​​​Precisely navigated: Correction signals

Correction signals are used in satellite-based automatic steering systems. In contrast to navigation with the help of satellites, for which the so-called "basic accuracy" is sufficient - for example for use in cars or mobile phones - this does not, however, meet the high demands of using modern agricultural technology and precise farming​ methods. After all, even 5% more accuracy through GPS-controlled driving assistance means, for example, that you also save 5% of the total costs on the bottom line. CLAAS therefore wants to know more.

The navigation inaccuracy in cars and smartphones is caused by the great distance of the satellites, but also by spatial conditions such as mountains, lakes, high buildings or power lines. The weather can also influence the accuracy of the signal. The quality of satellite positioning therefore generally increases with spatial proximity and short delays and decreases with long signal transit times.

To avoid interference with our machines, or to increase the locating accuracy and thus the precision, correction signals are used: they provide the machine with additional data that is automatically calculated with the determined position data of the satellite systems (GPS, GLONASS, BEIDOU...). This enables the steering systems to determine their own position much more accurately and to steer the machine more precisely accordingly. A distinction must be made between two basic variants of correction signals.

Satellite-based correction signals usually make use of a reference station network on the ground, but transmit the signals via satellite. In addition to the familiar satellite systems such as GPS or GLONASS, special geostationary satellites are used to calculate and transmit the correction signal. CLAAS exclusively offers such a signal in various accuracy levels under the name SATCOR.

To be able to work even more accurately and with repeatable precision over long periods of time, so-called RTK systems​ are used. For this purpose, so-called RTK (Real Time Kinematics) reference stations are used, which are either set up locally on the farm or can also be mobile and then transmit the signals to the machines via radio. Nowadays, however, the so-called RTK NET variant is more common, which is based on several networked reference stations and makes the signal available via mobile radio. RTK NET correction services are widely available to farmers in many countries.​