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ID Date Author Type Category Subject
4374   Thu Mar 3 18:32:33 2011 Larisa ThorneUpdateElectronicsHarmonic distortion calculations for RF distribution box

Finished calculations for harmonic distortion at each of the 10 outputs of the RF distribution box. The diagram can be found on Suresh's post  http://nodus.ligo.caltech.edu:8080/40m/4342

THD calculation consisted of gather data on the dBm at harmonics of the fundamental frequency. These dBm values were converted into units of power and plugged into the appropriate THD equation pulled from Wikipedia: $\mbox{THD} = \frac{P_2 + P_3 + P_4 + \cdots + P_\infty}{P_1} = \frac{\displaystyle\sum_{n=2}^\infty P_n}{P_1}$

On the table, the number 1-6 correspond to the harmonic number of the input frequency used. For example, the first five PD's listed used an 11MHz source, while the second set of five PD's listed used a 55MHz source. Values listed under certain harmonics are dBm measurements at the corresponding frequency. The P-subscript values are essentially the dBm measurements converted to units of power (Watts) for ease of calculation in the equation above. THD is then calculated using these power units; I have converted the ratios to percentages.

It should be noted that as with all THD calculations, the more data points collected, the more precise the THD % will be.

By the way, the outputs on the physical RF distribution box for REFL165 and AS165 are actually labeled as REFL166 and AS166.

Attachment 1: RFdistribboxcalcs.pdf
4376   Fri Mar 4 03:31:35 2011 kiwamuUpdateGreen LockingA first noise budget

I made a noise budget for the ALS noise measurement that I did a week ago (see #4352).

I am going to post some details about this plot later because I am now too sleepy.

4377   Fri Mar 4 09:47:46 2011 SureshUpdateElectronicsHarmonic distortion calculations for RF distribution box

Fast work indeed! It would be nice if we could have the following details filled in as well
a) A short title and caption for the table, saying what we are measuring
b) the units in which this physical quantity is being measured.

It is good to keep in mind that people from other parts of the group, who are not directly involved in this work, may also read this elog.

4378   Fri Mar 4 13:25:04 2011 ZachUpdateelogrestarted

with script

4379   Fri Mar 4 18:06:34 2011 kiwamuUpdateGreen Lockingnoise budget : differential noise

Here I explain how I estimate the contribution from the differential noise shown in the plot on my last entry (#4376) .

(background)

According to the measurement done about a week ago, there is a broadband noise in the green beatnote path when both Green and IR are locked to the X arm.

The noise can be found on the first plot on this entry (#4352) drawn in purple. We call it differential noise.

However, remember, the thing we care is the noise appearing in the IR PDH port when the ALS standard configuration is applied (i.e. taking the beatnote and feeding it back to ETMX).

So we have to somehow convert the noise to that in terms of the ALS configuration.

In the ALS configuration, since the loop topology is slightly different from that when the differential noise was measured, we have to apply a transfer function to properly estimate the contribution.

(How to estimate)

It's not so difficult to calculate the contribution from the differential noise under some reasonable assumptions.

Let us assume that the MC servo and the end PDH servo have a higher UGF than the ALS, and assume their gains are sufficiently big.

Then those assumptions allow us to simplify the control loop to like the diagram below:

Since we saw the differential noise from the beatnote path, I inject the noise after the frequency comparison in this model.

Eventually the noise is going to propagate to the f_IR_PDH port by multiplying by G/(1+G), where G is the open loop transfer function of the ALS.

The plot below shows the open loop transfer function which I used and the resultant G/(1+G).

In the curve of G/(1+G), you can see there is a broad bump with the gain of more than 1,  approximately from 20 Hz to 60 Hz.

Because of this bump, the resultant contribution from the differential noise at this region is now prominent as shown in the plot on the last entry (#4376).

 Quote: #4376 I made a noise budget for the ALS noise measurement that I did a week ago (see #4352). I am going to post some details about this plot later

4380   Mon Mar 7 17:22:39 2011 josephbUpdateCDSNew simulated plant work

[Joe, Jamie]

We modified the c1scx model to have a switch to go between simulated and real plants.  The channel is currently C1:SCX-SIM_SWITCH.

When this channel is zero, the simulated plant channels are going to the ADCs and zeros  are going out to the real DACs.  When this channel is one, the real ADCs are coming in, and real data is going out to the DACs.

Jamie will be adding a big green/red light to the suspension screens which indicate the state of the simulated plant.  We will also eventually add this to the overall status screen.

A control screen for the simulated plant is located at /opt/rtcds/caltech/c1/medm/c1spx/master/C1SUP_ETMX.adl.  These are currently a work in progress.

4383   Tue Mar 8 06:29:06 2011 kiwamuUpdateGreen LockingIntensity noise setup

[Jenne, Chris, Kiwamu]

A photo diode and an AOM driver have been newly setup on the PSL table to measure the intensity noise coupling to the beat note signal.

We tried taking a transfer function from the PD to the beat, but the SNR wasn't sufficient on the PD. So we didn't get reasonable data.

(what we did)

- put a DCPD after the doubling crystal on the PSL table. The PD is sitting after the Y1 mirror, which has been used for picking off the undesired IR beam.

