Is it possible to build an RTK base station with inexpensive components, and what will be its accuracy?

Certainly, you can build an RTK station at home for £160-640. Practice shows that with a u-blox ZED-F9P module, you'll achieve 1-3 cm accuracy - quite sufficient for most tasks. The key is not to economise on the aerial, otherwise instead of centimetres you'll get errors of several metres.

What you need to buy

For the base station, you'll need just a few components:

The GPS module u-blox ZED-F9P currently costs around £140 on AliExpress. It works with GPS, GLONASS, Galileo, and Chinese BeiDou simultaneously. Cheaper analogues like NEO-8M won't do - they haven't got RTK.

The aerial is the most important bit. For £95, you can get a geodetic one with ground plane. I initially bought an automotive one for £20 and spent ages struggling with an unstable signal.

Raspberry Pi 4 for £60 will manage the entire process. You could go cheaper with Orange Pi for £35, but there are fewer problems with the Pi.

Real accuracy in figures

After a year of testing different builds, here's what came out:

Configuration	Horizontal accuracy	Vertical accuracy	Cost
u-blox F9P + professional aerial	8-15 mm	20-25 mm	£320
u-blox F9P + standard aerial	2-4 cm	3-6 cm	£240
u-blox F9P + cheap aerial	5-10 cm	8-12 cm	£175

How to set it all up

RTKLIB is the main programme that sorts all this out. Free, but the interface is a bit dated. Still, it's worked reliably for 10 years.

U-center from u-blox will help configure the module - frequency, satellites, data formats. Can't do without it, though the appearance is also from 2010.

For distributing corrections over the network, I use SNIP - £48 per year, but you can find free alternatives on GitHub.

What affects quality

Time to "acquire" satellites: a good system gets a fix in 3-5 minutes, a poor one might struggle for half an hour.

Distance is critical. Up to 5 km everything's brilliant, up to 15 km still bearable. Beyond that - problems with atmospheric distortions begin.

Obstacles really mess up the operation. Near buildings or under trees, accuracy drops drastically. And mobile masts on 1800 MHz frequency can completely jam the signal.

Whether it's worth economising

Professional Trimble units cost like a decent motor - from £6,400. But there you get 3-5 mm accuracy and it works in any conditions. For a surveyor, that's critical.

A homebrew setup suits farmers, drone operators, amateur geologists. My mate who's an agronomist manages fine with 2-3 cm for controlling machinery.

If you only need "roughly here", even ordinary GPS in your mobile will give 3-5 metres accuracy for free.

The "golden mean" is to buy a ready-made RTK aerial from a domestic manufacturer for £920, and not reinvent the wheel.

Tips from experience

Position the base well away from metal structures - they reflect signals and create false echoes. Minimum 50 metres from large buildings.

Cable to the aerial - don't skimp. Poor RG-58 will "eat" half the signal over 20 metres. Better to use LMR-200 or similar.

Do survey-in patiently. Minimum 6 hours with 15,000 measurements for a proper base. Rush it - you'll spend ages afterwards battling coordinate drift.