DEFINITION AND CONCEPT

                 BASIC TELEPHONY

1 DEFINITION AND CONCEPT

                

Telecommunication deals with the service of providing electrical communication at a distance. The service is supported by an industry that depends on a large body of increasingly specialized scientists, engineers, and craftspeople. The service

may be private or open to public correspondence (i.e., access). Examples of the latter are government-owned telephone companies, often called administrations or private corporations that sell their services publicly.

1.1 Telecommunication Networks

The public switched telecommunication network (PSTN) is immense. It consists of hundreds of smaller networks interconnected. There are “fixed” and “mobile “counterparts. They may or may not have common ownership. In certain areas of the world the wired and wireless portions of the network compete. One may also serve as a backup for the other upon failure. It is estimated that by 2005 there will be as many wireless telephones as wired telephones, about 5 × 109 handsets worldwide of each variety. These networks, whether mobile or fixed, have traditionally been based on speech operations. Meanwhile, another network type has lately gained great importance in the scheme of things. This is the enterprise network. Such a network supports the business enterprise. It can just as well support the government “enterprise” as a private business. Its most common configuration is a local area network (LAN) and is optimized for data communications;  The enterprise network also has a long-distance counterpart, called a WAN or wide area network. The U.S. Department of Defense developed a special breed of WAN where the original concept was for resource sharing among U.S. and allied universities.

Since its inception around 1987, it has taken on a very large life of its own, having been opened to public worldwide. It is the internet. Its appeal is universal, serving its original intent as a resources-sharing medium extending way beyond the boundaries of universities and now including universal messaging service called email (electronic mail).

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telecom - (often plural) systems used in transmitting messages over a distance electronically telecommunication sampling - measurement at regular intervals of the amplitude of a varying waveform (in order to convert it to digital form) electronic converter - (telecommunication) converter for converting a signal from one frequency to another loop gain - (telecommunication) the gain of a feedback amplifier or system as a function of how much output is fed back to the input; "if the loop gain is too great the system may go into oscillation" telecommunication - (often plural) the branch of electrical engineering concerned with the technology of electronic communication at a distance medium - a means or instrumentality for storing or communicating information telephony, telephone - transmitting speech at a distance telegraphy - communicating at a distance by electric transmission over wire wireless - transmission by radio waves broadcasting - taking part in a radio or tv program multiplex - communicates two or more signals over a common channel plural, plural form - the form of a word that is used to denote more than one sunrise industry - a new industry that is expanding rapidly (especially telecommunications or electronics) sampling rate - (telecommunication) the frequency of sampling per unit time Nyquist rate - (telecommunication) the lowest sampling rate that will permit accurate reconstruction of a sampled analog signal sampling frequency - (telecommunication) the frequency of sampling a continuously varying signal Nyquist frequency - (telecommunication) twice the maximum frequency occurring in the transmitted signal call - send a message or attempt to reach someone by radio, phone, etc.; make a signal to in order to transmit a message; "Hawaii is calling!"; "A transmitter in Samoa was heard calling"