40m QIL Cryo_Lab CTN SUS_Lab TCS_Lab OMC_Lab CRIME_Lab FEA ENG_Labs OptContFac Mariner WBEEShop
  40m Log, Page 100 of 339  Not logged in ELOG logo
ID Date Author Type Categoryup Subject
  3530   Tue Sep 7 08:56:00 2010 AlbertoUpdateElectronicsFrequency Generation Box Assembly - Phase Noise Measurements

Here are the results of my phase noise measurements on the 7 outputs of the Frequency Generation Box. (BIN=95L applied by DTT). See attached pdf for a higher definition picture.

2010-09-03_FreqBoxPhaseNoise_AllOutputsComparison_smooth.png

The plot shows that the phase noise of the 11 MHz outputs (Source, EOM modulation signal, Demodulation signal) is as low as that of the Marconi. The Marconi is limiting my measurement's resolution.

The mode cleaner signal's oscillator (29.5 MHz output, blue trace) is higher than the 11MHz above 1KHz.

The 55MHz signals have all the same phase noise (traces overlapped), and that is higher than the 11 MHz ones from about 100Hz up. i don't know what's going on.

I need to use the spare 11MHz Wenzel crsytal to have a better reference source for the measurement.

Attachment 2: 2010-09-03_FreqBoxPhaseNoise_AllOutputsComparison_smooth.pdf
2010-09-03_FreqBoxPhaseNoise_AllOutputsComparison_smooth.pdf
  3532   Tue Sep 7 13:31:49 2010 AlbertoUpdateElectronicsRF System - Frequency Distribution Box - Priority Plan

We need a distribution unit in the LSC rack to: 1) collect the demod signals coming from the Frequency Generation Box 2) adjust the power level 3) generate 2nd harmonics (for POP) 4) distribute the demod signals to the single demodulation boards.

The base line plan is the following:

Visio-RFsystem_plan_distributiont.png

The box can be build up gradually, but the priority goes to these parts:

 RFsystem_plant_distribution_priority.png

I need help for this work. I know exactly how to do it, I just don't have the time to do it all by myself.

 Besides the Distribution Box, the demodulation part of the upgrade would still require two steps:

1) upgrade the Band Pass Filters of the demodulation boards (I have all the parts)

2) cabling from the distribution box to the demod board (one-afternoon kind of job)

  3552   Thu Sep 9 12:02:03 2010 AlbertoUpdateElectronicsFrequency Generation Box - Amplitude Noise Measurements

I measured the amplitude noise of the source outputs and the EOM outputs of the Frequency Generation box.

the setup I used is shown in this diagram:

FreqBoxAmplitudeNoiseMeasurementSetup.png

(NB It's important that the cables from the splitter to the RF and LO inputs of the mixers are the same length).

The results of the measurements are shown in the following plot:

 FreqBoxAmplitudeNoise_BusbyBox_AllChannels.png

Considerations:

1) both Crystals (29.5MHz and 11MHz) have the same noise

2) the 55MHz source's noise is bigger than the 11 MHz (~2x): the frequency multiplication and amplification that happen before it, add extra noise

3) the noise at EOM outputs is ~2x bigger than that of the relative sources

 

When I have the chance, I'll plot the results of my calculations of expected noise and compare them with the measurements.

  3555   Thu Sep 9 18:53:56 2010 AlbertoConfigurationElectronicsBusby Box, Rai's Box, SR554 in the RF cabinet

I stored the Busby Box, the Rai's Box and the SR554 preamp in the RF cabinet down the Y arm.

  3565   Mon Sep 13 11:40:50 2010 AlbertoUpdateElectronicsFrequency Box Documentation Added to the SVN

I uploaded all the material about the RF frequency Generation Box into the SVN under the path:

https://nodus.ligo.caltech.edu:30889/svn/trunk/docs/upgrade08/RFsystem/frequencyGenerationBox/

I structured the directory as shown in this tree:

freqBoxSVNdierctoryStructure.png

I'm quickly describing in a section of the Rf system upgrade document with LIGO # T1000461.

  3572   Tue Sep 14 18:07:41 2010 AlbertoUpdateElectronicsFrequency Box Documentation Added to the SVN

I completed a LIGO document describing design, construction and characterization of the RF System for the 40m upgrade.

It is available on the SVN under https://nodus.ligo.caltech.edu:30889/svn/trunk/docs/upgrade08/RFsystem/RFsystemDocument/

It can also be found on the 40m wiki (http://lhocds.ligo-wa.caltech.edu:8000/40m/Upgrade_09/RF_System#preview), and DCC under the number T1000461.

  3596   Thu Sep 23 02:23:04 2010 koji,taraSummaryElectronicsTesting new TTFSS

I tested the new table top frequency stabilization system(TTFSS),
I haven’t finished it yet, and accidentally fried one amplifier in the circuit.

We received three sets of a new TTFSS system which will replace the current FSS.
It needs to be checked that the system works as specified before we can use it.

- Result

I followed the instruction written on E10000405-v1
The first test inspected how much the currents were drawn from the +/- 24 V power supply.
+24 V drew 350 mA and -24 V drew 160 mA as shown on pwr supply’s current monitor.
They exceeded the specified value which was 200 +/- 20 mA, but nothing went wrong during the test.
Nothing got overheated, all voltage outputs were correct so I proceeded.
I have gone down the list to 6, and everything works as specified.

- Correcting the document for the test procedure

I found a few errors on the instruction document. I’ll notify the author tomorrow.

- How GVA-81 amplifier on D0901894 rev A got fried

During the test, I used a mirror on a stick that looked like a dental tool to see under the board.
Unfortunately, the steel edge touched a board and caused a spark. The voltage on -24 dropped to -16.
I think this happened because the pwr supply tried to decrease the current from shorted circuit,
as I shorted it only short time ( a blink of an eye), it could not reduce the voltage to zero.
When I was checking the power supply and about to adjust the voltage back to the right value
(about 4-5 seconds after the spark,) smoke came out of the circuit.

