40m
QIL
Cryo_Lab
CTN
SUS_Lab
TCS_Lab
OMC_Lab
CRIME_Lab
FEA
ENG_Labs
OptContFac
Mariner
WBEEShop
|
40m Log |
Not logged in |
 |
|
Wed Nov 18 22:49:06 2020, gautam, Update, ASC, Some thoughts about AS WFS electronics
|
Sun Nov 22 21:09:37 2020, gautam, Update, ASC, Planned mods for WFS head  
|
Wed Nov 25 18:18:41 2020, gautam, Update, ASC, Planned mods for WFS head 
|
Sat Nov 28 21:44:53 2020, rana, Update, ASC, Planned mods for WFS head
|
Thu Dec 10 22:46:57 2020, gautam, Update, ASC, WFS head assembled 
|
Thu Dec 17 15:23:56 2020, gautam, Update, ASC, WFS head characterization    
|
Wed Nov 25 18:30:23 2020, gautam, Update, ASC, Some thoughts about AS WFS electronics
|
Wed Dec 2 23:07:19 2020, gautam, Update, ASC, Electrical LO signal for AS WFS
|
Thu Dec 3 11:02:35 2020, rana, Update, Electronics, Electrical LO signal for AS WFS
|
Thu Dec 3 13:55:52 2020, Koji, Update, ASC, Electrical LO signal for AS WFS
|
Thu Dec 3 20:38:46 2020, gautam, Update, ASC, Electrical LO signal for AS WFS  
|
Thu Dec 3 21:14:38 2020, Koji, Update, ASC, Electrical LO signal for AS WFS
|
Thu Dec 3 21:44:49 2020, gautam, Update, ASC, Electrical LO signal for AS WFS
|
Fri Dec 4 03:02:40 2020, Koji, Update, ASC, Electrical LO signal for AS WFS
|
Fri Dec 4 22:41:56 2020, gautam, Update, ASC, Freq Gen Box revamp
|
Sat Dec 5 20:44:35 2020, gautam, Update, ASC, Freq Gen Box re-installed 6x
|
Mon Dec 7 12:38:51 2020, gautam, Update, IOO, IMC loop char  
|
Mon Dec 7 22:54:30 2020, gautam, Update, LSC, Modulation depth measurement
|
Sat Jan 16 18:59:44 2021, gautam, Update, LSC, Modulation depth measurement   
|
|
Message ID: 15690
Entry time: Wed Nov 25 18:30:23 2020
In reply to: 15682
Reply to this: 15697
|
Author: |
gautam |
Type: |
Update |
Category: |
ASC |
Subject: |
Some thoughts about AS WFS electronics |
|
|
An 8 channel whitening chassis was prepared and tested. I measured:
- TF from input to output - there are 7 switchable stages (3 dB, 6 dB, 12 dB and 24 dB flat whitening gain, and 3 stages of 15:150 Hz z:p whitening). I enabled one at a time and measured the TF.
- Noise with input terminated.
In summary,
- All the TFs look good (I will post the plots later), except that the 3rd stage of whitening on both boards don't show the expected transfer function. The fact that it's there on both boards makes me suspect that the switching isn't happening correctly (I'm using a little breakout board). I'm inclined to not debug this because it's unlikely we will ever use 3 stages of 15:150 whitening for the AS WFS.
- The noise measurement displayed huge (x1000 above the surrounding broadband noise floor) 60 Hz harmonics out to several kHz. My hypothesis is that this has to do with some bad grounding. I found that the circuit ground is shorted to the chassis via the shell of the 9pin and 15pin Dsub connectors (but the two D37 connector shields are isolated). This seems very wierd, idk what to make of this. Is this expected? Looking at the schematic, it would appear that the shields of the connectors are shorted to ground which seems like a bad idea. afaik, we are using the same connectors as on the chassis at the sites - is this a problem there too? Any thoughts?
Quote: |
Whitening chassis. Waiting for front panels to arrive, PCBs and interface board are in hand, stuffed and ready to go. A question here is how we want to control the whitening - it's going to be rather difficult to have fast switchable whitening. I think we can just fix the whitening state. Another option would be to control the whitening using Acromag BIO channels.
|
|