# Sokkia GCX3 / GRX3

The Sokkia GCX3 and GRX3 are professional survey-grade GNSS receivers by Sokkia (a Topcon subsidiary). The GCX3 is the flagship model featuring a built-in 4G modem, IMU tilt compensation, and multi-constellation tracking. The GRX3 is a versatile receiver — some models include an internal modem while others rely on a controller for internet connectivity (check your specific model variant). Both receivers are configured through **MAGNET Field** (Sokkia edition) running on an SHC5000 or SHC500 controller.

## Requirements

* **Sokkia GCX3 or GRX3** powered on with clear sky visibility
* **MAGNET Field** (Sokkia edition) v7.0+ on an SHC5000, SHC500, or compatible controller
* **Internet connection** via the receiver's internal 4G modem (SIM card) or the controller's cellular/Wi-Fi connection
* **RTKdata.com account** with active RTK credentials (username starting with `rtk` and password from your RTK dashboard)
* **Survey pole** with Sokkia adapter

{% 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

{% hint style="info" %}
Sokkia is a Topcon subsidiary — MAGNET Field (Sokkia edition) follows the same workflow as the Topcon version. If you are familiar with Topcon HiPer receivers, the NTRIP configuration is identical.
{% endhint %}

{% stepper %}
{% step %}

#### Connect to the receiver

1. Power on your GCX3 or GRX3 and wait for satellite tracking to begin (LED indicators confirm satellite lock).
2. Open **MAGNET Field** on your SHC5000 or SHC500 controller.
3. Go to **Configure** > **Survey Styles** and create a new style or edit an existing one.
4. Under **Instrument**, select your Sokkia receiver from the Bluetooth device list and pair if prompted.
   {% endstep %}

{% step %}

#### Configure the RTK rover correction source

1. In your survey style, navigate to **RTK** > **Rover**.
2. Set **Correction Source** to **Internet (NTRIP)**.
3. If using the **GCX3's internal modem** (or GRX3 with modem): select **Receiver Internet** and configure the APN for your mobile carrier if not already set.
4. If using the **controller's internet**: select **Controller Internet** and ensure the controller has an active data connection via cellular or Wi-Fi hotspot.

{% hint style="warning" %}
Not all GRX3 models include an internal modem. If your GRX3 does not have a built-in modem, you must use the controller's internet connection.
{% endhint %}
{% endstep %}

{% step %}

#### Enter RTKdata.com NTRIP settings

Fill in the NTRIP connection fields. Select the tab for your region:

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

* **Host / Caster Address:** `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`
  {% endtab %}

{% tab title="Europe" %}

* **Host / Caster Address:** `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`
  {% endtab %}

{% tab title="Australia" %}

* **Host / Caster Address:** `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`
  {% endtab %}
  {% endtabs %}

{% hint style="warning" %}
Type `AUTO` manually in all capital letters. Do not browse the mountpoint table — MAGNET Field may time out or return an incomplete list with large casters.
{% endhint %}
{% endstep %}

{% step %}

#### Verify GGA position sending

1. In the NTRIP settings, verify that **Send GGA** is set to **On** or **Automatic**.
2. MAGNET Field typically enables GGA by default, but confirm this has not been changed.

{% hint style="danger" %}
RTKdata requires GGA position data to select the nearest base station. Without GGA, the connection will succeed but no corrections will be delivered.
{% endhint %}
{% endstep %}

{% step %}

#### Start the RTK survey

1. Save the survey style and return to the main screen.
2. Tap **Survey** and select the style you just configured.
3. MAGNET Field will connect to the internet, then to the RTKdata NTRIP caster.
4. Watch the solution status: **Autonomous** > **Float** > **Fixed**.
5. Once Fixed, you are ready to collect points, stake out, or run your survey workflow.
   {% endstep %}
   {% endstepper %}

## GCX3 tilt compensation

The GCX3 features IMU-based tilt compensation. Once an RTK Fix is achieved, tilt compensation initializes after a brief walk calibration. You can then measure with the pole tilted without leveling. The controller displays a tilt icon and compensated position in real time.

## Vertical reference (heights)

{% hint style="info" %}
Heights from RTKdata.com are **ellipsoidal**, not orthometric (mean sea level). Configure a geoid model in MAGNET Field under **Configure > Coordinate System > Vertical Adjustment** if your project requires orthometric heights.
{% endhint %}

## Troubleshooting

| Problem                                 | Cause                                          | Fix                                                                                                                          |
| --------------------------------------- | ---------------------------------------------- | ---------------------------------------------------------------------------------------------------------------------------- |
| No internet connection (receiver modem) | SIM card not active or APN misconfigured       | Verify the SIM card has data. Configure the correct APN for your carrier in MAGNET Field or the receiver's network settings. |
| No internet connection (controller)     | Controller has no data connection              | Ensure the controller is connected to cellular data or a phone hotspot.                                                      |
| Empty mountpoint list                   | Source table timeout or wrong host             | Do not browse — type `AUTO` manually in all caps. Verify the host address is correct.                                        |
| No corrections received                 | GGA sending disabled                           | Verify **Send GGA** is enabled in the NTRIP settings. RTKdata requires GGA to select the nearest base.                       |
| Stuck on Float                          | Poor sky conditions or far from base           | Move to open sky. Check RTKdata base coverage at [rtkdata.com](https://rtkdata.com).                                         |
| Credentials rejected                    | Using website login instead of RTK credentials | Use the username (starting with `rtk`) and password from your RTK dashboard, not your website account.                       |
| NTRIP v2.0 features not available       | MAGNET Field version too old                   | Update to MAGNET Field v7.0 or later for full NTRIP v2.0 support.                                                            |

## Tips and tricks

* **GCX3's built-in 4G modem** provides the most reliable connection — insert a SIM card and select Receiver Internet to avoid phone hotspot dependency.
* **The MAGNET Field workflow is identical to Topcon** — if your crew uses both Sokkia and Topcon receivers, the same survey styles and NTRIP settings apply.
* **Save the survey style** so your entire crew can load it on their controllers without re-entering settings each day.
* **Update to MAGNET Field v7.0+** for NTRIP v2.0 support, improved connection handling, and the latest constellation support.
* **Check correction age** on the MAGNET Field status bar. Values above 5 seconds indicate an unstable internet link.
* **Keep receiver firmware updated** via Sokkia's Receiver Utility to benefit from the latest RTK engine improvements.