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See detailAccuracy assessment of the two-sample zero-crossing detection in a sinusoidal signal
Svitlov, Sergiy; Rothleitner, Christian UL; Wang, Lijun

in Metrologia (2012), 49(4), 413-424

The accuracy of a two-sample zero-crossing detection method is assessed by analytical uncertainty propagation and is verified in numerical simulations. Approximated expressions are given to evaluate ... [more ▼]

The accuracy of a two-sample zero-crossing detection method is assessed by analytical uncertainty propagation and is verified in numerical simulations. Approximated expressions are given to evaluate uncertainty components due to linear interpolation, quantization, white noise and time jitter. The combined standard uncertainty of a detected zero phase is expressed as a function of the signal frequency, power of external noise and parameters of the digitizer used. The evaluation of the uncertainty of the measurand, derived from several detected zero-crossings, is illustrated with applications in frequency, displacement and free-fall acceleration measurements. The reported results can be used for uncertainty analysis and parameter optimization of a measurement system or a procedure, involving processing of sinusoidal signals. [less ▲]

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See detailA method for adjusting the centre of mass of a freely falling body in absolute gravimetry
Rothleitner, Christian UL; Svitlov, S.; Mérimèche, H. et al

in Metrologia (2007), 44(3), 234

In absolute gravimeters, rotation of the falling body causes a systematic error. This error can be minimized by coinciding the centre of mass (COM) of the body with its optical centre (OC). A method to ... [more ▼]

In absolute gravimeters, rotation of the falling body causes a systematic error. This error can be minimized by coinciding the centre of mass (COM) of the body with its optical centre (OC). A method to measure the distance between these centres in 3D space is described. The method is based on a mechanical balancing technique. Using this method, the COM of a hollow corner cube mirror assembly is adjusted to the OC to within (43 ± 16) µm. An uncertainty budget is given. [less ▲]

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