What Is RTK GPS?

RTK GPS, short for Real-Time Kinematic positioning, is a way of correcting satellite positions in real time to centimeter accuracy. A standard GNSS receiver works out its distance to each satellite from timing codes in the signal, and errors in the atmosphere, satellite clocks and orbits leave it a few meters out. RTK removes most of that error.

It does so with two receivers. A base station sits at a precisely known point and sees the same satellites, through nearly the same atmosphere, as the moving receiver, called the rover. The base works out the errors in what it receives and sends corrections to the rover, which applies them in real time.

The other half of the trick is the carrier phase. Instead of only timing the code in the signal, an RTK receiver measures the phase of the radio carrier wave itself, which has a wavelength of around 19 cm on the GPS L1 frequency. Once the receiver resolves how many whole wavelengths lie between it and each satellite, its position is fixed to around a centimeter or two.

Although the name says GPS, modern RTK receivers use every constellation: GPS, Galileo, GLONASS and BeiDou, which gives more satellites to work with and faster, steadier fixes.

An RTK receiver reports the quality of its solution, and knowing the difference matters for anything that steers by it.

RTK is the most accurate real-time method, but not the only way to improve on standalone GNSS. The table compares the common options.

RTK accuracy falls slowly with distance from the base, typically by around 1 mm per kilometer, so a single base is usually used within 10 to 20 km. Network RTK covers whole regions by modeling errors between many reference stations.

Receiver choice matters too. Single-band receivers that track only L1 are cheaper but take longer to reach a fixed solution and lose it more easily. Multi-band receivers that also track L2 or L5 resolve the ambiguities in seconds and recover faster after passing under a bridge or a tree line, which is why they are the norm on machines that steer by RTK. The antenna matters as much as the receiver: a survey-grade or multi-band antenna on a clear roof position rejects reflected signals that would otherwise disturb the fix.

There are two ways to get RTK corrections. A local base station, often on a tripod or a farm building, broadcasts corrections over UHF radio to rovers nearby; this works without mobile coverage but needs its own setup. Alternatively, a correction network streams corrections over the internet using NTRIP (Networked Transport of RTCM via Internet Protocol), and the rover receives them over a cellular modem. Corrections themselves are formatted to the RTCM 3 standard, so receivers and networks from different makers work together.

Network corrections are available by subscription from national mapping agencies, equipment makers and private networks, and some regions have free community networks. Losing the cellular link for more than a short time drops the rover back to float, which is one reason RTK is often paired with an inertial sensor.

Centimeter accuracy is what lets an autonomous tractor follow a row precisely, a drone map a site without ground markers, and an excavator dig to a design surface. Common uses include farm guidance and controlled traffic, drone mapping and inspection, construction machine control, surveying, and robots that work outdoors.

Our autonomous tractor case study shows an edge AI computer taking RTK and LTE through mini PCIe, and our rugged Jetson computers are built for autonomous machines. On drones, the RTK receiver usually feeds the flight controller, and our guide to Jetson companion computers for drones covers how the AI computer fits alongside.

We supply edge AI and in-vehicle computers with GNSS, RTK and cellular modules fitted as standard, set up the drivers and test each system before it ships. Tell us your receiver and correction source and we will specify the build.