Use of electronic distance - meaduring E.D.M. instruments in three dimension ositioning

The direct measurement of distance in the filed is one of the more trouble some of surveying operations, especially if high accuracy is required. Before using of EDM the measurement of line with high accuracy required extensive effort over along period of time. Now using ( EDMI) the same accuracy could be made in the course few minutes by two people [1].The electromagnetic distance measuring EDM equipment did not come into wide use until 1960s [2] It is only about 60 years since the first successfulelectronic distance measurement was carried out using radio equipment. Prior.to that time no means had been found to measure distance directly. The firstdistance measurements were made using a primary pulsed radar. The firstsuccessful experiment using pulse radar was carried in 1935 By Sir Rebortwatson Watt. This radar had a range of 40 miles military and operated at 12MHz. This system is the mainstay of most military and commercial radar usedtoday. During World WAR IT several types of secondary radar or systemsrequiring cooperative targets were developed for navigational and identification application [3].It was First developed in the late 1940s as result of experiments todetermine the velocity of light. Particularly under the initiative of Erik Bergstrand in Sweden, the Geodimeter was developed and the first production model appeared in 1949. It was extremely heavy and bulky but those national