So this months QST magazine had an article about using a USB TV tuner dongle as a cheap SDR receiver capable of receiving ~60Mhz - 2.2Ghz (you can buy/build a converter to cover HF). I picked up this [amazon.com] tuner and followed the instructions in QST including using the automatic configuration script. It was amazingly easy to setup and worked first try. In the picture above it is receiving an AM aircraft signal at 133.75mhz. I did notice the accuracy isn't always perfect, it took me a second to find a local 440mhz repeater since it was a bit off. Also, I've noticed a couple of times that when I turned it off and come back later the frequency I was listening to had shifted slightly. But, with how cheap it is I really can't complain.
There are a few programs out there that work with these devices. SDR#, above, is probably one of the easiest. Most programs support AM, NFM, WFM, DSB, SSB, and CW with a few also supporting things like DRM. It is possible to listen to digital voice like p25 however that takes a lot more work and you need a pretty fast computer to keep up (as I understand it, I haven't figured that part out yet). I have also tried moving this to my linux laptop. After fighting with the RTL-SDR driver (the compile scripts refused to find libusb even though it was right where it was looking....) it did eventually install everything including the SDRSharp windows binaries which do run under mono since they are in C#, though I had to grab the source and compile myself as the precompiled binaries would just crash right away. It turns out a core duo running it under mono just didn't have the power, I would get 1-2 sec of audio followed by a few seconds of silence as it worked on the next bit.
One interesting thing a lot of people seem to be doing is monitoring airplanes ADS-B signals up on 1090mhz. There the planes ID themselves and provide a position which can then be mapped real time on your computer. It's like having an air traffic control terminal in your home. That might be next on my list, I got the receiver/decoder working I just need to find some software to try since the popular programs are payware and I'm more just doing it for the neat factor at this point.
Anyway, until next time.. 73 de N0QBX sk
