Evan, Stefan

When we came in the winds were relatively high, so we decided to take another loock at the AS_A_36 phasing. We did so in DRMI.

- To take out the effect of WFS centering and the otherASC loops, we lowered the total ASC gain by a factor 10, and increased the WFS centering gain from 1 to 200 (raising the centering gain by a factor of 20).
- We then drove the SRM at 0.3Hz in PIT and YAW.
- Interestingly PIT and YAW totaly disagree on the phase, by about 125deg...
- Attached are screen shots for the old phases (picture 1), phased for PIT (picture 2), and phased for YAW (picture 3)
- Additionally, while all 4 quadrants show a reasonable signal for PIT, the YAW signal is weak in quadrant 1 and not present in quadrant 2
- We decided to make a pragmatic choice:
  - For PIT AS_B_36_I is already a fine signal - only for YAW it doesn't work
  - Thus we decided to phase AS_A_36_I for YAW...
  - ... and only use quadrants 3 and 4 (the lower two quadrants).
  - Quadrants 3 & 4 also have a similar strength signal (with opposite sign) and similar RF offset (with the same sign)
  - So: this new YAW signal AS_A_36_I should be fine now.

YAW Input matrix for I and Q now is:
H1:ASC-AS_A_RF36_I_MTRX_2_1    0
H1:ASC-AS_A_RF36_I_MTRX_2_2    0
H1:ASC-AS_A_RF36_I_MTRX_2_3    -2
H1:ASC-AS_A_RF36_I_MTRX_2_4    2

With this new YAW sensor we updated the ASC sensing matrix (pictures 3 and 4).

This sensor seemed to do a good job at 17W and at 24W. However at 24W we still saw a 0.4Hz instability - see next alog.