As I reported in 14965, I suspected WHAM3 ISI OpLev Pitch and Yaw were reveresed as I believe is HAM2's. See the attach where I yaw'd WHAM3's HEPI. The HEPI Pitch moves as well but a couple of orders of magnitude less. Likewise on the OpLev, the Pitch responds much more than the Yaw, so yes,
JeffK suggested I might see coherence between the SEI inertial sensors and the OpLev channels. Not sure how good this is or maybe I need to taylor the measurement.
Anyway, the upper traces are YAW (RZ) channels of the SEI(HEPI IPS & L4Cs, ISI CPS & GS13) TF with the Pitch & Yaw of the OpLev. The strongest TF, only 0.7, is between CPS YAW and the OpLev Pitch. The lower traces are the Pitch (RY) of the SEI TF with the OpLev showing the strongest response of 1.0 is between CPS Pitch and the OpLev Yaw. There is some 'correct response too but it is lower.
There is no drive here just the input ground motion. This may be more clear with an active excitation.