Tracking commercial aircraft with salvaged electronics

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Early last year, [Edward] started work on an aircraft tracking system using components from old electronics he had sitting around the house. As you may or may not know, most modern aircraft continuously broadcast their current position over the 1090MHz band using the ADS-B protocol. [Edward] found that his old satellite receiver module was able to pick up the signals without too much trouble, and was more than happy to share how he did it.

The whole project cost him just under 5 Euros and requires the aforementioned satellite tuner as well as an ATMega48 microcontroller to decode the ADS-B messages. When the receiver is hooked up to a nice aerial and preamp he can listen in on planes within a 200km radius, but even with a simple piece of wire, he can locate aircraft up to 25 km away.

Raw ADS-B data isn’t terribly useful, so [Edward] put together a small application that plots nearby aircraft on a map for him. We imagine that it wouldn’t be too incredibly difficult to do the same sort of thing with the Google Maps API as well.

If you’re interested in putting together an aircraft tracking receiver of your own, be sure to swing by his site – he has a ton of useful information that will likely be a huge help along the way.

[Thanks, David]

56 thoughts on “Tracking commercial aircraft with salvaged electronics

  1. Wauw, so add this to the missile guiding system et voila.
    Tool of terror?

    Or just use it with a XY steered laser to “blind” the pilots.

    1. It’s not going to be realtime enough to guide anything that accurately. Tool of terror? If anyone thought so, it would be encrypted. Maybe all airliners should be stealth…that would be pretty cool actually.

      1. ADS-B broadcasts position once per second. Encryption would defeat the whole purpose (unless the keys were widely known, doing little to improve security), which is to provide more accurate real time positioning information to both air traffic control and other aircraft in the vicinity.

        I’m sure it has occurred to various parties that a technology meant to aid in collision avoidance can also be used for collision “optimization”. Keep in mind that international aviation standards take decades to develop, implement, and change…

      2. Why do you think it’s not realtime? I think this data is used at the airport trafic control to guide the planes, so it should be accurate and real time (airports don’t use normal radars for that as they are not good enough/too expensive?). It is a good question why it’s not encrypted.

      3. Very interesting read. Did anybody catch why it’s needed to get the signal level down just above the noise floor? I get it that the demodulator is FM and we need to demodulate PPM signals, but I still don’t get how this helps.
        I remember that I read one day about using USRP to decode data about aircraft or ship possitions and plotting it on google maps, but I can’t find it now.

    1. A strobe for the duration of the flight would be a good idea as well. FAA payload weight limits, somewhat hamper the installation of such.

  2. Wait for the US government to send a take-down “request” citing “security” concerns due to the aforementioned “terrorist” threat

    1. I doubt a PI ISP would care about US censorship anyhow. :)

      But, with [Edward] being in Cebu City (my family ancestral home!), he should be getting pretty good test data with several airfields being very close by. A decent antenna may just overwhelm his system in a country that depends on air transportation as much as the PI does…

    1. Thanks for the info :) Love this project and think I may give this one a go. While I’m a complete amateur at radio, I’ve had a good bit of luck in the area I’m in. Quick question: is there any pc software that you know of that can just decode the “clicks” or fsk or whatever marker and decode them? Maybe I’m going in the wrong direction with this one lol.

      1. Unfortunately I don’t know of any software which could decode the raw signal; but you might search through this whole conglomerate of ham radio software… ;)

      2. @ responders: Thanks! It sounds like I may have the software tools I already need. I just need to build this and start tinkering and cobbling together some a script to bind everything together. Could be a fun learning project for me when it gets chilly out ;)

  3. I wasn’t aware such transmissions exist. Perhaps it’s one of those day’s I’m having a difficult time following the write up.Need to come back to it later.I do recall a web page that displayed similar tracks on a map from information gleaned from the web, but it’s more fun to have your own receiver set up, not that it’s particularly useful.

  4. I may have to build one of these; as I’ve been waiting for something like this since the 1990s; unfortunately, the implementation does not include temperature data, which would be really useful to meteorologists.

    I do notice in the write-up that the software is still a bit buggy — it reads 2 airborne aircraft at FL360, 0 kts.

    1. another commenter who knew the area said that there are a a few airports around.
      A plane waiting for takeoff or recently landed might still transmit its stationary position.

