INTRODUCTION TO SIGNALS & SYSTEMS

SIGNAL A signal is a function of time representing a physical variable, eg: voltage, current etc. A signal is defined as a function of one or more independent variables.

CLASSIFICATION OF SIGNALS Signals are basically classified into two different types as follows. Continuous time signals Discrete time signals

CT Signals In continuous time signals the independent variable is continuous, and they are defined for a continuum of values

Example

DT Signal Discrete time signals are defined only at discrete times and for these signals the independent variable takes on only a discrete set of values

Example

Representation To distinguish between continuous-time and discrete time signals, we will use the symbol ‘t’ to denote the continuous time independent variable and ‘n’ to denote the discrete time independent variable.

Classifications of CT signals The CT signals can be further classified into the following Unit step Unit ramp Exponentional Impulse

Unit Step Signal

Ramp Signals

System A system can be viewed as a process in which input signals are transformed by the system or cause the system to respond in some way resulting in other signals as outputs.

CT system

DT system