The results of this morning's tests indicate that the "medium frequency" signals we've been seeing in the pressure spectra are from the reference! This may be caused by convection in the cylinder that Jim Wilczak warned us about. Since we don't have a perfect alternative at the moment, we've just plumbed all the references to the CHATS reference. Unfortunately, we had to disinter and rebury this reference in order to connect to it.
6b and 6t are now returned to their original configurations.
This work was done between 1500-1600 local. (6t should go offline and then online [was briefly online before being in the final config]).
I'm hopeful that earlier data can be recovered using Pref, but it will take some work (including despiking Pref) to work this all out.