关于手机发明和用途的英语作文

Before the devices that are now referred to as mobile phones existed,there were some precursors.The development of mobile telephony began in 1918 with tests of wireless telephony on military trains between Berlin - Zossen.In 1924 public trials started with telephone connection on trains between Berlin - Hamburg.In 1925 Zugtelephonie A.G.is founded to supply train telephony equipment[8] and in 1926 telephone service in trains of the Deutsche Reichsbahn and imperial post on the route between Hamburg and Berlin is approved and used.[8] This phone service was only offered to 1st class travelers,but in 1918,some 5 years after the invention of Meißnerischen tube based transmitters,the German Reichsbahn in Berlin led experiments with telephony via radio.
The first mobile telephone calls were made from automobiles in 1946.The Bell System's - Mobile Telephone Service - inaugural call was made on 17 June of that year in St.Louis,Missouri,followed by Illinois Bell Telephone Company's car radiotelephone service in Chicago on 2 October.The MTS phones were composed of vacuum tubes and relays,and weighed over 80 pounds (36 kg).There were initially only 3 channels for all the users in the metropolitan area,increasing later to 32 channels across 3 bands.This service continued into the 1980s in large portions of North America.Due to the small number of radio frequencies available,the service quickly reached capacity.In 1956,the world’s first partly automatic car phone system,Mobile System A (MTA),was introduced in Sweden.
Mobile phones are used for a variety of purposes,including keeping in touch with family members,conducting business,and having access to a telephone in the event of an emergency.Some people carry more than one cell phone for different purposes,such as for business and personal use.Multiple SIM cards may also be used to take advantage of the benefits of different calling plans—a particular plan might provide cheaper local calls,long-distance calls,international calls,or roaming.The mobile phone has also been used in a variety of diverse contexts in society.Today you can hardly find someone without a mobile phone.