ADS-B, MLAT and Mode-S via $18 SDR receiver
Inspired by G4VXE and a few others, I recently ordered a dongle-type SDR receiver via eBay. It’s due to arrive Wednesday.
This particular dongle has a few things going for it that make it ideal for experimentation (low price being first and foremost):
- Freq coverage is 25-1700 MHz – there’s a lot of stuff going on within that range and many modulation types.
- Its broad bandwidth and a fast clock mean that pulse-type modulation can be faithfully decoded…this is where ADS-B, MLAT and Mode-S come in.
I’m not sure many people have an understanding of what these transmissions are (particularly MLAT) or how they’re generated other than the fact that they’re used for air traffic control.
I may describe some of that if I can do it without it becoming overly tedious.
Aside from all that, I think it will be fun to explore to have such a wide window of the RF spectrum to explore for such a low price.
There are many such dongles available – if you decide to order one, be sure to research that particular model’s compatibility with your intended application & software. Complicating matters is the fact that – like everything else – models and internal circuitry constantly change due to upgrades, etc.
Here’s the one I bought and here is a YouTube video describing the device:
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Themocracy
That looks like the same DV-T dongle I got, John. It is surprisingly sensitive.
The antenna connector I believe is a type MMCX. I ordered an MMCX jumper cable on eBay with a view to making an adapter to something more convenient, but I discovered that once the supplied antenna plug is snapped into the socket, it won’t come out again. So it looks like I’ll have to chop the supplied antenna cable in situ to make an adapter. Hopefully I can do that without zapping the front-end, which I gather is easy to do.
If you manage to get your MMX plug out again I’d be interested to know how you did it!
Julian, G4ILO
Thanks for that info, Julian. It looks like the same type of connector as on my Garmin Nuvi for which I have an external antenna (though seldom use it). I’ll let you know how it goes.
I hope you’ll blog more about what you’re using yours for – I know that you initially regretted not buying a FunCube dongle when they became available – I think these new little gadgets are a much better deal, in terms of both performance and price.
Julian,
I just received my SDR dongle.
I find that if I twist AND pull the stock antenna connector, it comes off just fine.
Hope this works for you.
Bill N5AB
Believe it or not the PO lost mine! Tracking shows it was delivered yesterday but it wasn’t. Went to the PO today and no sign of it there either so gonna order another one Monday and ask for UPS shipping :-(
Yes, that worked, thanks Bill.
But I now find the connector is not an MMCX as I thought. The jumper cable I got from Ebay has an even smaller connector than the one on the dongle’s antenna cable. Guess I’ll just have to make that into an adapter.
John,
Thanks for the heads-up on this gizmo.
How can you *not* buy this for only $18 with free shipping?
Looking forward to playing with it.
That was my thought too – a lot of opportunity to experience a new part of the spectrun (and in a new way) for $18? I’m in!
Hi all,
I’ve also been playing with these dongles and found that the version with a 4000E chip is better for VHF/UHF. However, the dongle with a 820T chip is the one to go for if you are interested in ADSB as it is significantly better – I’m even tempted to say that it comes pretty close to a dedicated SBS-1 receiver.
73 to all
In two or three weeks I should have a bit of time to hook up the high $$$ test equipment I have access to and run some numbers at various freqs – MDS, 6 dB bandwidth, etc.
Will post that data when I get it.
I have noticed that ADS-B monitoring seems to be quite popular in Europe and almost unheard of here in the States…