> For the complete documentation index, see [llms.txt](https://docs.rtkdata.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.rtkdata.com/integration-hub/lidar-scanners-and-mobile-mapping/emesent-gx1.md).

# Emesent GX1 NTRIP Setup: RTK Corrections in Commander

Set up RTKdata on the Emesent GX1: nano-SIM, Scanner settings, NTRIP profile with host, port 2101 and AUTO, the 20-character username limit and Aura base CRS.

The **Emesent GX1** is a SLAM LiDAR scanner with a built-in 448-channel RTK receiver and an integrated 4G modem for a nano-SIM. RTKdata corrections reach it through an Emesent GX1 NTRIP profile over that SIM: you create the profile in the **Emesent Commander** app on an Android tablet, and the GX1 then fetches the corrections itself. The tablet does not relay corrections. This guide covers the GX1 in all its configurations (backpack, survey pole, supported handheld and vehicle mount). If you scan with a Hovermap ST or ST-X on Backpack RTK or Vehicle RTK, follow the [Emesent Hovermap RTK guide](/integration-hub/lidar-scanners-and-mobile-mapping/emesent-hovermap-backpack-vehicle-rtk.md) instead.

Select the tab for your region. Choose the server closest to your work area: all three servers share the same global base station network, see [NTRIP Server Settings](/get-started/network.md).

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

* **Host (domain):** `rtk.rtkdata.com` (field **Address**)
* **Host (IP fallback):** `13.56.117.10` (field **Address**, use only if the hostname is not accepted)
* **Port:** `2101` (field **Port**)
* **Username / Password:** From *RTK Credentials* in your [account dashboard](https://rtkdata.com/my-account/rtk-credentials/), not your website login (fields **Username** and **Password**)
* **Mountpoint (ALL CAPS):** `AUTO` (recommended), or `AUTO_ITRF2020`, `AUTO_ITRF2014`, `AUTO_WGS84` (field **Mount point**, chosen under **Select mount point**)
  {% endtab %}

{% tab title="Europe" %}

* **Host (domain):** `eu.rtkdata.com` (field **Address**)
* **Host (IP fallback):** `3.73.41.96` (field **Address**, use only if the hostname is not accepted)
* **Port:** `2101` (field **Port**)
* **Username / Password:** From *RTK Credentials* in your [account dashboard](https://rtkdata.com/my-account/rtk-credentials/), not your website login (fields **Username** and **Password**)
* **Mountpoint (ALL CAPS):** `AUTO` (recommended), or `AUTO_ITRF2020`, `AUTO_ITRF2014`, `AUTO_WGS84` (field **Mount point**, chosen under **Select mount point**)
  {% endtab %}

{% tab title="Australia" %}

* **Host (domain):** `aus.rtkdata.com` (field **Address**)
* **Host (IP fallback):** `54.206.56.130` (field **Address**, use only if the hostname is not accepted)
* **Port:** `2101` (field **Port**)
* **Username / Password:** From *RTK Credentials* in your [account dashboard](https://rtkdata.com/my-account/rtk-credentials/), not your website login (fields **Username** and **Password**)
* **Mountpoint (ALL CAPS):** `AUTO` (recommended), or `AUTO_ITRF2020`, `AUTO_ITRF2014`, `AUTO_WGS84` (field **Mount point**, chosen under **Select mount point**)
  {% endtab %}
  {% endtabs %}

| Field                      | Value                                                                                                                                                                                                                 |
| -------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| **Profile name**           | Any name, for example `RTKdata`                                                                                                                                                                                       |
| **Address**, North America | `rtk.rtkdata.com`, IP fallback `13.56.117.10`                                                                                                                                                                         |
| **Address**, Europe        | `eu.rtkdata.com`, IP fallback `3.73.41.96`                                                                                                                                                                            |
| **Address**, Australia     | `aus.rtkdata.com`, IP fallback `54.206.56.130`                                                                                                                                                                        |
| **Port**                   | `2101`                                                                                                                                                                                                                |
| **Mount point**            | `AUTO` in ALL CAPS (alternatives: `AUTO_ITRF2020`, `AUTO_ITRF2014`, `AUTO_WGS84`)                                                                                                                                     |
| **Username**               | Your NTRIP username from *RTK Credentials* in your [account dashboard](https://rtkdata.com/my-account/rtk-credentials/). It starts with `rtk` and is not your website login. Commander accepts at most 20 characters. |
| **Password**               | Your NTRIP password from *RTK Credentials*, case sensitive                                                                                                                                                            |

