Michael, Krishna,

No significant wind-storms yet. As discussed yesterday, in the quiet conditions (0-10 mph), when we tried to use sensor correction on the 90 mHz blend, we improved isolation in the 0.1-1 Hz region, but increased rms motion of the platform (as seen by the CPS) in the 10-30 mHz region. We tried to see if we could do a better trade-off.

We have been using a broadband sensor correction filter (Mitt_SC), originally made by Rich M. for the Z direction. After a few iterations, we came up with the filter shown in the first pdf, named Mitt_SC3. It has more gain-peaking in the 20-70 mHz region (where we get the best tilt-suibtraction), but suppresses motion below 20 mHz by a factor of ~3. I guess it will approach the Hua filter ultimately if we wanted even sharper roll-offs.

The attached pdfs show the result of this filter at EndY and EndX respectively in plots which have the same format as before. In this case, the overall rms of the CPS sensors is the same or smaller when using SC as compared to the 90 mHz blends alone. We still have a factor of 2-10 isolation improvement in the 0.1-1 Hz band as measured by the T240s on stage 1.