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switching

Discuss the transition from an analogue to digital PSTN environment and give rough dates for each development.

The first electrical telecommunications were transmitted by the wire telegraph, invented by Samuel Morse in the 1830s. The telegraph utilized the interruption or reversal of a direct current electrical circuit to cause a remote sounder to produce a click at the beginning and end of each interruption or reversal. A short interval between clicks was called a “dot,” and a longer interval (about three dot intervals in length) was called a “dash.”
Messages were transmitted by sending dots and dashes in conformance to the Morse code, which represented letters of the alphabet, numbers, and punctuation marks by combinations of dots and dashes. As many as six dots and dashes in combination were used to represent one character, and maximum sounder speed was around four clicks per second, resulting in a maximum transmission rate of about 20 words per minute. The messages were...

Posted by: Asare Mabel

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