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Entry  Tue Dec 8 23:13:32 2009, kiwamu, Update, SUS, free swinging spectra of ETMY and ITMX SUS-ETMY.pngSUS-ITMX.png
    Reply  Wed Dec 9 00:23:28 2009, Koji, Update, SUS, free swinging spectra of ETMY and ITMX 
       Reply  Wed Dec 9 21:09:28 2009, kiwamu, Update, SUS, Re: free swinging spectra of ETMY and ITMX Pitch-Yaw_modes.png
          Reply  Thu Dec 10 00:46:15 2009, Koji, Update, SUS, Re: free swinging spectra of ETMY and ITMX 
Message ID: 2369     Entry time: Wed Dec 9 00:23:28 2009     In reply to: 2368     Reply to this: 2374
Author: Koji 
Type: Update 
Category: SUS 
Subject: free swinging spectra of ETMY and ITMX 

Where is the plot for the trend?
It can be either something very important or just a daydream of you.
We can't say anything before we see the data.

We like to see it if you think this is interesting.

... Just a naive guess: Is it just because the seismic level got quiet in the night?

 

P.S.

You looks consistently confused some words like damping, Q, and peak height.

  • Q is defined by the transfer function of the system (= pendulum).
     
  • Damping (either active or passive) makes the Q lower.
     
  • The peak height of the resonance in the spectrum dy is determined by the disturbance dx and the transfer function H (=y/x).

dy = H dx

As the damping makes the Q lower, the peak height also gets lowered by the damping.
But if the disturbance gets smaller, the peak height can become small even without any change of the damping and the Q.

Quote:

By the way I found a trend, which can be seen in all of the data taken today and yesterday.

The resonances of pitch and yaw around 0.5Hz look like being damped, because their height from the floor become lower than the past.

I don't know what goes on, but it is interesting because you can see the trend in all of the data.

 

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