Fig.1. showed the results (Previous one was written in klog32007, there is not so large change)
I also performed the noise projection with same manner of the klog32588
The result can be seen in Fig.2.
I noticed the several frequency conversion during the injection as shown in Fig.3.
[R.Sato, Washimi]
We analyzed the swept sine shaker injection test for the IFI chamber's bellows leg performed on Feb. 11 (klog32636).
Even though the excited lines in the seismometer signal were narrow, the excess in the strain signal got wider around the injected frequencies.
Moreover, the strain signals around 60 Hz were also excited when the shaker oscillated around 120 Hz.
These results mean the couplings from the ground vibration to the strain are non-linear and transfer functions are inappropriate for estimating the noise budget.
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[R.Sato, Washimi]
We also analyzed the swept sine shaker injection test for the IFI floor using the large shaker performed on Feb. 11 (klog32636).
Similar to the results of the small shaker injection (klog32672), the excess in the strain signal got wider around the injected frequencies.
On the other hand, the unnatural excess around 50-60 Hz was not found. So It was due to an accidental coincidence in the measurement timing.
[R.Sato, Washimi]
We changed the target channel from the strain to the IMMT1 trans-QPD (pitch).
The excess in the trans-QPD signal was very narrow at the injected frequencies. So the noise path
floor -> in-vac table -> input STMs -> beam sitter
is the liner coupling and the non-linear processes happen after them.
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