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How to work with third-party rover over UHF radio

This guide explains how to configure your Reach RS4 / RS4 Pro to work with a third-party rover over UHF radio.

Overview​

You can configure your Reach RS4 or Reach RS4 Pro as a base to work with a third-party rover over UHF radio.

Reach RS4 and Reach RS4 Pro have a built-in UHF radio that operates in the 410–470 MHz band, provides up to 2 W output power, and works using the Trimtalk 450S* protocol, with regional limits applied according to local regulations. In most regions, the RS4 series ships with region-specific channel plans and power limits preconfigured in Emlid Flow to support compliant operation. Depending on your jurisdiction, UHF operation may still require a license.

To set up UHF radio communication, use the supplied UHF antenna.

*Trademark of Trimble Inc.

Set up Reach RS4 / RS4 Pro base​

To set up your base, follow the steps below:

  1. Open the Emlid Flow app and connect to Reach RS4 / RS4 Pro.

  2. Go to Settings and tap GNSS settings.

  3. Keep the default constellation selection and update rate, as shown in the screenshot below.

  4. Go back to the Receivers screen and tap Base settings.

  5. Tap RTCM3 messages. Select the messages and set the update rates as on the screenshot below:

  6. Go back to the Receivers screen and tap Base output 1.

  7. Select UHF radio and tap the Edit button to set up the output.


  1. note

    This step applies to the US only. In the United States, UHF transmission requires a valid FCC license issued by the Federal Communications Commission (FCC), the US government agency responsible for regulating radio communications. For this reason, the UHF output interface remains blocked until a valid license is submitted to our Support team for verification. For more information on obtaining a license, consult the FCC’s official licensing process.

    To request activation from our Support team, do as follows:

    1.  Select UHF radio.



    2.  Tap Submit license. This will open the form, where you can submit your FCC license, the receiver’s serial number, and your email address, required for the UHF output activation.



    3.  Once your submission is verified, usually within one working day, you will receive an activation code at the email address you provided in the form. The code is issued specifically for the receiver identified by the submitted serial number. Enter this code in Emlid Flow, and tap Apply code.

    After you enter the activation code, the UHF channel will operate only on the frequencies and output power allowed by your license. The UHF screen will display your license details, call sign, and expiration date. When your license expires, the system will automatically block the UHF channel, and you will have to submit a new license to restore access.

    If you take the receiver to another country, you need to provide a local license if the country requires one. If no license is needed, you can unlock the UHF channel for use without additional documentation.

    caution

    To remove the license, reflash the receiver. Resetting settings or updating the firmware will not remove it, because the license is stored on the receiver, not in the app. Consequently, if you connect a receiver without a license to Emlid Flow, the app will prompt you to enter one.

  2. Configure the output according to your requirements, then tap Save.

Set up your third-party rover​

Configure RTK settings and UHF radio communication on your third-party rover. Make sure that you use the same frequency and bandwidth as for the base. Setup details depend on the rover model you are using.

tip

To properly set up your third-party base, follow the manufacturer's instructions.

Place units​

When you configured settings on both base and rover, you are ready to go outside to place the base and complete the setup process. For the field works, you will need a tripod and a survey pole. To place the units, follow the steps below:

note

Before placing the base, make sure that you are in an open area with a clear sky view. This will ensure good signal reception and a fair number of available satellites.

  1. Mount your base on the tripod and accurately level the tripod.

  2. Put the rover on the pole.

  3. Attach UHF antennas to both units.

  4. Turn on the receivers.

  5. Complete the base setup by configuring base coordinates entry method.

    note

    Learn more about base coordinates entry method and specifying base position in the Choosing base setup method guide.

View results​

When you completed your RTK setup over UHF radio, check out the current solution status on your third-party rover:

  • SINGLE means that the rover has found a solution relying on its own receiver and base corrections are not applied. Precision in standalone mode is usually at the several-meter level.

  • FLOAT means that the rover receives corrections from the base but cannot resolve all ambiguities, and in this case, the precision is usually at the submeter-level.

  • FIX means that the rover using corrections from the base resolved the ambiguities in its positional calculation and achieved the solution with the centimeter-level precision.

After a short period of time, the rover gets a fixed solution. In good environments, it will take a few seconds to get a fixed solution. In tough conditions, it may take a little longer. Once rover gets FIX, you are all set for surveying.

Further reading​