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masayuki.nakano - 5:24 Monday 16 September 2019 (10534) Print this report
PR2, PR3 diagonalization

- Put excitation signal at the longitudinal resonance, and esimated the coupling raito between oplev yaw signal and len signal.
- No oplev control was engaged for this measurement
- resonant frequency is 0.66 Hz for PR3 and PR2
- The oplev signal with excitation after the diagonalization is shown in attached plot.
- PRM has been diagonalized by Shoda-san. I measered the spectrum with the excitation in L with/without non-diagonal component, and attached it. 
- Even after the diagonaization of the sensor, the PR2 has a large peak in yaw oplev even I excited in longitudinal direction. It might be because of the actuator, but I'm not sure.

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masayuki.nakano - 20:58 Monday 16 September 2019 (10546) Print this report
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masayuki.nakano - 21:31 Monday 16 September 2019 (10547) Print this report

I again diagonalized the PR2 with free-swinging condition. L and Y seems to be diagonalized well, however, L and P could not diagonalized. I also checked

  • I turned all damping filters off.
  • Take a ratio of the tilt oplev signal to the length oplev signal at the resonant frequency as follows:
    L: 0.453, P: 0.85, Y:1.0
  • Pitch cannot be diagonalized, since the coupling between the length oplev and the tilt oplev changes every measurement by factor of 2-3.
  • PRM diagonalization matrix introduce the noise above 1 Hz. I'm not sure what happen from yesterday, but I turned off it.
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