_LOCKIN2_Q 5 21 2      0      0 BTW0.01     1.351815922494362e-23  -1.9999929139431329   0.9999929139578397   2.0000000000000000   1.0000000000000000

SRM_LOCKIN2_I 5 21 2      0      0 BTW0.01     1.351815922494362e-23  -1.9999929139431329   0.9999929139578397   2.0000000000000000   1.0000000000000000

SRM_LOCKIN1_Q 5 21 2      0      0 BTW0.01     1.351815922494362e-23  -1.9999929139431329   0.9999929139578397   2.0000000000000000   1.0000000000000000

SRM_LOCKIN1_I 5 21 2      0      0 BTW0.01     1.351815922494362e-23  -1.9999929139431329   0.9999929139578397   2.0000000000000000   1.0000000000000000

SRM_SUSPIT 3 12 4  32768      0 Cheby       1.117558041371939e-23  -1.9972699801052749   0.9972743606395355   2.0000000000000000   1.0000000000000000

SRM_SUSPOS 3 12 4  32768      0 Cheby       1.117558041371939e-23  -1.9972699801052749   0.9972743606395355   2.0000000000000000   1.0000000000000000

SRM_SUSSIDE 3 12 4  32768      0 Cheby       1.117558041371939e-23  -1.9972699801052749   0.9972743606395355   2.0000000000000000   1.0000000000000000

SRM_SUSYAW 3 12 4  32768      0 Cheby       1.117558041371939e-23  -1.9972699801052749   0.9972743606395355   2.0000000000000000   1.0000000000000000

I have restarted the c1sus machine around 9:00 PM yesterday and then shut it down around 4:00 AM this morning after a little bit of taking care of the interferomter.

Our approach to making the F2A or F2P filters for the MC is to use the measured resonant frequencies and then calculating the appropriate mechanical dimensions of each suspension. This is basically because we don't have optical levers with normal incidence on these optics, but the method should be fine.

To find the formulas, I asked Gaby for her old cheat sheet: Its now in the DCC. Its only for Large optics, but you should be able to reconstruct the right ones for SOS by just changing the parameters.

Here is 5 days of trend of the EOM temp sensor and the heater driver monitor.  Unfortunately, it looks like we're regularly railing the heater.  Not so awesome. 

Can you zoom the temp mon? (V= -0.1 ~ +0.1)
The crystal was too cold and I tried to heat the PSL table by the lighting. But it seemed in vain.

 Locking activity last night:

  It became able to close the ALS loop (beat-note signal was fed back to ETMY).

The UGF was about 60 Hz, but somehow I couldn't bring the UGF higher than that.

Every time when I increased the UGF more than 60 Hz, the Y end PDH was unlocked (or maybe ETMY became crazy at first).

Perhaps it could be a too much noise injection above 60 Hz, since I was using the coarse frequency discriminator.

Anyway I will try a cavity sweep and the successive noise budgeting while holding the arm length by the beat-note signal.

Another thing : I need a temperature feedback in the Y end green PDH loop, so that the PZT voltage will be offloaded to the laser temperature.

 It is not working

I have restarted the c1sus machine and burt-restored c1sus and c1mcs to the day before Thank giving, namely 23rd of November.

I reset the modulation frequency to 11065910 Hz (#5530). It had been at 11065399 Hz probably since the power shut down.

Here is a 48 hours trend of the RFAM monitor (a.k.a StochMon):

The upper plot is the DC output from the StochMon PD and the lower plot shows the calibrated RIN (Relative Intensity) at each modulation frequency.

I have downloaded minutes trends of StochMon for 48 hours staring from 6:00AM of Nov/24.

I followed Koji's calibration formula (#6009) to get the actual peak value (half of the peak-peak value) of the RF outputs and then divided them by the DC output to make them RIN.

It looks the RINs are hovering at ~ 4 x 10^-4 and fluctuate from 1x10^-4 to 1x10^-3. Those numbers agree with what we saw before (#5616)

So it seems the StochMon is working fine.

There is still a problem why GUR, STS signals are poorly coherent to MC_L.  But at least we can see coherence at 2-5 Hz. It might be useful to do something with adaptive filtering because it does not work at all for a long time. We start with Wiener filtering. I still doubt that static filtering is useful. Adaptive filter output is linear to its coefficients, so why not to provide adaptive filter with a zero approximation equal to calculated Wiener filter coefficients. Then you automatically have Wiener filter ouput + adaptively control coefficients. But if Wiener filter is already present in the model, I tried to make it work. Then we can compare performance of the OAF with static filter and without it.

