Testing EDM of Total Stations The paper is devoted to testing electrooptical distance measuring devices (EDM) built in total stations, than can be used for various tasks in the contemporary geodetic works. A rich market offer and availability of these universal measuring systems with satisfying distance range, excellent accuracy and other parameters, make total stations as dominant terrestrial geodetic instruments. For succesfully applying these instruments, above all for relliable distance

more »

... urements, the stability of the modulation frequency is the most important pre-condition. In the article, therefore, there are given some methods to verify the modulation frequency stability. In addition, some ways for determining the EDM distance constant and periodical corrections of the phase measuring unit are introduced for 4 types of EDM : LEICA 1700L, TOPCON GTS6A, TOPCON GTS2, C.ZEISS ELTA50. It were also investigated their possibilities for precise distance survey. Values of the determined constants and periodical corrections are presented in Tab. 2. Based on the investigation results of the 4 EDM types and using the values m obtained for different distances S, equations of the a posteriori standard deviations in form : m = (a+b.S) were derived too. Key words: Testing of total station, determination of the modulation frequency, deternmination of the additional constant and the periodic error, investigation of the EDM -accuracy.