Koji investigated the circuit and found that a GVA 81 amplifier was broken.

This was checked by applying 5V to the amp, and slightly increasing the current.
The voltage dropped to zero as the amp was broken, so its circuit was shorted.

I’ll see if I can replace this at EE lab at Downs.
If I cannot find a spare one, I’ll replace it with a resistor and resume the test procedure.
Because it amplifies LO signal, which won’t be used during the test.

  3604   Fri Sep 24 00:56:35 2010 koji, taraUpdateElectronicstesting TTFSS

We found that a transistor was broken from yesterday spark too. We partially fixed TTFSS, and it should be enough for  testing purpose.

 

From yesterday test, we found that the RF amplifier for LO signal was broken. There was no spare at the electronic shop at Downs,

so we shorted the circuit for now.  Another part which was broken too was a transistor, Q3 PZT2222A, on D0901846.

It was removed and two connections, which are for Q3's 1 and 3 legs, are shorted. Now the voltages out from the regulators are back to normal.

 

We are checking a MAX333A switch, U6A on D0901894. it seems that the voltage that controls the switch disappears.

There might be a bad connection somewhere. This will be investigated next.

  3607   Fri Sep 24 23:47:10 2010 koji, taraUpdateElectronicstesting TTFSS

  Q3, a PZT2222A transistor, on D0901846 is replaced by a GE-82. However, the board is still not fully function.

 

Since Q3, PZT2222A, was broken, I went to Wilson house and got some SP3904's for replacement. But somehow, I broke it during

installation, and did not notice it, and resumed the test. When I got to test 8 on the list, the TTFSS did not work as specified.

Koji checked and found out that -15V, Nref, Vref voltages output did not work correctly. So the SP3904 I installed was removed

and replaced with another SP3904 by Koji, and Vref is working. 

Q4 transistor is broken as well and it was replaced by GE 82.

Q1 might be broken too since -15V out is not working.

I'll go to Wilson house to get more transistors next week.

 

After the broken parts have been replaced, I have to make sure that I separate the power supply board from the rest of the circuit and

check if all V outputs are  working, then reconnect the board and check if the current input is reasonable before resume the test.

I hope the wrong input voltage problem today wouldn't damage anything else.

 

  3608   Sat Sep 25 19:01:13 2010 KojiUpdateElectronicstesting TTFSS

How much current do you need for each voltages?

GE-82 was the only PNP transister I could find in the lab. It's too old but we just like to confirm any other components are still functioning.

Similarly, we can confirm the functionality of the other components by skipping those current boost transisters,
if we don't need more than 30mA.

 

  3617   Tue Sep 28 21:11:52 2010 koji, taraUpdateElectronicsFixing the new TTFSS

We found a small PCB defect which is an excess copper shorting circuit on the daughter board,

it was removed and the signal on mixer monitor path is working properly.

 

 We were checking the new TTFSS upto test 10a on the instruction, E1000405 -V1. There was no signal at MIXER mon channel.

It turned out that U3 OpAmp on the daughter board, D040424, was not working because the circuit path for leg 15 was shorted

because of the board's defect. We can see from fig1 that the contact for the OpAmp's leg (2nd from left) touches ground.

We used a knife to scrap it out, see fig 2, and now this part is working properly.

 

Attachment 1: before.jpg
before.jpg
Attachment 2: after.jpg
after.jpg
Attachment 3: before.jpg
before.jpg
Attachment 4: after.jpg
after.jpg
  3655   Tue Oct 5 18:27:18 2010 Joonho LeeSummaryElectronicsCCD cable's impedence

Today I checked the CCD cables which is connected to the VIDEOMUX.

17 cables are type of RG59, 8 cables are type of RG58. I have not figured out the type of other cables(23 cables) yet.

The reason I am checking the cables is for replacing the cables with impedance of 50 or 52 ohm by those with impedance of 75 ohm.

After I figures out which cable has not proper impedance, I will make new cables and substitute them in order to match the impedance, which would lead to better VIDEO signal.

To check the impedance of each CCD cable, I went to the VIDEOMUX and looked for the label on the cable's surface.

Type of RG59 is designated to the cable of impedance 75ohm. I wrote down each cable's input or output channel number with observation(whether it is of type RG59 or not).

The result of observation is as follows.

Type channel number where it is connected to
Type 59 in#2, in#11, in#12, in#15, in#18, in#19, in#22, in#26, out#3, out#4, out#11, out#12, out#14, out#17, out#18, out#20, out#21
Type 58 in#17, in#23, in#24, in#25, out#2, out#5, out#7, out#19
unknown type others

 

For 23 cables that I have not figured out their type, cables are too entangled so it is limited to look for the label along each cable.

I will try to figure out more tomorrow. Any suggestion would be really appreciated.

  3694   Mon Oct 11 23:55:25 2010 Joonho LeeSummaryElectronicsCCD cables for output signal

Today I checked all the CCD cables which is connected output channels of the VIDEOMUX.

Among total 22 cables for output, 18 cables are type of RG59, 4 cables are type of RG58.

The reason I am checking the cables is for replacing the cables with impedance of 50 or 52 ohm by those with impedance of 75 ohm.

After I figures out which cable has not proper impedance, I will make new cables and substitute them in order to match the impedance, which would lead to better VIDEO signal.

 

Today, I labeled all cables connected to output channels of VIDEO MUX and disconnect all of them since last time it was hard to check every cable because of cables too entangled.

With thankful help by Yuta, I also checked which output channel is sending signal to which monitor while I was disconnecting cables.

Then I checked the types of all cables and existing label which might designate where each cable is connected to.

After I finished the check, I reconnected all cables into the output channel which each of cable was connected to before I disconnected.

 

4 cables out of 22 are type of RG58 so expected to be replace with cable of type RG59.

