> 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-ntrip.md). # What is Ntrip NTRIP, short for Networked Transport of RTCM via Internet Protocol, is an open standard for streaming GNSS corrections over the internet. It is how the correction data reaches your receiver over a mobile connection, instead of over a short-range radio link. An NTRIP caster is the server at the centre of that stream. It collects correction data coming in from base stations or a correction network, and hands it out to the receivers that ask for it. When you connect a rover to receive RTK corrections over the internet, the caster is what it connects to. ### The three parts of NTRIP NTRIP has a simple shape, with three roles. The NTRIP server is the upstream side. It takes the raw correction data from a base station or a network engine and pushes it to the caster as a live stream. The NTRIP caster is the hub. It receives one or many incoming streams, checks who is allowed to connect, and distributes the right stream to each client. One caster can carry many separate streams at once. The NTRIP client is your receiver, or the software talking to it. It connects to the caster, signs in, and requests a stream. From there it receives a steady feed of corrections and applies them to its own measurements to compute a centimetre position. ### Mountpoints and the source table Each stream on a caster has a name, called a mountpoint. A provider often runs several, for example one per correction type or per region. Before you connect, your client can fetch the source table, which is the caster's published list of available mountpoints and what each one offers, then connect to the one that fits your receiver and your location. ### The GGA heartbeat For network RTK, the correction has to be tailored to where you actually are. To make that possible, the client sends its approximate position up to the caster as an NMEA GGA sentence when it connects, and then repeats it at intervals. That repeated message is the heartbeat. If it stops, the network can no longer generate a position-specific correction, so keeping it flowing matters on a moving platform. ### How NTRIP fits with our service Premium Positioning runs an NTRIP caster that streams RTK Premium corrections as RTCM 3.x in ETRS89. Any NTRIP-capable receiver can connect as a client to receive them. The exact host, port, mountpoint names, and sign-in details for your account live in the setup guide rather than here. ### FAQ What does NTRIP stand for? Networked Transport of RTCM via Internet Protocol. What is the difference between an NTRIP caster, server, and client? The server sends a correction stream up, the caster distributes it, and the client (your receiver) requests and receives it. What is a mountpoint? A named correction stream on the caster. You choose the one that matches your receiver and location. Do I need NTRIP for RTK? Only if you receive corrections over the internet. A local base can send corrections by radio instead, but NTRIP is how most network corrections are delivered. Why does my receiver send a GGA message? So the network knows roughly where you are and can generate a correction matched to your position. Ready to connect? See [Connect a receiver](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-ntrip.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.