Integration of Reach RS4 with Mergin Maps for iOS

This tutorial provides step-by-step instructions on how to integrate your Reach RS4 with Mergin Maps for iOS.

Overview

Mergin Maps is a mobile app for iOS that lets you collect, update, and share geospatial data in the field, with synchronization between field projects and QGIS for team collaboration.

To integrate your Reach RS4 / RS4 Pro with Mergin Maps, you will need the following:

• Reach RS4 / RS4 Pro
• A device on iOS
• Mergin Maps mobile app installed on your iOS device
• Mergin Maps account

You can connect Reach RS4 / RS4 Pro to Mergin Maps in two ways:

• Using the TCP method: Reach sends NMEA data directly to Mergin Maps over Wi-Fi. This method requires setting up NMEA output in Emlid Flow, but lets you see the RTK solution status and accuracy reported directly by Reach in Mergin Maps.
• Using the Internal GPS method: Reach connects to your iOS device via Bluetooth Classic, and Mergin Maps receives its position through iOS location services. This method doesn't require configuring an NMEA stream, but you'll need to use Emlid Flow to check the RTK solution status and accuracy before collecting data.

Choose the connection method based on how you want to connect Reach and monitor the RTK solution.

Workflow

To integrate your Reach RS4 / RS4 Pro with Mergin Maps follow the steps below.

Preconfigure Emlid Flow

Access Reach using Emlid Flow

In Emlid Flow, connect to Reach using the method that matches your Mergin Maps setup:

• If you choose to connect your Reach to Mergin Maps over Bluetooth (Internal GPS), you can access Reach in Emlid Flow either via BLE or Wi-Fi. BLE is the recommended option, especially when receiving NTRIP corrections through your mobile device.
• If you choose to connect your Reach to Mergin Maps over Wi-Fi (TCP), connect to Reach via Wi-Fi. Make sure your iOS device and Reach are connected to the same Wi-Fi network.

Follow the instructions below for your chosen connection method:

Bluetooth connection

1. Enable Bluetooth on your smartphone or tablet.

2. Open Emlid Flow. When prompted, tap Configure access and allow location permissions. This is required for full receiver functionality.

After granting permissions, your receiver will appear in the list. The app will connect to it automatically.

Hotspot connection

1. Go to Wi-Fi settings on your device.

2. Connect to Reach hotspot. It appears as reach:XX:XX.

3. Enter the network password. The default password is emlidreach. If you changed it previously, enter your custom password instead.

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   To restore the default Wi-Fi password, emlidreach, you need to reflash the receiver. Note that reflashing erases all logs stored on the receiver and restores all settings to their default values.

4. Open Emlid Flow and connect to your Reach.

Configure corrections in Emlid Flow

Check the following guides to configure receiving corrections on your Reach RS4 / RS4 Pro rover:

• How to set up RTK over Emlid Corrections
• How to set up RTK over NTRIP service
• How to work with third-party base over UHF radio
• How to set up RTK over LoRa radio

Enable tilt compensation

Reach RS4 / RS4 Pro supports IMU-based tilt compensation, allowing you to collect and stake out points even when the survey pole is tilted. The software calculates the tilt angle and distance to determine the pole tip position on the ground. To enable tilt compensation, follow the How to enable tilt compensation guide.

Configure communication between Mergin Maps and Reach RS4 / RS4 Pro

Configure communication between Mergin Maps and Reach RS4 / RS4 Pro using your chosen integration method.

Using Internal GPS

On iOS, you can use Reach RS4 as the location source for Mergin Maps through the Internal GPS option. This setup requires no additional TCP or NMEA stream configuration. Mergin Maps receives position data through iOS Location Services rather than directly from Reach.

When using the Internal GPS method, Reach position data passes through iOS Location Services before reaching Mergin Maps. iOS may modify the reported accuracy and Mergin Maps does not show the RTK solution status. Therefore, the accuracy displayed in Mergin Maps may not reflect the accuracy of the RTK solution. Use Emlid Flow to check the receiver’s solution status and accuracy.