The result of observation is as follows. 

Ch#
where its signal is sent type
1 unknown 59
2 Monitor#2  58
3 Monitor#3 59
4 Monitor#4 59
5 Monitor#5 58
6 Monitor#6 59
7 Monitor#7 58
8 unknown / labeled as "PSL output monitor" 59
9 Monitor#9 59
10 Monitor#10 59
11 Monitor#11 59
12 Monitor#12 59
13 Unknown 59
14 Monitor#14 59
15 Monitor#15 59
16 unknown / labeled as "10" 59
17 unknown 59
18 unknown / labeled as "3B" 59
19 unknown / labeled as "MON6 IR19" 58
20 unknown 59
21 unknown 59
22 unknown 59

I could not figure out where 10 cables are sending their signals to. They are not connected to monitor turned on in control room

so I guess they are connected to monitors located inside the lab. I will check these unknown cables when I check the unknown input cables.

Next time, I will check out cables which is connected to input channels of VIDEIO MUX. Any suggestion would be really appreciated.

  3739   Mon Oct 18 22:11:32 2010 Joonho LeeSummaryElectronicsCCD cables for input signal

Today I checked all the CCD cables which is connected input channels of the VIDEOMUX.

Among total 25 cables for output, 12 cables are type of RG59, 4 cables are type of RG58, and 9 cables are of unknown type.

The reason I am checking the cables is for replacing the cables with impedance of 50 or 52 ohm by those with impedance of 75 ohm.

After I figures out which cable has not proper impedance, I will make new cables and substitute them in order to match the impedance, which would lead to better VIDEO signal.

 

Today, I check the cables in similar way as I did the last time.

I labeled all cables connected to input channels of VIDEO MUX and disconnect all of them since last time it was hard to check every cable because of cables too entangled.

Then I checked the types of all cables and existing label which might designate where each cable is connected to.

After I finished the check, I reconnected all cables into the input channel which each of cable was connected to before I disconnected.

 

4 cables out of 25 are type of RG58 so expected to be replace with cable of type RG59.

9 cables out of 25 are of unknown type. These nine cables are all orange-colored thick cables which do not have any label about the cable characteristic on the surface.

The result of observation is as follows.

Note that type 'TBD-1' is used for the orange colored cables because all of them look like the same type of cable.

 

Channel number where its signal is coming type
1 C1:IO-VIDEO 1 MC2 TBD-1
2 FI CAMERA 59
3 PSL OUTPUT CAMERA 59
4 BS  C:1O-VIDEO 4 TBD-1
5 MC1&3 C:1O-VIDEO 5 59
6 ITMX C:1O-VIDEO 6 TBD-1
7 C1:IO-VIDEO 7 ITMY TBD-1
8 C1:IO-VIDEO 8 ETMX TBD-1
9 C1:IO-VIDEO 9 ETMY TBD-1
10 No cable is connected
(spare channel)
 
11 C1:IO-VIDEO 11 RCR 59
12 C1:IO-VIDEO RCT 59
13 MCR VIDEO 59
14 C1:IO-VIDEO 14 PMCT 59
15 VIDEO 15 PSL IOO(OR IOC) 59
16 C1:IO-VIDEO 16 IMCT TBD-1
17 PSL CAMERA 58
18 C1:IO-VIDEO 18 IMCR 59
19 C1:IO-VIDEO 19 SPS 59
20 C1:IO-VIDEO 20 BSPO TBD-1
21 C1:IO-VIDEO 21 ITMXPO TBD-1
22 C1:IO-VIDEO 22 APS1 59
23 ETMX-T 58
24 ETMY-T 58
25 POY CCD VIDEO CH25 58
26 OMC-V 59

Today I could not figure out what impedance the TBD-1 type(unknown type) has.

Next time, I will check out the orange-colored cables' impedance directly and find where the unknown output signal is sent. Any suggestion would be really appreciated.

  3740   Tue Oct 19 00:24:07 2010 DmassOmnistructureElectronicsMassive restocking of the 40m

I had a number of delinquent items on the sign out list from the 40m. I returned about half, and ordered replacements for most of the other half.

I put the photodiodes on the SP table, and the 560 on the electronics  bench.

  3762   Fri Oct 22 16:59:21 2010 JenneUpdateElectronicsEpic Takeover

As the suspension work winds down (we'll be completely done once the ETMs arrive, are suspended, and then are placed in the chambers), I'm going to start working on the RF system. 

Step 1: Figure out what Alberto has been up to the last few months.

Step 2: Figure out what still needs doing.

Step 3: Complete all the items listed out in step 2.

Step 4: Make sure it all works.

Right now I'm just starting steps 1 & 2.  I've made myself a handy-dandy wiki checklist: RF Checklist.  Hopefully all of the bits and pieces that need doing will be put here, and then I can start checking them off. Suggestions and additions to the list are welcome.

  3764   Fri Oct 22 18:22:27 2010 AlbertoUpdateElectronicsEpic Takeover

Quote:

As the suspension work winds down (we'll be completely done once the ETMs arrive, are suspended, and then are placed in the chambers), I'm going to start working on the RF system. 

Step 1: Figure out what Alberto has been up to the last few months.

Step 2: Figure out what still needs doing.

Step 3: Complete all the items listed out in step 2.

Step 4: Make sure it all works.

Right now I'm just starting steps 1 & 2.  I've made myself a handy-dandy wiki checklist: RF Checklist.  Hopefully all of the bits and pieces that need doing will be put here, and then I can start checking them off. Suggestions and additions to the list are welcome.

 There's also a page dedicated to the progress in the PD upgrade process:

http://lhocds.ligo-wa.caltech.edu:8000/40m/Upgrade_09/RF_System/Upgraded_RF_Photodiodes

There you can find a pdf document with my notes on that.

