Gabriele, Rahul, Jeff, Oli, Betsy
Find below the initial (no damping loop) transfer functions for the built X1 (Staging Building Test Stand) M1 (Top Mass) BBSS.
These were taken generally following Jeff and Oli's alog 74142, where we used their provided DTT template and tuned the excitation amplitude for each DoF to avoid overflows.
Files are saved on the X1 work station system under ligo/svncommon/SusSVN/sus/trunk/BBSS/X1/BS/SAGM1/Data/
They are dated 01/05/24.
Attached is a pdf of annotated frequency transfer functions for the above measurement.
Find below the Transfer Function resonant peaks frequencies in list form. The second column shows cross coupled freqs i.e. these same frequencies were seen/repeated on different degrees of freedom.
| Number of Resonant Peaks | Frequency (Hz) | |
| 1 | 0.40625 | 0.40625 |
| 2 | 0.414062 | 0.414062 |
| 3 | 0.421875 | |
| 4 | 0.445312 | |
| 5 | 0.453125 | |
| 6 | 0.96875 | |
| 7 | 1.03125 | |
| 8 | 1.15625 | |
| 9 | 1.16406 | 1.16406 |
| 10 | 1.32031 | |
| 11 | 1.4375 | |
| 12 | 1.54906 | |
| 13 | 1.875 | |
| 14 | 2.59375 | |
| 15 | 2.60156 | |
| 16 | 2.69531 | |
| 17 | 2.9919 | 2.99219 |
| 18 | 3.84375 | |
The "UNSURE" table contains some peaks that were somewhat noisy (and not included in the annotation). According to the model, there are supposed to be 2 peaks over 10 Hz (~19Hz and ~31Hz), but due to the noise, I couldn't determine if these were measured - there are definitely peaks in this region at the listed frequencies (none in the "right" spots though).
| UNSURE |
| 21.9375 |
| 26.75781 |
| 37.4375 |
| 37.39062 |
For ease of comparison, below is another table with the modeled peak frequencies. Note that while there are 18 peaks, they do not correspond to the same "18 modes" - this is a pure coincidence.
| Mode Number | Mode Frequency (Hz) |
| 1 | 0.412468 |
| 2 | 0.416083 |
| 3 | 0.425915 |
| 4 | 0.473335 |
| 5 | 1.03738 |
| 6 | 1.1633 |
| 7 | 1.16605 |
| 8 | 1.18585 |
| 9 | 1.45428 |
| 10 | 1.46622 |
| 11 | 1.53717 |
| 12 | 1.90606 |
| 13 | 2.64974 |
| 14 | 2.71041 |
| 15 | 3.03671 |
| 16 | 3.85694 |
| 17 | 19.6021 |
| 18 | 31.9402 |
This is still a WIP.