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u-center NTRIP Setup: u-blox ZED-F9P RTK

Configure the u-center NTRIP client for u-blox ZED-F9P boards with RTKdata. Set COM port, baud rate, host, port 2101 and AUTO mountpoint to verify RTK fix.

u-center is a free Windows desktop application from u-blox for configuring, testing, and monitoring u-blox GNSS receivers. It is the primary tool for working with u-blox ZED-F9P chips found in popular RTK boards such as the SparkFun RTK Facet, SparkFun RTK Express, ArduSimple simpleRTK2B, and standalone ZED-F9P evaluation kits. u-center includes a built-in NTRIP client that streams corrections from RTKdata.com directly to the receiver over USB, making it ideal for bench testing, firmware configuration, and verifying RTK performance.

Download: u-blox u-center (Windows, free)

u-center vs. u-center 2: This guide covers u-center (v1), the u-blox tool for M8, M9 and F9 receivers such as the ZED-F9P. The u-blox ZED-X20P and ZED-F20P are fully supported by u-center 2 only. In u-center 2, the NTRIP client is under Tools and Services → Services → NTRIP client, tab Manual: see u-center 2: ZED-X20P and ZED-F20P.

Requirements

  • u-blox ZED-F9P receiver board or device (SparkFun, ArduSimple, etc.)

  • Multi-band GNSS antenna connected to the receiver

  • USB cable connecting the receiver to your Windows PC

  • Windows PC with u-center installed and internet access

  • Active RTKdata.com account with username and password

Don't have an RTKdata.com account yet? 👉 Start 30-day Free Trial or View Pricing

Step-by-step setup

1

Connect the receiver via USB

  1. Connect your u-blox F9P board to your PC via USB.

  2. Launch u-center.

  3. In the toolbar, click the COM port dropdown (top-left) and select the correct COM port. If unsure, check Windows Device Manager → Ports (COM & LPT) for the u-blox device.

  4. Set the baud rate to match your receiver's configuration. Click the baud rate dropdown next to the COM port selector.

    • Common baud rates: 38400 (SparkFun default), 115200 (ArduSimple default), 9600 (u-blox factory default)

  5. Click the Connect button (plug icon) or press Ctrl+F9.

  6. The bottom status bar should begin showing satellite data, confirming the connection is active.

Baud Rate Troubleshooting: If the status bar shows no data or garbage characters, the baud rate is wrong. Try 38400, 115200, then 9600 until you see valid NMEA sentences in the Text Console (View → Text Console). The correct baud rate will immediately produce readable position data.

2

Verify satellite reception

  1. Open View → Docking Windows → Satellite Level to see the satellite sky plot.

  2. Confirm bars appear for GPS, Galileo, BeiDou, and/or GLONASS.

  3. The Fix Mode indicator in the status bar should show at least 3D Fix before proceeding.

3

Open the NTRIP client

  1. Go to Receiver → NTRIP Client... in the menu bar.

  2. The NTRIP Client dialog will open.

4

Enter RTKdata.com connection settings

Fill in the NTRIP Client fields:

  • Host (domain): rtk.rtkdata.com

  • Host (IP fallback): 13.56.117.10

  • Port: 2101

  • Username / Password: From RTK Credentials in the internal dashboard (not website login)

  • Mountpoint (ALL CAPS): AUTO (recommended), or AUTO_WGS84, AUTO_ITRF2020, AUTO_ITRF2014

  • Host (domain): eu.rtkdata.com

  • Host (IP fallback): 3.73.41.96

  • Port: 2101

  • Username / Password: From RTK Credentials in the internal dashboard (not website login)

  • Mountpoint (ALL CAPS): AUTO (recommended), or AUTO_WGS84, AUTO_ITRF2020, AUTO_ITRF2014

  • Host (domain): aus.rtkdata.com

  • Host (IP fallback): 54.206.56.130

  • Port: 2101

  • Username / Password: From RTK Credentials in the internal dashboard (not website login)

  • Mountpoint (ALL CAPS): AUTO (recommended), or AUTO_WGS84, AUTO_ITRF2020, AUTO_ITRF2014

5

Start the NTRIP stream

  1. Click OK or Connect to start the connection.

  2. A green NTRIP icon will appear in the toolbar when the connection is active.

  3. Monitor the Fix Mode in the bottom status bar: 3D → DGNSS → FLOAT → FIX.

  4. Convergence to RTK FIX typically takes 15 to 60 seconds with good sky conditions.

How to verify RTK is working:

  • Fix Mode in the status bar displays RTK FIX (GGA fix quality = 4).

