Agilent is starting a webcast series of sessions about Spectrum Analysis and RF basics. It may be of interest of (most) RF Explorer users and RF enthusiast out there.
RF Back to Basics: Part 1 - Signal Analysis on Jan 25, 2012.
For those of you who don't know, Agilent is the spinoff of HP for testing instruments and RF devices, a worldwide reference in RF for many decades. Besides that, they are the actual guys implementing the closest vision Bill and Dave had about their company when they created HP in the 30's, nothing close to main HP brand these days.
I recommend all the Agilent general guide I recommended to many people already. The link may get invalid anytime as it is internal to Agilent, but if it doesn't work just look for the famous "Application Note 150", the "5952-0292EN.pdf" document or simply "Spectrum Analysis Basics" within the Agilent site.
The Application Note 150 seems to be very well known. I've downloaded it and started reading it. A lot of it's going over my head so far!