Take a few minutes and watch [atlas of d00m], at Shmoocon 2012, presenting information about using the RF dongle from the Chronos to explore ISM bands. Admittedly, I’m not very familiar with many of the things he discusses, but the words make sense. The bits and pieces I am familiar enough with to comprehend are truly fascinating. He covers typical methods of RF modulation as well as some hardware specific information to that dongle.
If you have a few minutes, or want more security related stuff, check out all the coverage from Shmoocon 2012. Tons of great videos here.