  3773   Sun Oct 24 19:55:50 2010 kiwamuUpdateElectronicslonely RF amplifier on ITMX table
(Rana, Kiwamu)

Last Friday we found a lonely RF amplifier ZHL-3A on the ITMX table.
When we found him we were very sad because he's been setup unacceptably


For example, the signal input was disconnected although a 24V DC was still applied. So he has been making just a heat for a long time.
The power connector was a BNC style which is not official way.
The leg of a decoupling capacitor attached to the DC connector was apparently broken and etc,..

We salvaged him and then cleaned up those cables and the DC power supply.

We don't say like 'don't make a temporary setup', but please clean up them after finishing the work every time.
  3782   Tue Oct 26 01:53:21 2010 Joonho LeeUpdateElectronicsFuction Generator removed.

Today I worked on how to measure cable impedance directly.

In order to measure the impedance in RF range, I used a function generator which could generate 50MHz signal and was initially connected to the table on the right of the decks.

The reason I am checking the cables is for replacing the cables with impedance of 50 or 52 ohm by those with impedance of 75 ohm.

After I figures out which cable has not proper impedance, I will make new cables and substitute them in order to match the impedance, which would lead to better VIDEO signal.

 

To test the VIDEO cables, I need a function generator generating signal of frequency 50 MHz.

In the deck on the right of PSL table, there was only one such generator which was connected to the table on the right of the deck.

Therefore, I disconnected it from the cable and took it to the control room to use it because Rana said it was not used.

Then, I tired to find on how to measure the impedance of cable directly but I did not finish yet.

When I finished today works, I put the generator back to the deck but I did not connect to the previous cable which was initially connected to the generator.

 

Next time, I will finish the practical method of measuring the cable impedance then I will measure the cables with unknown impedance.

Any suggestion would be appreciated.

  3792   Wed Oct 27 09:02:29 2010 steveUpdateElectronicsHP4195A is NOT fixed

www.avalontest.com has fixed the 25MHz oscillation.  Contact: Jim Burnham 760-536-0191

Actually, NOT FIXED.

  3812   Thu Oct 28 19:10:26 2010 taraUpdateElectronicsTTFSS for 40m

I keep a set of new TTFSS for 40m in electronic cabinet along the North arm.

The set number is #6. It is working and has not been modified by me.

Other two sets,# 5 and #7, are kept at PSL lab.

  3858   Wed Nov 3 23:58:45 2010 ranaUpdateElectronicsCougars

I looked at this web page: http://www.teledyne-cougar.com/Index.asp for the RF company that Rich has recently started using.

There are ~15 amplifiers that they sell which have a NF < 2 dB and work in the 10-100 MHz band. We should call them to find out if they will package some amps for us or at least sell us a few with eval. boards so that we can make our own.

  3871   Fri Nov 5 19:33:18 2010 JenneUpdateElectronicsThe beginnings of the new phase of the RF work

Joon Ho and I took a look at the RF stuff that Alberto left, and we determined that we've got most everything that we need.  On Monday, Joon Ho will list off the stuff that we're missing, and we'll have Steve order it.

Joon Ho also replaced the temporary front panel to the RF generation box with Alberto's fancy new panel.  Pics are here (although you have to sign in as foteee to see them). 

Work on the frequency distribution box will continue on Monday.

  3890   Thu Nov 11 02:17:27 2010 KevinUpdateElectronicsREFL11 Photodiode Not Working

[Koji and Kevin]

I was trying to characterize the REFL11 photodiode by shining a flashlight on the photodiode and measuring the DC voltage with an oscilloscope and the RF voltage with a spectrum analyzer. At first, I had the photodiode voltage supplied incorrectly with 15V between the +15 and -15 terminals. After correcting this error, and checking that the power was supplied correctly to the board, no voltage could be seen when light was incident on the photodiode.

We looked at the REFL55 photodiode and could see ~200 mV of DC voltage when shining a light on it but could not see any signal at 55 MHz. If the value of 50 ohm DC transimpedance is correct, this should be enough to see an RF signal. Tomorrow, we will look into fixing the REFL11 photodiode.

  3893   Thu Nov 11 07:26:03 2010 AlbertoUpdateElectronicsREFL11 Photodiode Not Working

Quote:

[Koji and Kevin]

I was trying to characterize the REFL11 photodiode by shining a flashlight on the photodiode and measuring the DC voltage with an oscilloscope and the RF voltage with a spectrum analyzer. At first, I had the photodiode voltage supplied incorrectly with 15V between the +15 and -15 terminals. After correcting this error, and checking that the power was supplied correctly to the board, no voltage could be seen when light was incident on the photodiode.

We looked at the REFL55 photodiode and could see ~200 mV of DC voltage when shining a light on it but could not see any signal at 55 MHz. If the value of 50 ohm DC transimpedance is correct, this should be enough to see an RF signal. Tomorrow, we will look into fixing the REFL11 photodiode.

I just wanted to remind you that the most up to date resource about the RF system upgrade, including photodiodes, is the SVN.

https://nodus.ligo.caltech.edu:30889/svn/trunk/alberto/40mUpgrade/RFsystem/

There you can find everything: measurements, schematics, matlab scripts to plot and fit, etc. Poke around it to find what you need.
For instance, the schematic of the modified REFL11 photodiode is at:

https://nodus.ligo.caltech.edu:30889/svn/trunk/alberto/40mUpgrade/RFsystem/RFPDs/REFL11/REFL11Schematics/40mUpgradeREFL11schematic.pdf

Because I was doing new things all the time, the wiki is not up to date. But the SVN has all I've got.

  3904   Fri Nov 12 02:51:20 2010 KevinUpdateElectronicsPhotodiode Testing

[Jenne and Kevin]

I started testing the REFL55 photodiode. With a light bulb, I saw ~270 mV of DC voltage from the photodiode but still could not see any RF signal. I connected the RF out from the spectrum analyzer to the test input and verified that the circuit was working.

