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u-center (u-blox F9)

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 v1 vs. u-center 2: This guide covers the classic u-center (v1), which remains the most widely deployed version. u-center 2 has a redesigned interface — the NTRIP client is located under Receiver → Correction Services → NTRIP instead of Receiver → NTRIP Client. All field values remain the same.

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

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 15–60 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 0.01–0.02 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.

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