Revision History for USGS Open-File Report 77-224 Eaton, J.P., and Van Schaack, J.R., 1977, Factors limiting the sensitivity and dynamic range of a seismic system employing analog magnetic tape recording and a seismic amplifier with adjustable gain settings and several output levels: U.S. Geological Survey Open-File Report 77-224, 14 p. [http://pubs.usgs.gov/of/1977/0224/]. ----------------------------------------------------- Scanned, OCRed, and posted online at http://pubs.usgs.gov/of/1977/0224/ October 28, 2010 Released in paper form 1977 -----------------------------------------------------