There has been some speculation the 40Mpc dip in range was tidal related. It might just be coincident but this is because the dip sorta follows a portion of the ETMY tidal offset drive. However, it doesn't line up eactly and only follows for part of the drive, albeit the extrema. So it could be that once the HEPI hits a certain offset and its YAW misaligning pushes a WFS loop too far and allows a misalignment until it comes back in range.
See attached with the Range DMT above a 12 plot of the HEPI beam line position. I plotted these to make sure the platform was actually moving and looked too at the local sensors and saw that no corner hit some limit requiring others to make up any shortfalls to satisfy the cartesian loop.
I'll continue to dip down stream to look for trouble. But for now, it looks like HEPI is doing what it is told.
From looking at short term spectra, we know the noise is due to individual glitches.
The attached plot is DV trends with HEPI drive (nm), M0_LOCK_Y, M0 Coil Outs for YAW and the M0 OSEM F2 & F3 (Yaw).
Can't claim I understand all the paths or signals but Stefan pointed me to M0 Lock for the DC WFS drive and with Travis' guidance, F2 & F3 opposite sign should be YAW.
The signs going to the coils are not opposite for this yaw drive... Not sure where after this the signs could reverse but seems like they must...?
Looking at the OSEMs, this 'YAW' is not evident. Are we sure we are YAWing?
I thought maybe the pitch drive was overwhelming the yaw but the LOCK_P is much less (<10x) than LOCK_Y and the F1 coil drive is much less than the F2 & F3 so I don't see true Yaw being hidden by Pitch.
Someone straighten me out as to why the signs for F2 & F3 are the same and we don't see any Yaw on the OSEMs, thanks.
