M6OZA on ADSB Flight Tracking

M6OZA on ADSB Flight Tracking

So if you’re like me, a bit of a geek or maybe handy with technology, you’ve probably got drawers and shelves at home full of bits and bobs that “may come in useful one day”. This article is about how I made some of my “bits and bobs” into something quite useful…

I’ve always had an interest in radio, technology, and programming so when I was given a Raspberry Pi and a RTLSDR dongle for Christmas a few years ago I wanted to combine them into a radio project.

Up to this point the Raspberry Pi had spent a few short weeks being a Kodi box, and then a WiFi repeater, before being destined to the bottom drawer. My first experience of Software Defined Radio (SDR) was with the RTLSDR dongle, an entry level model, but it had done the trick of luring me back into radio monitoring and listening to shortwave. After a while I upgraded to a better model but having explorered everything I thought I could, it also ended up in the bottom drawer.

I’d started to acquire a small collection of old 1980’s – 1990’s Realistic scanners, these analogue scanners had served me well. Military air scanning had become “my thing” and I found myself scanning the frequencies after work listening to transmissions from practice flights off the North East coast. These flights were mainly controlled out of RAF Boulmer, not far from my location at the time. However, after a while I guess listening wasn’t enough and I was on the hunt to improve my setup when I came cross ADSB and MLAT aircraft tracking. I read up on the subject and eventually found an article that described how it was possible to use a Rasberry Pi and a RTLSDR dongle to make a suitable receiving station. I’ve included a link to the original article here.

I suggest you simply follow the instructions on the website to upload the software onto an sdcard and install it in your Rasberry Pi. All you then need to do is plug in your usb RTLSDR dongle and you’re ready to go.

So what type of antenna do I use, as the ADSB aircraft signals are on 1090MHz? As with a lot of things today the antenna can be purchased online, but why not make your own. You’ll need an empty beer can, if you don’t like beer a lager one will work just as well 🙂

The picture below is one I made. The beer can acts as a ground plane and the short vertical wire (1/4 wavelength long on 1090MHz) is connected to a sma connector.

The paint was just for practical reasons, to stop rain water shorting out the antenna to the can (groundplane). I happened to have Citroen saxo blue in the cupboard, but any colour will do. A blob of silicone around the connector would serve just as well. The measurements should you require them are: Antenna length 69mm, Can length 69mm.

For maximum receive range mount the antenna on a non-conductive mast, mine is on the chimney stack as a temporary measure. At this height I’m seeing a range of 100-150 miles from 200-350 tracked flights a day. It will work at ground level but range will be much shorter and the number of heard aircraft will be less.

Now I don’t only hear them I can see them as well…brilliant !

A year or  so down the line, I have now upgraded my system to include a flight-aware dongle to replace the RTLSDR, a 1090mhz pre amplifier, and I have upgraded the antenna to a high gain 8 section co-linear. Although not needed to get started, these upgrades have improved my receive capability significantly.

 

So don’t throw away your “bits and bobs” as they may come in useful one day. Have fun building your own ADSB receiver. If you liked this article please give it a thumbs up.

73 Ray M6OZA

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