Sampling and sampled-data models

Physical systems typically evolve continuously whereas modern controllers and signal processing devices invariably operate in discrete time. Hence sampling arises as a cornerstone problem in essentially all aspects of modern systems science. This paper reviews various aspects of sampling of signals and systems. We argue that careful consideration must be given to sampling to obtain meaningful results when interconnecting a physical system to a computer for the purpose of data storage, signal processing, or control. We also take the opportunity to dispel several common misconceptions about sampling and sampled-data systems.