total station
Introduction
Total station is an electro-optical device used in topography, whose operation is supported by electronic technology. It consists of incorporating a distance meter and a microprocessor to an electronic theodolite.
Some of the features it incorporates, and which theodolites do not have, are an alphanumeric liquid crystal display (LCD), warning LEDs, lighting independent of sunlight, calculator, distance meter, tracker (path follower) and in electronic format, which allows it to be used later on personal computers. They come equipped with various simple programs that allow, among other capabilities, the calculation of coordinates in the field, setting out points "Point (geometry)") in a simple and effective way, and calculation of azimuths and distances.
Operation
Viewed as a theodolite, a total station is made up of the same parts and functions. Parking and verticalization are identical, although for the total station there are electronic levels that facilitate the task. The three axes and their associated errors are also present: that of verticality, which with double compensation sees its influence on the horizontal readings reduced, and those of collimation and inclination of the secondary axis, with the same behavior as in a classic theodolite, except that the first can be corrected by software, while in the second the correction must be carried out by mechanical methods.
The instrument measures angles from marks made on transparent discs. Distance readings are made using an electromagnetic carrier wave (generally microwave or infrared) with different frequencies that bounces off a prism "Prism (optical)") located at the point to be measured and returns, the instrument taking the phase difference between the waves. Some total stations feature the ability to measure "to solid", meaning that a reflective prism is not necessary.
This instrument allows obtaining coordinates of points with respect to a local or arbitrary system, as well as to defined and materialized systems. To obtain these coordinates, the instrument performs a series of readings and calculations on them and other data provided by the operator. The readings obtained with this instrument are those of vertical and horizontal angles and distances. Another peculiarity of this instrument is the possibility of incorporating data such as point coordinates, codes, pressure and temperature corrections, etc.
The precision of the measurements is of the order of the ten-thousandth of a gradian in angles and millimeters in distances, and measurements can be made at points located between 2 and 5 kilometers depending on the device and the number of prisms used. For optimal performance of total stations, it is necessary that the equipment be calibrated; For this, maintenance and adjustments must be carried out through the use of a collimator.