- installed the AOM driver (the AOM itself had been already in place)

- injected some signals onto the AOM to see if we can see an intensity fluctuation on the PD as well as the beat signal

(intensity noise)

In order to have better SNR for the intensity measurement, we put an AC coupled SR560 with the gain of 100 just before the ADCs.

When a single frequency signal was applied from a Stanford Research's function generator to the AOM, we could clearly see a peak at the doubled frequency of the injected signal.

Also a peak at the same frequency was found on the beat note signal as well.

But when random noise was injected from the same function generator, the random noise looked below the ADC noise.

Jenne adjusted the output voltage from the PD to about 1 V to avoid a saturation in the analog path, but later we realized that the ADC counts was marely ~ 20 counts.

So we will check the ADC tomorrow. Hopefully we will get a good SNR.

4384   Tue Mar 8 14:50:19 2011 kiwamuUpdateCDSnames for filter modules

[Joe/Kiwamu]

We found there are some filter names that we can not properly build for some reason.

The following names are not properly going to be built :

- REFL_DC

- AUX

If we use the names shown above for filters, it doesn't compile any filter modules.

We took a quick look around the src files including feCodegen.pl, but didn't find any obvious bugs.

4385   Tue Mar 8 15:20:31 2011 kiwamuUpdateGreen Lockingdifferential noise on Mar.8th

Noise below 10 Hz became larger again compared with the data before (see here #4352)

Note that the Y-axis is in MHz.

4386   Tue Mar 8 15:23:16 2011 steveUpdatePEMclean room gloves

Ansell AccuTech 91-300 clean room gloves  ONLY in the 40m lab.

Cleaning and preparation must be carried out in these gloves also.

4388   Tue Mar 8 16:59:47 2011 josephbUpdateCDSSimulated Plant Work

The screens for the simplified c1spx model have been updated.  I re-introduced the suspension point information into the sensor output matrix so we can take into account the fact that as the entire supporting structure moves, the osems moves relative to the optic.

Master screens for the noise filters (i.e. 60 Hz, suspension point motion, and optic noise) have been created.

I have currently set the matrix values of the c1spx model to handle just longitudinal motion.  I.e. Coils drive only in the POS degree of freedom and sensor read outs are also only in the POS degree of freedom.  I've turned off all the noise inputs.

I added a simple double pole at 1 Hz in the C1:SUP_ETMX_PL_F2P_0_0 filter bank.

4389   Wed Mar 9 04:46:13 2011 kiwamuUpdateGreen Lockingmore intensity noise measurement

Here is a diagram for our intensity noise coupling measurement.

The below is a plot for the intensity noise on the DCPD. (I forgot to take a spectra of the PD dark noise)

For some reason, the RIN spectrum becomes sometimes noisier and sometimes quieter. Note that after 10 pm it's been in the quiet state for most of the time.

An interesting thing is that the structure below 3 Hz looks like excited by motion of the MC when it's in the louder state.

 Quote: from #4383 A photo diode and an AOM driver have been newly setup on the PSL table to measure the intensity noise coupling to the beat note signal. We tried taking a transfer function from the PD to the beat, but the SNR wasn't sufficient on the PD. So we didn't get reasonable data.

4390   Wed Mar 9 16:07:42 2011 kiwamuUpdateVIDEOcable session

[Koji, Steve, Suresh, Kiwamu]

The following video cables have been newly laid down :

- MC1F/MC3F (65 ft.)

- PMCR (100 ft.)

- PSL spare (100 ft.)

- PSL1  (100 ft.)

- PSL2  (100 ft.)

4392   Wed Mar 9 18:17:11 2011 kiwamuUpdateGreen LockingIntensity noise coupling

Here is a new plot for the differential noise measurement. I plot a noise contribution from the intensity noise (brown curve).

If we believe this data, the differential noise is NOT dominated by the intensity noise of the PSL.

(intensity noise coupling measurement)

Here is a plot for the transfer functions (TFs) from the intensity noise DCPD to the beat signal.

In principle these TFs tell us how much intensity noise are contributed into the differential noise.

When I measured the spectra shown above, the frequency offset of the beatnote was at about 8 MHz from the zero cross point.

Keeping the same lock, I measured the transfer function (red curve) by using the swept sine technique on DTT. The setup for this measurement is depicted on the last entry (#4389).

Then I made the spectra above by multiplying the intensity spectrum by this TF.

Later I measured another transfer function when the beatnote was at about 2 MHz from the zero cross point.

According to this measurement, our MFD gets insensitive to the intensity noise as the beat offset goes close to the zero cross point. This is consistent with what we expected.

4393   Wed Mar 9 23:19:04 2011 kiwamuUpdateCDSrebooted c1ioo

For some reason the c1ioo machine suddenly died just 30 miteus before.

It died after we added a DAQ channel for c1gcv and rebooted the frame builder.

It didn't respond to a ping command. Therefore I rebooted the machine by clicking the physical reset button.

Now it seems fine.

4395   Thu Mar 10 01:31:37 2011 KevinUpdateElectronicsAS55 Characterizations

I measured the transfer function, shot noise, and dark spectrum of AS55.

From the shot noise measurement, the RF transimpedance is (556.3 +- 0.8) Ohms and the dark current is (2.39 +- 0.01) mA. The dark noise agrees with the approximate value calculated from the circuit components.