I then set up the AM laser and looked at the laser light with REFL11 and an 1811 photodiode. I was able to see an RF signal and verified that the resonant frequency is 55 MHz.

The current setup is not very reliable because the laser is not mounted rigidly. Next, I will work on making this mounting more reliable and will continue to work on finding an RF signal with a flashlight.

  3911   Fri Nov 12 20:40:51 2010 josephb, yuta, valeraConfigurationElectronicsAA voltage range

We changed the range of the two SUS AA boards in the corner from +/-2 V to +/-10 V by changing the supply voltage from +/-5 V to +/-15 V. The change was made by switching the AA power feed wires on  the cross connect. The max supply according to the spec of DRV134/INA134 is +/-18 V.

We checked the new range by applying the voltage to the input of AA and measuring the output going to the ADCs. The local damping MC1,2,3 appears to work.

  3913   Sat Nov 13 16:57:21 2010 valeraConfigurationElectronicsPRM Side OSEM transimpedance change

Now that we have increased the range of the AA to +/- 10 V I have increased the PRM side OSEM transimpedance from 29 kV/A to 161 kV/A by changing the R64 in the satellite box. The first attached plot shows the ADC input spectrum before and after the change with analog whitening turned off. The PD voltage readback went up from 0.75 to 4.2 V. The second attached plot shows the sensor, ADC, and projected shot noise with analog whitening turned on and compensated digitally. The ADC calibration is 20 V/ 32768 cts. The PRM damping loops are currently disabled.

I checked for oscillation by looking at the monitor point at the whitening board. There was no obvious oscillation on a scope - the signal was 20 mV p-p on 1 us scale which was very similar to the LL channel.

Attachment 1: PRM-SD-ADC.pdf
PRM-SD-ADC.pdf
Attachment 2: PRM-SD-Current.pdf
PRM-SD-Current.pdf
  3916   Sun Nov 14 16:26:31 2010 jenne, valeraUpdateElectronicsSRM side OSEM noise with no magnet

We realized that the SRM sensors are connected to the readout but just sitting on the BS in vacuum table with no magnets and therefore no shadows in them. We swapped the inputs to the SRM and PRM satellite boxes to use the higher transimpedance gain of the PRM side sensor. The attached plot shows the current spectrum in this configuration. The PD readback voltage was 9.5 V. Since this is close to the rail we put a slightly higher voltage into the AA of this channel to test that we can read out more ADC counts to make sure we are not saturating. The margin was 15800 vs 15400 counts with p-p of 5 counts on the dataviewer 1 second trend. We returned all cables to nominal configuration.

The calibration from A to m is 59 uA/1 mm.

Attachment 1: SRM-SD-Current-NoMagnet.pdf
SRM-SD-Current-NoMagnet.pdf
  3918   Mon Nov 15 04:57:10 2010 ranaUpdateElectronicsSRM side OSEM noise with no magnet

IF I believe this calibration and IF I believe that the noise is the same with no magnet in there, then its almost 1 nm/rHz @ 1 Hz.

I am guessing that Jenne's calculation will show that this is an unacceptably high level of OSEM sensor noise, OAF-wise.

  3933   Tue Nov 16 15:32:18 2010 valeraUpdateElectronicsOSEM noise at the output of the satellite box

 I measured the SRM OSEM (no magnets at the moment) noise out of the satellite box with a SRS785 spectrum analyzer. I inserted a break out board into the cable going from the satellite box to the whitening board. The transimpedances of the SRM OSEMs are still 29.2 kOhm. The DC voltages out of the SRM satellite box are about 1.7 V. The signal was AC coupled using SR560 with two poles at 0.03 Hz and a gain of 10.

The noise is consistent with the one measured by the ADC except for the 3 Hz peak which does not show up in the ADC spectrum from Sunday. The peak appears in several channels I looked at. The instrument noise floor was measured by terminating the SR560 with 50 Ohm.

I recommend to change all OSEM transimpedance gains from 29 to 161 kV/A. Beyond this gain one will rail the AA filter module when the magnet is fully out of the OSEM.

The OSEM noise at 1 Hz is about factor of 10 above the shot noise. The damping loops impress this noise on the optics around the pendulum resonance frequency. Also the total contribution to the MC cavity length is sqrt(12) time the single sensor as there are 12 OSEMs contributing to MC length. The ADC noise is currently close but never the less not limiting the OSEM noise below 100 Hz. It can be further reduced by getting an extra factor of 2-3 in whitening gain above ~0.3 Hz. The rms of the ADC input of the modified PRM SD (R64 = 161 kOhm) channel is 10-20 cts during the day with damping loop off and whitening on.

The transimpedance amplifier LT1125CS is also not supposed to be limiting the noise. At 1 Hz the 1/f part of the noise: In<1pA/rtHz and Vn<20nV/rtHz.

Attachment 1: osemnoise.pdf
osemnoise.pdf
  3944   Thu Nov 18 01:52:58 2010 KevinUpdateElectronicsREFL55 Transfer Functions

I measured the optical and electrical transfer functions for REFL55 and calculated the RF transimpedance. To measure the optical transfer function, I used the light from an AM laser to simultaneously measure the transfer functions of REFL55 and a New Focus 1611 photodiode. I combined these two transfer functions to get the RF transimpedance for REFL55. I also measured the electrical transfer function by putting the RF signal from the network analyzer in the test input of the photodiode.

I put all of the plots on the wiki at http://lhocds.ligo-wa.caltech.edu:8000/40m/Electronics/REFL55.

  3949   Thu Nov 18 16:42:29 2010 Joonho LeeConfigurationElectronicsQuad Video for PMCT, RCT, RCR fixed.

The far right monitor in the control room is now displaying IMCR, PMCT, RCR, RCT.

Please note that top left quad is displying PMCT even if the screen is labeled with PMCR.

 

Control room monitor #13 - #16 had been out of order since the last week.

