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Entry  Tue Nov 15 12:25:38 2011, kiwamu, Update, Green Locking, Y arm ALS : beat-note free run fluctuation noise_budget.png
    Reply  Wed Nov 16 17:29:46 2011, kiwamu, Update, Green Locking, Some updates on the Y end green PDH Yarm_fluctuation.png
       Reply  Thu Nov 17 17:21:22 2011, kiwamu, Update, Green Locking, Y end green PDH servo : it's okay servoTF.pngservofilter.pngerr_suppression.png
          Reply  Fri Nov 18 11:28:39 2011, rana, Update, Green Locking, Y end green PDH servo : it's okay 
             Reply  Fri Nov 18 12:11:24 2011, Zach, Update, Green Locking, Y end green PDH servo : it's okay 
    Reply  Thu Nov 17 18:20:26 2011, kiwamu, Update, Green Locking, Y arm ALS : 1st trial of noise budget Yarm_ALS_2011Nov16.png
       Reply  Mon Nov 21 16:08:04 2011, kiwamu, Update, Green Locking, 2nd trial of Y arm ALS noise budget : broad band noise gone Yarm_ALS_2011Nov19.png
          Reply  Tue Nov 22 15:18:18 2011, kiwamu, Update, Green Locking, broad band noise depends on the gain of Y green PDH. and comaprator broken 
Message ID: 5970     Entry time: Mon Nov 21 16:08:04 2011     In reply to: 5930     Reply to this: 5978
Author: kiwamu 
Type: Update 
Category: Green Locking 
Subject: 2nd trial of Y arm ALS noise budget : broad band noise gone 

Quote from #5930

Right now the fluctuation of the green beat-note seems mostly covered by unknown noise which is relatively white.

The 2nd trial of the Y arm ALS noise budgeting :

(Removal of broad band noise)

  + The broad band noise decreased somewhat after I fixed a broken connection in the discriminator.
  + I took a look at the frequency discriminator setup and found one of the SMA-BNC adapter was broken.
     This adapter was attached to one of the outputs of the 4-way power splitter, which splits the signal into the coarse and find discriminator paths.
     And this broken adapter was in the coarse path, which actually I am not using for the noise budget.
     Depending on the stress acting on the adapter it was creating broadband noise, even in the fine path.
     So I threw it away and put another SMA-BNC adapter.
 
Here is a plot of the latest noise : high frequency noise is still unknown.

Yarm_ALS_2011Nov19.png

I will add the dark noise of the broad-band beat-note PD  and the MFD read out noise on the budget.

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