High-accuracy, simultaneous calibration of controlled-source EM field systems

Ben K. Sternberg, Richard W. Nopper

Research output: Contribution to conferencePaperpeer-review

2 Scopus citations


A new calibration method is described which makes possible a very high-accuracy calibration of a signal measuring system. In this method, a precisely known calibration signal is injected into the measuring system at the same time that data are being collected. The calibration signal is designed to have a discrete frequency spectrum which interleaves with, but does not contaminate, the spectrum of the data signal. Since the calibration is performed simultaneously with data acquisition, there is no danger that the equipment response will change between the time when the data are collected and when the instrument is recalibrated. Furthermore, this procedure may be automated so that typical field operations are much more efficient than with separate and frequent calibrations. The instrumentation which we outline here can obtain routine measurement accuracies of better than 0.05 percent for magnitude and 0.3 mrad for phase. Of course, an additional and very important consideration in the overall measurement accuracy is the signal-to-noise (S/N) ratio of the measurement. The uncertainty due to random noise which occurs in geophysical field measurements can be reduced by increasing the strength of the source, lengthening the signal processing time at the receiver, reducing instrument electronics noise, and employing noise cancellation technique (e.g., gradient arrays, remote noise references, etc.). S/N improvement is beyond the scope of the present paper; nevertheless, potential accuracies that may be obtained with simultanteous calibration indicate that significantly higher resolution is possible with controlled-source electromagnetic sounding measurements.

Original languageEnglish (US)
Number of pages6
StatePublished - 1986
Event1986 Society of Exploration Geophysicists Annual Meeting, SEG 1986 - Houston, United States
Duration: Nov 2 1986Nov 6 1986


Other1986 Society of Exploration Geophysicists Annual Meeting, SEG 1986
Country/TerritoryUnited States

ASJC Scopus subject areas

  • Geophysics


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