**Address** is a free text field, and Emesent does not document whether it expects a hostname or an IP address. Enter the hostname of your region first, typed without `http://` and without `:2101`. Switch to the IP fallback of the same region only if the hostname is not accepted, for example when **Select mount point** stays empty although the GX1 shows **4G** and **Internet not available** does not appear (see the section on an empty mount point list below).

## Which Emesent device do you have?

The Emesent GX1 has its own RTK receiver and SIM and takes RTKdata corrections through an NTRIP profile in Commander, while a Hovermap ST or ST-X gets RTK from an external GNSS rover on the Backpack RTK or Vehicle RTK kit.

| Topic                      | Emesent GX1                    | Hovermap ST / ST-X with Backpack RTK or Vehicle RTK                                                                 |
| -------------------------- | ------------------------------ | ------------------------------------------------------------------------------------------------------------------- |
| RTK receiver               | Built into the scanner         | External GNSS rover on the kit                                                                                      |
| Internet for corrections   | nano-SIM in the GX1            | Through the rover or a mobile device                                                                                |
| Where the NTRIP details go | **NTRIP profile** in Commander | NTRIP client of the rover                                                                                           |
| Guide                      | This page                      | [Emesent Hovermap RTK](/integration-hub/lidar-scanners-and-mobile-mapping/emesent-hovermap-backpack-vehicle-rtk.md) |

For other scanners, see the [LiDAR Scanners & Mobile Mapping](/integration-hub/lidar-scanners-and-mobile-mapping.md) overview.

## What does the GX1 need for RTK corrections?

The Emesent GX1 needs a nano-SIM with a data plan in its own 4G modem, Emesent Commander 2.3.0 with Cortex 4.2.0 firmware on the scanner, and RTKdata NTRIP credentials; Emesent Aura 2.2.2 with the RTK module then processes the RTK data.

* **Emesent GX1 on Cortex 4.2.0.** Emesent's Supported Devices page (updated 3 September 2026) lists Commander 2.3.0 and Cortex 4.2.0 for the GX1: "The GX1 needs Cortex 4.2.0." Check the version under Options Menu > **About** and update with **Upgrade Payload Firmware**. Move your scans off the scanner first, because Emesent warns that a failed upgrade can leave existing scans inaccessible.
* **Emesent Commander 2.3.0 on a supported Android device.** Minimum Android 10, Android 14 or newer recommended. The Android version alone does not decide support: Emesent recommends the Samsung Galaxy Tab S9 5G, DJI RC Plus and Freefly Pilot Pro, and does not support the Samsung Galaxy Tab Active Pro and Tab Active3. Commander is installed as an APK from `manage.emesent.com`.
* **WPA3 on the tablet.** The GX1 Wi-Fi access point works with WPA3-Personal only. Devices limited to WPA2-PSK cannot connect.
* **nano-SIM with a data plan.** You supply the SIM yourself. Make sure the site has cellular coverage. The carrier must allow outbound TCP on port 2101; some mobile carriers block this port, see [NTRIP Server Settings](/get-started/network.md).
* **RTKdata account** with active RTK credentials (username starts with `rtk`, at most 20 characters for Commander).
* **RTKdata coverage** at your site. Check the [Coverage Map](/get-started/coverage-map.md) before the job.
* **Emesent Aura 2.2.2** on Windows with the RTK module in your licence, for processing. Aura 2.2.2 also fixes merging RTK scans with scans captured without RTK.
* **Open sky** for the first correction test.

Current app version when this page was written: Emesent Commander 2.3.0 with Cortex 4.2.0 and Aura 2.2.2 (September 2026).

