Short note: Total station principle, data recording

Principle of a total station

A total station is an electronic theodolite with a built-in EDM and a microprocessor. The electronic circle measures the horizontal and vertical angles; the EDM sends an infrared or laser beam to a prism and calculates the slope distance from the phase shift of the returned signal. The microprocessor corrects the readings and computes horizontal distance $H = S\cos\alpha$, vertical difference $V = S\sin\alpha$ and the coordinates of the target.

Digital data recording fundamentals

1. Job set-up: a job file is created and the station name, coordinates, instrument and prism heights and the atmospheric data are entered.
2. Orientation: backsight is taken on a reference station to set the azimuth.
3. Measurement: each sighted point is stored in the memory (or card) automatically as point number, horizontal angle, vertical angle, slope distance and code (feature).
4. Storage and transfer: data are kept in internal memory or on a card and transferred to a computer through cable, USB or Bluetooth in standard formats.
5. Processing: the raw data are edited and adjusted with software, and coordinates, maps and sections are produced.

Digital recording removes manual booking errors and speeds up the survey.