How to calculate a harmonic of a square wave

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Homework Help Overview

The discussion revolves around calculating the harmonics of a square wave in the context of additive synthesis, specifically focusing on the 5th harmonic with a fundamental frequency of 200Hz.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • Participants discuss the calculation of the 5th harmonic, with initial attempts involving sine functions and frequency relationships. Questions arise regarding the correct formula and the role of time in the calculations.

Discussion Status

Some participants have provided feedback on the calculations, noting missing components in the formulas. There is an ongoing exploration of the correct representation of the harmonics and the significance of time in the context of the square wave.

Contextual Notes

There is mention of a convention regarding the relationship between harmonics and the fundamental frequency, as well as the need for specific constants in the formulas to achieve the correct amplitude for a square wave.

bigfattyfatfat
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Hi,

I'm a bit of a newbie to additive synthesis.. I just want to clarify that I am doing the correct calculation before continuing.

If I wanted to calculate the 5th harmonic of a square wave (the fundamental freq. being 200Hz and the amplitude of the fundamental being 1)

would the calculation be

1/5 * sin (2 * 3.14 * 1000) =

?

Thanks in advance
 
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there's a 4/pi and a "t" missing in there somewhere ...

other than that, yes.
 
Thanks.

Actually I've just realized the 5th harmonic would be 9, so it would be

1/9 * sin (2 * 3.14 * 9F * t) =

But do you know what the 't' is equal to?

Thanks
 
bigfattyfatfat said:
Thanks.

Actually I've just realized the 5th harmonic would be 9, so it would be

1/9 * sin (2 * 3.14 * 9F * t) =

But do you know what the 't' is equal to?

Thanks

No, convention is that the nth harmonic is harmonically related to the first (the fundamental) by fn = n*f1.

"t" is time. You have a square wave that is a summation of harmonics, each of which is also a function of time (a sinusoidal one).

You still don't have a 4/π in your formulas ... you need it to get a square wave of unity amplitude.
 

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