Comparison Euromet.EM-K8 of DC Voltage Ratio: Results
Twenty National Metrology Institutes have participated in the European DC voltage ratio key comparison (EUROMET.EM-K8). The results for the voltage ratios 1000V/10V and 100V/10V are reported
AN IMPROVEMENT OF DC VOLTAGE RATIO MEASURUREMENTS BY CHARACTERIZATION OF THE DC VOLTAGE DIVIDER AT UME Tezgül CO Ş KUN ÖZTÜRK
The accuracy of the DC voltage measurements higher than 10 V depends on the accura cy of DC voltage ratio measurements. Reference standards for DC voltage ratio measurements are resistive voltage di viders which are generally self calibrated by their own br idges. Calibration of a absolute voltage divider with wide ratio range, such a Datron 4902S, using its bridge is dif ficult and time consuming calibration. Three different methods for the calibration have been investigated in order to make simpler divider calibration without losing from uncertainty . An extensive set of measurements were performed on Dat ron 4902S and its ratio drift for one year has been det ermined as less than 0.3·10 -6 for all ratios from 20V:10V to 1000 V:10 V. The measurement results of Datron 4902S are pres ent d.
Modeling Coherent Backscattering Errors in Fiber Optic Gyroscopes for Sources of Arbitrary Line Width
We present a new model of the noise and drift induced by coherent backscattering in a fiber optic gyroscope (FOG) interrogated with a light source of arbitrary temporal coherence. This study is critical to understand whether a FOG driven with a laser instead of a broadband source can attain high sensitivity and stability, which would have the overwhelming benefit of improving the FOG scale factor stability by at least ten-fold and would enable the use of FOGs for inertial navigation of aircrafts. Analytical and numerical solutions bring to light two significant new predictions. First, coherent-backscattering noise can be made negligibly small by utilizing a laser with a very narrow linewidth (less than ~ 20 kHz), although in this regime the drift is high. Second, by using a laser with a broad linewidth (greater than ~ 10 MHz), both the noise and the drift are low enough for aircraft inertial navigation. The dependencies of the noise and drift on fiber loss, loop coupling coefficient, and backscattering coefficient are also presented to define the optimum mode of operation of this new class of FOGs.