RTKdata streams RTCM 3.2 with MSM messages, see [Correction format](/integration-hub/ntrip-clients-and-field-software/ntrip-and-gga-essentials.md#correction-format). The **NEW NTRIP PROFILE** form has no format setting, and Emesent does not list which RTCM messages the GX1 receiver decodes.

{% hint style="warning" %}
The GX1 receives corrections only through the SIM in the scanner. Emesent documents no other internet path for NTRIP: the tablet on the GX1 Wi-Fi does not supply corrections, even when it has internet itself. According to Emesent, the mobile data interface is outbound only and restricted to RTK correction traffic.
{% endhint %}

{% 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 %}

## How do you create the Emesent GX1 NTRIP profile in Commander?

In Emesent Commander you create the RTKdata NTRIP profile under Options Menu > **Scanner settings** > **NTRIP profile** > **+ NEW**, once the tablet is connected to the GX1 Wi-Fi and the scanner SIM is online.

Emesent's knowledge base text uses slightly different words than the app (for example Mountpoint, Save and Connect, +New). The steps below use the labels shown on the Commander screens.

{% stepper %}
{% step %}

### Log in to Commander before you join the GX1 Wi-Fi

Commander needs internet for the login, and the GX1 access point has none. Log in while the tablet is still on office Wi-Fi or mobile data. A login session lasts 180 days; **Session ends** under **Logout** in the Options Menu shows the countdown. Without a login, Commander offers 14 days of **Temporary Access** as a fallback.
{% endstep %}

{% step %}

### Insert the nano-SIM

1. Make sure the GX1 is not running.
2. Remove the **Battery Bay Door** by squeezing the **Battery Door Actuators**.
3. Press the **SIM card tray** on the right side of the battery bay and pull it out.
4. Place the nano-SIM in the tray and push the tray back in until it clicks.

{% hint style="warning" %}
A microSD slot sits right next to the SIM card tray. Insert the SIM only into the **SIM card tray**.
{% endhint %}
{% endstep %}

{% step %}

### Power on and connect the tablet

1. Hold the **Power Button** for 2 to 3 seconds and wait about one minute for the GX1 to start.
2. On the tablet, join the Wi-Fi network `GX1_<serial>`. A new or reset GX1 uses the password `hovermap`.
3. On the first connection, Commander asks for a new Wi-Fi password of at least 15 characters. Write it down straight away: it takes effect after the next restart of the GX1 and is separate from your Commander account.
4. Open Commander and check that the GX1 serial number appears at the top right, next to the Wi-Fi icon.
   {% endstep %}

{% step %}

### Switch on the scanner SIM

1. Open the Options Menu (hamburger icon, top left), scroll down and tap **Scanner settings**. The **Scanner Settings** screen opens. If the entry is missing, the tablet is not connected to the GX1.
2. In the **RTK** section, switch on **Scanner SIM card**.
3. Only if your mobile carrier requires APN details (according to Emesent, most do not): tap **SCANNER SIM SETTINGS**, enter the **APN** on the **Scanner mobile data setup** screen, choose the **Authentication Type** (default **None**) and tap **SAVE**. Commander warns: "Incorrect APN credentials may cause internet connection to fail."
4. Wait until a mobile data icon such as **4G** appears in the status bar.

If **Scanner Settings** shows **Internet not available**, the GX1 has no data connection. Wait until it has finished starting, remove and reinsert the SIM, or move to a place with cellular coverage.
{% endstep %}

{% step %}

### Create the NTRIP profile

Do this outdoors with a clear view of the sky, so the first connection can deliver corrections.

1. Under **NTRIP profile**, tap **+ NEW**. The **NEW NTRIP PROFILE** screen opens.
2. Fill in the fields:
   * **Profile name:** any name, for example `RTKdata`
   * **Address:** the host for your region, `rtk.rtkdata.com` (North America), `eu.rtkdata.com` (Europe) or `aus.rtkdata.com` (Australia), without `http://` and without `:2101`
   * **Port:** `2101`
   * **Mount point:** tap **Select mount point** and choose `AUTO`
   * **Username:** your NTRIP username from *RTK Credentials* (starts with `rtk`)
   * **Password:** your NTRIP password. The eye icon shows what you typed.
3. Tap **CONNECT AND SAVE**.

