Research on the pre-setting initial readings of electronic theodolites

Measuring of angles in sets is a common method used by the theodolite to measure the horizontal angle. When angle measurement is carried out by the method of measuring of angles in sets, all surveying specifications regulate to presetting the initial readings using the optical theodolite, while most of the surveying specifications do not have such requirement for the electronic theodolite (including the total station), which causes a problem for the instrument users. Most users default to the fact that the electron theodolite does not pre-set the initial readings when measure angles in sets, but there is no theoretical basis, which should be solved theoretically. In this paper, the angle measurement in sets using electronic theodolites is carried out in two ways: with pre-setting the initial reading and without pre-setting the initial reading, and the obtained data are analyzed by hypotheses test method. The results show that there is no obvious difference between the two methods of angular measurement of the same electronic theodolite. Therefore, it is recommended that when electronic theodolites are used in angle measurement in sets, there is no need to pre-setting the initial readings. Thus, makes the field work efficiently.