There are no anomalous oscillations when there is no light on the photodiode. I am working on fitting the transfer function in LISO but the other plots are on the wiki at http://blue.ligo-wa.caltech.edu:8000/40m/Electronics/AS55

4396   Thu Mar 10 13:44:56 2011 josephbUpdateCDSAdded digitization noise to the c1spy model for simulated ADCs/DACs

To simulate digitization noise, the easiest way I found was to use the MathFunction block, found in the CDS_PARTS model, under simLinkParts.

The MathFunction block supports square of input value, square root of input value, reciprocal of input value, and modulo of two input values.

The last is useful because it casts the input values as integers before taking the modulo.By placing this block after the saturation block (set to +/- 32768), adding 32768.5, choosing the 2nd input to be larger than 2 * 32768 (100,000 in this case), and then subtracting 32768, we wind up with a rounding function.

The above method has been applied to the c1spy model in the CI and SO out sub-blocks.

4397   Thu Mar 10 14:06:54 2011 kiwamuUpdateGreen LockingIntensity noise limits the beatnote sensitivity

We are limited by the intensity noise of the X arm transmitted green light.

Since the intensity noise from the PSL wasn't big enough to explain the differential noise (#4392), so this time I measured the noise contribution from the X arm transmitted light.

(coupling measurement)

I performed the same intensity noise coupling measurement, but this time between the DC signal of the beatnote RFPD and the beatnote signal.

While measuring it, I excited the intensity of the PSL laser by using the same AOM like I did yesterday. This AM cause the observable intensity noise on the beatnote RFPD.

With the excited AM, we can pretend to have an excited AM on the green transmitted light from the X arm, of course assuming the intensity noise coupling from the PSL is less.

4398   Thu Mar 10 14:22:58 2011 kiwamuUpdateGreen LockingIntensity noise limits the beatnote sensitivity

The next steps we should do are :

- to investigate a cause of the intensity fluctuation
* end green laser
* suspensions' angular motions
* doublecheck the RIN contribution if it's from the PSL or the X arm in the beatnote RFPD to make sure the RIN is dominated by the X arm transmitted light

- to think about how to make the system insensitive to the intensity noise
- bring the beat frequency to the zero cross point of the MFDs ?
- PLL ?

 Quote: We are limited by the intensity noise of the X arm transmitted green light.

4399   Thu Mar 10 14:29:05 2011 KojiUpdateGreen LockingIntensity noise limits the beatnote sensitivity

We can modify the freq divider circuit to make it a comparator.

Quote:

The next steps we should do are :

- to investigate a cause of the intensity fluctuation
* end green laser
* suspensions' angular motions
* doublecheck the RIN contribution if it's from the PSL or the X arm in the beatnote RFPD to make sure the RIN is dominated by the X arm transmitted light

- to think about how to make the system insensitive to the intensity noise
- bring the beat frequency to the zero cross point of the MFDs ?
- PLL ?

 Quote: We are limited by the intensity noise of the X arm transmitted green light.

4400   Thu Mar 10 14:30:53 2011 ranaUpdateGreen LockingIntensity noise limits the beatnote sensitivity

There are 3 standard techniques to reduce this effect:

1) Stabilize the end laser by sensing the green light coming into the PSL before recombination and feeding back with SR560 (this is the only one that you should try at first).

2) Moving to the center of the MFD fringe via ETM steps.

3) Auto-alignment of the beam to the arm.

4401   Thu Mar 10 16:00:53 2011 Aidan, JoeUpdateGreen LockingIntensity stabilization loop using beatnote DC.

Aidan: Joe and I have added a channel that takes the DC output from the vertex beatnote PD and sends it, via RFM, to a DAC at the ETMX end. Immediately before the output is a filter C1GCX_AMP_CTRL. The output of the DAC is connected to the CURRENT LASER DIODE modulation input on the back of the Innolight driver. This will modulate the current by 0.1A/V input.

We should be able to modulate the green laser on the end now and stabilize the intensity of the amplitude on the beatnote PD at the vertex. (In this configuration, the ampltiude noise of the PSL laser will be injected onto the end laser - we may want to revisit that).

I added a RFM connection at the output of the C1:GCV-XARM_BEAT_DC filter in the c1gcv model.  The RFM connection is called: C1:GCV-SCX_ETMX_AMP_CTRL.

This RFM connection goes to the c1scx model and into Kiwamu's GCX box, which uses top_names.  There's a filter inside called AMP_CTRL, so the full filter name is C1:GCX-AMP_CTRL.  The output then goes to the 7th DAC output.

Photos:

1. NPRO CURRENT CTRL plugged into DAC channel 7
2. You can actually see it's channel 7 in this image
3. The other end plugged into the back of the Innolight driver
4. Schematic of the setup
5. Updated C1ALS_OVERVIEW MEDM screen (I don't know why the field in the background turned orange - maybe it's coming into a long dry summer?)

 Quote: There are 3 standard techniques to reduce this effect: 1) Stabilize the end laser by sensing the green light coming into the PSL before recombination and feeding back with SR560 (this is the only one that you should try at first).

The reason that I chose this PD is that, apparently, the green light coming from the cavity is clipped when it is picked off for its DC PD.

Attachment 1: P1000313.jpg
Attachment 2: P1000314.jpg
Attachment 3: P1000315.jpg
Attachment 4: GREEN_ISS_LOOP.pdf
4403   Thu Mar 10 21:45:34 2011 ranaUpdateGreen LockingIntensity stabilization loop using beatnote DC.