Type the username and password instead of pasting them, with no spaces at the start or end. Both are case sensitive. One set of RTKdata credentials allows one connection at a time, so each device that is connected at the same time needs its own data stream, see [Account & Credentials](/get-started/account-and-credentials.md#using-one-subscription-with-several-devices).

You can also add a profile during the mapping mission workflow, in **GNSS Settings**.

{% hint style="warning" %}
Commander accepts at most 20 characters in **Username** (Emesent: "Currently limited to a maximum of 20 characters."). A shortened username fails at the caster. If your RTKdata username is longer than 20 characters, ask [RTKdata support](mailto:support@rtkdata.com) to change it. RTKdata usernames are generated automatically and are changed through support, see [Account & Credentials](/get-started/account-and-credentials.md#changing-your-ntrip-username).
{% endhint %}
{% endstep %}

{% step %}

### Select the profile and check the corrections

1. On **Scanner Settings**, tap **Select NTRIP Profile** and choose your RTKdata profile. The RTK display updates automatically.
2. Outdoors, watch the **RTK** section:
   * The status badge leaves **NO GNSS**.
   * **Satellites in use** rises.
   * **Baseline** shows a plausible distance to the base station.
   * **Last correction** keeps updating.

Emesent does not document which status text the GX1 shows for a fix or a float solution. Judge the connection by **Last correction** and **Baseline** rather than by a specific word. **Position** and **Precision** (σN, σE, σU) show the current solution.

{% hint style="warning" %}
The `AUTO` mountpoint needs the device's position (NMEA GGA) to select the nearest base station. Without it, the login succeeds but no corrections arrive, see [NTRIP & GGA Essentials](/integration-hub/ntrip-clients-and-field-software/ntrip-and-gga-essentials.md#what-happens-when-gga-is-not-sent). The same applies to `AUTO_ITRF2020`, `AUTO_ITRF2014` and `AUTO_WGS84`. The **NEW NTRIP PROFILE** form has no GGA option, and Emesent does not document whether or when the GX1 sends its position. Indoors there is no position to send, which looks like a credentials problem. Run the first correction test outdoors and give the GX1 1 to 2 minutes with satellites in view before you doubt the credentials. A **Last correction** time that keeps updating shows that corrections arrive.
{% endhint %}

{% hint style="info" %}
A factory reset (**Factory Reset Scanner** in Commander, or the reset button in the battery bay held for at least 10 seconds) deletes the NTRIP profiles and settings, the Wi-Fi password and the scan data on the GX1. Afterwards, create the RTKdata profile again and check the SIM and APN settings.
{% endhint %}
{% endstep %}
{% endstepper %}

## What if the mount point list stays empty?

If **Select mount point** shows no `AUTO` entry on the Emesent GX1, first check that the scanner is online, then replace the hostname in **Address** with the RTKdata IP fallback for your region (`13.56.117.10`, `3.73.41.96` or `54.206.56.130`).

1. Check the status bar for a mobile data icon such as **4G**. If there is none, check that **Scanner SIM card** is on, that the SIM sits in the **SIM card tray** and that the APN is right, if your carrier needs one.
2. Check that **Scanner Settings** does not show **Internet not available**. If it does, wait until the GX1 has finished starting, remove and reinsert the SIM, or move to a place with cellular coverage.
3. Check that **Address** contains only the hostname for your region (`rtk.rtkdata.com`, `eu.rtkdata.com` or `aus.rtkdata.com`), without `http://` and without `:2101`, and that **Port** is `2101`.
4. If the list still shows no `AUTO` entry although **4G** is shown and **Internet not available** does not appear, replace **Address** with the IP fallback for your region: `13.56.117.10` (North America), `3.73.41.96` (Europe) or `54.206.56.130` (Australia). Keep **Port** at `2101` and choose `AUTO` again.
5. If the IP fallback also shows no `AUTO` entry, the network of the SIM may block outbound TCP on port 2101, which some mobile carriers do. Test with a SIM from a different carrier.

