Telegrafia

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Telegraphy is a historical form of communication that involves sending messages over long distances. This method of communication dates back to ancient times, with notable examples such as the signal towers on the Great Wall of China and the use of flag signaling by 200 BC. The advent of the electric telegraph in the mid-19th century, pioneered by inventors like Chappe and Morse, marked a significant shift in telegraphy. Telegraph systems, including telegrams, cablegrams, telex messages, wirephotos, and diplomatic telegrams, played a critical role in communication, particularly in the 19th century. Over the years, telegraphy evolved, with automated systems like teleprinters and punched tape transmission becoming popular. However, the rise of the internet[1] in the late 20th century led to the decline of traditional telegraph applications. Despite this, telegraphy’s legacy persists, especially in the continued use of the Morse code, a standard in telegraphy.

Definições de termos
1. internet. A Internet é um sistema global de redes informáticas interligadas que utilizam protocolos de comunicação normalizados, principalmente o TCP/IP, para ligar dispositivos em todo o mundo. Com origem no termo "internetted" utilizado em 1849, o termo "Internet" foi mais tarde utilizado pelo Departamento de Guerra dos EUA em 1945. O seu desenvolvimento começou com cientistas informáticos que criaram sistemas de partilha de tempo na década de 1960 e progrediu com a criação da ARPANET em 1969. A Internet é autónoma, sem uma autoridade central, e os seus principais espaços de nomes são administrados pela Internet Corporation for Assigned Names and Numbers (ICANN). Transformou significativamente os meios de comunicação tradicionais e tem crescido exponencialmente ao longo dos anos, com os utilizadores da Internet a aumentarem anualmente de 20% para 50%. Em 2019, mais de metade da população mundial utilizou a Internet. O conjunto de protocolos da Internet, que inclui o TCP/IP e quatro camadas conceptuais, orienta os pacotes da Internet para os seus destinos. Serviços essenciais como o correio eletrónico e a telefonia via Internet funcionam na Internet. A World Wide Web, uma coleção global de documentos interligados, é uma componente essencial da Internet.
Telegrafia (Wikipédia)

Telegrafia is the long-distance transmission of messages where the sender uses symbolic codes, known to the recipient, rather than a physical exchange of an object bearing the message. Thus flag semaphore is a method of telegraphy, whereas pigeon post is not. Ancient signalling systems, although sometimes quite extensive and sophisticated as in China, were generally not capable of transmitting arbitrary text messages. Possible messages were fixed and predetermined, so such systems are thus not true telegraphs.

Replica of a Chappe telegraph on the Litermont near Nalbach, Germany

The earliest true telegraph put into widespread use was the Chappe telegraph, an optical telegraph invented by Claude Chappe in the late 18th century. The system was used extensively in France, and European nations occupied by France, during the Napoleonic era. O electric telegraph started to replace the optical telegraph in the mid-19th century. It was first taken up in Britain in the form of the Cooke and Wheatstone telegraph, initially used mostly as an aid to railway signalling. This was quickly followed by a different system developed in the United States by Samuel Morse. The electric telegraph was slower to develop in France due to the established optical telegraph system, but an electrical telegraph was put into use with a code compatible with the Chappe optical telegraph. The Morse system was adopted as the international standard in 1865, using a modified Morse code developed in Germany in 1848.

O heliograph is a telegraph system using reflected sunlight for signalling. It was mainly used in areas where the electrical telegraph had not been established and generally used the same code. The most extensive heliograph network established was in Arizona and New Mexico during the Apache Wars. The heliograph was standard military equipment as late as Segunda Guerra Mundial. Wireless telegraphy developed in the early 20th century became important for maritime use, and was a competitor to electrical telegraphy using submarine telegraph cables in international communications.

Telegrams became a popular means of sending messages once telegraph prices had fallen sufficiently. Traffic became high enough to spur the development of automated systems—teleprinters e punched tape transmission. These systems led to new telegraph codes, starting with the Baudot code. However, telegrams were never able to compete with the letter post on price, and competition from the telephone, which removed their speed advantage, drove the telegraph into decline from 1920 onwards. The few remaining telegraph applications were largely taken over by alternatives on the internet towards the end of the 20th century.

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