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U.S. Geological Survey Open-File Report 78-266

Five-Day Recorder Seismic System

By J.P. Eaton and J.R. Van Schaack

With a section on The Time Code Generator by Jim Ellis


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The 10-day recorder seismic system used by the USGS since 1965 has been modified substantially to improve its dynamic range and frequency response, to decrease its power consumption and physical complexity, and to make its recordings more compatible with other NCER systems to facilitate data processing. The principal changes include:

   1. increasing tape speed from 15/160 ips to 15/80 ips (reducing running time from 10 days to 5 days with a 14" reel of 1 mil tape),

   2. increasing the FM center frequency by a factor of 4, from 84.4 Hz to 337.6 Hz,

   3. replacing the original amplifiers and FM modulators with new low-power units,

   4. replacing the chronometer with a higher quality time code generator (with IRIG-C) to permit automation of data retrieval,

   5. eliminating the amplifier/WWVB radio field case by incorporating these elements, along with the new TCG, in the weatherproof tape-recorder box,

   6. reducing the power consumption of the motor-drive circuit by removal of a redundant component.

In the new system, the tape-recorder case houses all components except the seismometers, the WWVB antenna, the 70-amp-hour 12-VDC battery (which powers the system for 5 days), and the cables to connect these external elements to the recorder box.

The objectives of this report are:

   1. to describe the new 5-day-recorder seismic system in terms of its constituent parts and their functions,

   2. to describe modifications to parts of the original system that were retained and to document new or replacement components with appropriate circuit diagrams and constructional details,

   3. to provide detailed instructions for the correct adjustment or alignment of the system in the laboratory, and

   4. to provide detailed instructions for installing and operating the system in the field.

Last modified December 17, 2010
First released in paper form 1978

  • This report is available only on the Web.

For additional information:
Contact Information, Earthquake Science Center, Menlo Park Science Center
U.S. Geological Survey
345 Middlefield Road, MS 977
Menlo Park, California 94025

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Suggested citation:

Criley, Ed, and Eaton, J.P., 1978, Five-day recorder seismic system, with a section on the time code generator by Ellis, Jim: U.S. Geological Survey Open-File Report 78-266, 85 p.


I. Introduction

II. Description of the Five-Day Recorder Seismic System

III. Documentation of Changes and New Components

IV. Field Operating Instructions for the Five-Day-Recorder Seismic System

V. Appendix: Auxiliary Equipment

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