I made a noise budget of the new accelerometer which is installed in last Wednedday (klog#14794).
- Red : accelerometer signal taken today
- Black (solid) : Trillium 120Q which is installed in IXV. X axis of this seismometer is aligned to axis of the accelerometer.
- Black (dash) : ADC noise when 1-6 pins for the LVDT signal are shorted.
- Cian : LVDT noise when LVDT_IN connecter for LVDT board was pulled out. [Case2]
- Mazenda : Proof mass was fixed. ADC and LVDT_IN were connected. [Case1]
- Working space is here : /users/VIS/AccTest/ProtoType/200727
Accelerometer siganl is consistent with a seismometer in IXV between 0.1Hz to 2Hz.
Above and below this region, LVDT noise limits the accelerometer signal.
- We found the LVDT noise in low frequency would come from the LVDT board because the Case1 was larger than the Case2. And it depends on the time.
- We had better to insert a pre-amp not to covered by ADC noise and to investigate the low-frequency LVDT noise.
I think purpose of this measurement is to conclude whether the new accelerometer has better sensitiviy than Geophone or not.
Then, I will install Geophone near the accelerometer in this week to compare the perforrmance.
