In the last post, I showed that SRCL element in the MICH sensor (AS55I-mich) is chaned 1% due to RAM.
Here I calculated how is this 1% residual in MICH sensor (AS55 I-mich) shown in MICH sensitivity. The senario is:
(1) we assume we are canceling SRCL in MICH by feed forward first (original matrix (2,3) element).
(2) SRCL in MICH (matrix(2,3) is changed 1% due to RAM, but you keep the same feed forward with the same feedforward gain
(3) You get 1% SRCL residual motion in MICH sensor. This motion depends on how SRCL is quiet/loud. The assumed level is
Pollution level = SRCL shot noise level in SRCL sensor x SRCL closed loop TF x 1% residual .... the following plot.
AS sensor = AS55I-mich --- SN level 2.4e-11 W/rtHz ------- MICH SN level 6e-17 m/rtHz
SRCL sensor = AS55 I-SRCL --- SN level 2e-11 W/rtHz --- SRCL SN level 5e-14 m/rtHz

Quote: |
Adding some more results with more realistic RAM level assumption.
(4) With 0.1% RAM mod index of PM (normalized by (1) )
|
PRCL |
MICH |
SRCL |
REFL11I |
0.99999 |
-0.001807 |
-0.000148 |
AS 55 Im |
0.000822 |
1.000002 |
0.000475 |
AS 55 Is |
1.068342 |
906.968167 |
1.00559
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