I started with GUR1_X and MC_F signals recorded 1 month ago to figure out how stable TF is. Will the same coefficients work now online? In the plot below offline Wiener filtering is presented.

This offline filtering was done with 7500 coefficients. This FIR filter was converted to IIR filter with the following procedure:

1. Calculate frequency responce of the filter. It is presented below.

2. Multiply this frequency response by a window function. This we need because we are interested in frequencies 0.1-20 Hz at this moment. We want this function to be > 1e-3 at ~0Hz, so that the DC component is filtered out from seismometer signal. From the other hand we also do not want huge signal at high frequenies. We know that this signal will be filtered with aggresive low-pass filterd before going to the actuator but still we want to make sure that this signal is not very big to be filtered out by the low-pass filter.

The window function is done in the way to be a differential function to be easier fitted by the vectfit3. Function is equal to 1 for 0.5 - 20 Hz and 1e-5 for other frequencies except neighbouring to the 0.5 and 20 where the function is cosine.

3. I've used vectfit3 software to approximate the product of the frequency response of the filter and window fucntion with the rational function. I've used 10 complex conjugate poles. The function was weighted in the way to make deviation as small as possible for interesting frequencies 0.5 - 10 Hz. The approximation error is big below 20 Hz where the window function is 1e-5 but at least obtained rational function does not increase as real function do at high frequencies.

I tried to make a foton filter out of this approximation but it turns out that this filter is too large for it. Probably there is other problem with this approximation but once I've split the filter into 2 separate filters foton saved it. Wiener21 and Wiener22 filters are in the C1OAF.txt STATIC_STATMTX_8_8 model.

I've tested how the function was approximated. For this purpose I've downloaded GUR and MC_F signals and filtered GUR singla with rational approximation of the Wiener filter frequency response. From power spectral density and coherence plots presented below we can say that approximation is reasonable.

Next, I've approximated the actuator TF and inverted it. If TF measured in p. 5900 is correct then below presented its  rational approximation. We can see deviation at high frequencies - that's because I used small weights there using approximation - anyway this will not pass through 28 Hz low-pass filter before the actuator.

I've inverted this TF p->z , z->p, k->1/k. I've also added "-" sign before 1/k because we subtract the signal, not add it. I placed this filter 0.5Actuator20 to the C1OAF.txt SUS-MC2_OUT filter bank.

The next plot compares online measured MC_L without static filtering and with it. Blue line - with online Wiener filtering, red line - without Wiener filtering.

We can see some subtraction in the MC_L due to the static Wiener filtering in the 2-5 Hz where we see coherence. It is not that good as offline but the effect is still present. Probably, we should measure the actuator TF more precisely. It seems that there some phase problems during the subtraction. Or may be digital noise is corrupting the signal. 

[Rana, Jenne]

Some of the funniness is some kind of mysterious interaction between 2 filter modules in the filter banks.  Just FM1 (30:0.0) or just FM4 (Cheby, which is 2 cheby1's) has reasonable coherence.  Both FM1 and FM4 together doesn't do so well - the coherence goes way down.

Just FM1 (30:0.0)

Just FM4 (Cheby)

 Both FM1 and FM4

 All the coherences plotted together

You'd think that the signal encounters FM1, gets filtered, and that result is the signal sent to the next active filter module, FM4, so the 2 filter modules shouldn't interact.  But clearly there's some funny business here since engaging both makes things crappy. 

Matlab investigations to replicate this behavior offline are in progress.

To see what might be causing the problem, I used a version of the filter noise test matlab code that Matt had in the elog.

To see if it was a single precision problem, I just recast the input data:   x = single(x)

This is not strictly correct, since some of the rest of the operations are as double precision, but I think that attached plot shows that a casting from double to single is close to the right amount of noise to explain our excess noise problem in the 0.1-1 Hz region.

Den is going to interview Alex to find out if we have some kind of issue like this. My understanding was that all of our filter module calculations were being done in double precision (64 bit), but its possible that some single stuff has crept back in. Currently the FIR filtering code IS single precision and in the past, the SUS code which didn't carry the LSC signals (meaning ASC and damping) were done in single precision.

I inspected the temperature stabilization circuit today to see why it wasn't working. It didn't make sense that it just kept railing the heater even though the error signal was negative (which should turn the heater current OFF).

It turns out that the LF356 (FET-input op amp) that serves as the filter stage for the heater driver was broken---I measured a full, railed positive output even though the input was negative. We didn't have any more LF356s, so I replaced it with an OPA604 (Burr-Brown FET-input), and all seemed to work fine.

