An animated introduction to the Fourier Transform.
Home page: https://www.3blue1brown.com/
Brought to you by you: http://3b1b.co/fourier-thanks

Follow-on video about the uncertainty principle: https://youtu.be/MBnnXbOM5S4

Interactive made by a viewer inspired by this video:
https://prajwalsouza.github.io/Experiments/Fourier-Transform-Visualization.html

Also, take a look at this Jupyter notebook implementing this idea in a way you can play with:
https://github.com/thatSaneKid/fourier/blob/master/Fourier%20Transform%20-%20A%20Visual%20Introduction.ipynb

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Animations largely made using manim, a scrappy open-source python library.  https://github.com/3b1b/manim

If you want to check it out, I feel compelled to warn you that it's not the most well-documented tool, and has many other quirks you might expect in a library someone wrote with only their own use in mind.

Music by Vincent Rubinetti.
Download the music on Bandcamp:
https://vincerubinetti.bandcamp.com/album/the-music-of-3blue1brown

Stream…

Theory of digital signal processing (DSP): signals, filtration (IIR, FIR, CIC, MAF), transforms (FFT, DFT, Hilbert, Z-transform) etc. - capitanov/dsp-theory