> 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/guides/rtklib-str2str-rtknavi.md).

# RTKLIB (str2str / RTKNAVI)

These steps connect a RTKLIB (str2str / RTKNAVI) to the Premium Positioning correction network over NTRIP, using RTKLIB on Windows/Linux. They assume you already have your NTRIP credentials.

### Before you start

* Your NTRIP username and password, from your Premium Positioning welcome email or your account on the customer portal.
* RTKLIB on Windows/Linux.
* A working internet connection on the controller or phone.
* A clear view of the sky at the point you are measuring.

### Network settings

These are the same for every Premium Positioning customer. Only your username and password are unique to you.

* Server or host: rtkpremium.xyz
* Port: 2101
* Mountpoint: COMMON
* Protocol: NTRIP

### Steps

1. Get your RTKLIB build: Download RTKLIB - the official 2.4.2 release from rtklib.com, or the demo5 fork from rtklibexplorer (recommended for u-blox ZED-F9P). On Windows the GUI apps (rtknavi.exe, strsvr.exe, rtkpost.exe) and CLI tools (str2str, rtkrcv, convbin) are in the bin folder. No install needed.
2. Have your details ready: You need YOUR OWN NTRIP credentials from your welcome email - a username and password unique to your account; do not reuse anyone else's. The caster details are the same for everyone: Host rtkpremium.xyz, Port 2101, Mountpoint COMMON, Protocol NTRIP.
3. Confirm the receiver COM port and baud: Connect the receiver (e.g. ZED-F9P) by USB. In Windows Device Manager > Ports (COM & LPT) note the port (e.g. COM3) and the baud (u-blox USB is commonly 115200; confirm in u-center). You need both for either method.
4. Make sure the receiver outputs raw observations: For RTK you feed RTCM3 IN and read raw measurements OUT. In u-center enable raw output (UBX-RXM-RAWX and UBX-RXM-SFRBX) if computing in RTKNAVI; or, if the receiver computes internally, just ensure it accepts RTCM3 input. The caster delivers standard RTCM3.
5. Method A - str2str: build the NTRIP-to-receiver command: str2str pipes the caster into the receiver. Input is an NTRIP Client; the connection string is ntrip\://USER:PASSWORD\@addr:port/mountpoint. Using YOUR credentials: -in ntrip\://YOUR\_USERNAME:<YOUR_PASSWORD@rtkpremium.xyz>:2101/COMMON.
6. Method A - str2str: set the serial output and run: Output is the receiver serial port: serial://port:bitrate:bytesize:parity:stopbits:flowcontrol - e.g. serial://COM3:115200:8:n:1:off (Linux: serial://ttyACM0:115200:8:n:1:off). Full command: str2str -in ntrip\://YOUR\_USERNAME:<YOUR_PASSWORD@rtkpremium.xyz>:2101/COMMON -out serial://COM3:115200:8:n:1:off. Run it from the str2str folder; it relays RTCM3 to the receiver.
7. Method A - str2str: send position (GGA) if needed: Some casters need the rover's approximate position (NMEA GGA) before sending corrections. str2str -b relays a message from the output (receiver) stream back to the caster (typically GGA). The exact -b behaviour varies by RTKLIB version - check str2str -h. The single COMMON stream usually doesn't require a precise position, but enable GGA relay if the connection won't start without it.
8. Method A - verify the receiver reaches FIX: In u-center on the same receiver, watch the fix/RTK status: single → FLOAT → FIXED as valid RTCM3 arrives. Fix Mode reads FIXED and the NTRIP/RTK indicator turns green.
9. Method B - RTKNAVI: open Input Streams: Launch RTKNAVI and click the Input Streams ('I') button. Tick the Rover row, set Type to Serial, and click its Opt ('...') to set the COM port, baud, and Format (ZED-F9P = u-blox).
10. Method B - RTKNAVI: set the Correction stream to NTRIP Client: Enable the Correction stream (labelled Base Station / row 2 in some versions - wording differs between 2.4.2 and demo5; pick the incoming-corrections row) and set Type to NTRIP Client.
11. Method B - RTKNAVI: enter the caster in NTRIP Client options: Click the Opt ('...') on the NTRIP Client row: Ntrip-Caster Host rtkpremium.xyz, Port 2101, Mountpoint COMMON, User-ID YOUR\_USERNAME, Password YOUR\_PASSWORD (from your welcome email). Set Format to RTCM3. OK, then OK to close Input Streams.
12. Method B - RTKNAVI: set Positioning Mode to Kinematic: Click Options. On Setting1 set Positioning Mode to Kinematic (Static only for a stationary survey). For ZED-F9P set Frequencies to L1+L2 (demo5 may show L1+L2+E5b) and confirm the receiver type/format is u-blox. Apply / OK.
13. Method B - RTKNAVI: Start and watch for FIX (Q=1): Click Start. The solution progresses single (Q=5) → FLOAT (Q=2) → FIX (Q=1). FIX with Q=1 is a cm-level RTK fixed solution. If it stays FLOAT/single, check the credentials, that COMMON connected, and that the receiver outputs raw observations with clear sky.

### If the fix will not hold

str2str (Method A) is best when the receiver computes RTK internally; RTKNAVI (Method B) when you want RTKLIB to compute and display/log the solution. Demo5 (rtklibexplorer) is recommended over stock 2.4.2 for the ZED-F9P. Exact menu/field labels differ between 2.4.2 and demo5 - match controls by role. Setup is confirmed when you see an RTK FIX (Q=1).

For more, see RTK corrections troubleshooting and Fix inconsistent RTK accuracy on site.

### Need help

Support is available 24/7. Include your receiver model, the mountpoint, the solution status, and the correction age when you get in touch.