Spectrum of pulse and square waveforms

[Yichao L]

Hi,

From the lab exercise I can see that the spectrum of a sine wave, e.g. of 100Hz, has an very obvious spike at 100Hz in the spectrum. But for the pulse and square waveforms, their spectrums are all quite flat throughout the whole frequency domain, and the differences between them of different frequencies are also quite small.

I’m sure you’ve mentioned about it somewhere but I have not found it so far. Could you please give me any pointers to some resources or explanations about why this happens?

Best regard,

Yichao

[Simon]

You are probably using a too short analysis window, which is preventing you from resolving the spectrum with enough detail.

In Wavesurfer’s spectrum window, the parameter to change is “FFT points”. Try a larger value such as 4096 (which would be about 0.25 seconds at a 16 kHz sampling rate) or 8192.

[Author]

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