IntroductionChapter 1

Outline• Signal

• System

• Signal Processing

Signal• A signal is defined as any physical quantity that varies

with time, space or any other independent variable or variables.

• Mathematically, we can describe signal as a function of one or more independent variables.

S1(t)=5t.

S2(t)=20t2.

S3(x,y)=3x+2xy+10y2.

• Examples of natural signals are speech signals, electrocardiogram (ECG), electroencephalogram (EEG) etc.

System• A system is a physical device or an algorithm which performs required

operation on a signal.• A filter used to reduce the noise and interference corrupting a desired

information-bearing signal.

• Natural signals are also generated by some system.

• Speech signals are generated by forcing air through the vocal cord; i.e. the system consists of vocal cord and vocal tract called the vocal cavity.

• Images are obtained by exposing photographic film to a scene or an object.

• Thus signal generation is usually associated with a system that responds to a stimulus or force.

• The stimulus in combination with the system is called the signal source.

Signal Processing• The operations that are performed on a signal by a

system is referred to as signal processing.• Filtering