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MIF (General)
tomotada.akutsu - 14:31 Friday 24 March 2023 (24529) Print this report
Comment to Install the sound protect sheet to IFI bellows leg (24526)

Following the Yokozawa-san's original post, I just checked the spectra by my self and compared some, and found strange points.

In Fig. 1,

PRFPMI locked

  • Blue 3/22 04:47 UTC
  • Brown 3/23 6:29:00 UTC

PRFPMI Unlocked (only IMC locked with IMC ASC)

  • Green 3/23 15:00 UTC
  • Magenta: 3/24 0:00 UTC
  • Red 3/24 03:00 UTC

Fig. 2 is the one that the red curve is removed from Fig. 1 for clearity.

What I found are:

  • 60Hz peak and its harmonics can be seen when PRFPMI unlocked. I am not sure if this would be occasional or not, but might be related to electric grounding issue.
  • Bumps at 20-30 Hz and 120Hz and 180? Hz can be seen when PRFPMI locked, but not seen when unlocked. Does this fact suggest that these bumpy structure might be introduced via MCL feed around path from CARM???
  • Diaggui time stamp bug? Against the original post by Yokozawa-san, the time stamp assignment for the red and magenta curves are opposite. If this would be true, locating the sheets on the IFI chamber bellows legs might not be so effective (or at least this instance the noise floor got larger, but in my observation, this seems occasional... I am actually puzzeld. -> due to differet choice of frequeny resolution, according to Yokozawa-san. So breathing...
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