Designing IIR Digital Filters Using the Bilinear Transform Method
Using the bilinear transform method to design an IIR digital filter: (1) Design a Butterworth low-pass IIR digital filter with bilinear transformation. Design specifications require maximum attenuation below 1dB in the passband for frequencies under 0.2π, and minimum attenuation greater than 15dB in the stopband within the frequency range [0.3π, π]. (2) Plot the magnitude-frequency response characteristics of the digital filter over the frequency range [0, π/2] with a sampling interval of 0.02π. (3) Perform simulation filtering on actual ECG signal sampling sequences (provided later in this experiment) using the designed filter, and plot both pre-filtering and post-filtering ECG signal waveforms to observe and summarize the filtering effects.