To separate a carrier or credentials problem from the scanner, you can first test the SIM and your RTKdata credentials in a phone with an NTRIP client app such as [SW Maps](/integration-hub/ntrip-clients-and-field-software/sw-maps.md), with **Send NMEA GGA to Caster** switched on. Disconnect the phone before you connect the GX1, because one set of credentials allows one connection at a time.

Emesent does not document where the entries under **Select mount point** come from.

{% hint style="info" %}
The RTKdata sourcetable, the caster's public list of mountpoints, loads without a login (checked on 25 September 2026). It can show further entries besides `AUTO` and its three variants; choose `AUTO`. A visible mountpoint list proves neither that your credentials are correct nor that corrections are arriving. A **Last correction** time that keeps updating is the better sign.
{% endhint %}

### Other connection problems

| Problem                                                                       | Cause                                                                                                                               | Fix                                                                                                           |
| ----------------------------------------------------------------------------- | ----------------------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------- |
| **Scanner settings** is missing in the Options Menu                           | The tablet is not connected to the GX1                                                                                              | Join `GX1_<serial>` and check that the serial number appears in Commander.                                    |
| The tablet does not connect to the GX1 Wi-Fi                                  | The tablet supports only WPA2-PSK, or the Wi-Fi password changed at the last restart                                                | Use a device with WPA3. Enter the new password (at least 15 characters) you set on the first connection.      |
| Commander asks for a login in the field                                       | The GX1 Wi-Fi has no internet                                                                                                       | Log in before you join the GX1 Wi-Fi, or use **Temporary Access**.                                            |
| **Internet not available**                                                    | The GX1 has no data connection                                                                                                      | Wait until the GX1 has finished starting, reinsert the SIM, check cellular coverage.                          |
| The username does not fit                                                     | Commander limits **Username** to 20 characters                                                                                      | Ask RTKdata support to change the username.                                                                   |
| **Last correction** does not update outdoors                                  | Wrong username or password, another device on the same credentials, or no satellite position yet, so no position reaches the caster | Retype the credentials, disconnect every other device that uses them, and wait 1 to 2 minutes under open sky. |
| No RTK after a factory reset                                                  | The reset deleted the NTRIP profiles                                                                                                | Create the RTKdata profile again.                                                                             |
| **Select mount point** stays empty with the hostname and with the IP fallback | The mobile carrier may block outbound TCP on port 2101                                                                              | Test with a SIM from a different carrier, see [NTRIP Server Settings](/get-started/network.md).               |

If **Last correction** still does not update, email <support@rtkdata.com> with: the device (GX1), the Commander and Cortex versions, the server and whether you entered the hostname or the IP fallback, your RTKdata username (never the password), the time of the attempt and a screenshot of **Scanner Settings**. A connection that reaches the caster without a position appears in RTKdata session logs as a 0 GGA session, see [NTRIP & GGA Essentials](/integration-hub/ntrip-clients-and-field-software/ntrip-and-gga-essentials.md#what-happens-when-gga-is-not-sent).

For the general checks, see [Fix NTRIP Connection Issues](/support/common-connection-issues.md).

## How do you start a scan with RTK?

To scan with RTK on the Emesent GX1, start a mapping mission in Commander, switch on **Enable RTK during Scan** with your RTKdata profile in **GNSS Settings**, and begin the scan outdoors with an RTK fix.

1. Tap **New mission** and choose the **MAPPING MISSION** tile.
2. In **GNSS Settings**, switch on **Enable RTK during Scan** and select your RTKdata NTRIP profile. The switch only takes effect with a profile selected.
3. Optional: switch on **PPK Logging RINEX** as a fallback in case corrections drop. PPK needs separate base station data, see [Can the GX1 log PPK data while RTK is running?](#can-the-gx1-log-ppk-data-while-rtk-is-running) below.
4. Confirm a good GNSS position, wait for **Scanner standby, waiting for scan to start**, enter a scan name, tap **Continue** and then **Start Scan**. The pre-scan checks take up to about 60 seconds.
5. Start the scan outdoors with a fix, even if the job continues indoors.

