L. Trozzo, Y. Fujii

After report 5531, we tried to check the sensing noise level of the accelerometers, but we found somthing strange during this work: In 2 accelerometers, the signal-to-noise ratio became much worse than the values which were measured in the last week.(even if we did not change the configuration.) also, we found that the sensor  signal-to-noise ratio depends on the combination of cables and drivers, and so on. In any case, we did not get much infomarion about sensing noise from today's work.

For the next step, I will check the noise level of the accelerometers and the geophones by using same input (I will measure spectra at the same position and at the same time), and then I will confirm if the ACCs are noisy indeed or not (compared with geophone).

FYI, the attached shows a measured noise level of the ACCs and the geophones. but I have to note that the input was different in this plot; the spectra of ACCs and geophons were measured at different situation/date. Thus this is just a rough result, but the noise level of geophones (at around 0.1 Hz) looks better than the level of the ACCs. In any case, we will see it tomorrow.