Hak5 - episodes of interest

http://hak5.org/ is running a series of video tutorials using one of the TV receiver  dongles as a cheap spectrum analyzer gadget.

For example, http://hak5.org/episodes/hak5-1602 is "Decoding Digital Subcarriers with a $20 SDR".

Here are some other more recent episodes that maybe be interesting:

Carrier Waves, Amplitude and Frequency:
https://www.youtube.com/watch?v=YI3muAKAeok

Building Software Radios With A Little Bit Of Python:
https://www.youtube.com/watch?v=qUxff4i0KDE

Just a bit on Antenna Theory:
https://www.youtube.com/watch?v=MC0GuRgrVAM

Time Division Multiplexing:
https://www.youtube.com/watch?v=o8VBV6v2Tcs