Quick Answer
If you need centimetre-level positioning on a UK worksite and don't want to waste money on the wrong kit, here are the three RTK GNSS receivers we actually stock, sell and support: the SparkFun RTK Express for budget-conscious makers, the Emlid Reach RS4 Pro as the all-round sweet spot for surveyors, and the HolyBro H-RTK F9P Rover Lite when you need tight UAV integration.
Budget Pick: SparkFun RTK Express
The SparkFun RTK Express is the entry point we keep recommending to people who want to experiment with centimetre-accurate positioning without committing serious money. Built around the u-blox ZED-F9P receiver, it tracks GPS, GLONASS, Galileo and BeiDou on multiple bands simultaneously — the same core silicon used in receivers costing three times as much.
Out of the box it works as a rover with NTRIP corrections over Wi-Fi or Bluetooth. It also runs as a base station, broadcasting its own RTCM corrections to a second unit. The built-in display shows fix status, satellite count and correction source, which saves you firing up a laptop just to check if you have a fix.
Who it suits: Makers, hobbyists, agricultural tinkerers and anyone adding precise location to an existing project on a budget. If you're doing occasional topographic work and already have a pole and data collector, the Express gets you RTK accuracy for somewhere in the region of £350-450.
Key specs: Multi-band (L1/L2), concurrent reception of four constellations, RTK fix in under 10 seconds with good corrections, built-in 4 Hz display, NTRIP client and server, USB-C and Bluetooth connectivity.
Sweet Spot: Emlid Reach RS4 Pro
The Emlid Reach RS4 Pro is what most UK surveyors should probably buy. It's the unit we see going out the door most often for professional surveying work, and for good reason — it hits the balance between capability, build quality and price that makes purchasing managers and sole traders equally happy.
The RS4 Pro receives signals across L1, L2, L5 and L6 bands from GPS, GLONASS, Galileo, BeiDou, QZSS and NavIC. That's more satellites and more bands than most surveyors will ever need, but it translates directly into faster fix times and more reliable positioning under tree canopy and near buildings — exactly the conditions that trip up cheaper single-band receivers.
Emlid's ReachView software (iOS, Android and desktop) handles base-rover setup, NTRIP corrections, coordinate systems and point collection. It supports OSGB36 and OSTN15 natively, which matters if you're working to UK national grid coordinates rather than WGS84. The IP67-rated housing shrugs off British weather, and the dual cameras on the RS4 Pro let you photograph survey points directly from the receiver — a small feature that saves a surprising amount of time on as-built surveys.
Who it suits: Professional surveyors, engineering consultancies and utility contractors who need reliable centimetre accuracy day in, day out. Budget sits in the £2,500-3,000 range depending on configuration.
Key specs: All-band multi-constellation, 868 MHz LoRa radio built in for base-rover link, IMU tilt compensation, dual cameras, IP67, 22 hours battery, ReachView 4 software with OSGB36/OSTN15 support.
Not sure which Emlid receiver fits? See our RS4 vs RS3 vs RS2 comparison for the full breakdown. We also stock the Emlid Reach RS2 if you need a solid multi-band receiver at a lower price point.
Premium / Drone Integration: HolyBro H-RTK F9P Rover Lite
The HolyBro H-RTK F9P Rover Lite occupies a different niche. It's not a handheld survey receiver — it's a lightweight module designed to mount on drones and rovers running ArduPilot or PX4. If your surveying workflow involves photogrammetry flights or corridor mapping from a UAV, this is the RTK unit that lives on the aircraft.
At around 30 grams, it adds negligible payload. It outputs RTCM corrections to the flight controller, which tags each photo with centimetre-accurate EXIF position data. That eliminates the need for ground control points in many mapping scenarios — a huge time saving on larger sites. Pair it with the matching HolyBro H-RTK F9P Base for a complete base-rover RTK link, or feed it NTRIP corrections from any OS Net or SmartNet base station.
Who it suits: Drone surveyors, photogrammetry operators and anyone running ArduPilot/PX4 who needs PPK or RTK-tagged imagery. Also works well on ground rovers for automated survey grids.
Key specs: u-blox ZED-F9P, multi-band L1/L2, four constellations, 30 g weight, UART and USB output, ArduPilot and PX4 compatible, CRC24Q RTCM input support.
For a deeper look at correction methods for drone mapping, see our RTK vs PPK drone mapping comparison.
Which One Should You Buy?
| SparkFun RTK Express | Emlid Reach RS4 Pro | HolyBro H-RTK F9P | |
|---|---|---|---|
| Best for | Hobbyists and makers | Professional surveyors | Drone/UAV mapping |
| Bands | L1/L2 | L1/L2/L5/L6 | L1/L2 |
| Use case | Bench projects, light fieldwork | Full survey workflow | Onboard drone positioning |
| Form factor | Enclosed, display | Rugged handheld, pole-mount | Lightweight bare module |
| UK price range | £350-450 | £2,500-3,000 | £150-250 |
| Correction source | NTRIP / base-rover | NTRIP / LoRa / cell | NTRIP / HolyBro base |
If you're a land surveyor working in the UK, the RS4 Pro is the one to beat. If you're flying mapping missions, pair the HolyBro F9P with your aircraft and an NTRIP subscription. And if you're just getting started with RTK and want to understand the technology before spending serious money, the SparkFun Express is the safest first step.