Setup · NTRIP Configuration
The right mountpoint depends on two things: your device and your baseline. Choose the wrong one and you may get Float instead of Fix, or Fix without the accuracy your receiver is capable of. Use the tool below for an instant answer.
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RTKsub exposes four mountpoints. Each is optimised for a different combination of device type and working distance.
The standard mountpoint. Delivers RTCM3 corrections in MSM4 format — compact, efficient and compatible with virtually every modern RTK receiver. Includes GPS, GLONASS, Galileo and BeiDou on all frequencies.
Use this when you are within 30 km of a reference station and your device is not a DJI drone or a high-end survey receiver that benefits from MSM7.
MSM5 adds Doppler observations to the standard MSM4 data. DJI's RTK implementation specifically requires Doppler to initialise correctly — using MSM4 with a DJI drone results in Float or no Fix, even when the connection appears successful.
Outside of DJI, MSM5 is rarely needed. Standard devices perform identically on MSM4 and MSM5 since Doppler data is redundant for their processing engines.
MSM7 provides the same observations as MSM4 but at full extended precision — measurements stored with more decimal places. Survey-grade receivers from Trimble, Leica and Septentrio can exploit this extra precision to achieve slightly better accuracy, particularly in challenging baselines and environments.
MSM7 uses roughly twice the bandwidth of MSM4. In most field conditions this is irrelevant, but in areas with very limited mobile data capacity it is worth knowing.
VRS generates a virtual reference station 1–2 km from your rover using data from multiple surrounding physical stations. The effective baseline drops from tens of kilometres to under 2 km — regardless of where you are in the network coverage area. Fix initialisation is faster and Fix stability is higher.
VRS requires your NTRIP client to send a GGA position sentence to the server. Without GGA, the server has no location to generate corrections for, and the stream returns zero bytes. Enable "Send GGA to caster" or equivalent in your NTRIP client before connecting.
The VRS stream is in MSM4 format. Any device that works with RTCM3_NL works with RTCM3_NL_VRS — the only requirement is GGA transmission.
| Mountpoint | MSM level | GGA required | DJI works | Trimble / Leica best | Use when |
|---|---|---|---|---|---|
RTCM3_NL |
MSM4 | No | No | No | Default for most devices, baseline <30 km |
RTCM3_NL_MSM5 |
MSM5 | No | Yes | No | DJI drones only |
RTCM3_NL_MSM7 |
MSM7 | No | No | Yes | Trimble, Leica, high-end survey |
RTCM3_NL_VRS |
MSM4 + VRS | Yes | Yes* | Yes | Baseline >30 km or Fix instability |
* DJI on VRS: use RTCM3_NL_VRS for long-baseline DJI work. For short baselines, use RTCM3_NL_MSM5.
The consequences of the wrong mountpoint depend on which way you get it wrong. None of them produce an obvious error message — which is why choosing correctly matters.
| Situation | Symptom | What is actually happening |
|---|---|---|
DJI drone on RTCM3_NL (MSM4) |
Stuck on Float indefinitely | DJI needs Doppler data (MSM5 minimum). MSM4 corrections flow but Fix never initialises. |
| Any device on VRS without GGA | Connected, 0 bytes/sec | Server cannot generate virtual station. Connection appears active but stream is empty. |
Emlid on RTCM3_NL_MSM7 |
Works fine — no problem | Emlid ignores the extra precision in MSM7. Slightly higher bandwidth, otherwise identical result. |
Trimble on RTCM3_NL (MSM4) |
Fix achieved, slightly lower accuracy | Works correctly. Missing the extended precision that MSM7 provides — marginal difference in most conditions. |
| Any device, wrong region mountpoint | No corrections or very poor Fix | Connecting to a mountpoint for a different country gives corrections from distant stations. Baseline is huge. |
The DJI mistake is the most common
The most frequent support question about mountpoints is: "My DJI drone connects fine but never reaches Fix." The answer is almost always MSM4 instead of MSM5. If you fly DJI, always use RTCM3_NL_MSM5.
Every NTRIP server publishes a sourcetable — a list of all available mountpoints with metadata. Your NTRIP client usually has a "Get Mountpoints" or "Download Source Table" button that fetches and displays this list.
If you need to read the raw sourcetable, you can request it from any NTRIP server by connecting to the host address in a browser or with a tool like curl. Each line starting with STR; is a mountpoint. The fields are semicolon-separated and include the mountpoint name, format, message types and coordinates of the reference station.
Sort by distance in Trimble Access
When the sourcetable loads in Trimble Access, tap the sort button and choose Distance. The nearest physical station appears at the top. If the nearest station is more than 30 km away, switch to the VRS mountpoint rather than the top result.
Still unsure? Ask the AI.
If you have an unusual device or a situation not covered here, describe it to the AI at the top of the page — your device model, your NTRIP client and what you are trying to achieve. It will give you a specific answer.