By now, most hams have probably heard about the cheap SDR dongles that everyone is getting. Meant for DVB-T use in other parts of the world, radio amateurs have figured out that these powerful, affordable devices are great for listening to local traffic across a sizable chunk of the RF spectrum.
All you have to do is just plug it into your computer’s USB port, fire up the software of your choice and you’re on your way to listening to local amateur, commercial, and aircraft traffic, tracking aircraft positions, and more. If you’re a radio head, it’s (almost) the most fun you can have in front of your PC screen – but who wants to be stuck at their desk or mess with their laptop just to listen to a little radio?
If you like to go mobile with your tech, you’re living in a golden age. The market is flooded with cheap, no-name Android tablets that may or may not work as well as their brand name counterparts. Microsoft and other manufacturers have been cranking out Windows tablets, but the Windows RT versions are neutered and can’t run much useful ham software while the Windows 8.1 “Pro” models still have sky-high prices. iPads… Well, some of the older models are coming down in price, but there just isn’t much there for radio amateurs. Enter the new generation of affordable tablets.
For our demo, I’m using a Toshiba Encore Mini (WT7-CT16) – a 7″ touchscreen tablet with USB support that runs Windows 8.1 and has an MSRP of just $100 for the 8GB model that I got. With flash memory chips’ capacity going up and prices going down, 8GB models are getting harder to find, though, so you may have to “settle” for the 16GB model. I gather that the non-signature edition comes with some bloatware, but I’m not sure since I do have the MS signature version. This is a pretty amazing deal, considering that an OEM copy of Windows 8 by itself costs about as much or more. This tablet is perfect for this application (and lots of others!). Since it runs a full version of Windows 8.1 and has a quad core Intel Atom x86 processor with a gig of RAM, it can run “real” Windows software. Since it’s a touch screen, it doesn’t need extra gadgets like a keyboard or mouse to use it, although a stylus may help avoid “fat fingering” the controls.
Next, of course, we need the SDR dongle. We’re using the Nooelec RTL2832 + R820T dongle. The dongle, stubby antenna with cable and useless remote control sells for right around $20. There is nothing special about this particular unit, I use this one because it’s the first one I heard of, so I got excited when I found out about it and ordered it.
Next, you need a USB on-the-go (OTG) adapter so you can plug the SDR dongle into the micro-USB port on the tablet (note: this is the only USB port on this tablet and it also uses it to charge the battery, so you can’t do both things at the same time). The one above is less than $7.
Finally, you’ll need some software for the dongle to play with. For general listening from 25MHz to 1750MHz, I just use SDR# (SDR Sharp). For tracking aircraft, I use RTL1090 and feed the output to Flight Radar 24 (which, by the way, gets you a free premium account). All of this software is free.
There you have it. For right around $130, you have a portable, go-anywhere SDR receiver that you can use to monitor radio traffic, track aircraft and more. For more information on setting up the SDR dongle and software, see our post about it.
A Raspberry Pi board would be another small, mobile solution, but then you would need to go through the trouble of installing an operating system on it, finding ARM compatible SDR software and installing it (or playing with something like Wine to get Windows software to run), and then you would still things like a power supply, portable display, and user input like a keyboard and mouse. Plus it should all go into a case to keep it safe. By that point, your time and costs are really adding up and you’re beginning to have a lot of stuff to carry around.