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Entry  Tue Oct 8 08:08:18 2019, gautam, Update, PEM, PEM BLRMS anomaly PEManomaly.png
    Reply  Wed Oct 23 11:49:21 2019, gautam, Update, PEM, PEM BLRMS anomaly seisAll_20191021.pdfspecGrams.zip
       Reply  Thu Oct 24 18:37:15 2019, gautam, Update, PEM, T240 checkout 
          Reply  Tue Nov 5 12:37:50 2019, gautam, Update, PEM, T240 interface unit pulled out T240_recenter.pdfffPotential.pdf
             Reply  Wed Nov 13 19:34:45 2019, gautam, Update, PEM, Follow-up on seismometer discussion seisAll_20191111.pdfffPotential.pdf
                Reply  Wed Nov 13 20:15:56 2019, rana, Update, PEM, Follow-up on seismometer discussion 
                   Reply  Wed Nov 13 23:40:15 2019, gautam, Update, PEM, Follow-up on seismometer discussion seisAll_20191111_1Hz.pdf
                      Reply  Thu Nov 14 12:11:04 2019, rana, Update, PEM, Follow-up on seismometer discussion 
                      Reply  Fri Nov 15 00:18:41 2019, rana, Update, PEM, Follow-up on seismometer discussion MCshake.pdf
                         Reply  Fri Nov 15 12:16:48 2019, gautam, Update, PEM, Follow-up on seismometer discussion BS_ZspecGram.pdf.zip
                            Reply  Mon Nov 18 14:32:53 2019, gautam, Update, PEM, Follow-up on seismometer discussion 
                               Reply  Tue Nov 19 21:53:57 2019, gautam, Update, PEM, Follow-up on seismometer discussion seisxSpec.pdf
Message ID: 15025     Entry time: Thu Nov 14 12:11:04 2019     In reply to: 15024
Author: rana 
Type: Update 
Category: PEM 
Subject: Follow-up on seismometer discussion 

at 1 Hz' this effect is not large so that's real translation. at lower frequencies a ground tilt couples to the horizontal sensors at first order and so the apparent signal is amplified by the double integral. drawing a free body diagram u can c that

x_apparent = (g / s^2) * theta

but for vortical this not tru because it already measures the full free fall and the tilt only shows up at 2nd order

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