1. Systems and Signals

In this chapter we discuss what we call a system in these notes. What different types of systems do we have? In what way are they characterized? We will restrict ourselves to the simplest of them all: linear time invariant systems with one input and one output. Later sections will explain these restrictions.

Basically a system can be considered a black box. You feed some input into the system and it delivers some output. What is fed into the system is most often not just one value or set of values, no we feed a system with an input stream. Such a time dependent input stream is called a signal. In a separate section we will look into the basic time varying signals.