Ridiculous and hacky. Digital stabilization removed as well as the old "leave a pile of equipment on a stool" strategy.

We used a a BNC cable to send a pickoff of the beam before the recombination to the end via an SR560.

4404   Fri Mar 11 11:33:24 2011 josephbUpdateCDSFixed mistake in Matrix of Filter banks naming convention

While fixing up some medm screens and getting spectra of the simulated plant, I realized that the naming convention for the Matrices of Filter banks was backwards when compared to that of the normal matrices (and the rest of the world).  The naming was incorrectly column, row.

This has several ramifications:

1) I had to change the suspensions screens for the TO_COIL  output filters.

2) I had to change the filters for the suspension with regards to the TO_COIL output filters so they go in the correct filter banks.

3) Burt restores to times previous March 11th around noon, will put your TO_COIL output filters in a funny state that will need to be fixed.

4) The simplant RESPONSE filters had to be moved to the correct filter banks.

5) If you have some model I'm not aware of that uses the FiltMuxMatrix piece, it is going to correctly build now, but you're going to have to move filters you may have created with foton.

4405   Fri Mar 11 16:30:42 2011 steveUpdateGeneralhigh speed servo unit is here

New Focus Servo Controller has just arrived. We have 25 days to evaluate this product.

It will have to be shipped back to the vendor on April 4, 2011 the latest in order to get full refund.

Attachment 1: P1070462.JPG
4406   Fri Mar 11 18:32:45 2011 josephb, Chris, JamieUpdateCDSDebugging simplant damping

The FM1 filter module change for XXSEN was propagated to the ETMX suspension.  This was a change from a 30,100:3 with a DC gain of 1 to a 3:30 which just compensates the hardware filter.

The good gains for the Sim damping were found to be:  100 for ETMX_SUSPOS, 0.1 ETMX_SUSPIT, and 0.1 ETMX_SUSYAW, ETMX_SUSSIDE is -70.  Gains much higher tended to saturate the simulated coils (i.e. hitting 10V limit) and then had to have the histories cleared for the RESPONSE matrix.

These seem to work to damp the real ETMX as well.

4408   Sun Mar 13 04:00:53 2011 ranaUpdateCDSETMY Sim work

I did some work on the ETMY real and Sim.

1. Set SUS coil gains to have the same quadropole arrangement as the magnets do (-1, 1, 1, -1) so that POS = POS instead of pringle.
2. Set the Sim Magnet polarities to match this. These are the ETMY_CI filter banks.
3. Found that the Xycom cable from the ETMY slow controls was unplugged at the Xycom side. This was preventing enabling the ETMY coil driver and so there was no real damping of the suspension going on. I plugged it in and checked that the mirror could now be moved.
4. The C1SUS_ETMY master screen's BLUE output filter area is now mis-labeled. If you trust the screen you would set it up to drive the suspension incorrectly. This MUST be fixed along with all of the other misleading features of the screen.
5. ETMY SUSSIDE filter bank had a 2048 Hz sample rate and was making the damping not work correctly. Fixed to 16384 Hz.
6. 12 Hz, 4th order Cheby low pass added and turned on for the local damping filtering. This is not optimum, but its just there to give us some filtering without introducing some instability via phase lag around 3 Hz.
7. ETMY OL beam re-aligned on ISCT-EX.
8. TM Offset buttons not working on the main overview screen.

It seems like there is still a problem with the input whitening filters. I believe the Xycom logic is set such that the analog whitening of the OSEM signals is turned ON only when the FM1 is turned OFF. Joe has got to fix this (and elog it) so that we can damp the suspension correctly. For now, the damping of the ETMY and the SETMY require different servo gains and signs, probably because of this.

4409   Sun Mar 13 16:46:48 2011 josephbUpdateCDSETMY Sim work

4. The blue Output Filters  section has been changed to agree with the new filter of matrices row, column labeling.  My fault for not testing it and realizing it was broken.  The change was made in /opt/rtcds/caltech/c1/medm/master/C1SUS_DEFAULTNAME.adl and then ,/generate_master_screens.py was run, updating all the screens.

5.  I have swapped the logic for the sensor filter banks (ULSEN, URSEN, etc).  It now sends a "1" to the Binary Output board controlling the OSEM analog whitening when the FM1 filter is ON.  This has been done for all the suspensions (BS, ITMX,ITMY, SRM, PRM, MC1, MC2,MC3, ITMX, ITMY).

I am also updating the first sensor filter banks for the BS, ITMX, ITMY, SRM, PRM,MC1,MC2,MC3, called "3:30", to match the Y and X ends.

8.  I can't find any documentation on how to get a momentary button press to toggle states.  I could stick a filter bank in and use the on/off feature of that part, but that feels like a silly hack.  I've decided for the moment to split the TM offset button into 2, one for ON, one for OFF.  I'll put in on the list of things to have added to the RCG code (either a method, or documentation if it already exists).

EDIT:  TM offset still doesn't work.  Will worry about it next week.

