Advantages of Morse Code In the modern age, the Morse code is still as relevant as it was in the days of old. Here are the advantages of Morse code. Cheap


Download 0.84 Mb.
bet10/15
Sana18.06.2023
Hajmi0.84 Mb.
#1593657
1   ...   7   8   9   10   11   12   13   14   15
Bog'liq
Документ Microsoft Word

Teleprinters[edit]


Main articles: Teleprinter and Telex



This section needs additional citations for verification. Please help improve this article by adding citations to reliable sources in this section. Unsourced material may be challenged and removed. (January 2020) (Learn how and when to remove this template message)


Phelps' Electro-motor Printing Telegraph from circa 1880, the last and most advanced telegraphy mechanism designed by George May Phelps

A Creed Model 7 teleprinter in 1930

Teletype Model 33 ASR (Automatic Send and Receive)
An early successful teleprinter was invented by Frederick G. Creed. In Glasgow he created his first keyboard perforator, which used compressed air to punch the holes. He also created a reperforator (receiving perforator) and a printer. The reperforator punched incoming Morse signals onto paper tape and the printer decoded this tape to produce alphanumeric characters on plain paper. This was the origin of the Creed High Speed Automatic Printing System, which could run at an unprecedented 200 words per minute. His system was adopted by the Daily Mail for daily transmission of the newspaper contents.
With the invention of the teletypewriter, telegraphic encoding became fully automated. Early teletypewriters used the ITA-1 Baudot code, a five-bit code. This yielded only thirty-two codes, so it was over-defined into two "shifts", "letters" and "figures". An explicit, unshared shift code prefaced each set of letters and figures. In 1901, Baudot's code was modified by Donald Murray.
In the 1930s, teleprinters were produced by Teletype in the US, Creed in Britain and Siemens in Germany.
By 1935, message routing was the last great barrier to full automation. Large telegraphy providers began to develop systems that used telephone-like rotary dialling to connect teletypewriters. These resulting systems were called "Telex" (TELegraph EXchange). Telex machines first performed rotary-telephone-style pulse dialling for circuit switching, and then sent data by ITA2. This "type A" Telex routing functionally automated message routing.
The first wide-coverage Telex network was implemented in Germany during the 1930s[67] as a network used to communicate within the government.
At the rate of 45.45 (±0.5%) baud – considered speedy at the time – up to 25 telex channels could share a single long-distance telephone channel by using voice frequency telegraphy multiplexing, making telex the least expensive method of reliable long-distance communication.
Automatic teleprinter exchange service was introduced into Canada by CPR Telegraphs and CN Telegraph in July 1957 and in 1958, Western Union started to build a Telex network in the United States.[68]

Download 0.84 Mb.

Do'stlaringiz bilan baham:
1   ...   7   8   9   10   11   12   13   14   15




Ma'lumotlar bazasi mualliflik huquqi bilan himoyalangan ©fayllar.org 2024
ma'muriyatiga murojaat qiling