EE 4720 - What is it?

What do the plots below depict? They are both the same kind of plot but the second is zoomed in alot more (but does not zoom in on the same area).
First plot.Second plot.
ECE Home Page 4720 Home Page
David M. Koppelman - koppel@ece.lsu.edu
Modified 16 May 2002 16:42 (2142 UTC)