[sdiy] Yet another try at explaining beat tones, etc.

[Aaron Lanterman]

On all of this, I need to put in a plug for the textbook we use in  
ECE2025: Introduction to Signal Processing:

J.H. McClellan, R.W. Schafer, and M.A. Yoder, Signal Processing First,  
Prentice Hall.

(Don't get DSP First, which is the older version and only has 2/3 of  
the material.)

Most signals & systems and DSP texts are written at the junior/senior  
college level. This is one of the few texts written for sophomores, so  
designed to be digestable.

- Aaron