[ANSS-netops] reftek unity or x32?

[Richard Godbee]

On Mar 17, 2011, at 12:49 PM, mwithers at memphis.edu wrote:

> We're upgrading some of our analog 3-c S-13 sites to digital telemetry
> and Reftek RT130 DAS's.  We're trying to decide whether to run at
> unity or x32 gain.

Chapman, Martin
A Comparison of Short-Period and Broadband Seismograph Systems in the Context of the Seismology of the Eastern United States
Seismological Research Letters 2009 80: 1019-1034

http://srl.geoscienceworld.org/cgi/content/full/80/6/1019#SEC6

The most relevant section here is the "Dynamic Range" section, where unity gain and 32x gain are compared on a REF TEK 72A-07 with a three-component S-13 sensor package.

> Being lazy and indecisive, my immediate question
> is what do other people do?

32x gain on all of our REF TEK 72A-07/08s, which all have S-13 or L4-3D sensors.

In Virginia and West Virginia, we have a whopping seven stations (ANSS + VTSO stations) covering 173,540 km^2 of land, so we don't have anything close to the station density required to run at unity gain and still see small events.

(As suggested in the "A Dual-Gain System" section of Martin's paper, we'd be recording the output of our sensors at both unity and 32x gain if we had six channel digitizers.)

Richard

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Richard Godbee, Unix Systems Administrator
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