Design of FIR Digital Filters

This article provides a comprehensive exploration of FIR digital filter design methodologies. Initially, we examine three fundamental design approaches: the window function method, frequency sampling method, and optimal design technique. For each method, we detail the underlying principles and implementation steps, including key algorithmic considerations such as window type selection for spectral leakage control, frequency domain specification mapping, and optimization criteria for minimizing ripple effects. Subsequently, we demonstrate practical implementation using MATLAB programming, featuring complete code examples that illustrate filter coefficient calculation using functions like fir1 and firpm, frequency response analysis through freqz, and real-time filtering applications. The discussion includes debugging procedures for common issues such as passband ripple optimization and transition bandwidth control. Through this systematic approach, readers will gain thorough understanding of FIR filter design and acquire practical skills for effective implementation in engineering applications.