  • Accuracy estimates in the Navigation window (View → Docking Windows → Navigation) show horizontal accuracy of 0.01 to 0.02 m.

  • The NTRIP icon in the toolbar stays green with no red indicators.

  • In the Text Console (View → Text Console), GGA messages show fix quality = 4 (RTK FIX) or 5 (Float).

Troubleshooting

Problem
Cause
Fix

No data after connecting COM port

Wrong baud rate

Try 38400, 115200, or 9600

"Connection failed" in NTRIP Client

Wrong hostname/port or no internet

Verify hostname, confirm port 2101, check internet

NTRIP connects but stays on FLOAT

No initial 3D fix (GGA = 0,0)

Wait for 3D fix before starting NTRIP

Mountpoint error

Lowercase or misspelled

Enter AUTO in ALL CAPS

"Timeout" errors

Firewall blocking port 2101

Add u-center to firewall exceptions; allow outbound TCP on 2101

Corrections received but no RTK improvement

Antenna indoors or obstructed

Move antenna to clear 360-degree sky view

Tips for u-center

  • u-center is a configuration and testing tool, not a field tool. Use it to verify your F9P board works with RTKdata.com before deploying with a mobile app like SW Maps.

  • Save configuration to flash. After confirming RTK works, go to View → Configuration View → CFG and send "Save current configuration." This stores settings in non-volatile memory.

  • Monitor RTCM data. The Packet Console (View → Packet Console) shows raw UBX and NMEA messages, including incoming RTCM3 correction data.

  • GGA output rate. Ensure the receiver outputs GGA at 1 Hz. Check via View → Configuration View → MSG.

  • Multi-receiver setups. u-center supports multiple simultaneous COM port connections for testing several F9P boards at once.

u-center 2: ZED-X20P and ZED-F20P

u-center 2 is the u-blox tool for gen 10 and gen 20 receivers, including the ZED-X20P and ZED-F20P. It runs on Windows 10 and later, asks you to log in with a u-blox account at first start, and has an NTRIP client that sends your position to RTKdata and writes the corrections to the receiver over USB. The RTKdata values are the same as for u-center: the host for your region, port 2101, the mountpoint AUTO and your RTK credentials.

What you need for this section:

  • A u-blox ZED-X20P or ZED-F20P receiver with a USB port, for example the ArduSimple simpleRTK 4 Optimum or the SparkFun ZED-X20P breakout

  • A multi-band GNSS antenna. ArduSimple asks you to connect the antenna before you power the board.

  • A Windows 10 (or later) PC with u-center 2 and a u-blox account for the login at first start

  • Internet on the PC with outbound TCP on port 2101

  • RTK credentials from RTK Credentials in your account dashboard (the username starts with rtk)

1

Connect the receiver

Connect the antenna, then connect the receiver to your PC over USB (on the ArduSimple simpleRTK 4 Optimum, the USB port labelled POWER+GPS). In u-center 2, click Data sources in the left bar, then Add data source, select the COM port and click Add device.

2

Wait for a position

Wait for a 3D fix outdoors. u-center 2 needs the receiver's position before it starts the NTRIP connection. The ZED-X20P outputs NMEA GGA on USB by default; if you changed the configuration, enable NMEA GGA or UBX-NAV-PVT on the USB port.

3

Open the NTRIP client in u-center 2

Open Tools and Services → Services → NTRIP client and select the Manual tab, where you enter the RTKdata caster.

4

Enter the RTKdata settings

Set NTRIP version to v1.0 and Protocol to HTTP. Enter the host for your region in Hostname (or IP address), 2101 in Port, and your RTK credentials in Username and Password.

  • Hostname (or IP address): rtk.rtkdata.com (IP fallback 13.56.117.10, only if the hostname does not connect)

  • Port: 2101

  • Username / Password: From RTK Credentials in your account dashboard, not your website login

  • Mount point: AUTO, selected from the list in the next step (alternatives: AUTO_WGS84, AUTO_ITRF2020, AUTO_ITRF2014)

  • Hostname (or IP address): eu.rtkdata.com (IP fallback 3.73.41.96, only if the hostname does not connect)

  • Port: 2101

  • Username / Password: From RTK Credentials in your account dashboard, not your website login

  • Mount point: AUTO, selected from the list in the next step (alternatives: AUTO_WGS84, AUTO_ITRF2020, AUTO_ITRF2014)

  • Hostname (or IP address): aus.rtkdata.com (IP fallback 54.206.56.130, only if the hostname does not connect)

  • Port: 2101

  • Username / Password: From RTK Credentials in your account dashboard, not your website login

  • Mount point: AUTO, selected from the list in the next step (alternatives: AUTO_WGS84, AUTO_ITRF2020, AUTO_ITRF2014)

5

Select the AUTO mount point

Click Get mount points (some guides call this button Save & Retrieve). In the Mount points table, click the row AUTO. The list can show more entries: click only AUTO (or one of the alternatives from the previous step), then check that Selected mount point shows it. If AUTO is already selected, for example after an interruption, click Connect.

