Telecommunication

Telecommunication is the transmission of messages over significant distances, for the purpose of communication. Initially, telecommunications were configured through a centralized mainframe computer with remote dumb terminals. Later on, researchers started to investigate packet switching, a technology that allows chunks of data to be sent between different computers without first passing through a centralized mainframe. In an analog telephone network, the caller is connected to the person they want to talk to via various telephone exchanges. The switches form an electrical connection between the two users and the setting of these switches is determined electronically when the caller dials a number. Once the connection is made, the caller’s voice is transformed to an electrical signal using a small microphone in the caller’s handset.

There have been dramatic changes in telephone communication behind the scenes, starting with the widespread adoption of systems based on optic fibers. The benefit of communicating with optic fibers is the drastic increase in data capacity that they offer, as opposed to copper cables. Assisting communication across many modern optic fiber networks is a protocol known as Asynchronous Transfer Mode. The ATM protocol allows for side-by-side data transmission. It is suitable for public telephone networks because it establishes a pathway for data through the network and associates a traffic contract with that pathway. The traffic contract is an agreement between the client and the network about how the network is to handle the data. If the network cannot meet the conditions of the traffic contract, it does not accept the connection. This is important because telephone calls can negotiate a contract so as to guarantee themselves a constant bit rate, something that will ensure a caller’s voice is not delayed in parts or cut-off completely.

A basic telecommunication system consists of three primary units that are always present in some form: a transmitter that takes information and converts it to a signal, a transmission medium (also called the “physical channel” that carries the signal) and a receiver that takes the signal from the channel and converts it back into usable information. Telecommunication over telephone lines is called point-to-point communication because it is between one transmitter and one receiver. Telecommunications in which multiple transmitters and multiple receivers have been designed to cooperate and to share the same physical channel are called multiplex systems.

A communications network is a collection of transmitters, receivers, and communications channels that send messages to one another. Some digital communications networks contain one or more routers that work together to transmit information to the correct user. A communications channel is a physical medium that carries a signal between the transmitter and the receiver. A communication channel is also a subdivision of a transmission medium so that it can be used to send multiple streams of information simultaneously.

The shaping of a signal to convey information is known as modulation. Modulation can be used to represent a digital message as an analog wave form. It can also be used to transmit the information of low-frequency analog signals at higher frequencies. This is helpful because low-frequency analog signals cannot be effectively transmitted over free space, meaning that information from a low-frequency analog signal must be impressed into a higher-frequency signal before transmission.

In addition to usage in telephony, worldwide networks of computers can communicate with each other using the Internet Protocol. Any computer on the Internet has a unique IP address that can be used by other computers to route information to it. Hence, any computer on the Internet can send a message to any other computer using its IP address. These messages carry with them the originating computer’s IP address, allowing for two-way communication. The Internet is thus an exchange of messages between computers.

Related links

• Telephony - Plum IVR Glossary
• VoiceXML - Plum IVR Glossary