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Entry  Sun Oct 14 16:44:20 2012, Den, Update, PEM, ETMX table DSC_4742.jpg14OCT2012.pdf14OCT2012.xml
    Reply  Sun Oct 14 17:26:03 2012, Den, Update, PEM, ETMX table etmx.pdf
       Reply  Sun Oct 14 20:51:20 2012, Den, Update, PEM, AA board acc.pngDSC_4747.JPG
          Reply  Mon Oct 15 10:14:22 2012, Den, Update, PEM, AA board 
Message ID: 7542     Entry time: Sun Oct 14 17:26:03 2012     In reply to: 7541     Reply to this: 7543
Author: Den 
Type: Update 
Category: PEM 
Subject: ETMX table 


 I've measured ETMX table motion compared to ground motion using accelerometers. Data and settings in the xml file are at the svn directory 40m_seismic/etmx

 High frequency (>60 Hz) resonances that are present at the ETMX motion spectrum seem to be understandable. Amplification ETMX/GROUND of a factor of 2 at 1 Hz is interesting. I've monitored ACC DQ channels for a few hours and noticed that usually spectrum looks like in the previous elog. But every ~40 min ETMX motion is much higher then ground motion at low frequencies (<5 Hz). I wonder if this a reaction of a table to outside disturbances or accelerometer issue.


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