Wednesday, September 12 2012

It’s a known problem in all fields of geekery; you get in to something, you get a device here, a tool there, and all of a sudden, you have a completely insane set of stuff doing all manner of weirdness.

So, too, have been my adventures in software-defined radios. I picked up a FunCube Dongle Pro last year, and now….

Well, I decided that I should be able to play with a few different bands, not just ham radio but also unlicensed bands. The sudden appearance in March/April 2012 of the RTLSDR meant I had an even better, even cheaper SDR than the FunCube, so it deserved a better antenna than the 3”-high one it ships with.

I also picked up a Kisbee, courtesy of Dragorn, and had a near-endless amount of fun this summer listening to the local SCADA traffic. So I thought a better antenna might serve it well– but obviously, the two couldn’t share– that would be horrible! So the Kisbee picked up a 14dBi Omni Antenna, and the RTLSDR is attached to a truly massive, insanely broadband Diamond D-3000N Discone Antenna (yes, 67” high from tip to tails).

Also, relics of Defcon 18 two years ago, I had a couple Alfa Outdoor WiFi Rigs with integrated 12dBi patch antennas that, like the Kisbee, are USB-powered.

So, combined with one of my Raspberry Pis, I tossed the lot up, with the sensitive bits in a hugely overkill outdoor-proof box that was supposed to hold high-end fiber optic equipment (also a product of DC18, and Unix Surplus). The Alfas and Kisbee are connected to the RPI; the Discone/RTLSDR is not, because I haven’t gotten GnuRadio to compile on the RPI, and I’m not sure it would have the horsepower even if I did. So the Discone runs a signal back into my main computer. The RPI and accessories are powered using Power Over Ethernet– which is perfectly ordinary, but I hadn’t used it for a project before. (Technically I’m using the knockoff DWL-P200 rather than a true 802.3af rig, but it meets my needs perfectly.) The RPI’s data/power cable, along with the signal from the discone, run down a floor and into the window of my office.

The antennas are on 10-foot masts, on my deck, which is ~30 feet off the ground. So I get decent signal. Not too bad, for a motley collection of parts!

A few pictures will make the nerds in the audience drool, so here you go.

Discone (Wideband)


Radio Reception

Box Open

Box Closed

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