# 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](https://www.u-blox.com/en/product/u-center) (Windows, free)

{% hint style="info" %}
**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.
{% endhint %}

## 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

{% hint style="info" %}
Don't have an RTKdata.com account yet? 👉 [Start 30-day Free Trial](https://rtkdata.com/try-rtk-corrections-free-for-30-days/) or [View Pricing](https://rtkdata.com/pricing/)
{% endhint %}

## Step-by-step setup

{% stepper %}
{% step %}

#### 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.

{% hint style="warning" %}
**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.
{% endhint %}
{% endstep %}

{% step %}

#### 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.
   {% endstep %}

{% step %}

#### Open the NTRIP client

1. Go to **Receiver → NTRIP Client...** in the menu bar.
2. The NTRIP Client dialog will open.
   {% endstep %}

{% step %}

#### Enter RTKdata.com connection settings

Fill in the NTRIP Client fields:

{% tabs %}
{% tab title="North America" %}

* **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`
  {% endtab %}

{% tab title="Europe" %}

* **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`
  {% endtab %}

{% tab title="Australia" %}

* **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`
  {% endtab %}
  {% endtabs %}
  {% endstep %}

{% step %}

#### 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).
  {% endstep %}
  {% endstepper %}

## 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.