Since we were having too much digitization noise, I also added a temperature monitor buffer using a non-inverting OP27 circuit with G=99. This makes the overall calibration ~7.6 V/K into the ADC.

Below is a time series showing that it is working. The circuit was turned on near the beginning, and you can see that the heater is railed at +10V until shortly after the error signal goes negative, at which point it adjusts and ultimately approaches a steady-state value of ~7.8V.

I have no figures to demonstrate this, but it seems that even with this 100x increase in monitor gain, the error signal is still below the ADC noise level. This could be because the ambient temperature fluctuations are just that small on timescales of less than a few hours. I'm not sure if we really need to be able to see the temperature noise level above a few mHz, but if we do we will have to find some way to increase our dynamic readout range. 

Also, Koji told me where he stashed the nice protoboards, so I will get onto transferring this circuit onto one ASAP. Since it is working now, I think I'll leave it until after the TAC.

I have shut down the c1sus machine at 3:30 AM.

 As part of the initiative to get a good daily summary page for aLIGO commissioning, Josh is spearheading his Detector Characterization group to produce such web pages for the 40m.

They're starting out with this launching point and then we can add all kinds of other information and plots as we want (e.g. Vac, PEM, Weather, coffee status). If you have suggestions/ideas, just edit this entry and add them, or email Josh directly.

I left the EOM stabilization running overnight, so we can finally see how the EOM temperature stabilization does over long periods of time.

Here are both long-term (~13-hr) and short-term (1-hr) trends of the EOM temperature and the heater drive level. From the long trend you can see that the heater departed the steady value of ~7.8V that I observed last night to accommodate the diurnal heating of the lab in the morning---the temperature was held near zero offset.

From the short-term trend, there are 2 things to notice:

1. We are still very close to the digitization noise level for both signals. This is bad, because we want to look at the residual noise level, etc.
2. There appears to be some strange sort of disturbance of f~0.01-0.02 Hz. I'm not sure what causes the strange shape

Finally, here is a trend over the last ~24 hours of the EOM temperature, heater drive level, and the 11- and 55-MHz Stochmon signals. I believe that the abrupt shelves noticeable on the Stochmon trends are when c1sus was turned on and shut down, respectively (I'm not sure why that causes the signals to die, but the times seem right, and nothing obvious happens to the EOM temp stabilization signals at either time). The controller was turned on at ~8:40 UTC, and you can see that the Stochmon signals quiet down a lot right at that time. There is some residual drift (common-mode to both RF frequencies), which is most likely caused by a drift in some other parameter (e.g. laser frequency or power).

I took some relatively inconclusive power spectra and coherence measurements, but I'd rather wait until we have an uncontrolled data stretch with which to compare. I think what we should do now is disconnect the controller and then let it sit for a while.

 It is not obvious what is working.

So I tracked down where the currently-used filter function code is defined (the following is all relative to /opt/rtcds/caltech/c1/core/release):

Looking at one of the generated front-end C source codes (src/fe/c1lsc/c1lsc.c) it looks like the relevant filter function is:

filterModuleD()

which is defined in:

src/include/drv/fm10Gen.c

and an associated header file is:

src/include/fm10Gen.h

We are interested in the following question : Can the structures defined in fm10Gen.h (or some other *.c *.h files with defined as FLOAT variables) create single precision instead of double in the filter calculations?

typedef struct FM_OP_IN{

  UINT32 opSwitchE;     /* Epics Switch Control Register; 28/32 bits used*/

  UINT32 opSwitchP;     /* PIII Switch Control Register; 28/32 bits used*/

  UINT32 rset;          /* reset switches */

  float offset;         /* signal offset */

  float outgain;        /* module gain */

  float limiter;        /* used to limit the filter output to +/- limit val */

  int rmpcmp[FILTERS];  /* ramp counts: ramps on a filter for type 2 output*/

                        /* comparison limit: compare limit for type 3 output*/

                        /* not used for type 1 output filter */

  int timeout[FILTERS]; /* used to timeout wait in type 3 output filter */

  int cnt[FILTERS];     /* used to keep track of up and down cnt of rmpcmp */

                        /* should be initialized to zero */

  float gain_ramp_time; /* gain change ramping time in seconds */

} FM_OP_IN;  

One of the possibilities that we see a large low-frequency digital noise is due to Foton. I've checked the SOS coefficients that saves Foton with a Matlab coefficients. I used a 3 order low-pass cheby1 filter cheby1("LowPass",3,0.1,3) 

