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Don't Let the FFT Fool You - Avoiding its pitfalls for a more accurate frequency analysis

Mark Newman - Watch Now - DSP Online Conference 2024 - Duration: 01:01:07

Don't Let the FFT Fool You - Avoiding its pitfalls for a more accurate frequency analysis
Mark Newman

The Fast Fourier Transform is a cornerstone of audio processing providing a representation of a time domain signal in the frequency domain. The ability to manipulate signals in the frequency domain gives us the power to isolate, enhance, and sculpt specific frequency components, redefining the very essence of sound. However, for this to work, an accurate frequency domain representation is essential.

As DSP enthusiasts, we tend to treat the FFT as a magic bullet solution, a library function that is so commonplace, we can implement it with an “include” statement and a few lines of code. But what do we really know about its inner workings, its nuances and most importantly, its limitations? Can we be confident that the frequencies reported by the FFT are truly present in the original signal, or is our ignorance of how it works pulling the wool over our eyes and causing unwanted artefacts in our output?

In this presentation we’re going to lift the hood on the FFT and discover:

  1. How the Fourier Transform works
  2. Why the FFT is only an approximation (albeit a good one) of the true Fourier Transform
  3. What the limitations of the FFT’s approximation are
  4. How to mitigate these limitations by windowing your signal before it enters the FFT
  5. How to navigate the trade-off between processing speed and frequency resolution in the FFT

This presentation aims to equip you with a practical understanding of the FFT, empowering you to create higher-quality and more precise DSP applications.

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RandyYates
Score: 0 | 3 weeks ago | 1 reply

Mark, VERY nice presentation! Can I pick your brain on how you did this? Was it all via PowerPoint?
--Randy

Mark NewmanSpeaker
Score: 0 | 4 days ago | no reply

Thanks. No, I didn't use PowerPoint, PowerPoint can't do what I wanted. The animations and graphs are all programmed in JavaScript and HTML.

Mayur.S
Score: 0 | 1 month ago | 1 reply

Mark, Learned a lot, lots to digest and great visuals.
Thank you for sharing your knowledge and creativity.
Kind Regards,
Mayur

Mark NewmanSpeaker
Score: 0 | 1 month ago | no reply

My pleasure. It was great fun to do. Thanks for watching.

RichardLyons
Score: 0 | 1 month ago | 1 reply

Hello Mark. This video of yours is surely the most visually beautiful Fourier transform presentation I have ever seen. Great job!

Mark NewmanSpeaker
Score: 0 | 1 month ago | no reply

Thank you. When I was learning this stuff at University, I found the only time I could understand the formulae was when the lecturer showed a graph of what was happening. I very much wanted to "show" rather than "tell" the Fourier Transform.

Gary
Score: 0 | 1 month ago | 1 reply

Major points for bringing Legos to a science conference!
Oh, and it's "j", not "i" (I'm an engineer... :) )

Mark NewmanSpeaker
Score: 0 | 1 month ago | no reply

Haha... yes, all those hours building Lego space ships as a kid finally paid off. Yes it was always j for me too in electronics, in fact I originally had a line in the talk about that, but it hit the cutting room floor together with a load of other stuff when I saw that the talk was overrunning.

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