I remember coming to the understanding that a square wave, which is a collection of fundamental and (odd) harmonics frequencies, could then be used to give an indication of frequency response.

For the uninitiated, harmonic drives, also known as strain-wave gears, are a compact, high-torque gearbox that has become popular with “robotic dog” makers and other roboticists. The idea is ...

This motion may be approximated by that of the tines of a tuning fork when struck, and could be seen as a sinusoidal or SINE WAVE from the trace of a pen attached to the tine and moving against paper ...