The image above represents everything nerdy Geoff wanted growing up. Alas, it hadn’t been invented yet. I waited.
The display shows the output from a small radio plugged into my computer. I was listening to FM radio.
I have a few SDR dongles hidden away among my techie booty. SDR stands for software defined radio, itself a crazy concept.
The radios we all listened to into the last decade were filled with physical components like coils and mesh capacitors. No more. That stuff’s now done in software. No moving parts.
My SDR dongles are plugged into the USB port of my laptop then connected to an antenna. I’m doing this from the couch on the patio. It’s all very simple.
The dongle is ready to be a radio. All it needs is instructions on what exactly to listen to. That’s accomplished with software like SDR# (pictured above). As with most hobby software, SDR# is free and open source.
Since it’s just data being manipulated amazing things are possible. It’s possible to record a wide band of frequencies containing many stations all at once. As far as I can tell it can record around ⅓ the FM band at once. Play back a slice of time and hear anything that was going on. Then rerun that same time and listen to something else.
The dongle I have is supposed to receive AM broadcasts, but I’ve had zero luck. Same goes for shortwave. Work in progress.
Did I mention the whole shooting match was under $25? I love the future!
Geoff, As a fellow radio nerd kid, with a ham license I wasn’t supposed to use because my folks thought it would interfere with people’s TV sets, and violate their lease, I still loved turning the dials, getting QSL cards, hearing my mail to Radio Switzerland read over the air, lugging radio abandoned chassies home and firing them up, etc.. I find the era of the internet has taken some of the romance of radio from us (along with bookstores, record stores, and even the smell of the soldering iron.) That said, it is useless to stand in the way of progress, and the internet has shrunken the world down to one big interconnected neighborhood of sorts (as we know from growing up in Electchester, neighborhoods had good neighbors and sometimes bad). As the 1950’s radio/TV signals of broadcasts of I Love Lucy, traveling at the speed of light, should be reaching some of our nearest start (and planet?) neighbors, what happens when we stop sending radio signals altogether–only a hundred or so years after we first sent them? That’s our transient and limited footprint out there in the galaxy. Just a thought…
Since the dongles arrived on the scene, SDRs have really taken off. I reviewed one of the first SDRs from a company called SDRplay in the UK and recently they asked me to review their updated SDR called the RSP2. You can find those at http://www.wtfda.org. The really neat thing about those is that you can “see” up to 10mhz of spectrum at a time. Who would have thought that possible just a few years ago! Just a few weeks ago I took the SDR, packed in a plastic bag with my toothbrush and other stuff, along with a USB cable and a five foot piece of wire and used it for FM DXing in Aruba. Imagine what you’d have to take to accomplish the same task even five years ago! I really wished we’d had this stuff when I was a kid.