PBS
Pbs Learning Media: Radio Waves: Fm vs. Am
This brief essay from A Science Odyssey Web site describes the difference between FM and AM radio waves.
Other
Computer Music: Guide to Fm Synthesis
Computer Music provides a detailed site of the history, advantages/disadvantages, and uses of FM synthesis. Provides many graphics.
PBS
Pbs Learning Media: How Is a Radio Wave Emitted?
This illustrated essay from A Science Odyssey Web site explains the science behind radio waves, including the role of electrons and electromagnetic fields.
Other
Karbos Guide: A Guide to Sound Cards and Digital Sound
Informative site about the use of sound cards and the necessity for them in today's computer world.