Setting Up an NTRIP Caster for Your Base Station
A step-by-step walkthrough for sharing your base corrections with rovers over the internet.
NTRIP (Networked Transport of RTCM via Internet Protocol) lets a base station send corrections over the internet so any rover with mobile data can use them. The system has three parts: the server (your base), the caster (a relay that rovers connect to) and the client (the rover).
1. Install and survey the base
Mount a multi-band antenna somewhere stable with a clear view of the sky, such as a rooftop. Work out precise coordinates for it, either by averaging for 24 hours or by submitting a static log to a free online processing service. Wrong base coordinates shift every rover position by the same amount.
2. Configure RTCM output
- Station position: message 1005 or 1006.
- Observations: MSM4 or MSM7 messages for each constellation, for example 1074, 1084, 1094 and 1124.
- GLONASS biases: message 1230.
- Send observations once per second and the position every 10 seconds.
3. Choose a caster
You can use a hosted caster such as RTK2go or Emlid Caster, or run your own with software like SNIP or open-source tools on a small server. Hosted casters are quickest to start; your own gives full control and privacy.
4. Connect the base to the caster
Set the base to output NTRIP server data with the caster address, port (usually 2101), a mountpoint name and a password. Many receivers support this directly; otherwise a small computer such as a Raspberry Pi can forward the data.
5. Connect your rover
On the rover, enter the same caster address, port and mountpoint, plus your user credentials. Many networks require the rover to send its position (an NMEA GGA message). Within a minute or two you should see a 'fix' status.
Troubleshooting
- No data: check the mountpoint name is exactly right; it is case-sensitive.
- Float only: check base coordinates, distance to the base and sky view.
- Frequent drops: check mobile signal and try a lower data rate.