= ETMY, geophone calibration, noise measurement =
-- The three geophones for ETMY were calibrated after closing the flanges. (The previous test logged in klog#6957 was for a sanity check.)
-- The noise level was estimated again with 3 correlation analysis, and the calibrated geophone signals were compared with seismometers in the tunnel.
== calibration ==
-- As defined in klog#6957, (1) was fitted with (2), the fitting parameters were generator condtant Ge[V/(m/s)], f0 [Hz] and intrinsic damping ratio eta.
-- The fitted values are:
|
geo_name |
Ge [V/(m/s)] |
f0 [Hz] |
eta |
Note |
|
geo-5 |
267.535 |
1.193 |
0.5558 |
geo_test1, reference |
|
|
|
|
|
|
|
geo-21 |
273.399 |
1.342 |
0.5147 |
geo_test2 |
|
geo-18 |
271.819 |
1.085 |
0.6596 |
geo_test3 |
|
geo-23 |
249.245 |
1.018 |
0.6285 |
geo_test4 |
== Noise level ==
-- Using [1], the noise level of the newly assembled geophones were estimated as shown in fig1 (in displacement) and 2(in velocity).
-- It was confirmed that those calibrated geophone spectra were consistent with the ones measured by seismometer at IXV(*), at around 0.2 Hz, in fig3.
[1] Sleeman et al. 2006
(*) In this test, I used the seismometers in the 2nd floor (IXV) since one seismometer at MCF was in a maintenance (and was not available at that time), and also it was reported that at least the microseismic peak at around 0.2 Hz was observed by the seismometers in the center area coherently. The spectra would not exactly same though, this would be available for a sanity check.
== NOTE ==
-- one screw (M8*35mm) on geo-21 was galled and stucked in the assembly. The flange was closed properly though, the washer was floating.. we might find something in higher frequency region. If this affect to something, we will want to cut the screw or glue it to the flange.
-- The measurement files are in:
/users/VIS/TypeA/geo_check/181115/*1240*
== For next ==
-- ship the geophones to the Y-end.
-- update the MEDM screen
The photos are stored in:
https://photos.app.goo.gl/Fpq3tuQXAmEg5Zrd9
