I’m carrying out Fourier analysis and synthesis on square and sawtooth waves as part of a university project, however, I’ve run into a problem and am unsure whether I have done something incorrectly or not. I’ve been effectively told “generate some waveforms and see what happens”, so my knowledge of Fourier is still very limited.
Using FFT in Audacity, I was successful in building a 1 KHz square wave out of sin waves. However, when I attempted the sawtooth wave, I found that the resulting shape of my waveform was inverted (see picture below).
The top waveform is a 1 KHz sawtooth wave created using the tone generator.
The bottom wave is my reconstructed wave using the first 5 harmonics. As you can see, the shape is inverted.
Have I incorrectly analyzed the waveform or is something else happening here?