(the monitor number is shown at : http://lhocds.ligo-wa.caltech.edu:8000/40m/Electronics/VideoMUX )

I found that the connections between camera and the cable to the VIDEO MUX were missing so I connected them.

Initially, PMCT camera was sending its signal to the small monitor on the PSL table.

I splitted the signal so that one signal is going to the small monitor and another is going to the VIDEO MUX.

The "PMCR" is shown on the screen #13 in the control room but it actually showing PMCT camera's signal.

 

This is a temporary VIDEO configuration. It will be upgraded as well when the whole VIDEO will be upgraded.

  3950   Thu Nov 18 17:42:20 2010 Joonho LeeSummaryElectronicsCCD cables.

I finished the direct measurement of cable impedances.

Moreover, I wrote the cable replacement plan.

The reason I am checking the cables is for replacing the cables with impedance of 50 or 52 ohm by those with impedance of 75 ohm.

After I figures out which cable has not proper impedance, I will make new cables and substitute them in order to match the impedance, which would lead to better VIDEO signal.

Moreover, as Koji suggested, the VIDEO system will be upgraded for better interface.

 

I measured the cable impedance by checking the reflection ratio at the point connected to the terminator with 50 ohm or 75 ohm.

The orange colored cables are measured to be 75ohm so we do not need to replace them.

Combining the list of cable types and the list of desired length,

I need to make total 37 cables and to remove 10 cables from the current connection.

Detailed plan is attached below.

I currently ordered additional cables and BNC plugs.

 

From now on, I will keep making CCD cables for VIDEO upgrade.

Then, with your helps, we will replace the CCD cables.

 

In my opinion, I will finish VIDEO upgrade by this year.

Attachment 1: Upgrade_plan_(Nov18).pdf
Upgrade_plan_(Nov18).pdf Upgrade_plan_(Nov18).pdf
  3952   Fri Nov 19 03:43:33 2010 KevinUpdateElectronicsREFL55 Characterizations

[Koji, Rana, and Kevin]

I have been trying to measure the shot noise of REFL55 by shining a light bulb on the photodiode and measuring the noise with a spectrum analyzer. The measured dark noise of REFL55 is 35 nV/rtHz. I have been able to get 4 mA of DC current on the photodiode but have not been able to see any shot noise.

I previously measured the RF transimpedance of REFL55 by simultaneously measuring the transfer functions of REFL55 and a new focus 1611 photodiode with light from an AM laser. By combining these two transfer functions I calculated that the RF transimpedance at 55 MHz is ~ 200 ohms. With this transimpedance the shot noise at 4 mA is only ~ 7 nV/rtHz and would not be detectable above the dark noise.

The value of 200 ohms for the transimpedance seems low but it agrees with Alberto's previous measurements. By modeling the photodiode circuit as an RLC circuit at resonance with the approximate values of REFL55 (a photodiode capacitance of 100 pF and resistance of 10 ohms and an inductance of 40 nH), I calculated that the transimpedance should be ~ 230 ohms at 55 MHz. Doing the same analysis for the values of REFL11 shows that the transimpedance at 11 MHz should be ~ 2100 ohms. A more careful analysis should include the notch filters but this should be approximately correct at resonance and suggests that the 200 ohm measurement is correct for the current REFL55 circuit.

  3955   Fri Nov 19 15:51:50 2010 KojiUpdateElectronicsREFL55 Characterizations

RF Transimpedance of 200Ohm means the residual impedance at the resonance (R_res) of 40,
if you consider the amplifier gain (G_amp) of 10 and the voltage division by the 50Ohm termination,
this corresponds to the thermal noise level of Sqrt(4 kB T R_res)*G_amp/2 = 4nV/rtHz at the analyzer, while you observed 35nV/rtHz.

35nV/rtHz corresponds to 7nV/rtHz for the input noise of the preamp. That sounds too big if you consider the voltage noise of opamp MAX4107 that is 0.75nV/rtHz.

What is the measurement noise level of the RF analyzer?

Quote:

[Koji, Rana, and Kevin]

I have been trying to measure the shot noise of REFL55 by shining a light bulb on the photodiode and measuring the noise with a spectrum analyzer. The measured dark noise of REFL55 is 35 nV/rtHz. I have been able to get 4 mA of DC current on the photodiode but have not been able to see any shot noise.

I previously measured the RF transimpedance of REFL55 by simultaneously measuring the transfer functions of REFL55 and a new focus 1611 photodiode with light from an AM laser. By combining these two transfer functions I calculated that the RF transimpedance at 55 MHz is ~ 200 ohms. With this transimpedance the shot noise at 4 mA is only ~ 7 nV/rtHz and would not be detectable above the dark noise.

The value of 200 ohms for the transimpedance seems low but it agrees with Alberto's previous measurements. By modeling the photodiode circuit as an RLC circuit at resonance with the approximate values of REFL55 (a photodiode capacitance of 100 pF and resistance of 10 ohms and an inductance of 40 nH), I calculated that the transimpedance should be ~ 230 ohms at 55 MHz. Doing the same analysis for the values of REFL11 shows that the transimpedance at 11 MHz should be ~ 2100 ohms. A more careful analysis should include the notch filters but this should be approximately correct at resonance and suggests that the 200 ohm measurement is correct for the current REFL55 circuit.

 

  3971   Tue Nov 23 01:27:33 2010 KevinUpdateElectronicsPOX Characterizations

I measured the RF transimpedance of the POX photodiode by measuring the optical transfer function with the AM laser and by measuring the shot noise with a light bulb. The plots of these measurements are at http://lhocds.ligo-wa.caltech.edu:8000/40m/Electronics/POX.

I measured the noise of the photodiode at 11 MHz for different light intensities using an Agilent 4395a. The noise of a 50 ohm resistor as measured by this spectrum analyzer is 10.6 nV/rtHz. I fit this noise data to the shot noise formula to find the RF transimpedance at 11 MHz to be (2.42 ± 0.08) kΩ. The RF transimpedance at 11 MHz as measured by the transfer function is 6.4 kΩ.

