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Entry  Mon Jan 24 02:58:46 2011, kiwamu, Update, Green Locking, X arm locked ! time_series.pnggreen_one_arm.png
    Reply  Mon Jan 24 09:33:08 2011, rana, Update, Green Locking, X arm locked ! 
       Reply  Mon Jan 24 13:08:07 2011, kiwamu, Update, Green Locking, Re: X arm locked ! e_pll_oltf.png
    Reply  Mon Jan 24 10:19:21 2011, Koji, Update, Green Locking, X arm locked ! 
       Reply  Mon Jan 24 14:27:13 2011, kiwamu, Update, Green Locking, Re: X arm locked ! masslock_oltf.png
Message ID: 4191     Entry time: Mon Jan 24 02:58:46 2011     Reply to this: 4192   4193
Author: kiwamu 
Type: Update 
Category: Green Locking 
Subject: X arm locked ! 

I succeeded in green-locking the X arm by feeding back the beat signal to ETMX.

Here are some quick reports. Some more details will be posted tomorrow.

 

The below shows a time series data of the PLL feedback signal when the servo was acquiring the lock.

time_series.png

At t = -2 sec. I started feeding back the signal to ETMX with the gain 50 times smaller than its nominal.

Then at t = 0 sec.I switched on a low frequency boost (pole 0.1Hz and zero 1Hz) to make it more robust.

At t = 3 sec. I increased the gain to the nominal.

Finally the UGF became ~ 60 Hz according to my open loop measurement by diaggui.

However I couldn't make the UGF higher than 60Hz because the more gain caused a instability for some reasons.

 

Here is a diagram for the green locking.

I used the same VCO box as we setup on the last Friday (see #4189).

 green_one_arm.png

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