UNIT – I
ELEMENTS OF DIGITAL COMMUNICATION SYSTEMS
source to a user destination via a communication channel.
MODEL OF A COMMUNICATION SYSTEM
The purpose of a Communication System is to transport an information bearing signal from a
Fig. 1.1: Block diagram of Communication System
The three basic elements of every communication systems are
The Overall purpose of this system is to transfer information from one point (called Source)
to another point, the user destination.
The message produced by a source, normally, is not electrical. Hence an input transducer is
used for converting the message to a time – varying electrical quantity called message signal.
Similarly, at the destination point, another transducer converts the electrical waveform to the
The transmitter is located at one point in space, the receiver is located at some other point
separate from the transmitter, and the channel is the medium that provides the electrical
connection between them.
The purpose of the transmitter is to transform the message signal produced by the source of
information into a form suitable for transmission over the channel.