  3976   Tue Nov 23 11:32:03 2010 JoonhoSummaryElectronicsRF distribution unit.

The last time(Friday) I made an arrangement for RF distribution unit.

I am making RF distribution unit for RF upgrade which is designed by Alberto.

 

To reduce a noise from loose connection,

I tried to make the number of hard connect as much as possible while reducing the number of connection via wire.

This is why I put splitters right next to the front pannel so that the connection between pannel plugs and splitters could be made of hard joints.

I attached the arrangement that I made on the last Friday.

 

Next time, I will drill the teflon(the supporting plate) for assembly.

Any suggestion would be really appreciated.

Attachment 1: Frequency_Distribution_Unit_Arrangement.jpg
Frequency_Distribution_Unit_Arrangement.jpg
  4010   Fri Dec 3 15:56:50 2010 Joonho, Jenne.SummaryElectronicsRF distribution unit plan

The last time(Moonday) Jenne and I worked on the RF distribution unit's structure.

We are making RF distribution unit for RF upgrade which is designed by Alberto.

 

Rana, Koji, Jenne suggested a better design for RF Distribution unit.

So Jenne and I gathered information of parts and decided what parts will be used with specific numbers.

Specific circuit is shown in the attached picture.

 

Any suggestion would be really appreciated.

Attachment 1: RFsystem_plant_VISIO2.png
RFsystem_plant_VISIO2.png
  4034   Thu Dec 9 01:54:15 2010 JenneUpdateElectronicsSome Refl 11 fixes

The Backstory:

Kevin was working on characterizing all of our RF photodiodes for the upgrade, and he discovered that REFL11 didn't work, as described in elog 3890.  Rana was working on fixing it, but then he went off to Japan.

Today's Activities:

I visually inspected the components inside the RF cage on the REFL 11 circuit board inside the PD.  Most of them were okay, but the connection between L5 and C33 (the big tunable inductor and the next capacitor in the path) was totally flaky.  the leg of the inductor had been soldered directly to the trace on the PCB, and the inductor was a little bit tipped over, and pulling the trace off the board.  I wiggled it a little while trying to see what was going on, and the trace broke.  Since there is nothing going on between L5 and C33, just the trace, I used a piece of resistor lead to attach the two.  The connection now seems very robust.  I'm a little worried about the connection between the inductor and the board on the other side, but I can't see it since it's under the inductor itself.

Also, the soldering of L4 (a standard surface mount component type body) to the board seemed totally shoddy.  I was desoldering the first side, and the whole inductor popped off.  It was clear that the inductor was making a physical connection to the board, but not a nice solid electrical connection.  So I resoldered it on.  (On Alberto's schematics, it is listed as a 633nH inductor.  I can't find any of this value, so I just put the same one back on.  The best I could do to confirm the component was still okay was measure its resistance, and compare that to a similar inductor of a similar value.  It seemed okay.)

After that I powered up the PD, and took an electrical transfer function, just to have a look-see.  It seems kind of okay, although the resonance seems to be closer to 13MHz than 11MHz. 

Since we would like to remove the capacitor that is in parallel with the diode itself, which will then change all of the resonant conditions on other components, I didn't worry too much about the resonant peak for tonight.  We're going to have to look in on this though.

Also, I'm leaving the optical check-out for Kevin, so he will let us know if I magically fixed the PD, or if it needs some more work.

Photos of the circuit board (mostly Alberto's mods) before and after I fitzed with it are on Picasa

The Future:

More testing. Probably more fixing.

 

  4048   Mon Dec 13 21:03:30 2010 KevinUpdateElectronicsRF Photodiode Characterizations

[Koji, Jenne, Kevin]

Jenne worked on fixing REFL11 last week (see elog 4034) and was able to measure an electrical transfer function. Today, I tried to measure an optical transfer function but REFL11 is still not responding to any optical input. I tried shining both the laser and a flashlight on the PD but could not get any DC voltage.

I also completed the characterizations of POX. I redid the optical transfer function and shot noise measurements. I also took a time series of the RF output from the PD when it was powered on with no light. This measurement shows oscillations at about 225 MHz. I also measured the spectrum with no light which also shows the oscillations at 225 MHz and smaller oscillations at ~455 MHz.

The plots can be found at http://lhocds.ligo-wa.caltech.edu:8000/40m/Electronics/POX?action=show.

  4051   Tue Dec 14 04:14:53 2010 ranaUpdateElectronicsRF Photodiode Characterizations

This is looking better, but the fit data for the TF should be plotted along with the data. The data should be made up of points and the fit a line.

For the fit, we should have the Q of the main resonance as well as the peak height of the main resonance and the values of the gain at the notch frequencies.

Also the peak as well as the notches should have the frequencies fit for and labeled. In principle, you can make the plot on the wiki have all of the data. Then in the end we can print the plot in a small size and glue it to the PD's backside.

  4164   Mon Jan 17 20:13:38 2011 ranaUpdateElectronicsPOX_11 Optical TF

I used 50 mA to drive the laser diode. The light is split 50/50 between the DUT (Device Under Test) and the New Focus 1611 (1 GHz BW) diode used as the reference.

This measurement is the TF of DUT/(New Focus). The resonances are there, but clearly there's an issue with instability around 200 MHz. The setup is still powered up, so please be careful around the RFPD testing table (don't stomp around yank the cables out of the power supplies).

I looked at the RF Photodiode wiki that Alberto has started - most of the TF features are replicated there. Todo:

* Update the 'schematic' with a real schematic instead of the cartoon.
* Change the circuit to remove the resistor in the RF path.
* Add compensation to avoid the 200 MHz instability.
* Make sure to include opamp current noise in the noise model (it is the dominant noise source but has been left out in the noise estimation plot).
* Make the output into a true 50 Ohms.
Attachment 1: A.TIF
A.TIF
  4167   Wed Jan 19 04:25:54 2011 KevinUpdateElectronicsPOX Transfer Functions

I redid the optical POX transfer functions and updated the wiki at http://lhocds.ligo-wa.caltech.edu:8000/40m/Electronics/POX.

