You can build your own radar using open source software and relatively cheap off the shelf hardware. Basic principles of Radio Detection and Ranging system sounds simple – but converting the idea into a working gadget is a bit of challenge. Info on how to build passive radar titled I See Airplanes! How to build your own radar system is on the web. It is an archived presentation at the 22nd Chaos Communication Congress in 2005 consisting of a 2MB PDF and links to a video of the lecture. The Digital Amateur Rocket Tracking System project had an extensive section on the hardware angle titled Building Your Own Amateur Radar – Components for Personal Amateur Radar with links to hardware vendors but its no longer online.
I lack the knowledge to evaluate it myself let alone pull off the programming skill require to bring the thing to life. But somewhere in the blogosphere must lurk the neurones & the tech knowledge – perhaps distributed across geographically disparate skulls – to build a crude radar (I want to use my quota of reckless assumptions).
Building your own radar : basic concepts
(listed on slide 16)
- “Read” the disturbances in the radio waves from commercial transmitters
- Identify the disturbances caused by flying objects
- Derive the position of flying objects causing those disturbances by analysing the radio signals (fun with triangulation and GPS)
- Pump all this data into a nice easy to understand visual.
Easy to summarise but hard to do.
The idea seems to be based around the concept of passive radar. Found a NASA page that describes the concept with a little more detail and friendly graphics.
All this obviously requires the airspace being surveilled to be flooded with radio waves of some sort. Sri Lanka has quite a gob of radio stations & transmitters. With the Sri Lanka Broadcasting Corporation in the city, this shouldn’t be a problem (as if I know :).
To sift through the signal noise and identify flying objects you need the appropriate software. Enter the GNU Radio software collection founded by Eric Blossom who is (surprise) the presenter of the lecture.
Took me a while to figure out how the GNU Radio stuff fitted in. Here’ my understanding of tech jargon (PLEASE correct me if I’m wrong): The GNU Radio software collection (in this application) makes it easier to sort out the disturbances caused by objects moving through air space “flooded” with radio signals. The incoming radio waves are treated as software so apparently this process is quite efficient. The radio signal goes through some sort of conversion process via a hardware gadget called Universal Software Radio Peripheral (USRP) a that you can plug into a USB port. Ok so it costs a wad (US$700) and I’m barely clinging on to an understanding here.
Theoretically its just an issue of telling (programming/”doing some math” as the presenter calls it) the software what to look out for. Essentially filter out the noise.
Passive radar: real world examples
Apparently there are applications of the concept in the real world. The presenter lists two:
- Manastash Ridge Radar system at the University of Washington
- Lockheed Martin’s Silent Sentry®system which is a commercial system meant for keeping an eye on your airspace.
Apparently the Lockeed Martin system is more in line with what you might want. Their big selling point is:
“Silent Sentry will cost less than traditional radar systems to buy and operate, because it is based on Commercial Off The Shelf (COTS) office and radio receiver equipment, and doesn’t include any transmitter equipment. Silent Sentry will easily benefit from improvements in performance and reductions in cost of COTS components”
There is no price tag or a shopping cart facility on the site. Clearly you’ll have to call sales.
Normally I blog about what I know but this one pushes envelope. Similar to that older post about a radar simulation of Sri Lankan airspace. Remember that at this point I hardly understanding what I’m blogging about. But here you are. So thank you reading.
This should be obvious by now but there are apparently gullible idiots loafing the internet and the blogosphere so vut tu do kno (VTDK)?
I’m not associated or a promoter of any of the products/devices technologies described, refered to and/or in the links in this post. I am NOT implying that any of this will actually work if you try to put it together. If you wasted too much time and/or $$$$ building a dud of a radar based on the info in this post, well too bad. 😈