1. Deterministic signal modeling and representation

We generally distinguish two areas of signal processing: the analog world, which concerns "physical" signals, and the digital world, which concerns signals stored on computers (or other digital media, such as CDs or DVDs). The problems of processing these two classes of signals are faced with specific constraints. However, most of the approaches developed in one framework can be used in the other, as we shall see in this section, limiting ourselves first to the deterministic framework.

The first problem facing the "signal processor" is that of signal representation. A signal can be seen abstractly as an information carrier, which can be represented in various ways. These representations are mathematically equivalent, but may be more or less suited to a particular processing task. Let's take the example of a signal describing a measurement as a function of time....