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Q: How to Set Up Emlid Reach as Base and Rover for RTK Surveying

Updated 3 min read

How to Set Up Emlid Reach as Base and Rover for RTK Surveying

Real-Time Kinematic (RTK) surveying delivers centimetre-level accuracy by using a fixed base station to send correction data to a mobile rover. Emlid Reach receivers make this process straightforward, whether you are using the compact Reach RX, the rugged Reach RS4, or the feature-packed RS4 Pro. This guide walks through setting up a base and rover pair for accurate field surveying.

Understanding the Base and Rover Concept

An RTK system needs two receivers working together. The base stays in a fixed position with known coordinates, tracking satellites and calculating atmospheric errors. It broadcasts correction data to the rover, which applies these corrections to achieve centimetre-accurate positions. The key advantage over standard GPS is that both units experience similar atmospheric conditions, allowing the rover to cancel out most timing errors.

The distance between base and rover, called the baseline, affects accuracy. For best results, keep the baseline under 10 kilometres. Beyond this, atmospheric differences start to degrade precision. In practice, most survey work keeps the base within 2 to 5 kilometres of the survey area.

Choosing Your Base Station Location

Proper base placement is critical for reliable RTK performance. The base needs a clear view of the sky to track as many satellites as possible. Avoid positions near tall buildings, dense tree cover, or metal structures that can block signals or cause multipath interference.

There are three common methods to establish base coordinates:

  • Average single: The simplest method. The base averages its position over several minutes. Accuracy is typically 1 to 2 metres, suitable only for relative surveys.
  • Average FIX: More accurate. The base receives NTRIP corrections whilst averaging, achieving centimetre accuracy. Ideal when a CORS network is available.
  • Manual entry: Most precise. You enter known coordinates from a previous survey or control point. This anchors all subsequent measurements to an established coordinate system.

Use a tripod or pole to mount the base at a stable height. The RTK survey tripod with its built-in spirit level makes this process quick and reliable.

Configuring the Base Station

Open the Emlid Flow app on your phone or tablet and connect to your base receiver via Bluetooth or Wi-Fi. Navigate to the Base mode settings and select your coordinate entry method. If using manual entry, input the known latitude, longitude, and height in your chosen coordinate system.

Under GNSS settings, select all available satellite constellations: GPS, GLONASS, Galileo, BeiDou, and QZSS. More satellites mean faster fixes and better reliability in challenging environments. Set the update rate to 5 Hz for smooth real-time corrections.

For data link configuration, choose between LoRa radio, UHF radio, or NTRIP. LoRa is simplest for short-range work (up to 8 kilometres), whilst UHF provides longer range (up to 15 kilometres) in open terrain. For drone mapping applications, the Reach UAV Mapping Kit pairs a ground base with an airborne module.

Setting Up the Rover

With the base transmitting, connect to your rover unit in Emlid Flow. Under RTK settings, select the correction input method that matches your base: LoRa, UHF, or NTRIP caster. Match the frequency, channel, and ID settings exactly.

Configure the rover GNSS settings identically to the base, selecting the same satellite constellations and update rate. The Status screen should now show incoming corrections and transition from a float solution to a fixed solution. A FIX indicates centimetre accuracy, typically achieved within 5 seconds of receiving corrections.

If the rover remains in float mode for more than a minute, check your radio link, verify matching settings, and ensure the base has a clear sky view. Large baseline distances or atmospheric disturbances can also delay or prevent fixes.

Tips for Reliable RTK Performance

  • Always wait for a FIX before recording points. Float solutions are accurate to only 20 to 50 centimetres.
  • Keep both base and rover powered throughout the survey. Battery life on Reach units typically exceeds 16 hours, but carry spares for long sessions.
  • Use tilt compensation features on newer RS4 models to capture points at awkward angles without perfectly levelling the pole.
  • Log RINEX data on the base as backup. If RTK fails, you can post-process the data using PPK methods.
  • Check your coordinate system in Emlid Flow before starting. Exported points must match your project's datum and projection.

With practice, setting up an Emlid Reach base and rover pair becomes a 10-minute task. The combination of straightforward app-based configuration and robust hardware makes centimetre-accurate surveying accessible for construction, agriculture, and mapping applications.