6

Check the connection and the fix

u-center 2 connects as soon as you click the row. The log shows Authentication successful, then Location data sent to caster with your position, then Received data from Caster. u-center 2 sends your position again every 10 seconds. In Data view (Add view → Data view), Fix mode moves to FLOAT and then to FIXED.

7

Disconnect before you switch devices

Closing the NTRIP client window does not end the connection. Click Disconnect before you use the same RTK credentials on another device or app.

For a test indoors without a fix, turn on Manual position, enter your real approximate latitude and longitude in Latitude[deg] and Longitude[deg], and fill in Altitude MSL[m] and Geoid sep.[m] as well, for example 0 in both. With one of the four fields empty, u-center 2 does not connect. u-center 2 keeps this setting for the next start: set Manual position back to Not used before you work outdoors, and check that the position in Location data sent to caster is where you are.

Corrections and signals with the ZED-X20P and ZED-F20P

RTKdata streams RTCM 3.2 with MSM4 messages (1074, 1084, 1094, 1114, 1124, 1134) and 1005. The ZED-X20P and ZED-F20P list 1005, 1074, 1094 and 1124 among their RTCM input messages, and the ZED-X20P-01B also lists 1084 (u-blox integration manuals and data sheets for both modules). RTKdata streams carry L5, E5a and B2a where the base station tracks them; some older base stations send L1 and L2 only.

RTCM 1230 (GLONASS code-phase biases) comes from the base station, and most RTKdata base stations do not send it. The ZED-X20P-01B needs 1230 or 1033 to fix GLONASS ambiguities and otherwise estimates them as float, so GLONASS does not contribute to the RTK fix. GPS, Galileo and BeiDou are not affected. The ZED-X20P-00B and the ZED-F20P do not track GLONASS.

With AUTO, the receiver reports its position in your region's datum, because u-blox bases the rover position on the reference frame of the correction service. Heights are ellipsoidal, see Understanding Heights and Coordinate Systems & Datums.

Troubleshooting u-center 2

Problem
Cause
Fix

Unable to start NTRIP service. Enable UBX-NAV-PVT or NMEA-Standard-GGA.

The receiver has no position yet, or neither NMEA GGA nor UBX-NAV-PVT reaches u-center 2

Wait for a 3D fix outdoors, then enable NMEA GGA or UBX-NAV-PVT on the USB port

Unable to retrieve mount points: [NTRIPClientHTTPService]: Error: getaddrinfo ENOTFOUND, followed by the host

Host misspelled or pasted with a space

Type the host again, or enter the IP fallback for your region

Unable to retrieve mount points: [NTRIPClientHTTPService]: Connection attempt timed out. Verify validity of host and/or port number.

Wrong port, or outbound TCP on port 2101 is blocked by a firewall, VPN or mobile network

Check that Port is 2101 and that your network allows outbound TCP on port 2101

Authentication failed

Wrong username or password, or the website login was used

Copy username and password from RTK Credentials again. If they still fail, contact support@rtkdata.com

Unknown data received. Check the log.

The Username or Password field is empty, so u-center 2 sent no credentials

Fill in both fields and connect again

Received data from Caster appears, but Fix mode never reaches FLOAT

A row other than AUTO or its alternatives AUTO_WGS84, AUTO_ITRF2020 and AUTO_ITRF2014 was clicked

Click Disconnect, then click the row AUTO

Connection timed out and Reconnecting... with no Received data from Caster

Manual position is on with a position far from your site

Click Disconnect, set Manual position to Not used, click Connect and check the position in Location data sent to caster

Connection closed by Caster, and the log shows An error occurred

The network connection to RTKdata failed, for example Wi-Fi dropped or outbound TCP on port 2101 is blocked

Check the internet connection and port 2101, then click Connect

Fix mode keeps dropping back and the log shows Reconnecting... again and again

Another device or app uses the same RTK credentials at the same time

Disconnect the other device or app. One data stream allows one connection at a time, see Account & Credentials

The Manual tab or Get mount points is greyed out

An NTRIP connection is active, PointPerfect access was granted on the EVK or ZTP tab, or Hostname or Port is empty

Click Disconnect, click Revoke access on the EVK or ZTP tab, or fill in Hostname and Port

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