Rotational sensors—a comparison of different sensor types
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We present laboratory tests for two types of rotational motion sensors, the liquid-based rotational seismometers type R1 and type R2 manufactured by Eentec and the closed loop fiber optic gyroscope LCG-Demonstrator by Northrop Grumman LITEF. All instruments were calibrated absolutely at different temperatures, characterization and quantification of self-noise was carried out, and a comparison with the ring laser gyroscope G from the Geodetic Observatory in Wettzell, Germany is drawn. The generator constant of the R1 varies up to 27% in the nominal operating temperature range. In the closed-loop system LCG-Demonstrator, the compensation for temperature variation works very well, and the generator constant can be seen as constant within the error bars. For both instrument types, we measured sensitivities in the order of 10 − 7 rad/s in a period range from 10 to 100 s. While this sensitivity is already sufficient for civil engineering applications, it has to be improved by at least 1 order of magnitude for applications in weak motion seismology.
KeywordsRotational seismology Instrumentation Rotational motion sensors Absolute calibration Instrument self noise
We would like to thank the editor of this special issue, J. R. Evans, and our two reviewers whose comments were very helpful. We would also like to thank the team of Northrop Grumman LITEF for their efficient cooperation and C. Sens-Schoenfelder for making the R2 available. This work was partially funded by the Deutsche Forschungsgemeinschaft in the project number Ig16/8.
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