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chat-allday.MyForum.ro
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Otravitus
Administrator
Data inscrierii: 28/Apr/2008
Mesaje: 231
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 Trimis: 02/08/2008 22:35 Titlul subiectului: Telefonia mobila |
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Stiati ca…?
Prima generatie de telefoane mobile (AMPS si NMT) a aparut in Japonia, in anul 1979? Dupa 12 ani, in 1991, apare generatia a doua de echipamente de telefonie mobila (GSM, CDMA si TDMA) , in Finlanda (de unde provine si Nokia, renumitul producator de telefoane mobile). Actuala generatie, a treia (3G), a aparut tot in Japonia in anul 2001
Transmitatorul incorporat in telefonul mobil poate oferă informatii catre antenele terestre la o distanta de maxim 13 kilometri? Pentru majoritatea telefonelor mobile, raza de actiune este situata intre valorile 8-13 kilometri.
denumirea populara de “telefon celular” este data de forma structurii din care este alcatuita o retea de telefonie mobila? Transmitatoarele GSM sunt asezate in forma de fagure, fiecare acoperind o portiune de cativa kilometri in jurul sau. |
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alohafromhell
Membru junior
Data inscrierii: 08/Aug/2008
Mesaje: 102
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| Trimis: 10/08/2008 11:19 Titlul subiectului: |
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| ce m-asi face io fara telefonie mobila...:-< :whistle: |
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Brutal
Membru junior
Data inscrierii: 13/Apr/2009
Mesaje: 73
Localitate: Tg-mures
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| Trimis: 13/04/2009 13:33 Titlul subiectului: |
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Ai uitat cate ceva:
First generation:
Main article: 1G
On April 3, 1973, Motorola employee Dr. Martin Cooper placed a call to a rival, Dr. Joel S. Engel, head of research at AT&T's Bell Labs, while walking the streets of New York City talking on the first Motorola DynaTAC prototype in front of reporters. Motorola has a long history of making automotive radio, especially two-way radios for taxicabs and police cruisers.
In 1978, Bell Labs launched a trial of the first commercial cellular network in Chicago using AMPS [1], but this network was not approved by the FCC until 1982.
The first commercial launch of cellular telecoms was launched by NET in Tokyo Japan in 1979. In 1981 the NMT system was launched in Denmark, Finland, Norway and Sweden.
The first handheld mobile phone in the US market was the Motorola_Dyna 8000X, which received approval in 1983.
Mobile phones began to proliferate through the 1980s with the introduction of "cellular" phones based on cellular networks with numeroase base stations located relatively close to each other, and protocols for the automated "handover" between two cells when a phone moved from one cell to the other. At this time analog transmission was in use in all systems. Mobile phones were somewhat larger than current ones, and at first, all were designed for permanent installation in vehicles (hence the term car phone). Soon, some of these bulky units were converted for use as "transportable" phones the size of a briefcase. Motorola introduced the first truly portable, hand held phone. These systems (NMT, AMPS, TACS, RTMI, C-Net, and Radiocom 2000) later became known as first generation (1G) mobile phones.
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