Tech talk: 14 precision farming terms explained

If you are just getting into the world of precision farming and GPS you will have to get to grips with a baffling array of terms and phrases.

Our speedy jargon buster should help you get your head around the subject in no time.

1. Assisted steering

Generic term for bolt-on, retrofit GPS-controlled automatic steering systems.

2. Differential global positioning system (DGPS)

Uses a series of fixed correction signals from either geostationary satellites or ground-based transmitters to improve GPS accuracy.

See also: How to avoid the pitfalls when buying used GPS kit

3. European geostationary navigation overlay service (Egnos)

Provides a correction signal for the US GPS system to improve accuracy in Europe.

4. Global navigation satellite system (Glonass/GNSS)

Russian version of the GPS satellite system. Having a combined GPS/Glonass system significantly improves coverage.

5. Correction level

Refers to the level of accuracy of a system – for example, JD SF1&2, Omnistar HP.

6. Omnistar

A network of geostationary satellites that provide a correction signal to improve the accuracy of standard GPS systems. Often requires an annual subscription.

7. Real time kinematic (RTK)

Provides a live correction signal from a single ground reference point or the mobile phone network to provide 1-2.5cm accuracy, which can be repeated time and time again without satellite drift. Currently the most precise option available.

8. Virtual Reference Station (VRS)

Uses a series of pre-existing, fixed reference points (such as mobile phone masts) and then broadcasts a correction signal by the mobile network to provide RTK-level accuracy and repeatability. Often referred to as mobile RTK.

9. VR (Variable Rate)

The practice of applying fertiliser or drilling seed using GPS at varying rates depending on crop needs/soil types.

10. Receiver

The dome mounted on top of a tractor, combine or sprayer to get a fix from the satellite network.

11. Controller

The brains of the system that takes the satellite feed, RTK signal and other data, processes it and then tells the steering system what to do.

12. Steering wheel motor

Either replacing the existing steering wheel or bolting on to it, an electric motor automatically turns the wheels in the right direction.

13. Isobus

A standardised system of communication for tractors, implements, control boxes and other agricultural machinery.

14. Repeatable accuracy

While mid-range systems such as Omnistar and StarFire 2 can provide +/-2.5-8cm accuracy, they can suffer from satellite drift so there’s no guarantee they will return to exactly the same spot time after time.

An RTK-enabled system has a constant ground reference point so drift is no longer an issue – essential for operations such as controlled-traffic farming, where tramlines need to be fixed year after year.