In matlab I generated SOS model using 3 approaches 

[A,B,C,D]=cheby1(3,0.1,3/1024) % create SS form

[sos,g]=ss2sos(A,B,C,D)  % convert to SOS form

[z, p, k]=cheby1(3,0.1,3/1024) % create ZPK form

[sos,g]=zp2sos(z,p,k)  % convert to SOS form

[b, a]=cheby1(3,0.1,3/1024) % create TF form

[sos,g]=tf2sos(b,a)  % convert to SOS form

As this is a 3 order filter, in the SOS representation we'll get 2 by 6 SOS - matrix. It is presented below. In each matrix place there 4 numbers - from the Foton file and obtained using these 3 methods.

GAIN

1.582261654653329e-07

1.582261654653329e-07

1.582261654653329e-07

1.582261655030947e-07

SOS-MATRIX

1              1.0000000000000000      #           0                                              #       1      #         -0.9911172660954457     #       0

1              1.0005663179617605      #           0                                              #       1      #         -0.9911172660954457     #       0

1              1.0000000000000000      #           0                                              #       1      #         -0.9911172660954457     #       0

1              0.9999894976396830      #           0                                              #       1      #         -0.9911172660997303     #       0

############################################################################################################

1              2.0000000000000000      #          1.0000000000000000         #       1      #        -1.9909750803252266      #      0.9911175825477769

1              1.9994336820732397      #          0.9994340026283055         #      1       #       -1.9909750803252262       #     0.9911175825477765

1              2.0000000000000000      #          1.0000000000000000         #      1       #       -1.9909750803252262       #     0.9911175825477765

1              2.0000105023603174      #          1.0000105024706190         #      1       #       -1.9909750803209423       #     0.9911175825434912

It seems that smth analog to zp2sos is used in Foton. We can see that due to representation error we have derivations in the 4 and 6 digits for SS and TF forms. This means that a pretty big mistake can run due to digital transforms even using double precision as in the Matlab test.

Alex Ivanov said that he'll fix that single precision problem and in the 2.5 release we won't have any FLOAT variables. Though we still do not understand how that variables declared as FLOAT can cause filter calculations. 

It should be. As I mentioned, you can only trust the Stochmon signals between 0840 and 1130 UTC; before this time, the temperature controller was not connected, and after this time, c1sus is shut down and the MC is not locked, as you can see in your DV plot.

Within this time frame, the Stochmon signals are relatively stabilized (though there is some residual common-mode-ish drift since we are not using RFAM as the error signal---i.e., other things like laser power and frequency can mix in). Also, anytime after 0840, the controller signals behave as they should (these are unaffected by the status of c1sus):

• The EOM temperature signal (error signal) is stabilized to a value very near zero
• The heater drive signal (control signal) moves around in such a way as to null the error signal, and you can confirm that it looks roughly like the opposite of the FSS_RMTEMP signal, as it should.

I am concerned with the other issues that I mentioned in my previous post, namely:

1. Error signal dominated by digitization noise above some low frequency despite 100x amplification
2. Strange ~0.01-Hz level disturbances in error signal.

 In the previous elog we've compared Matlab and Foton SOS representations using low-order filter. Now we move on to high order filters and see that Foton is pretty bad here.

We consider Chebyshev filter of the first type with cuf off frequency 12 Hz and ripple 1 dB. In the table below we summarize the GAINS obtained by Matlab and Foton for different digital filter orders.

We can see that for high orders the gains are completely different (ORDER of 2!!!). Interesting that besides of very bad GAIN, SOS-MATRIX Foton calculates pretty well. I checked up to 5 digit - full coincidence. Only GAIN is very bad.

The filter considered is cheby1("LowPass",6,1,12) and is a part of the bad Cheby filter where we loose coherence and see some other strange things.

[Zach / Kiwamu]

 Woke up the c1sus machine in order to lock PSL to MC so that we can observe the effect of not having the EOM heater.

I disconnected the heater at ~2:20 UTC, leaving the sensor circuit operational. Don't be fooled by the apparent railing of the heater in the monitor trace below---the heater has been physically disconnected, so there is no current flowing even though the servo is railed (since the error signal is huge with the loop open).

Kiwamu and I also restarted c1sus and locked the MC so that we can get some uncontrolled Stochmon data. I think he is planning to reconnect the heater some hours from now so that we can get yet another controlled data stretch (since the first one was cut short by c1sus's going down).