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AOS (Beam Reducing Telescopes)
naoki.aritomi - 11:01 Thursday 04 October 2018 (6414) Print this report
[TMSX] polarity check of geophones
[Aritomi, Kita, K. Tanaka, K. Nagano, Akutsu]
To check the polarity of geophones, we excited LVDT coils (VIS-TMSX_COILOUTF_**_EXC) and measured relative phase of LVDT signals (VIS-TMSX_LVDTINF_**_OUT) and geophone signals (VIS-TMSX_ACCINF_**_OUT).
Attached figure is the transfer fucntion from LVDT V1 signal to geophone V1 signal. Between 3-7 Hz, relative phase is around -90 deg . (after 8 Hz there is sneak current of LVDTs)
The results are as follows.
Geophone V1: neg
Geophone V2: neg
Geophone V3: neg
Geophone H1: pos
Geophone H2: pos
Geophone H3: pos
After this measurement, we changed the sign of damping filters of geophone V1,2,3 as second attached figure.
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