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Self-calibrating seismic amplifier and telemetry system

January 1, 1975

A frequency modulated, constant bandwidth, telemetry system has been designed to transmit simultaneously up to 8 channels of seismograph data from remote locations to a central recording site via radio or voice-grade telephone circuit. By utilizing state-of-the-art integrated circuits, the size of the remote unit has been considerably reduced over previous equipment and the power consumption has been decreased by a factor of over 100 to less than 2 milliwatts. This reduction in size and power makes it possible to package the electronic equipment, together with a year's supply of batteries, in a container the size of a tennis-ball can. The field equipment for a short-period station is now sealed in a 3-inch plastic tube 22 inches long . The tube, together with the connecting cable to the telephone terminal, is buried; greatly reducing losses due to water flooding, pilferage, etc. An important addition to the field unit is a daily calibration of the seismometer and amplifier.

Specifications and instructions for the three units that compose the system are presented separately, as follows:

1. J302 Preamplifier and voltage controlled oscillator

2. C-4 Calibrator

3. J101 Discriminator 

Publication Year 1975
Title Self-calibrating seismic amplifier and telemetry system
DOI 10.3133/ofr7564
Authors John R. Van Schaack
Publication Type Report
Publication Subtype USGS Numbered Series
Series Title Open-File Report
Series Number 75-64
Index ID ofr7564
Record Source USGS Publications Warehouse