Koseki, Yoshinori,

= PRM =
-- As reported in klog#6126, one LVDT-driver chassis (for BF-LVDTs) had been outside the tunnel fot the reparing, and it was re-installed into PR0 rack for the BF-LVDTs.
-- Since some trimmer configuration of BFV-LVDT-card had been changed during the repairing work, we had to tune the parameters again. However, all the stuffs were already inside the hamber and it was difficult to calibrate the LVDTs again. then we tried to copy the parameters of BFH-LVDT-card, as BFV-LVDT-card.

== Procedure ==
-- tune the gain in accordance with (3) in [1].
-- tune the phase so that the reference signal and the probe siganl have 90 deg difference.

[1] https://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=4798

== what we found ==
-- the BF-LVDT-V signals became *typical* ones, even though K1:VIS-PRM_BF_LVDTINF_V1/2/3_OUT should not hve the unit of um anymore.
-- electromagnetic noise at higher frequency (like above 5 Hz) grew up much, and then we had to change the shape of the damping filters which cut the higher frequency gain more effectively. they are now labeled as damp1.
-- the new damping filters worked properly, not optimized though. (in the figure, the dashed cooresponds to damped configuration, while slid curves are the undamped ones.)

-- oscillation amplitude looked smaller than the healthy one. the height might be optimized.