I tried to set up an acoustic injection that reproduced several of the bumps in DARM (last time I only did one shaker bump) and tried PR2 pitch, yaw and length injections and IM2 pitch. The best was PR2 pitch, see attached figure. The behavior at other bumps was similar.
x5 scatter reduction at 50Hz.
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Taking Robert's observation as a hit, we moved the PR2 spot position in PIT (using the PR2_SPOT_MOVE state), looking for variations in scatter coupling while driving with acoustic noise.
Indeed, as we move from -275urad to -302urad PR3 PIT alignment counts, the scatter peak at 50Hz varies like a bar code reader.
The starting alignment (PR3 PIT = -296.72urad) corresponds to a maximum in scatter at 50Hz . We found minima at -301.72, -299.32, -292.47, -290.22 and -278.52 urad or PR3.
We thus picked -292.47, which seemed to be the best perfoming spot. It corresponds to a PR2 PIT alignment of 1767.24urad (see alignment snap shot).
The attached plot 1 shows the undriven DARM noise (blue), the acoustically driven DARM noise at the original position (-296.72urad of PR3 PIT), and the acoustically driven DARM noise at the final position (-292.47urad).
Plot 2 is an alignment snap shot.
Finally, to lock this position in, we had to add a POP_A_PIT_OFFSET of -0.05. Jenne ran a PR2 A2L script (demodulating PRCL) to mark the new PR2 spot position. The required M3 drive align numbers are in snapshot 3.
