The Principle Of The Digital Level, Test, And Applied Research

Since the introduction of the first digital level by Leica in 1990, this type of equipment has rapidly gained acceptance because of its advantage. In many fields such as precision leveling, deformation monitoring and appropriate industrial surveying, digital levels will take the place of optical levels. At present, four manufacturers, Leica, Zeiss, Topcon, Sokkia, introduced different models of digital levels to the surveying market with different measurement principle and code staff. Because of the large difference between digital level and optical level, the suitable method to assess the precision of digital level is needed.In this paper, the measurement principle of various digital levels and error sources is discussed. On the basis of summarizing the methods for calibration of digital levels, we present a measurement procedure for system calibration of digital levels with double-frequency laser interferometer. The reliable results of test according to the procedure are provided. At the last section of this paper we discuss the program design based on Windows CE to communicate with digital levels.