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. In subsequent sections we will delve into these restrictions.

Basically a system can be considered as 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, instead we feed a system with a stream of input values. Such a time dependent input stream is called a signal. In a separate section we will look into the basic time varying signals.

• 1.1. Systems
• 1.2. Signals
• 1.3. Decibels
• 1.4. Exercises