> For the complete documentation index, see [llms.txt](https://docs.premium-positioning.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.premium-positioning.com/learn/what-is-rtk.md). # What is RTK RTK, short for real-time kinematic, is a GNSS positioning technique that achieves 1 to 2 cm accuracy in real time. It works by correcting a moving receiver's position against measurements from a reference receiver whose position is already known, so that errors common to both cancel out. A phone or a basic GNSS receiver is accurate to a few metres at best. The signal is degraded on its way down by satellite orbit and clock errors and by delays through the ionosphere and troposphere. RTK removes almost all of that error and turns a few-metre fix into a centimetre one. ### How RTK works RTK relies on two things that ordinary positioning does not use. The first is the carrier phase. Instead of only reading the coarse code in the satellite signal, an RTK receiver measures the phase of the carrier wave itself, which has a wavelength of about 19 cm and can be tracked to the millimetre. The second is a reference receiver, called the base. Because the base sits close to the rover and sees the same satellites through nearly the same atmosphere, it measures nearly the same errors. The base streams those measurements to the rover, the rover differences them against its own, and the shared errors drop out. The hard part is the integer ambiguity: the receiver knows the fraction of a wavelength to the satellite but not the whole number of wavelengths. Resolving those integers is what separates a decimetre-level "float" solution from a centimetre-level "fixed" solution. Once the rover reports RTK Fixed, you can trust the result to 1 to 2 cm and collect positions several times a second. For the fix to hold, the rover needs a clear view of the sky, a continuous correction stream, and an unbroken lock on the satellites. Pass under a tree or beside a building and the fix can drop to float until the receiver re-initialises. ### RTK, NRTK, and PPP A single base covers a few kilometres before the shared-error assumption weakens. Network RTK (NRTK) solves that by interpolating corrections from a network of permanent stations, so you carry only a rover and the base network does the rest. PPP and PPP-RTK take a different route again, using precise satellite data rather than a nearby base. The [Learn](https://claude.ai/chat/b419af49-7d48-49a1-832b-42d52fe66419#) section has a page on each. ### How we provide RTK Premium Positioning delivers RTK and network RTK corrections as RTCM 3.x over the internet, across more than 25 European countries, with 1 to 2 cm accuracy and 99.98% uptime since 2018. Your receiver connects as an NTRIP client to receive the stream. ### FAQ How accurate is RTK? In a fixed solution, 1 to 2 cm horizontally in real time. What is the difference between RTK and GPS? GPS is one of the satellite systems an RTK receiver uses. RTK is the correction technique applied on top of GPS and the other constellations to reach centimetre accuracy. What do I need to use RTK? A GNSS receiver that supports RTK, a clear view of the sky, and a correction stream from a base or a correction network. What is a fixed versus a float solution? Float is the decimetre-level result before the integer ambiguities are resolved. Fixed is the centimetre-level result after they are. Ready to connect a receiver? See [Connect a receiver to our NTRIP caster](https://claude.ai/chat/b419af49-7d48-49a1-832b-42d52fe66419#). --- # Agent Instructions This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com. ## Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter, and the optional `goal` query parameter: ``` GET https://docs.premium-positioning.com/learn/what-is-rtk.md?ask=&goal= ``` `ask` is the immediate question: it should be specific, self-contained, and written in natural language. `goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.