File:Fourier synthesis sqwave.png

Summary
Image demonstrating Fourier synthesis of a square wave signal. The blue line demonstrates an ideal square wave with a frequency of 20 MHz. The red line is an approximation of an ideal square wave with fundamental frequency 20 MHz, created by summing the DC values and first seven harmonics in the Fourier series that represents the square wave.

Plot made in MATLAB and rendered using Ghostscript and GIMP