9.  Fixed a connection in SPY/SPX models where  the side senor path that was missing a constant to a modulo block.

 Quote: I did some work on the ETMY real and Sim. Set SUS coil gains to have the same quadropole arrangement as the magnets do (-1, 1, 1, -1) so that POS = POS instead of pringle. Set the Sim Magnet polarities to match this. These are the ETMY_CI filter banks. Found that the Xycom cable from the ETMY slow controls was unplugged at the Xycom side. This was preventing enabling the ETMY coil driver and so there was no real damping of the suspension going on. I plugged it in and checked that the mirror could now be moved. The C1SUS_ETMY master screen's BLUE output filter area is now mis-labeled. If you trust the screen you would set it up to drive the suspension incorrectly. This MUST be fixed along with all of the other misleading features of the screen. ETMY SUSSIDE filter bank had a 2048 Hz sample rate and was making the damping not work correctly. Fixed to 16384 Hz. 12 Hz, 4th order Cheby low pass added and turned on for the local damping filtering. This is not optimum, but its just there to give us some filtering without introducing some instability via phase lag around 3 Hz. ETMY OL beam re-aligned on ISCT-EX. TM Offset buttons not working on the main overview screen. It seems like there is still a problem with the input whitening filters. I believe the Xycom logic is set such that the analog whitening of the OSEM signals is turned ON only when the FM1 is turned OFF. Joe has got to fix this (and elog it) so that we can damp the suspension correctly. For now, the damping of the ETMY and the SETMY require different servo gains and signs, probably because of this.

4410   Fri Mar 18 11:29:36 2011 josephbUpdateCDSMinute trend issues

[Joe, Alex]

Steve pointed out to me today he couldn't get trends for his PEM slow channels like C1:PEM-count_full.

I experimented a bit and found for long time requests (over 20 days), it would produce minute trends up to the current time, but only if they started far enough back.  So the data was being written, but something was causing a problem for dataviewer/NDS to find it.

On further investigation it looks to be some incorrect time stamps at several points in the last few months are causing the problems.  Basically when Alex and I made mistakes in the GPS time stamp settings for the frame builder (daqd) code, the wrong time got written for hours to the raw minute trend data files.

So Alex is going to be running a script to go through the roughly 180 gigabytes of affected trend data to write new files with the correct time stamps.  Once it done, we'll move the files over.  We'll probably lose a few hours worth of recent trend data, depending on how quickly the scripts run, but after which minute trends should work as they are supposed to.

4411   Fri Mar 18 12:22:04 2011 kiwamuUpdateGreen LockingY arm plan for today

Prior to the works on the Y end setup I propose to perform the temperature scan business like Koji and Suresh did before (see this entry).

This business will allow us to easily find a beatnote at 532nm after the installation on the Y end.

I guess the right persons for this work are Bryan and Suresh.

Bryan will have a safety guidance from Steve in this after noon. So after that they can start working on it.

/* - - - coarse plan - - - */

* remove Alberto's laser from the AS table

* setup Alberto's laser on the PSL table

* put some stuff such as lenses, mirrors and etc. (Use the IR beam picked off after the doubling crystal for the main laser source)

* mode matching

* measurement

Which laser are we going to use,  Alberto's laser or MOPA laser ?

4413   Fri Mar 18 16:06:30 2011 kiwamuUpdateGreen LockingRe: Y arm plan for today

We use Alberto's laser for the Y end Green Locking.

 Quote: Which laser are we going to use,  Alberto's laser or MOPA laser ?

4414   Fri Mar 18 16:31:11 2011 Suresh UpdateGreen LockingRe: Y arm plan for today

The reason for using Alberto's laser is that some amount of work has already gone into characterising its phase noise.  Ref elog entry 2788

4415   Fri Mar 18 17:25:21 2011 josephbUpdateCDSLockins in c1sus update, suspension screens updated

I updated our lockin simulink pieces to use the newer, more streamlined lockin piece that is currently in CDS_PARTS (with new documentation block!).  It means we are no longer passing clock signals through three levels of boxes.

In order to use the piece, you need to right click on it after copying from CDS_PARTS and go to Link Options->Disable Link.  This forces the .mdl to save all the relevant information about the block rather than just a pointer to the library.  I talked with Rolf and Alex today and we discussed setting up another model file, non-library format for putting generically useful user blocks into, rather than using the CDS_PARTS library .mdl.

The BS, ITMX, ITMY, PRM, SRM, ETMX, ETMY now have working lockins, with the input matrix to them having the 2nd input coming from LSC_IN, the 3rd from the oplev pitch, and the 4th from oplev yaw.

This necessitated a few name changes in the medm screens.  I also changed the lockin clock on/off switch to a direct amplitude entry, which turns green when a non-zero value is entered.

Currently, the Mode cleaner optic suspension screens have white lockins on them.  I started modifying a new set of screens just for them, and will modify the generate_master_screens.  Unfortunately, this requires modifying two sets of suspension screens going forward - the main interferometer optics and the MC optics.

4417   Mon Mar 21 13:26:25 2011 KojiUpdatePSLPMC Trans/RFPDDC

PMC TRANS/REFL on MEDM showed red values for long time.
TRANS (a.k.a C1:PSL-PSL_TRANSPD) was the issue of the EPICS db.

REFL (a.k.a. C1:PSL-PMC_RFPDDC) was not physically connected.
There was an unknown BNC connected to the PMC DC output instead of dedicated SMA cable.
So they were swapped.

