(Eric A., Corey G.)

Over the last few days, we've bypassed our original BNC feed-thrus on our Interface Board, and are now using actual BNC feed-thrus.  The issue here is that the original BNC feed-thrus proved to be troublesome and sacrificed the performance of our Sensors.  We've found that using the "real" feed-thrus (and also buying better/expensive feed-thrus) have made our Sensors perform much better.

Switching to the new feed-thrus has changed the DC value of of our sensors.  At "zero" our Sensors were all under ~1000 counts, but with the new feed-thru the zeroes have increased to around 10,000 counts.  Because of this we had to re-gap the Sensors.  This sort of change required us to re-do a few more Sensor Tests (according to document T1000329).

New Power Spectra for the Displacment Sensors have been run.  The measurement is located here:

/opt/svncommon/seisvn/seismic/HAM-ISI/X1/Data/unit_1/dtt/unit_1/dtt/20100720_all_disp_spectra.xml

Attached are plots of spectra with BOTH Sensor Mini-Racks ON, and with only one ON.