1973 in April, marty cooper, an engineer and technician of the famous American Motorola Company, invented the world's first civil mobile phone. When Cooper made the world's first mobile phone, he could use any electromagnetic frequency band. The first generation of analog mobile phones is actually to distinguish different mobile phones of different users by different frequencies. The second generation mobile phone -GSM system distinguishes users with a very small time difference. At present, the frequency resources are obviously insufficient, and the number of mobile phone users is growing rapidly in geometric series. As a result, the updated CDMA technology, using different codes to distinguish different computers, came into being. The mobile phone using this technology not only has better call quality and confidentiality, but also can reduce radiation, which is called "green mobile phone".
Development history
1832, Faraday discovered the phenomenon of electromagnetic induction in England. Maxwell further expounded the research results of Faraday and others with mathematical formulas, and extended the theory of electromagnetic induction to space. More than 60 years later, Hertz confirmed the existence of electromagnetic waves in experiments. The discovery of electromagnetic waves has become the turning point from "wired communication" to "radio communication" and the origin of the whole mobile communication. As a scientist said, "Mobile phones were born on the shoulders of telegrams and telephones. Wireless communication is impossible without the efforts of predecessors.
124 May 844 [4]. Morse's telegram sent the first telegram from Washington to Baltimore in human history. "What a miracle God has created!" "
1On June 2, 875, Bell accidentally spilled sulfuric acid on his leg while doing the experiment. In pain, he shouted to his colleague in the other room, "Walter, come and help me!" " And this sentence was transmitted to the living ear of another room through the telephone in the experiment, which became the first sentence transmitted by telephone [5].
1902, an American named "Nathan Stubblefield" made the first wireless telephone equipment in his country house in Murray, Kentucky. This kind of wireless mobile communication telephone is the earliest exploration and research on "mobile phone" technology [6].
1940, Bell Laboratories made mobile phones.
1946, the first telephone call in the world was made in a moving car in St. Louis [7].
1957, Leonid, an outstanding engineer in the Soviet Union. Kupriyan Norwich invented лк- 1 mobile phone. In 1958, he further improved his mobile phone. The weight of the equipment is reduced from 3 kg to 500 g (including the battery weight), and the shape is simplified to the size of two cigarette cases, so that you can make a phone call anywhere in the city and connect any fixed telephone. By the early 1960s, the mobile phones in Norich, Kupriyan had been able to work effectively within 200 kilometers [8].