August 6, 2003

The advent of wireless telegraphy

The electric telegraph and the telephone gave a major boost to the development of telecommunications.

However, the use of cables to connect transmitters and receivers soon began to show its limitations. By the late 19th century, research was being conducted into electromagnetic waves. The laws of electromagnetic wave propagation showed that information could be transmitted without cables.

The advent of wireless telegraphy and telephony offered enormous potential, despite the poor quality of the first transmissions. Its many applications include the arrival of radiotelephony and the first cordless telephones, as well as radio equipment for maritime safety and military communications.

The relief of the Earth's surface and the huge distances involved (see picture) still posed a problem, though. Due to the number of relay stations required, the system soon proved expensive. It also had limited application for intercontinental links.

Electromagnetic waves travel in straight lines. The Earth, however, is round. This means that signals transmitted over long distances cannot reach the receiver, as the curve of the Earth's surface and other obstacles get in the way. To overcome this problem, relay stations are used.
Satellites make an ideal relay, and are also cheaper.

Following the launch of the first Sputnik satellite in 1957, the idea of using satellites orbiting the Earth as radio relays emerged as a natural solution to the problem. Thus began a revolution in telecommunications. The potential offered by satellites far exceeded anything offered by ground-based systems, and the last geographic limits were finally overcome.
Since then, numerous satellite-based telecommunications networks have been developed to meet growing demand in a wide range of specialist areas.

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