Beginnings: the first hardware digital filters
L. B. Jackson · IEEE Signal Processing Magazine · 2004
The article narrates the beginnings of the first digital hardware filters based from the author's historical perspective. It all began when the author was assigned to design and build an all-digital touch-tone receiver (TTR). In the course of analysis and experimentation, a new and exciting area of digital filtering that is largely based on earlier results from the field of sampled-data control system was discovered.