Guide
How to set up an ADS-B receiver in the UK
About £30 of parts, an evening, and an upstairs window. What to buy, where to put the aerial, what range to expect, and the mistakes that cost the most coverage.
What to buy
Three parts, and only one of them matters much.
An RTL-SDR dongle
A USB software-defined radio, around £25 for one with a temperature-compensated oscillator, which turns the 1090 MHz broadcast into something a computer can read. The cheap generic sticks work, but they drift as they warm up and lose messages. This is the one part where the cheapest option is a false economy.
A 1090 MHz aerial
The stub that comes taped to the dongle will work on a windowsill. A proper tuned 1090 MHz aerial costs about £20 and roughly doubles the useful range. Anything sold for general scanning is a compromise; you want one cut for this band.
Something to run it
A Raspberry Pi is the usual answer and needs no monitor once running. An old laptop or the PC already driving your display works too: decoding ADS-B is not demanding.
Where to put it
Height beats everything. A better aerial three metres lower is the worse aerial.
1090 MHz is line of sight. The signal does not bend around hills or buildings, so the question is not how strong your aerial is but how much sky it can see. A loft is usually the best compromise in a house: a few feet of roof tile costs less than the twenty feet of height you gain over a downstairs window.
Outside is better again, if you are willing to run coax and weatherproof the joint. A mast on a gable end with a clear horizon is what the long-range receivers are doing.
Keep the coax short. At this frequency cheap cable loses signal quickly: five metres of thin RG58 can cost more than the aerial gained. If the run has to be long, put the dongle at the aerial and run USB rather than coax, or spend the money on better cable.
Point nothing. A vertical whip is omnidirectional by design, which is what you want: aircraft arrive from every direction.
What to expect
Range, and what changes it.
Typical numbers
A stub aerial on a windowsill: 30 to 60 km. A tuned aerial in a loft: 100 to 150 km for aircraft at altitude. A good aerial outside with a clear horizon: 250 km and beyond, occasionally past 400.
Those figures are for high aircraft. Anything low is limited by the horizon, which is why you may see a jet over the Netherlands and miss a helicopter two towns away.
What costs you coverage
In rough order: height, then cable loss, then the aerial itself, then the dongle. People commonly buy a better aerial when moving the existing one up a floor would have done more.
Foil-backed insulation in a loft is a good reflector and a poor neighbour to an aerial. So is a solar array, and so is a metal-framed conservatory roof.
Questions
The ones we are asked.
- Do I need a licence to receive ADS-B in the UK?
- No. Receiving an unencrypted broadcast is legal here. Transmitting on the band is not, and nothing in a receiving setup transmits.
- Will a receiver interfere with anything?
- No. A receiver is passive: it listens and emits nothing beyond the ordinary noise any USB device makes.
- What software should I run?
- readsb or dump1090 to decode, and tar1090 for a map in a browser. All free and open source. If you would rather not assemble it yourself, FlightAware's PiAware image packages the lot.
- Can I feed the data to a network?
- Yes, and most people do. Networks such as adsb.lol aggregate volunteer receivers so that everybody gets wider coverage than their own aerial can manage. Feeding costs you a trickle of bandwidth. We also place free receivers where coverage is thin.
- How much power does it use?
- A Raspberry Pi and a dongle draw a few watts, so under £10 a year of electricity at current prices. It is meant to be left running.
- Is it worth it if I already use a flight tracking website?
- It depends what you want. A website gives you the world; your own aerial gives you your own sky with no delay, no filtering, and no dependency on somebody else's servers. Most people who put one up keep it. If you want the result on a wall rather than a laptop, the ways of doing that are compared here.
The product this comes from
Airborne draws what is overhead, on a screen in your room.
The airline's own livery on that airframe, with the route and the height beside it, redrawn every thirty seconds. Five views on one screen. If it cannot identify something, the frame stays empty rather than guessing.