Now I run the following commands to change the EPICS thresholds:

ezcawrite C1:PSL-PMC_PMCTRANSPD.LOLO 0.8 ezcawrite C1:PSL-PMC_PMCTRANSPD.LOW 0.85 ezcawrite C1:PSL-PMC_PMCTRANSPD.HIGH 0.95 ezcawrite C1:PSL-PMC_PMCTRANSPD.HIHI 1 ezcawrite C1:PSL-PMC_RFPDDC.HIHI 0.05 ezcawrite C1:PSL-PMC_RFPDDC.HIGH 0.03 ezcawrite C1:PSL-PMC_RFPDDC.LOW 0.0 ezcawrite C1:PSL-PMC_RFPDDC.LOLO 0.0

As these commands only give us the tempolary fix, /cvs/cds/caltech/target/c1psl/psl.db was accordingly modified for the permanent one.

grecord(ai,"C1:PSL-PMC_RFPDDC") {         field(DESC,"RFPDDC- RFPD DC output")         field(DISV,"1")         field(SCAN,".1 second")         field(DTYP,"VMIVME-3113")         field(INP,"#C0 S32 @")         field(EGUF,"10")         field(EGUL,"-10")         field(EGU,"Volts")         field(PREC,"3")         field(LOPR,"-10")         field(HOPR,"10")         field(AOFF,"0")         field(LINR,"LINEAR")         field(LOW,"0.0")         field(LSV,"MINOR")         field(LOLO,"0.0")         field(LLSV,"MAJOR")         field(HIGH,"0.03")         field(HSV,"MINOR")         field(HIHI,"0.05")         field(HSV,"MAJOR") }

grecord(ai,"C1:PSL-PMC_PMCTRANSPD") {         field(DESC,"PMCTRANSPD- pre-modecleaner transmitted light")         field(DISV,"1")         field(SCAN,".1 second")         field(DTYP,"VMIVME-3123")         field(INP,"#C0 S10 @")         field(EGUF,"10")         field(EGUL,"-10")         field(EGU,"volts")         field(PREC,"3")         field(LINR,"LINEAR")         field(HOPR,"10")         field(LOPR,"-10")         field(AOFF,"0")         field(LOW,"0.8")         field(LSV,"MINOR")         field(LOLO,"0.85")         field(LLSV,"MAJOR")         field(HIGH,"0.95")         field(HSV,"MINOR")         field(HIHI,"1.00")         field(HSV,"MAJOR") }

Bryan Barr is visiting us from Glasgow for a month. He received 40m specific safety training on Friday.

4420   Mon Mar 21 18:34:10 2011 kiwamuUpdateGreen Lockingadded a new ADC channel on 1X9

I added a new ADC channel for a DC signal from the X end green PD.

It is called C1:GCX-REFL_DC and connected to adc_0_1, which is the second channel of ADC_0.

By the way, when I tried connecting it to an ADC I found that most of the channels on the AA board on 1X9 were not working.

Since the outputs form the board are too small the circuits may have benn broken. See the picture below.

In addition to that  I realized that the signal from the PDH box for the temperature actuation is limited by +/- 2V due to the range of this AA board.

In fact the signal is frequently saturated due to this small voltage range.

We have to enlarge the range of this AA board like Valera did before for the suspensions (see this entry).

4424   Tue Mar 22 16:39:51 2011 kiwamuUpdateGreen Lockingcomaprator installed : 80 pm residual displacement

A comparator has been installed before the MFDs (mixer-based frequency discriminator) to eliminate the effect from the amplitude fluctuation (i.e. intensity noise).

As a result we reached an rms displacement of 580 Hz or 80 pm.

(differential noise measurement)

Here is the resultant plot of the usual differential noise measurement.

The measurement has been done when the both green and red lasers were locked to the X arm.

In the blue curve I used only MFD. In the black curve I used the combination of the comparator and the MFD.

Noise below 3 Hz become lower by a factor of about 4, resulting in a better rms integrated from 40 Hz.

Note that the blue and the black curve were taken while I kept the same lock.

A calibration was done by injecting a peak at 311 Hz with an amplitude of 200 cnt on the ETMX_SUS_POS path.

(installation)

Yesterday Koji modified his comparator circuit such that we can take a signal after it goes thorough the comparator.

The function of this comparator is to convert a sinusoidal signal to a square wave signal so that the amplitude fluctuation doesn't affect the frequency detection in the MFD.

I installed it and put the beat-note signal to it. Then the output signal from the comparator box is connected to the MFDs.

The input power for the comparator circuit has been reduced to -5 dBm so that it doesn't exceeds the maximum power rate.

4426   Wed Mar 23 00:51:47 2011 kiwamuUpdateGreen Lockingplan for tomorrow

- Plan for tomorrow

* Video cable session (I need ETMY_TRNAS) (team)

* Characterization of the Y end laser  (Bryan / Suresh)

* LPF for the X end laser temperature control (Larisa)

* Frequency Divider  (Matt)

* X end mechanical shutter (Kiwamu)

4427   Wed Mar 23 05:11:08 2011 kiwamuUpdateGreen Lockingservo handig off

Succeeded in handing off the servo from the green to the red.

(noise performance)

This time we found that the fluctuation in the IR signals became lesser as the gain of the ALS servo increased.

Therefore I increased the UGF from 40 Hz to 180 Hz to have less noise in the IR PDH signal.

