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FFT swept filtering: a bias-free method for processing fringe signals in absolute gravimeters
Pálinkáš, Vojtěch ; Vaľko, Miloš

Source: Journal of Geodesy : 93. (2), s.219-227 ISSN: 0949-7714

Publication type: článek v odborném periodiku
Extent9 stran

Link: https://link.springer.com/article/10.1007/s00190-018-1154-y
Annotation:
Absolute gravimeters, based on laser interferometry, are widely used for many applications in geoscience and metrology. Although currently the most accurate FG5 and FG5X gravimeters declare standard uncertainties at the level of 2-3 µGal, their inherent systematic errors affect the gravity reference determined by international key comparisons based predominately on the use of FG5-type instruments. The measurement results for FG5-215 and FG5X-251 clearly showed that the measured g-values depend on the size of the fringe signal and that this effect might be approximated by a linear regression with a slope of up to 0.030 µGal/mV. However, these empirical results do not enable one to identify the source of the effect or to determine a reasonable reference fringe level for correcting g-values in an absolute sense. Therefore, both gravimeters were equipped with new measuring systems (according to Křen et al. 2016 applied for FG5), running in parallel with the original systems. The new systems use an analogue-to-digital converter HS5 to digitize the fringe signal and a new method of fringe signal analysis based on FFT swept bandpass filtering. We demonstrate that the source of the fringe size effect is connected to a distortion of the fringe signal due to the electronic components used in the FG5(X) gravimeters. To obtain a bias-free g-value, the FFT swept method should be applied for the determination of zero-crossings. A comparison of g-values obtained from the new and the original systems clearly shows that the original system might be biased by approximately 3-5 µGal due to improperly distorted fringe signal processing.

Citation: PÁLINKÁŠ, Vojtěch a Miloš VAĽKO. FFT swept filtering: a bias-free method for processing fringe signals in absolute gravimeters. Journal of Geodesy [online]. Spolková republika Němeko: Springer-Verlag, 2019, 93(2), 219-227 [cit. 2020-11-09]. ISSN 0949-7714. Dostupné z: doi:10.1007/s00190-018-1154-y

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Focus on VÚGTK > VÚGTK Departments > Geodesy and Geodynamics
Focus on VÚGTK > Researchers > Vojtěch Pálinkáš
Focus on VÚGTK > Researchers > Miloš Vaľko
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