Introduction to communication Engineering Introduction to communication Communication

Introduction to communication Engineering

Introduction to communication • Communication: *Communication deals with the transmission of information across a channel such as a co-axial cable, optical fiber or free space. *Transmissions across free space require information to be encoded in a carrier wave in order to shift the information to a carrier frequency suitable for transmission, this is known as modulation. *Popular analog modulation techniques include amplitude modulation and frequency modulation.

What is a Signal? • A signal is a pattern of variation of some form • Signals are variables that carry information Examples of signal include: Electrical signals – Voltages and currents in a circuit Acoustic signals – Acoustic pressure (sound) over time Mechanical signals – Velocity of a car over time Video signals – Intensity level of a pixel (camera, video) over time

Analog Signal: • * An analog or analogue signal is any continuous signal for which the time varying feature (variable) of the signal is a representation of some other time varying quantity, i. e. , analogous to another time varying signal. * For analog signals, signal processing may involve the amplification and filtering of audio signals for audio equipment or the modulation and demodulation of signals for telecommunications.

Digital Signal • *For digital signals, signal processing may involve the compression, error checking and error detection of digital signals. *A digital signal is a physical signal that is a representation of a sequence of discrete values (a quantified discrete-time signal), for example of an arbitrary bit stream, or of a digitized (sampled analog-to-digital converted) analog signal.