Jim and I have been working to tune up the gain matching for the vertical GS-13s in the HAM-ISIs. We are making good progress. I've got a new fancy-pants comb-drive which allows us to get good SNR for the HAMs from about 0.1 Hz to 3ish Hz, and maybe up to 6 or 7 Hz with the v4 version. If you have some interest in frequency-dependant comb drives, LMK and we can talk. These really improve your life for measurements below 1 Hz, so maybe this is just a seismic thing.

There's a bunch of development, some measurements, and some analysis documented in SEI log 2316 and attachments. This is mostly off-line stuff, but I wanted to link it in the log because we'll probably start using this stuff in ernest at the sites very soon to see if we can improve the microseismic performance of the HAM-ISIs.