[Yamamoto, Ushiba]

Abstract:

We tested to turn off dewhitening filter gently and succeeded by modifying foton filters on COILOUTF from 'zero history mode' to 'Always on' mode.
So, we need to modify all COILOUTF filters for gentle transition of dewhitening filters.

Detail:

Since O4a era, we have known issue that turning off dewhitening filter kicks the suspension a lot while turning on doesn't affect the suspension (fig1).
Then, we found that filters on the COILOUTF is implemented with "zero history" mode, which should be "always on" mode for continuous calculation of the filters.
So, we tested by using ITMX MN vertical dewhitening filters.

We modified FM1, FM2, and FM3 of ITMX_MN_COILOUTF_V{1,2,3} from "zero history" to "always on".
After the modification, we tested to turn off dewhitening filters with ALIGNED state and confirmed that no kick happened (fig2).
So, we can gently turn off dewhitening filters if we modified the modes of all the COILOUTF filter banks.

At some point, we would like to do that.