Notes on a Broad-Band Variant of the NCER Seismic Data Multiplex System for Use with Field Tape Recorders

By Jerry P. Eaton

Introduction

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Tests of the standard NCER multiplex system recorded and played back on both the Bell and Howell 3700B (about 0.1% tape speed variation) and on the Sony TC-126 cassette recorder (about 1% tape speed variation) showed that subtractive compensation employing a reference frequency multiplexed on the data track was remarkably effective in reducing tape-speed-variation-induced noise 1 and, hence, in increasing the dynamic range of the record/playback system. Further tests suggested that the 0 to 30 Hz bandwidth of the standard system (8 data channels) might be increased substantially, at the "price" of reducing the number of data channels to 3 or 4, without serious loss of dynamic range if subtractive compensation could be implemented effectively with the broader-band system.

Last modified October 22, 2010
First released in paper form 1976

Report PDF (4.9 MB)

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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
http://earthquake.usgs.gov/

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Suggested citation:

Eaton, J.P., 1976, Notes on a broad-band variant of the NCER seismic data multiplex system for use with field tape recorders: U.S. Geological Survey Open-File Report 76-87, 68 p.

Contents

I. Introduction

II. Broad-band Multiplex System Design, Components, and Tests

III. Broad-band System Recorded and Played Back on the Sony TC-126 Cassette Recorder

IV. Hybrtd system employtng the P.L 5100 5-day tape recorder