Design of a Low-Pass Digital Filter

Resource Overview

Design a low-pass digital filter that meets the following design specifications: passband cutoff frequency of 0.2π with 1 dB ripple, and stopband cutoff frequency of 0.3π with 15 dB attenuation. This requires developing designs using Butterworth, Chebyshev Type I, Chebyshev Type II, and elliptic filter prototypes, comparing their filter orders, actual stopband attenuation, and analyzing the experimental results. Key implementation considerations include filter type trade-offs, parameter selection methods, stability, computational complexity, and performance evaluations.

Detailed Documentation

Design a low-pass digital filter that satisfies the following design specifications:

- Passband cutoff frequency: 0.2π

- Passband ripple: 1 dB

- Stopband cutoff frequency: 0.3π

- Stopband attenuation: 15 dB

Requirements: Implement designs separately using Butterworth, Chebyshev Type I, Chebyshev Type II, and elliptic filter prototypes. Compare the filter orders and actual stopband attenuation achieved by each design, and analyze the experimental results. During the design process, the following aspects must be considered:

- Advantages and disadvantages of different filter types (e.g., Butterworth's flat passband vs. elliptic's steeper roll-off)

- Parameter selection methods in design processes (using functions like `buttord`, `cheb1ord`, `cheb2ord`, and `ellipord` for order determination)

- Filter stability and implementation complexity (assessing pole-zero placement and computational requirements)

- Performance comparisons and trade-offs among various designs while meeting specifications (e.g., transition bandwidth vs. filter order trade-offs)