How a square or sawtooth wave can have a certain frequency?

[MrMuscle]

Hello!

I know that a square or saw tooth wave consists of infinite amount of sinousoids each having different frequency and amplitude. But when I look at their plot they seem to have a well defined frequency or period. Which term in the Fourier series determines their frequency? Does a saw tooth or square wave have an uncertainty in its frequency? How can I calculate the frequency of such a wave?

Thanks for all the answers in advance!

 

[phinds]

You've got this somewhat backwards. The square or sawtooth wave is something we generate in the real world. It has amplitude, frequency, and so forth. The Fourier analysis gives us a mathematical way to analyze it. The map is not the territory.

An IDEAL square wave, for example, is in fact the same as its Fourier analysis says it is ... a sum of an infinite sequence of sine waves. No ACTUAL square wave is like that but we can pretend they are for the purpose of analysis.

 

[Meir Achuz]

What is called the frequency or period is usually that of the fundamental (lowest) harmonic.