Demonstrations

01

Rotating phasors

\(z(t)=Ae^{i(\omega t+\phi)}\)
  • Euler’s formula
  • complex exponentials
  • phasors
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02

Two-dimensional sinusoid

\(\operatorname{Re}\{Ae^{i\phi}e^{ikx}e^{i\ell y}\}\)
  • spatial frequency
  • wave vector
  • 2D Fourier transform
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03

Maxwell plane wave

\(\operatorname{Re}\{E(x,t)\}=E_0\cos(\omega t-kx)\)
  • plane waves
  • electromagnetism
  • wave propagation
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04

2D FFT image compression

Python + NumPy + WebAssembly
  • image compression
  • sparse spectral representations
  • 2D FFT
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05

Cepheid variable star

Programming task 1 · Fourier series
  • Fourier series
  • periodic signals
  • spectrum
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06

Zebrapard phase swap

\(\mathcal{F}^{-1}\{|I_1|e^{i\angle I_2}\}\)
  • magnitude and phase
  • image reconstruction
  • 2D FFT
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07

Dirac comb

\(x_N(t)=T^{-1}\sum_{k=-N}^{N}e^{i2\pi kt/T}\)
  • impulse train
  • Fourier series
  • sampling
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08

Audio FFT compression

Listen to sparse Fourier reconstruction
  • audio compression
  • sparse spectral representations
  • FFT
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09

Gibbs phenomenon

\(x_N(t)=\frac12+\frac{2}{\pi}\sum_{m=0}^{N-1}\frac{\sin((2m+1)2\pi t/T)}{2m+1}\)
  • Fourier series
  • Heaviside step
  • overshoot
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10

Waterfall spectral analyzer

\(\left|\operatorname{STFT}\{x(t)\}\right|\)
  • waterfall spectrum
  • STFT
  • time-frequency analysis
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