What is RTK and how GNSS positioning works
What RTK is and how it works: GNSS satellites, base station and rover, RTK FIX and FLOAT status, and why a base station network gives centimetre accuracy.
GNSS (Global Navigation Satellite System) is the umbrella term for satellite navigation systems: the American GPS, Russian GLONASS, European Galileo and Chinese BeiDou. A standard receiver (a phone, a car navigation unit) computes its position from these signals with an error of several metres – caused by the atmosphere (ionosphere, troposphere), satellite clock and orbit errors, and signal reflections.
RTK – Real-Time Kinematic
RTK removes most of these errors. A base station sits at a precisely known position and continuously compares what it measures with what it "knows". It sends the difference – the corrections – to the rover (a tractor, a survey receiver, a drone). The rover also uses carrier-phase measurements, so instead of metres it achieves centimetre-level accuracy.
- Base station – a fixed multi-frequency GNSS receiver on a point with known coordinates, with its antenna on a stable mount, connected to the internet 24/7.
- Rover – your receiver in the field.
- Baseline – the distance between rover and base. The shorter, the better; the recommendation for single-base RTK is up to ~30 km.
Solution status
| Status | GGA quality | Typical accuracy | Meaning |
|---|---|---|---|
| RTK FIX | 4 | 1–2 cm (H), 2–3 cm (V) | Ambiguities resolved – full RTK accuracy. This is what you want. |
| RTK FLOAT | 5 | 10 cm – 1 m | Corrections are arriving, but the solution is not fixed yet (start-up, obstructions, poor signal). |
| DGPS | 2 | 0.3 – 1 m | Code corrections – no carrier phase. |
| Single / autonomous | 1 | 1 – 5 m | No corrections. |
After connecting, a receiver usually passes through FLOAT and reaches FIX within a few seconds to a minute. Under open sky, with a modern multi-frequency receiver tracking four constellations, FIX is typically achieved within seconds.
Why a network of base stations
A single base covers a limited area. A network of base stations – together with our AUTO mountpoint, which always connects you to the nearest healthy one – means you don't need your own base, you don't carry it from field to field, and you don't have to worry when one station goes down.
Related: See where you get RTK FIX on the coverage map, and learn what affects accuracy in what RTK accuracy depends on. Unfamiliar term? Check the glossary.