ABSTRACT
Signals (in signal processing) are nothing but mathematical models capturing the essence of a flow of information. Discrete-time signals are the model of choice in two archetypal processing situations: the first, which encompasses the long-established tradition of observing physical phenomena, captures the process of repeatedly measuring the value of a physical quantity at successive instants in time for analysis purposes (precipitation levels, stock values, etc.). The second, which is muchmore recent and dates back to the first digital processors, is the ability to synthesize discrete-time signals by means of iterative numerical algorithms (mathematical simulations, computer music, etc.). Discrete-time is the mechanized playground of digital machines.