The spelling of the two switches in the mission workflow comes from the Emesent knowledge base. On **Scanner Settings** the same switch reads **Enable RTK During Scan**.

Before the job, Emesent's mission planning checklist covers three points: cellular coverage on site for NTRIP corrections, enough data on the SIM, and a backup plan if corrections drop.

{% hint style="info" %}
The 15 mm RTK/PPK accuracy in the GX1 specification sheet was measured with a local base station less than 1 km away. With RTKdata network RTK, the distance to the reference station adds error: the GX1 receiver is specified at 0.6 cm + 0.5 ppm horizontal and 1 cm + 0.5 ppm vertical. For the best accuracy with RTKdata, work within 15 km of a base station, see [Accuracy Expectations](/get-started/accuracy-expectations.md). Check **Baseline** on **Scanner Settings** before you scan, and check the result against control points. The RTKdata `AUTO` mountpoint selects the nearest reference station from the position your device reports.
{% endhint %}

## Which base CRS do you set in Aura?

In Emesent Aura, set **Georeferencing mode** to **RTK (Built-in)** for the GX1 and set **Base coordinate reference system** to the datum your RTKdata mountpoint delivers: with `AUTO` that is the regional datum of the area you scan in, with `AUTO_WGS84` it is `EPSG:4326` WGS 84.

1. In the **Process** tab, click **+ Process Scan**. In **CONFIGURE NEW SCAN JOB**, choose the **SLAM / RTK** workflow (Emesent's Aura 2.2 PPK article calls it **SLAM / RTK / PPK**) and click **ADD DATASET**.
2. Switch on **Use RTK data**.
3. In the georeferencing settings under **PROCESSING SETTINGS**, set **Georeferencing mode** to **RTK (Built-in)**.
4. Set **Base coordinate reference system** (required) according to the table below.
5. Click **Save**, then **START**, and check the result in the **Visualize** tab.

The Aura labels come from Emesent's Aura articles; the published screenshots show an earlier Aura version, so the wording in Aura 2.2.2 can differ slightly.

{% hint style="info" %}
`AUTO` delivers corrections in your regional datum, for example NAD83(2011) in the USA, NAD83(CSRS)v7 in Canada, ETRS89 (realization ETRF2000) in Europe and GDA2020 in Australia. `AUTO_ITRF2020` and `AUTO_ITRF2014` deliver that frame at the current epoch, and `AUTO_WGS84` delivers WGS84(G2139) in the middle of the current year. The datum and epoch for every region are listed in [Coordinate Systems & Datums](/get-started/coordinate-systems-and-datums.md).
{% endhint %}

| Mountpoint   | Where you scan              | Base coordinate reference system |
| ------------ | --------------------------- | -------------------------------- |
| `AUTO`       | Europe                      | `EPSG:4258` (ETRS89)             |
| `AUTO`       | USA, except Hawaii and Guam | `EPSG:6318` (NAD83(2011))        |
| `AUTO`       | Canada                      | `EPSG:4617` (NAD83(CSRS))        |
| `AUTO`       | Australia                   | `EPSG:7844` (GDA2020)            |
| `AUTO`       | South America               | `EPSG:4674` (SIRGAS 2000)        |
| `AUTO_WGS84` | Anywhere                    | `EPSG:4326` (WGS 84)             |

Aura lists these entries as `EPSG:<code> - <name>`, for example `EPSG:4326 - WGS 84`, so look for the code in the list.

The base CRS has to match the frame the RTK data was recorded in. With `AUTO`, leaving the base CRS on `EPSG:4326` WGS 84 in a region with its own datum labels the data with the wrong datum. Stay on `AUTO` with its regional datum as base CRS unless your project needs a global frame. With `AUTO_ITRF2020` or `AUTO_ITRF2014`, set the matching ITRF frame. In Canada, `AUTO` delivers NAD83(CSRS)v7: choose the NAD83(CSRS) entry (`EPSG:4617`), or a v7 entry if Aura lists one. Hawaii (NAD83(PA11)), Guam (NAD83(MA11)) and all other regions are listed in [Coordinate Systems & Datums](/get-started/coordinate-systems-and-datums.md); where no regional datum is listed, `AUTO` falls back to WGS84(G2139) at the mid-year epoch. Ask <support@rtkdata.com> if you are unsure which EPSG code matches. If a code is not in the Aura list, use **Custom base coordinate reference system**, which takes a PROJ string.

