J. Kissel

For quick reference -- the current HAM-ISI blend filters are:
    (X, Y, Z) are all using the "comp_250" blend filter pair, whose blend frequency is 0.18 Hz (or 180 mHz -- hilariously *not* 250 mHz...)
    (RX, RY) are both using the "many_notches" blend pair, whose blend frequency is 0.375 mHz
    (RZ) is using the "fc_yaw_filt_lp." 

The recent ECR E2200473 that improves the performance of switching between blend filters also completely revamped the naming scheme for the filter banks which house the blend filters. That means older, extremely useful code like 
    /ligo/svncommon/SeiSVN/seismic/Common/MatlabTools/plot_current_blends.m
which converts the "as installed" foton representation of the blend filters into their design-intent, dimensionless "complementary" form broke.

Not having that code forced the infrequent viewer / non-designer to cut corners and only look at the displacement sensor blend, and either waive their hands guessing at the blend frequency / frequency-shaping or invent their own metric for "at what frequency do we start to get inertial isolation," e.g. as in LHO:70313.

I've now fixed the above mentioned code for the HAMs -- see attached collection of plots which show the 4 pairs of blend filters which are in play on ALL HAM ISIs at LHO (ISI HAMs 2 - 8).

Along the way, I couldn't help myself but to improve the plots:
    (1) I've added an explicit indication of the the blend frequency,
    (2) tightened up the frequency range and magnitude limits so you can quantitatively read off the magnitude better
    (3) For the phase, we used to plot both the individual filter's phase and the sum, but really only the sum matters. The sum of the HP and LP pair's deviation from 1.0 magnitude and 0.0 phase is a metric for *lack* of complementarity, and thus 
        (a) how much the open loop gain shape is impacted for *this* pair of filters and 
        (b) how much the phase will *change* when we switch to another set of blends with different [lack of] complementarity)

The code still needs further updates to handle BSC-ISI ST1 sensor blends, but I leave that for another day, or the initiative-full reader.