Exploding the Nyquist barrier misconception

The author comments that Smith (IEEE Signal Processing Magazine, Forum Feedback, May 1996) continues to proclaim the novelty of an approach (Smith, 1995) that he purports to "break the Nyquist barrier," in spite of the revelation (Marple Jr., 1996) that his approach is simply a special two-filter case of well known analysis and synthesis filter banks performed with sample-and-hold waveforms. Smith's Fig.4(b) in Smith (1995) can be compared with the conventional filter banks of Fig.4 in Marple Jr. (1996) and it is observed that they are identical. Smith also makes further observations to which the present author responds with additional commentary. However, the primary purpose of this contribution is to expose a fundamental misconception regarding the universality of the sampling theorem as taught in most digital signal processing textbooks. It is this misconception that led Smith to prematurely claim victory over a perceived impenetrable Nyquist barrier.