Butterworth / Chebyshev IIR

This interactive simulator explores Butterworth / Chebyshev IIR in Визуализация математики. Design Butterworth, Chebyshev I/II LP/HP filters: |H(f)|, phase, impulse response, and z-plane pole–zero plot via bilinear transform. Use the controls to change the scenario; watch the visualization and any graphs or readouts to connect the model with lectures, labs, and homework.

Для кого: For learners comfortable with heavier math or second-level detail. Typical context: Визуализация математики.

Ключевые понятия

  • butterworth
  • chebyshev
  • iir
  • iir filter design
  • math

Как это работает

**IIR digital filter design**: pick an analog prototype (**Butterworth** flat passband, **Chebyshev I** equiripple in passband, **Chebyshev II** equiripple in stopband), apply the **bilinear transform** with **pre-warping** and watch the magnitude response, optional phase, and the **z-plane pole / zero map** update live. Crank up the order to sharpen the roll-off (steeper transition); pull **f_c** through the spectrum to see how poles slide along the unit circle. Chebyshev I gains roll-off at the cost of in-band ripple R_p; Chebyshev II is flat in the passband but ripples in the stopband around R_s.

Основные формулы

Butterworth: |H(jΩ)|² = 1 / (1 + (Ω/Ωc)^{2N})
Chebyshev I: |H(jΩ)|² = 1 / (1 + ε² Tₙ²(Ω/Ωp)), ε = √(10^{R_p/10} − 1)
Bilinear: z = (1 + sT/2) / (1 − sT/2), pre-warp Ωc = (2/T) tan(ωc/2)