J. Kissel, S. Dwyer

As we battle against wind again tonight, Sheila asked "Are there windy blends on the ITMs?" I replied, "No, but we can easily copy them from the ETMs."

As such, I've copied and pasted FM10, the 90mHz blends, of the H1ISIETMX CPS, L4C, and T240, CUR filter bank on ST1 into the corresponding CUR and NXT filter banks of H1ISIITMX, H1ISIBS, and H1ISIITMY. I attach a comparison between the 45mHz and 90mHz blends, generated by 
/ligo/svncommon/SeiSVN/seismic/Common/MatlabTools/plot_current_blends.m
(where I've removed the RY filters by hand, because they're split between two banks and therefore what would be plotted can't be trusted)
 'cause I've never seen such a comparison before -- at least their complementary filter form.

We'll need more time with the IFO when it's more stable, but preliminary results -- where we'd switched the blends on ITMX in X and ITMY in Y to 90 [mHz] -- say that it isn't better. But they're preliminary, and I can't rule out that I've screwed up the copy-and-paste process. I'll double check everything once I don't have two more aLOGs to write.


P.S. Questions about the blend filters:
90mHz: 
- Do we really like these 90 [mHz] blends? 
- Seems like we should roll off the T240s way faster above 10 [Hz], like is done in the 45 [mHz] blends. 
- Do the Q's of the 0.5 and 1 [Hz] notches need to be that deep, or that what's *really* giving us the improvement when it's windy?
- Seems like the notches are at the wrong frequency, and could be moved down to get similar notching as the 45 mHz blends, and to better match the 0.43 [Hz] mode of the QUAD. Or maybe it's matching the 0.56 [Hz] pitch mode, which is actually the problem under windy conditions?

45mHz:
- Do we really like that much *un*complementarity in the 45 [mHz]? Maybe at this low a frequency, the loop gain is large enough -- even without the boost -- that any phase wiggle doesn't impact the stability during ramp up or nominal operations. But it'll certainly change the isolation loop error signal at low frequency when switching *between* blends. But also maybe not, because we've been able to successfully switch between 90 and 45 mHz blends on the ETMs for months now...