I measured each transfer function several times to calculate uncertainties for each measured point. There is one large transfer function from 1 MHz to 500 MHz showing a resonance peak at 11 MHz and notches at 22 MHz and 55 MHz. I also made more detailed measurements around each of these resonance peaks. These measurements were fit to a resonance curve to determine the resonant frequency, transimpedance at resonance, and Q for each peak. These measurements agree with the shot noise measurement for the transimpedance at 11 MHz taken earlier considering that this measurement was made at 11 MHz instead of at the resonant frequency of 11.14 MHz.

I measured these transfer functions with the Agilent 4395a using the netgpib.py script last week. I realized that when using this script to save multiple copies of the same measurement after setting up the instrument, the first and second measurements are saved but all measurements saved after are identical to the second measurement until the instrument is physically reset. This happens because the analyzer switches the trigger from continuous to hold after making a measurement using this script. Kiwamu said that the script can be modified to return the trigger to continuous after saving the data so that multiple measurements can be saved without being at the analyzer physically. I did not want to waste more time figuring out how to modify the script to do this so I used one of the netbooks and sat at the analyzer manually returning the trigger to continuous after each measurement.

  4169   Wed Jan 19 10:45:00 2011 KojiUpdateElectronicsPOX Transfer Functions

TF looks fine except for the large peak at around 200MHz which has been reported by Rana. The time series and the spectrum without the light are pathetic...

I still prefer to see the fit by LISO as the pole/zero fitting of LISO as the fit result is more physically understandable.
Anyone can ask me about the instruction how to use LISO

I guess Idc of 24mA would be just a mistake. It looks like ~0.2mA from the plot that sounds normal for the transimpedance of 2kOhm.

Question: What is the HWHM of the reesonance when you have f0 and Q.

 

  4170   Wed Jan 19 17:00:23 2011 KevinUpdateElectronicsPOX Transfer Functions

 The value of I_dc was a mistake. The value should be 240 µA.

The widths of the resonance peaks are listed below the fits to each peak on the wiki.

  4172   Thu Jan 20 01:50:30 2011 KevinUpdateElectronicsPOX Transfer Functions

[Koji, Kevin]

We fit the entire POX optical transfer function from 1 MHz to 500 MHz in LISO. The fit is on the wiki at http://lhocds.ligo-wa.caltech.edu:8000/40m/Electronics/POX. Using LISO's root fitting mode, we found that the transfer function has five poles and four zeros.

I will work on making plots of the residuals. This is difficult because by default, LISO does not calculate the fitting function at the frequencies of the data points themselves and I haven't figured out how to force it to do this yet.

  4210   Thu Jan 27 03:24:56 2011 KevinUpdateElectronicsPOY Optical Transfer Function

[Rana and Kevin]

I measured the optical transfer function of POY and fit the data using LISO. The fit can be found at http://lhocds.ligo-wa.caltech.edu:8000/40m/Electronics/POY. POY was missing the RF cage and back cover so I took those parts from AS55 in order to make these measurements.

POY does not have the unwanted oscillations at 225 MHz that POX has. Attachment 1 shows the transfer functions of POX and POY.

To measure the transfer functions, I used a 50/50 beam splitter to send half the light from an AM laser to POY and half the light to a New Focus 1611 reference photodiode. The transfer function for POY was measured as the transfer function of the signal from POY divided by the signal from the 1611. When I was measuring the transfer function for POX, I failed to ensure that the photodiodes were operating linearly. Before making the measurements for POY, I varied the RF power modulating the AM laser and recorded the magnitude of the transfer function at the 11 MHz peak. Attachment 2 shows these values. The measurements for POY were made in the linear region at an RF power of -10 dBm. The measurements for POX were made at 0 dBm and were most likely not in the linear region for POX.

Attachment 1: tf_pox_poy.png
tf_pox_poy.png
Attachment 2: linearity.png
linearity.png
  4242   Thu Feb 3 01:46:54 2011 KevinUpdateElectronicsPOY Shot Noise and Dark Spectrum

[Koji and Kevin]

I measured the shot noise of POY and fit the data to determine the RF transimpedance at 11 MHz and the dark current. The transimpedance is (3.860 +- 0.006) kΩ. I realize that there are not many data points past the dark current but I did not want to take any further data because the light bulb was getting pretty bright. If this is a problem, I can try to redo the measurement using a lens to try to focus more of the light from the bulb onto the photodiode.

I also measured the spectrum and recorded a time series of the RF signal with the light to the photodiode blocked. These measurements do not show any large oscillations like the ones found for POX.

The plots of the measurements are on the wiki at http://lhocds.ligo-wa.caltech.edu:8000/40m/Electronics/POY.

  4243   Thu Feb 3 04:43:58 2011 SureshUpdateElectronicsAdded two new DAQ channels

[Suresh, Joe]

We added the following two new DAQ channels into the c1:GCV model.  The daq:analog input channels are on card ADC0 and correspond to channels 3 and 4 on the card.

c1:GCV-EXT_REF_OUT_DAQ   Sampling rate=2kHz  acquiring a 1Hz sine wave from the SRS Function Generator DS345.  This is using the Rb 10MHz signal as an external frequency reference.

c1:GCV-PLL_OUT_DAQ    Sa.rate=2kHz acquiring the demodulated signal from the PLL servo.

This work is connected to the study of VCO PLL loop noise at frequencies below 0.1Hz.    We are trying to measure phase noise in the VCO PLL servo at low frequencies as this noise would result in arm length fluctuations in the green-locking scheme.

 

 

 

ELOG V3.1.3-