This thesis deals with low level DC voltage measurement by three methods. First part of this thesis describes each method. It is about potentiometric method, reference step method and direct method. This thesis also describes Josephson voltage standard which was used for calibration nanovoltmeter and Zener reference. The theoretical part of this thesis also deals with the evaluation of key comparison data. The main goal of this thesis is the comparison of methods used to measure low level DC voltage. The practical part of the thesis deals with the implementation of measurement with all methods in cooperation with Czech metrology institute. The measured values are processed including uncertainty evaluations. The final part of this thesis focuses on comparison of measurement methods. The key comparison reference value and the degree of equivalence of the measurement of each method are determined. Next part of comparison consisted of graphic comparison of methods. The end of the thesis contains evaluation of the achieved results.

This Master’s thesis contains an overview of determining measurement uncertainties of direct and indirect measurements. It describes a way of creating a magnetic field with the help of Helmholtz coil and a more detailed description of some principles of magnetic field sensors. This thesis also contains a description of the experiments and the factors influencing them. The last part deals with the quantification of uncertainties from measured experiments and with the discussion of the results from these measurements.