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How to Set Up Antenna Height for RTK

This guide explains how to set up the antenna height on your base and rover to ensure accurate elevations in RTK.

Overview​

Reach receivers calculate positions at the antenna phase center (APC). The APC is the effective point where GNSS signals are received. However, for surveying tasks, you usually need the coordinates of the point on the ground. To get accurate ground-level coordinates, you need to enter the antenna height in Emlid Flow.

For GNSS receivers, antenna height is the distance from the mark on the ground up to the antenna phase center (APC). This height consists of two elements:

  • the distance between the mark on the ground and the center point on the bottom of the Reach, the antenna reference point (ARP),

  • the antenna offset between the ARP and APC.

In Emlid Flow, you only need to enter the height to the ARP, which is the height to the bottom of the receiver. The app automatically adds the antenna offset, which depends on your Reach model. Also, when you set the antenna height in one app section, it's updated everywhere else. This keeps the values consistent across the workflow.

caution

To automatically sync antenna height across sections, ensure your receiver is running firmware version 32 or later. In earlier versions, you’ll need to update the height manually in each section.

Difference between base and rover antenna height setup​

The base sends its APC position to the rover. When you enter known base coordinates using the Manual entry method, those coordinates usually refer to the point on the ground. So, Emlid Flow adds the measured height to the antenna offset to get the APC position, and sends this data to the rover.

If you use the Average coordinates entry method, you have the APC position right away.

The rover’s coordinates in RTK are determined at the antenna phase center. To get the point coordinates on the ground, enter the pole height in the Survey tab—Emlid Flow will automatically adjust the measurements.

note

When using an NTRIP service, the antenna height of the selected CORS station is already included in the correction stream.

Workflow​

Base​

To set up antenna height for your Reach base, follow the steps below:

  1. Open the Emlid Flow app and connect to your receiver.

  2. Open Base settings.

  3. Tap Configure and add the measured height of your tripod. Remember, the antenna offset will be added automatically.

  4. Tap Save.

Now that your antenna height is set correctly, you can proceed with accurate data collection.

Rover​

To set up antenna height for your Reach rover, follow the steps below:

note

Enter antenna height in the same units as the project. To learn more, read our coordinate system setup guides.

  1. Open the Emlid Flow app and connect to your receiver.

  2. Go to the Survey tab and tap +.

  3. Tap the Pole icon.

  4. Here, you can set the height of your survey pole. Keep in mind that the antenna offset will be added automatically. You can see the final result right above the picture of the receiver.

  5. Tap Save.

Now you can proceed with data collection.

tip

The exported CSV file includes the rover's antenna height to the APC for each collected point, making it easy to review and verify your data.

Further reading​