The noise floor of the accelerometers are obtained with 3 channel correlation analysis. Fig 1 shows spectra of the accelerometers on a desk (this should measure the ground motion at our frequencies.) Fig 2 is the ACC's noise floor compared with the noise floor of geophones for SRs. I will do a double check, but it seems that the noise level of the ACCs are much higher than our expectation and also higher than the geophone's level. This might be improved by modifying cabling conditions or by debugging the cuicuits though, we have to start to think about using other inertial sensors, like geophones for the time being.