Quick mountpoint finder
Choose by device first, then use VRS whenever the nearest reference station is more than 30 km away or Fix is unstable.
Most devices within 30 km → RTCM3_NL
Use MSM4 for Emlid Reach RS / RX, u-blox ZED-F9P, SW Maps, FieldGenius and most generic NTRIP clients.
Any DJI RTK drone → RTCM3_NL_MSM5
DJI requires MSM5 Doppler observations to initialise Fix. Do not use the MSM4 default mountpoint for DJI.
Trimble, Leica or high-end survey → RTCM3_NL_MSM7
MSM7 supplies extended-precision observations that high-end survey receivers can use.
Any device beyond 30 km → RTCM3_NL_VRS
VRS shortens the effective baseline to 1–2 km. Enable GGA transmission before connecting.
All mountpoints explained
RTKsub exposes four mountpoints. Each is optimised for a different combination of device type and working distance.
RTCM3_NL — MSM4
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 it within 30 km when your device is not a DJI drone or a high-end survey receiver.
RTCM3_NL_MSM5 — MSM5
MSM5 adds Doppler observations to the standard MSM4 data. DJI's RTK implementation specifically requires Doppler to initialise correctly. Outside DJI, MSM5 is rarely needed because standard devices perform identically on MSM4 and MSM5.
RTCM3_NL_MSM7 — MSM7
MSM7 provides the same observations as MSM4 but at full extended precision. Trimble, Leica, Septentrio and NovAtel receivers can use this extra precision, particularly in challenging baselines and environments. It uses roughly twice the bandwidth of MSM4.
RTCM3_NL_VRS — VRS MSM4
VRS generates a virtual reference station 1–2 km from your rover using data from multiple surrounding physical stations. Fix initialisation is faster and Fix stability is higher. Send GGA to the caster or the stream returns zero bytes.
Side-by-side comparison
| 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.
What happens with the wrong mountpoint
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 a virtual station. The connection appears active but the 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 — a marginal difference in most conditions. |
| Any device, wrong region mountpoint | No corrections or very poor Fix | Corrections come from distant stations, so the 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.
Finding mountpoints in the sourcetable
Every NTRIP server publishes a sourcetable — a list of all available correction streams 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 your device model, NTRIP client and intended work. You can then get a specific recommendation.
