What is NTRIP? — How corrections reach you over the internet

To get cm accuracy with RTK, you need to receive a base station's correction information. The mechanism that delivers that correction over the internet is NTRIP. You will always meet this word when using RTK, so let's sort out the cast of characters and how they connect, in plain language.

Distributing base-station corrections over the internet

A base station measures “how much error is on the satellite signals right this moment” and produces correction data in a format called RTCM. Distributing this over the internet (HTTP-based) is NTRIP (Networked Transport of RTCM via Internet Protocol).

The cast — caster, mountpoint, client

NTRIP has three roles. The caster is the server that distributes corrections. The mountpoint is the “channel name” of each base station on the caster. The client is your receiver or app that receives corrections. Connect to the mountpoint you want, and that station's corrections start flowing.

The connection flow

In your receiver or app, set the caster address, port, mountpoint and username / password and connect. Corrections arrive, and once the ambiguity is resolved you get an RTK Fix (cm accuracy). The closer the base station (the shorter the baseline), the higher the accuracy.

The public “goodwill” networks

Around the world, volunteers publish thousands of base stations for free, out of goodwill (RTK2GO, BizStation, GeoRTK, Centipede-RTK and more). At KUON you can check their location, status and connection details on a map and ranking. Base stations are a public good — use them with gratitude and moderation.