To set up communication between Mergin Maps and your receiver using the internal GPS, follow the steps below:

Configure Bluetooth connection

Enable Bluetooth discoverability, so your device can be found by other devices. To do so, follow the steps below:

1. Go to Settings in Emlid Flow and tap Bluetooth.

2. Tap Discoverability and turn on the Discoverability option. Tap Save to apply changes.

   

Pair Reach RS4 / RS4 Po and iOS device

To use Reach RS4 / RS4 Pro with Mergin Maps, first you need to pair the receiver with your iOS device:

1. Navigate to the Bluetooth configuration screen on your iOS device and enable Bluetooth.

   

2. Wait for your Reach RS4 / RS4 Pro to be listed as an available device.

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   Keep Reach within a few meters from the device.

   

3. Tap the name of your Reach in the list of available devices on the iOS device. You should see the note "Connected".

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   If your device requires a PIN code, you can check on the Bluetooth tab in Emlid Flow.

   

Configure communication between Mergin Maps and Reach RS4 / RS4 Pro

1. Open the Mergin Maps app and create an account if you don’t have it yet to access the app.

   

2. Open or create a new project.

3. If prompted, allow precise location.

   

4. On the opened screen in the lower right corner, tap More and Settings.

   

5. In Settings, tap Select GPS receiver.

   

6. Choose Internal.

   

7. Go back to Settings and set the antenna height. For Reach RS4 / RS4 Pro, the antenna height is the distance from the mark on the ground to the center point on the Reach’s bottom, antenna reference point (ARP), plus the height of the receiver to the antenna phase center (APC), antenna height offset. The antenna height offset equals to 95 mm.

   

8. Go to the GPS tab and check the RTK status and accuracy on the map. To check the detailed GPS info, go to Emlid Flow.

   

Now you are ready to start collecting data!

Using TCP

With TCP, Mergin Maps connects directly to Reach and receives position data through an NMEA stream. The stream also provides the RTK solution status and receiver-reported accuracy, so you can check this information in Mergin Maps while surveying.

To set up the TCP connection, follow the steps below:

Set up NMEA stream in Emlid Flow

To send position data to external applications, configure position streaming in NMEA format as follows:

1. In Emlid Flow, go to Settings.

2. Tap Position streaming 1 and select TCP server.

   

3. To configure position streaming, tap the Edit button in the TCP server cell.

   

4. Tap Format and choose NMEA.

5. If you want to customize the NMEA output, tap NMEA settings and apply the necessary changes.

   

6. To use the tilt-compensated position in Mergin Maps, enable sending compensated NMEA messages in Emlid Flow.

   
   

7. Set the antenna height. You only need to enter the pole height. Emlid Flow automatically applies the antenna phase center offset and adjusts the measurements accordingly.

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   When sending compensated NMEA messages, set the antenna height only in Emlid Flow. Setting it in third-party apps as well may cause discrepancies.

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   If you use a quick release, turn on the toggle to include its height in the antenna height calculation.

   

Now you can start receiving the corrected position in a third-party GIS or data collection application.

Configure communication between Mergin Maps and Reach RS4 / RS4 Pro

1. Open the Mergin Maps app and create an account if you don’t have it yet to access the app.

   

2. Open or create a new project.

3. If prompted, allow precise location.

   

4. On the opened screen in the lower right corner, tap More and Settings.

   

5. In Settings, tap Select GPS receiver.

   

6. Tap Connect new receiver.

   

7. Add the TCP credentials of your receiver, then tap Confirm.

   You need to add the following credentials:

   • IP Address
   • Port
   • Receiver nickname (optional)
   

8. When prompted, allow the app to find devices on local networks.

9. This step is only required when you don’t stream compensated NMEA position. Go back to Settings and set the antenna height. Antenna offset is not added automatically in Mergin Maps. The value you enter should be the sum of the pole height and 95 mm, plus the quick release (50 mm) if you use it.

10. Go to the GPS tab and check the RTK status and accuracy on the map. To check the detailed GPS info, tap the tab one more time.

    
    

You have successfully set up your Reach RS4 / RS4 Pro with Mergin Maps. You can now use Reach for surveying in Mergin Maps.