For the wider workflow across scanners, see [Georeferencing SLAM Point Clouds with RTK](/integration-hub/lidar-scanners-and-mobile-mapping/georeferencing-slam-point-clouds-with-rtk.md).

{% hint style="warning" %}
Use **Reprojection** (**Horizontal** for the project system, **Vertical** or **Import geoid file** for heights) only for single scans. If you plan to merge scans, leave it off and reproject in the merge workflow. Aura warns: "If you intend to merge this data please note reprojected point clouds are not suitable for alignment in merge. Consider reprojecting all point clouds as part of the merge workflow instead."
{% endhint %}

{% hint style="info" %}
RTKdata corrections deliver **ellipsoidal heights**. **Vertical** under **Reprojection** converts them to orthometric heights with a geoid model, and **Import geoid file** loads your national geoid as a GTX or TIF file (available since Aura 2.1). Check the heights at a known benchmark. See [Understanding Heights](/get-started/understanding-heights.md).
{% endhint %}

## Frequently asked questions

### Which NTRIP settings does the Emesent GX1 need for RTKdata?

For RTKdata on the Emesent GX1, enter `rtk.rtkdata.com` (North America), `eu.rtkdata.com` (Europe) or `aus.rtkdata.com` (Australia) in **Address**, `2101` in **Port**, choose `AUTO` under **Select mount point**, and enter the username and password from *RTK Credentials*. If the hostname is not accepted, use the IP fallback `13.56.117.10`, `3.73.41.96` or `54.206.56.130` for the same region. Commander accepts at most 20 characters in **Username**; if your RTKdata username is longer, ask RTKdata support to change it. Run the first connection test outdoors, because `AUTO` needs the device's position to select a base station.

### Does the Emesent GX1 need its own SIM card for RTK corrections?

Yes. The Emesent GX1 fetches RTKdata NTRIP corrections only through a nano-SIM with a data plan in its built-in 4G modem, and you supply the SIM yourself. The Android tablet running Commander connects to the GX1 Wi-Fi and does not pass corrections to the scanner.

### Why can't I enter my full NTRIP username in Emesent Commander?

Emesent Commander limits the **Username** field of an NTRIP profile to 20 characters. If your RTKdata username is longer, contact RTKdata support to have it changed, because a shortened username fails at the caster.

### Where is the NTRIP profile in Emesent Commander?

The RTKdata NTRIP profile goes under Options Menu (hamburger icon, top left) > **Scanner settings** > **RTK** > **NTRIP profile** > **+ NEW**, where you enter your regional RTKdata host and port `2101` and choose the `AUTO` mount point. The **Scanner settings** entry only appears while the tablet is connected to the GX1 Wi-Fi. You can also add a profile in **GNSS Settings** during the mapping mission workflow.

### Which base coordinate reference system should I choose in Aura for GX1 RTK data?

Choose the datum your RTKdata mountpoint delivers. With `AUTO` that is the regional datum, for example `EPSG:4258` ETRS89 in Europe, `EPSG:6318` NAD83(2011) in the USA, `EPSG:4617` NAD83(CSRS) in Canada, `EPSG:7844` GDA2020 in Australia and `EPSG:4674` SIRGAS 2000 in South America. With `AUTO_WGS84`, choose `EPSG:4326` WGS 84. Set **Georeferencing mode** to **RTK (Built-in)**.

