Telecommunication

Telecommunication is the transmission of signals over a distance for the purpose of
communication. In modern times, this process almost always involves the sending of
electromagnetic waves by electronic transmitters but in earlier years it may have involved
the use of smoke signals, drums or semaphore. Today, telecommunication is widespread
and devices that assist the process such as the television, radio and telephone are common
in many parts of the world. There is also a vast array of networks that connect these
devices, including computer networks, public telephone networks, radio networks and
television networks. Computer communication across the Internet, such as e-mail and
instant messaging, is just one of many examples of telecommunication.
Telecommunication systems are generally designed by telecommunication engineers.


Major contributors to the field of telecommunications include Alexander Bell who
invented the telephone (as we know it), John Logie Baird who invented the mechanical
television and Guglielmo Marconi who first demonstrated transatlantic radio
communication. In recent times, optical fibre has radically improved the bandwidth
available for intercontential communication helping to facilitate a faster and richer
Internet experience and digital television has eliminated effects such as snowy pictures
and ghosting. Telecommunication remains an important part of the world economy and
the telecommunication industry’s revenue has been placed at just under 3% of the gross
world product.


telecommunication systems are two-way and devices act as both a transmitter and
receiver or transceiver. For example, a mobile phone is a transceiver. Telecommunication
over a phone line is called point-to-point communication because it is between one
transmitter and one receiver, telecommunication through radio broadcasts is called
broadcast communication because it is between one powerful transmitter and numerous
receivers.Signals can either be analogue or digital. In an analogue signal, the signal is varied
continuously with respect to the information. In a digital signal, the information is
encoded as a set of discrete values .

A collection of transmitters, receivers or transceivers that communicate with each other is
known as a network. An analogue network may consist of one or more switches that
establish a connection between two or more users. For both types of network, a repeater
may be necessary to amplify or recreate the signal when it is being transmitted over long
distances. This is to combat attenuation that can render the signal indistinguishable from
noise.A channel is a division in a transmission medium so that it can be used to send multiple
independent streams of data. For example, a radio station may broadcast at 96 MHz while
another radio station may broadcast at 94.5 MHz. In this case the medium has been
divided by frequency and each channel received a separate frequency to broadcast on.
Alternatively one could allocate each channel a recurring segment of time over which to broadcast.