Here is a preliminary plot for today's noise spectra.

The blue curve is the ALS in-loop spectrum, that corresponds to the beat fluctuation.

The red curve is an out-of-loop spectrum taken by measuring the IR PDH signal.

Since the UGF is at about 180 Hz the rms is integrated from 200 Hz.

The residual displacement noise in the IR PDH signal is now 1.2 kHz in rms.

I am going to analyze this residual noise by comparing with the differential noise that I took yesterday (see the last entry ).

4428   Wed Mar 23 08:50:36 2011 AidanUpdateGreen Lockingservo handig off

Nicely done!

 Quote: Succeeded in handing off the servo from the green to the red.

Attachment 1: green-to-red.jpg
4429   Wed Mar 23 09:48:20 2011 steveUpdatePSLPSL enclosure: gets new window & laser

Solid door, numbered 4 at south west corner of PSL enclosure was replaced by laser protective window.

The carpenter shop's Mark is making 4 more identical ones for the east side.

The Lightwave NPRO126 of 700mW was moved from the AP-table into the PSL-enclosure temporarily.

It's emergency shutdown switch can be seen at the center bottom picture

Attachment 1: P1070471.JPG
4431   Wed Mar 23 10:34:17 2011 josephbUpdateCDSTrend issue fixed

[Joe, Alex]

Yesterday during the day, Alex ran a script to fix the time stamps in the trends files we had messed up back during the daqd change overs around Feb 17th and 23rd.  See this elog for more information on the trend problem.

Due to how the script runs, basically taking all the data and making a new copy with the correct time stamps, the data collected while the script was running didn't get converted over.  So when he did the final copy of the corrected data, it created a several hour gap in the data from yesterday during the day time.

The original files still exist on the fb machine in /frames/trend/minute_raw_22mar2011 directory.

4434   Wed Mar 23 16:06:20 2011 Larisa ThorneUpdateElectronicsUpdate on cable laying

[Steve, Suresh, Larisa]

The following cables were laid today: ETMYT, ETMY, IFOPO, MC1, OMCR, AS Spare, and MC2T.

Though the paper suggested 135' for the MC2T, we used a 110'. This is too short: need at least another 15' for the MC2T.

The RCR cable wasn't crossed off on the list, but a cable exists at the RCR cable which is black and is labeled (old label, 75 ohms)

There was no indication of which length was needed for MC1, so a 95' cable was used.

4438   Thu Mar 24 13:56:05 2011 josephbUpdateelogelog restarted at 1:55pm

Restarted elog.

4441   Thu Mar 24 19:48:13 2011 Aidan, KiwamuUpdateGreen LockingDesigns for permanent electronics for ALS

Kiwamu and I looked at all the electronics that are currently in place for the green locking on the X-arm and have made a set of block diagrams of the rack mounted units that we should build to replace the existing ... "works of art" that sprawl around out there at the moment.

Main items

1. "ETM Green Oscillator/PDH support box". Not a great name but this would provide the local oscillator signal for the end PDH (with a controllable phase rotator) as well as the drive oscillator for the end laser PZT. Since we need to hit a frequency of 216.075kHz with a precision that Kiwamu needs to determine, we'd need to be able to tune the oscillator ... it needs to be a VCO. It'd be nice to be able to measure the output frequency so I've suggested dividing it down by N times to put it into the DAQ - maybe N = 2^7 = 128x to give a measured frequency of around 1.7kHz. Additionally this unit will sum the PDH control signal into the oscillation. This box would support the Universal PDH box that is currently at the X-end.

2. "Vertex X-arm beatnote box" - this basically takes the RF and DC signals from the beatnote PD and amplifies them. It provides a monitor for the RF signal and then converts the RF signal into a square wave in the comparator.

3. "Mixer Frequency Discriminator" - just the standard MFD setup stored in a box. For temperature stability reasons, we want to be careful about where we store this box and what it is made of. That's also the reason that this stage is separated from the X-arm beatnote box with it's high-power amps.

Other things

4. RS232 and EPICS control of the doubling ovens

5. Intensity stabilization of the End Laser

P.S. I used Google Diagrams for the pictures.

Attachment 1: GreenLockingElectronics.pdf
Attachment 2: GreenEndPDHsupportboxandLO.pdf
Attachment 3: VertexBeatnoteAmplifierandComparator.pdf
Attachment 4: MixerFrequencyDiscriminator.pdf
4443   Fri Mar 25 08:58:38 2011 AidanUpdateTreasureCleared stuff off SP table

I tidied up some of the stuff that was on the SP table. The ISS box that has been sitting on there for months is now underneath the X-arm on top of the spare Marconi which is stored there.

Attachment 1: ISS_box.JPG
4445   Mon Mar 28 15:18:04 2011 josephbUpdateCDSCDS updates on Friday

Last Friday, we discovered a bug in the RCG where the delay part was not actually delaying.  We reported this to Alex who promptly put a fix in the same day.  This allowed Matt's newly proposed frequency discriminator to work properly.

It also required a checkout of the latest RCG code (revision 2328), and rebuild of the various codes.  We backed up all the kernel and executables first such as mbuf.ko and awgtpman.

We did the following:

2) Go to /opt/rtcds/caltech/c1/core/advLigoRTS/src/drv/mbuf and run make.  Copy the newly built mbuf.ko file to /diskless/root/modules/2.6.34.1/kernel/drivers/mbuf/mbuf.ko on the fb machine.

