introduction to switching system


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INTRODUCTION
Telecommunication networks carry information signals among entities, which are
geographically far apart. An entity may be a computer or human being, a facsimile machine, a
teleprinter, a data terminal and so on. The entities are involved in the process of information
transfer which may be in the form of a telephone conversation (telephony) or a file transfer
between two computers or message transfer between two terminals etc. Today it is almost
truism to state that telecommunication systems are the symbol of our information age.

HISTORICAL DEVELOPMENT
By the early 1800’s scientists had developed ways to generate and transmit electricity. In
1819, oersted discovered the relation between magnetism and electricity. Ampere, Faraday
and others continued this work in 1820. In 1834, Gauss and Weber wired over the roofs of
Gottingen to make a telegraph system.


SIGNAL CHARACTERISTICS
Telecommunication is mainly concerned with the transmission of messages between two distant
points. The signal that contains the messages is usually converted into electrical waves before
transmission. Our voice is an analog signal which has amplitude and frequency characteristic.

ELEMENTS OF COMMUNICATION SWITCHING SYSTEM
The purpose of a telecommunication switching system is to provide the means to pass
information from any terminal device to any other terminal device selected by the originator.
Telecommunication system can be divided into four main parts. They are
1. End system or Instruments
2. Transmission system
3. Switching system
4. Signaling.