Software Defined Radio

On one of her visits a little while ago, Ms Geek brought over a box full of her hobby stuff for me to try if I was interested. One of the things in the box was a HackRF One Software Defined Radio (SDR). I had no idea devices like this existed, and we downloaded some software and she showed me how it worked. It’s… well, it’s a radio receiver (the HackRF One can also transmit!) that you connect to a computer by USB. If you’ve got the right software, the right drivers, and the right antenna, you can browse a good chunk of the radio spectrum and listen in to all kinds of neat stuff.

I tinkered with the HackRF for a while but didn’t have a lot of luck. One day, I found some old cable, soldered some BNC ends to it, and put the antenna outside.

What a difference – the whole thing came to life and I could hear (and thanks to the software, see) all kinds of stuff! Conversations between aircraft and the tower at the airport, weather reports, radio stations, what was wrong with city buses… all kinds of fascinating things.

Here’s the HackRF One, it’s roughly smartphone sized:

Not a great picture, it’s dark in here…

And what a neat machine it is! Radio and antennas are two things I know very little about, and while there’s a learning curve, it didn’t take too long before I was able to tell the difference between voice and data signals and use some of the software settings.

I figured that Ms Geek would probably want her SDR back at some point, so I figured I’d look into picking up one of my own. While the HackRF One is a really nice device, it cost more than what I’d hoped to spend, particularly since this is a brand new hobby.

Enter the NESDR SMArt:

Yep, still dark…

I found a bundle online for about 35 bucks that included the SDR, three antennas, and a magnetic antenna mount. The NESDR is a lot smaller than the HackRF One but it can’t listen to as much of the spectrum and can’t transmit. That’s okay though – I’m still just barely scratching the surface what what these devices can do.

I’ve been spending a lot of time browsing the airwaves and listening to various services or systems and trying to figure out what they are. Some are pretty easy, like the airport. They announce who they are with every transmission. Others, though, aren’t quite as easy to figure out, like who was whistling and then asking about a trailer of dirt, or where “home one” is. Then, there’s stuff like this:

What the hell is that? It whistles and every once in a while it changes pitch and frequency like in the picture. I have no idea what it is but I’m fascinated.

I’ve been playing with the SDR stuff every day since I moved that antenna outside, and every day I find something new and different. What a neat hobby!

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