3) Use "sudo cp" to copy the newly built mbuf.ko file to /diskless/root/modules/2.6.34.1/kernel/drivers/mbuf/

4) Go to /cvs/cds/rtcds/caltech/c1/core/advLigoRTS/src/gds and run make.

5) Copy the newly built awgtpman executable to /opt/rtcds/caltech/c1/target/gds/bin/

6) Go to /opt/rtcds/caltech/c1/core/advLigoRTS/src/mx_stream/ and run make.

7) Copy the newly built mx_stream executable to /opt/rtcds/caltech/c1/target/fb/

4446   Mon Mar 28 15:49:18 2011 josephbUpdateCDSLessons from LST

[Koji,Joe]

PART 1:

Koji was unable to build his c1lst model first thing this morning.  Turns out there was  a bug with RCG parser that was introduced on Friday when we did the RCG updates.  We talked Alex who did a quick comment fix.  The diff is as follows:

Index: Parser3.pm ==============================

===================================== --- Parser3.pm  (revision 2328) +++ Parser3.pm  (working copy) @@ -1124,8 +1124,8 @@   print "Flattening the model\n";   flatten_nested_subsystems($root); print "Finished flattening the model\n"; - CDS::Tree::do_on_nodes($root, \&remove_tags, 0, $root); - print "Removed Tags\n"; + #CDS::Tree::do_on_nodes($root, \&remove_tags, 0, $root); + #print "Removed Tags\n"; #print "TREE\n"; #CDS::Tree::print_tree($root);   CDS::Tree::do_on_nodes($root, \&remove_busses, 0,$root);

This was some code to remove TAGs from the .mdl file for some reason which I do not understand at this time.  I will ask tommorrow in person so I can understand the full story.

PART 2:

Koji then rebuilt and started the c1lst process.  This is his new test version of the LSC code.  We descovered (again) that when you activate too many DAQ channels (simply uncommenting them, not even recording them with activate=1 in the .ini file) that the frame builder crashes.  In addition, the c1lsc machine, which the code was running on, also hard crashed.

When a channel gets added to the .ini file (or uncommented) it is sent to the framebuilder, irregardless of whether its recorded or not by the frame builder.  There is only about 2 megabytes per second bandwidth per computer.  In this case we were trying to do something like 200 channels * 16384 Hz * 4 bytes = 13 megabytes per second.

The maximium number of 16384 channels is roughly 30, with little to no room for anything else.  In addition, test points use the same allocated memory structure, so that if you use up all the capacity with channels, you won't be able to use testpoints to that computer (or thats what Alex has led me to believe).

The daqd process then core dumped and was causing all sorts of martian network slowdowns.  At the same time, the c1lsc computer crashed hard, and all of the front end processes except for the IOP on c1sus crashed.

We rebooted c1lsc, and restarted the c1sus processes using the startc1SYS scripts.  However, the c1susfe.ko apparently got stuck in a wierd state.  We were completely unable to damp the optics and were in general ringing them up severely.  We tried debugging, including several burt restores and single path checks.

Eventually we decided to reboot the c1sus machine after a bit of debugging.  After doing a burt restore after the reboot, everything started to damp and work happily.  My best guess is the kernel module crashed in a bad way and remained in memory when we simply did the restart scripts.

4448   Mon Mar 28 16:24:35 2011 kiwamuUpdateGreen Lockingpower budget on PSL table

I measured some laser powers associated with the beat-note detection system on the PSL table.

The diagram below is a summary of the measurement. All the data were taken by the Newport power meter.

The reflection from the beat-note PD is indeed significant as we have seen.

In addition to it the BS has a funny R/T ratio maybe because we are using an unknown BS from the Drever cabinet. I will replace it by a right BS.

(background)

During my work for making a noise budget I noticed that we haven't carefully characterize the beat-note detection system.

The final goal of this work is to draw noise curves for all the possible noise sources in one plot.

To draw the shot noise as well as the PD dark noise in the plot, I started collecting the data associated with the beat-note detection system.

(Next actions)

* Estimation and measurement of the shot noise

* measurement of the PD electrical noise (dark noise)

* modeling for the PD electrical noise

* measurement of the doubling efficiency

* measurement of an amplitude noise coupling in the frequency discriminators

4449   Mon Mar 28 17:06:15 2011 kiwamuUpdateGreen Lockinga mixer school

In the last week Matt and I modified the MFD configuration because the mixer had been illegally used.

Since the output from the comparator is normally about 10 dBm, a 4-way power splitter reduced the power down to 4 dBm in each output port.

In order to reserve a 7 dBm signal to a level-7 mixer, we decided to use an asymmetric power splitter, which is just a combination of 2-way and 3-way splitter shown in the diagram above.

With this configuration we can reserve a 7 dBm signal for a mixer in the fine path.

However on the other hand we sacrificed the coarse path because the power going to the mixer is now 2.2 dBm in each port.

According to the data sheet for the mixer, 1 dB compression point for the RF input is 1dBm. Therefore we put a 1 dB attenuator for the RF port in the coarse system.

In the delay line of the fine path we found that the delay cable was quite lossy and it reduced the power from 2.2 dBm to about 0 dBm.

ELOG V3.1.3-