ABSTRACT
Still higher demands on the quality and accuracy of geodetic works are required. In order to achieve the required precision of geodetic works in all areas it is necessary to use such instruments in the measuring process, whose characteristics are in good agreement with specified requirements. One of these features is the consistency, accuracy and repeatability of values of horizontal directions. The process for the quality verification of theodolite horizontal circles is based on the standard STN ISO 17123-3, some service centres or specialized laboratories perform the control of divided circles in accordance with the manufacturer requirements under the DIN and ISO standards or corresponding to the specific references of the laboratory. The automated etalon device EZB-3 of the Slovak Institute of Metrology in Bratislava allows the calibration of horizontal circles surveying instruments using a primary standard of planar angle of the Slovak Republic.