### How accurate is the Emesent GX1 with RTKdata network RTK?

The 15 mm RTK/PPK accuracy in the Emesent GX1 specification sheet was measured with a local base station less than 1 km away. With RTKdata network RTK, the distance to the reference station adds error: the GX1 receiver is specified at 0.6 cm + 0.5 ppm horizontal and 1 cm + 0.5 ppm vertical. For the best accuracy with RTKdata, work within 15 km of a base station, see [Accuracy Expectations](/get-started/accuracy-expectations.md). Check **Baseline** on **Scanner Settings** before you scan, and check the result against control points. The RTKdata `AUTO` mountpoint selects the nearest reference station from the position your device reports.

### Can the GX1 log PPK data while RTK is running?

Yes. Emesent confirms that RTK and PPK can run at the same time, so RTKdata corrections can stay on while PPK logging runs as a fallback: switch on **PPK Logging RINEX** in addition to **Enable RTK during Scan** in the mission's **GNSS Settings**. PPK processing needs Aura 2.2 or newer and base station data at 1 Hz or faster with a navigation file. Emesent does not support correction networks without a navigation file for PPK. The RTKdata NTRIP stream is not a PPK base file. Raw observation data is managed by RTKdata; contact <support@rtkdata.com> if you need base station observation files for PPK.

## Quick reference

1. Log in to Commander 2.3.0, insert a nano-SIM with data, and join the `GX1_<serial>` Wi-Fi (GX1 on Cortex 4.2.0).
2. Options Menu > **Scanner settings** > **RTK**: switch on **Scanner SIM card** and wait for **4G**.
3. **NTRIP profile** > **+ NEW**: **Address** `rtk.rtkdata.com` (North America), `eu.rtkdata.com` (Europe) or `aus.rtkdata.com` (Australia), IP fallback `13.56.117.10`, `3.73.41.96` or `54.206.56.130`; **Port** `2101`; **Mount point** `AUTO`; **Username** and **Password** from *RTK Credentials* (username at most 20 characters), then **CONNECT AND SAVE**.
4. Outdoors: **Select NTRIP Profile**, check that **Last correction** updates, then switch on **Enable RTK during Scan** in the mission's **GNSS Settings**.
5. Aura 2.2.2: **Georeferencing mode** **RTK (Built-in)**, **Base coordinate reference system** set to the datum of the mountpoint (for `AUTO` in Europe: `EPSG:4258`).

## Related Guides

* [LiDAR Scanners & Mobile Mapping](/integration-hub/lidar-scanners-and-mobile-mapping.md): overview of all scanner guides in this category
* [Emesent Hovermap RTK](/integration-hub/lidar-scanners-and-mobile-mapping/emesent-hovermap-backpack-vehicle-rtk.md): Hovermap ST and ST-X on Backpack RTK or Vehicle RTK, where an external rover takes the NTRIP details
* [NTRIP Server Settings](/get-started/network.md): regional hostnames, IP fallbacks, port 2101 and the mountpoints
* [NTRIP & GGA Essentials](/integration-hub/ntrip-clients-and-field-software/ntrip-and-gga-essentials.md): why `AUTO` needs the device's position and what happens when no GGA is sent
* [Coordinate Systems & Datums](/get-started/coordinate-systems-and-datums.md): the datum and epoch `AUTO` delivers in each region
* [Understanding Heights](/get-started/understanding-heights.md): ellipsoidal and orthometric heights and when a geoid model is needed
* [Account & Credentials](/get-started/account-and-credentials.md): where the NTRIP credentials are, one connection per data stream, and username changes
* [Fix NTRIP Connection Issues](/support/common-connection-issues.md): what to check when the login works but no corrections arrive
* [Coverage Map](/get-started/coverage-map.md): check the reference station coverage for your site before the job
* [Accuracy Expectations](/get-started/accuracy-expectations.md): how the distance to the base station affects network RTK accuracy
* [SW Maps](/integration-hub/ntrip-clients-and-field-software/sw-maps.md): a phone NTRIP client for testing the SIM and your credentials without the scanner
* [Georeferencing SLAM Point Clouds with RTK](/integration-hub/lidar-scanners-and-mobile-mapping/georeferencing-slam-point-clouds-with-rtk.md): how the base CRS, reprojection and heights fit together for SLAM scans


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