current state of the rtl-sdr (plug and chug) art...

[Robert Seastrom]

Readers of this list are almost certainly well-acquainted with the "$20 USB SDR" (RTL2832U and R820T[2]) sticks that were originally intended for DVB-T reception.  Plenty of bad things to say about them (wide open front end, low resolution ADC, uncertain build quality when acquired via eBay etc), but hey for $20 what do you want?  Complaining would be like griping about your Baofeng or Wouxun HT not being up to the quality you've come to expect from Icom.

GNU Radio supports these on Linux and there's a cast of various other programs for Windows and Mac that work too.

These little radios-on-a-stick have attracted the attention of the Flightaware folks and their community of ADS-B receiver-and-feeder folks (same thing as AIS for ships and APRS for hams, but on 1090 MHz rather than VHF high band).  For a while now they've had a setup known as PiAware which turns a Raspberry Pi (use a B+ or a 2; the original B was weak in the USB power department) into an ADS-B receiver that can feed to FlightAware (you get an "Enterprise" level account for free as a thank-you for feeding them data).   There are two ways to put it together:  download and write a ready-to-go canned distribution (easy) and download NOOBS or Raspbian and do package installs and driver blacklisting by hand (hard).  Naturally I chose the hard way, which explains why it took me 20 minutes to get it up and running instead of 5.

Of course it's a good idea to put a better antenna on it than the crummy telescoping mag-mount that comes with it.  The popular antenna for this application seems to be a coax stacked collinear of 8 or 10 elements - more is way into the land of diminishing returns.  There are youtube videos out there on how to make these.

Some people use amplifiers, often the inline amplifiers intended for use with satellite tv receivers (available for a few bucks on Amazon), powered with a bias tee.  I'll confess I don't know where to get the latter on the cheap, which Mini-Circuits sure isn't.  Not sure it's necessary anyway if you have a short cable run and a good antenna.

I don't have a good antenna yet.  My setup is sitting on a window sill at my office on the 7th floor overlooking Dulles Airport.
http://flightaware.com/adsb/stats/user/res3066

To see what can be done when you throw a few bucks at it and don't have the facilities guys getting in your way, check out my friend's setup:
http://flightaware.com/adsb/stats/user/jaredmauch

Anyway, pretty spiffy and pain-free to put together and get on the air.  More at http://flightaware.com/adsb/piaware/

(the RTL stick I got was http://www.amazon.com/dp/B00P2UOU72/ )

-r