在雅思阅读备考中,各位考生可以选择的练习教材比较多,其中真题对于考生来说参考意义比较大。今天小编为大家准备的是雅思阅读真题回忆-莫尔斯电码,这篇文章主要涉及到哪些背景知识呢?大家可以做一些阅读练习和积累。

  雅思阅读真题回忆:Morse Code莫尔斯电码

  Morse code ii being replaced by a new satellite-based system fo r sending distress calk at sea. Its dots and dashes have had a good run fo r their money.

  A "Calling all. This is our last cry before our eternal silence." Surprisingly this message, which flashed over the airwaves in the docs and dashes o f Morse code on January 31sr 1997, was not a desperate transmission by a radio operator on a sinking ship. Rather, it was a message signalling the end of the use o f Morse code for distress calls in French waters. Since 1992 countries around chc world have been decommissioning their Morse equipment with similar (if less poetic) signoffs, as the world's shipping switches over to a new sacellice-based arrangement, the Global Maritime Distress and Safety System. The final deadline for the switch-over co GMDSS is February 1st a date that is widely seen as the end o f an era.

  B The code has, however, had a good history. Appropriately for a technology commonly associated with radio operators on sinking ships, the idea o f Morse code is said co have occurred to Samuel Morse while he was on board a ship crossing the Atlantic. Ac chc time Morse was a painter and occasional inventor, but when another o f the ships passengers informed him o f recent advances in electrical theory, Morse was suddenly taken with the idea o f building an electric telegraph to send messages in codes. Ocher inventors had been crying co do ju st chat for the best part of a century. Morse succeeded and is now remembered as "the father o f the relegraph" partly thanks co his single-mindedness- it was 12 years, for example, before he secured money from Congress to build his first telegraph line— but also for technical reasons.

  C Compared w ith rival electric telegraph designs, such as the needle telegraph developed by William Cooke and Charles W heatstone in Britain, Morses design was very simple: it required lirtle more chan a Mkey" (essentially, a spring-loaded switch) co send messages, a clicking "sounder" to receive them, and a wire co link the two. But although M orses hardware was simple, there was a catch: in order co use his equipment, operators had to learn the special code o f dors and clashes chat still bears his name. Originally, Morse had not intended co use combinations of docs and dashes co represent individual letters. H is first code, sketched in his notebook during chat cransarlanric voyage, used dors and clashes to represent che digits 0 to 9. M orses idea was that messages would consist o f strings of numbers corresponding co words and phrases in a special numbered dictionary. But Morse later abandoned this scheme and, with che help o f an associate, Alfred Vail,devised the Morse alphabet, which could be used co spell out messages a letter at a time in docs and clashes.

  D At first, the need to learn this complicated-looking code made Morses telegraph seem impossibly rricky compared with other, more user-friendly designs. Cookes and Wheatstones telegraph, for example, used five needles to pick ouc letters on a diamond-shaped grid. But although this meant that anyone could use it, it also required five wires berween telegraph stations. Morses telegraph needed only one. And some people, it soon transpired, had a natural facility for Morse code.

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