A courseware package for iterative design of FIR digital filters

A computer algorithm written in BASIC is presented for the realization of a finite impulse response (FIR) digital filter designed using the Fourier series method. This method produces a linear-phase FIR filter of length L subject to an idealized geometry which assumes the passband is flat, the transition band is zero, and the stopband has infinite attenuation. The design technique allows the user to specify the minimum stopband attenuation (in dB). The resulting amplitude response is displayed on the terminal screen with the desired attenuation identified by a horizontal line throughout the stopband. The user either can modify L or insert/change the window function until the response is acceptable. The program is written for use with a personal computer and does not require a graphics board. The digital filter design package converts the Fourier series design algorithm from a hit-and-miss proposition to an iterative procedure which provides reasonable solutions