The last few months have seen an explosion of activity in the field of Software Defined Radio (SDR), after it was discovered that cheap USB TV tuners based on the Realtek RTL2832U chip could be dialed into frequencies well outside their advertised ranges. What was designed and sold as a simple device for watching TV on your computer could be turned into a radio capable of receiving anything between 64 MHz to 1700 MHz with open source software.
Now, anyone with about $20 USD to spare can tune into everything from police and fire transmissions to the International Space Station.
Before you can start exploring the airwaves, you’ll need a USB tuner supported by RTL-SDR, the software used to unlock the full potential of the Realtek RTL2832U chip. For best results, you’ll also want to get one that uses the Elonics E4000 tuner, as that will give you the broadest frequency response. The RTL-SDR project maintains a short compatibility list which can help narrow things down a bit:
I purchased the Ezcap EZTV668 from DealExtreme and can confirm it works perfectly with the latest RTL-SDR build. The only downside when ordering from DealExtreme is that shipping can often take a very long time; it was well over a month before the device arrived. You can try your luck on eBay, though it looks like the prices have gone up a bit since sellers are now realizing the market for these devices has just expanded considerably.
The proper selection, construction, and tuning of antennas is a very complex subject that is far outside of the scope of this document. That being said, the antenna that comes with your tuner is probably going to suck, hard.
In almost all cases, the pack-in antenna that comes with these tuners is just a little metal stick and a thin unshielded wire. With this antenna, the best you could realistically hope to receive is a strong local FM radio station (of course, to be fair, that’s more or less all these things were designed to do in the first place). For anything else, you’ll need to swap out the stock antenna with something a little less worthless.
Luckily, it doesn’t take a whole lot to improve on the situation. Even a cheap set of “rabbit ears” will work much better than the included antenna, and will give you good enough performance to start exploring the higher frequencies. Though you’ll still need a more robust antenna for long range reception, and satellite work will require its own type of antennas if you hope to succeed.
As a starter antenna I’ve had good luck with the RadioShack “Budget TV Antenna” (Catalog #: 151874), though cheaper versions of the same concept can certainly be found online. With this type of antenna you will be able to pick up broadcasts from the police and fire department, NOAA weather reports, and local ham conversations pretty easily. On the subject of antennas, depending on which tuner you get, your device may need an adapter to use standard coax.
Your tuner may have a Belling-Lee connector, commonly (though incorrectly) called a “PAL connector”. RadioShack sells an appropriate adapter as a “European TV Adapter” (Catalog #: 278261) for under $10. With this adapter installed, you’ll be able to connect your RTL2832U tuner to essentially any standard antenna either directly (in the case of a TV antenna) or through an adapter (such as F to SO-239).