  5. The transmissions need to be unencrypted because all other aircraft need to be able to recieve them.

    Most bigger aircraft are nowadays equipped with the TCAS system: Traffic Collision Avoidance System. If a collision seems imminent (in the next 30 seconds or so) the system will warn of the possibility of a collision and recommend an avoidance strategy (up or down).

    I’m interested in building such a setup. But apparently the guys doing this have much more RF experience than I do. To build an antenna, I would need to measure SWR, which I don’t even know what it means, let alone that I have the equipment to measure it.

    I THINK I need to take apart an old satelite TV reciever, right? My father might have one of those….

  6. you know if google poured some money into this and created a network they could upload the info to a maps function and give users a “real-time” look at where their flights are. would be cool to know if your plane is delayed from your Xg phone before its announced.

    1. No way the guv’mint would allow it. You can already check out websites (flightaware and others) to see that info and can even find a .kml plug in for Google Earth, but the feds require that the info be delayed 5-15 minutes. Only thing you can get close to real-time is an airport arrival time

  7. There are already a few commercially built units that receive and decode ADS-B transmissions. Some can be quite up there in price range. I went for a small usb stick one, from microadsb.com . Works great and I share my date with multiple websites that make it very pretty too look at, such as planefinder.net This is nothing new and nothing that the government is trying to crack down on so far.

  8. Do military and government aircraft also transmit this information. At least once a day there is a fighter jet that flies low to my house and it would be neat to have a “heads up” when it is about to fly over.

    1. Typically military aircraft don’t use Mode S or ADS-B. Some larger military aircraft do (C-130s and the like), but the fighter jets I’ve attempted to track have been using Mode C, which doesn’t provide a unique airframe ID and so isn’t as useful.

  9. It’s interesting to note the there’s I2C on VGA output – so you could use that to drive the tuner and feed the received signal direct into a sound card to do a simple decode.

  10. It would be really nice to see an open source SDR module for 1090MHz that could decode all the 112bit pulse position modulated data and verify the 24bits of parity. From these messages display the position and speed which is broadcast twice a second and the airplane ID which is send every 2.5 or 5 seconds depending on size of plane. And maybe the other status/intent messages sent every 1.7 seconds.

  11. There is a website showing the airline traffic over the airport of Zurich, Switzerland on Google maps. For safety reasons there is a slight delay between the real position in the air and the position shown on the map. However, it’s quite cool. Similar to flightradar24.com: http://radar.zhaw.ch/radar.html

  12. Interesting note, it seems that people are repurposing old analogue TV tuners now the digital switchover is here.

    Often, removing the tuner does not affect the TV’s functionality at all and you can build a small transverter that generates baseband video and audio (iirc its 27.3 MHz) to feed into the TV’s chip.
    This means that in theory any TV can be digihacked if you can find a receiver small enough.

    I tried this on an old Sony VCR but had some problems because the tuner kept muting video if it didn’t see a valid signal on the antenna.

  13. Yeah, this is why you need to be very careful with radio projects.
    If your transmitter happens to have a harmonic where it shouldn’t (and many do) then it could disrupt something important.

    Always best to either buy commercial modules which are certified, or test your device at an EMC lab.
    Cost is relatively low compared with the >$10K fine

    1. All in all noting the possibility of spurious emissions from any RF device is a good idea, but state consequences should be realistic. QST regularly features RF projects. I have yet to read the suggestion that finished item be sent to a lab to test for spurious emissions outside the amateur radio allocations. Unless any interference is cause by blatant violations of FCC regulations a $10K+ fine is unlikely. At worst there will be knock at the door request that the FCC be allowed to inspect for a source of interference, and if found it will be carted off. In less severe cases you will receive a notice to repair the problem or stop using the equipment. Personally I’m unafraid to work with RF projects.

  14. Someone used to make a unit for purchase, it interfaced with your PC, had an antenna with it, a little black box and it did just what he is doing.

    1. Btw, this is not saying good job, its awesome he did this, im saying that obviously there not to worried about it, you can still hear planes on scanners, and track them via the internet, by the time you used the data you have they would be gone. And what else are you gonna do with this information. Not a whole lot.

  15. For those looking for ‘out of the box’ hardware to experiment with SDR and/or GnuRadio, check out:

    http://www.funcubedongle.com/

    Intended as a HAM satellite outreach project, they have a ‘pro’ version which is 64K to 1.7GHz (80KHz bandwidth). USB ‘sound card’ providing IQ output direct into PC

    They also community written apps for Windows, Linux and Mac.

    (no affiliation, I just think it’s really cool)

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