Tuesday, 29 January 2019

More range, more fun - ADS-B setup updates

Quick post today...

I've updated my ADS-B receiving station about a week ago and today, most likely due to radio propagation conditions change, I set a new detection range record of 241nm (or 466km) - here's the view from my FlightRadar24 dashboard, and the day's not over yet!


Strangely most detections are due South today, which wasn't the case over the rest of the week (most are N-NW due to window where the antenna is being exactly North facing). This is the magic of radio propagation - band conditions change constantly, sometimes in most surprising way.

Right, so what what were the updates I made last week? I made only one...

Updated RTL-SDR dongle from old generic one to one built by RadaBox24 (a.k.a. AirNav.Systems) - aircrafts seen count jumped approx 50% right away. I noticed this dongle thanks to a blog post on rtl-sdr.com as a very cheap, purpose built (LNA and filters) upgrade and at the price they go at, it was obvious I'll have at least one!
Cool thing for us folks in UK - I ordered directly from the RadarBox online store (no Amazon or anything), it was 3 working days to get the package - it was posted from UK as RM48.

As for the antenna - well, as the dongle has SMA connector and my antenna had TV-type one, I tried for a day my 2m/70cm mag-mount mobile antenna, it was really "ok" but once proper SMA adapter arrived and I hooked up the old antenna (now the real comparison begins), I was blown away... My home made ADS-B antenna is performing sooooo much better and making it took maybe 10 minutes - it's just a piece of TV coax cable (that would be 75 Ohm instead of 50 Ohm I should be using, but that's what I had in my drawer at the time). Design is simple and similar thing is presented here as "Handy Spider", my dimensions are also very similar to what's shown there. I don't even cut the coax cable - just make antenna at one end, coil surplus close to the dongle and use a plastic zip tie to make sure the 8 counterpoises don't fall out on their own.

Finally, as I was already running dump1090-mutability (Rasbian package) and bought receiver from Radabox, I also started feeding data to them. On a normal propagation day, my polar plot looks like the one below and there's a ton of spare CPU to feed a few more systems.


So, onwards and upwards. Go experiment, it's fun... and you get business account on both FR24 and RB24, just in case you have an actual use for it :-)

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