Sunday, January 18, 2009

Cell Phone History

The history of mobile phones traces the development of handheld radio telephone technology from two-way radios appended to vehicles and handheld cellular telephones.

Two-way radios started to be in use in motor vehicles like taxicabs, police cruisers, ambulances, and the like. They weren't yet classified as cell/mobile phones since they were not yet connected to the phone network. That being said, it was not possible to dial phone numbers from two-way radios. Later, a growing community of mobile radio users, who were known as the mobileers, popularized the technology that would eventually lead to the early mobile phone.

The first mobile phones were permanently installed in vehicles, but the versions that followed such as the so-called transportables or "bag phones" were equipped with a cigarette lighter plug so that they could also be carried, and thus could be used as either mobile or as portable two-way radios. In the early 1940s, Motorola has designed a backpacked two-way radio, the Walkie-Talkie and later developed a large hand-held two-way radio for the use of the US military. This battery powered "Handie-Talkie" (HT) was as big as a man's forearm.

In December 1947, Bell Labs engineers Douglas H. Ring and W. Rae Young recommended hexagonal cells for mobile phones. Philip T. Porter, also of Bell Labs, proposed further that the cell towers be at the corners of the hexagons rather than at the centers and have three-directional antennas that would transmit/receive (see picture at right) into 3 adjacent hexagon cells. But the technology did not exist yet then and there was not yet any frequency allocated. It was not until the early 1960s when cellular technology was introduced by Richard H. Frenkiel and Joel S. Engel of Bell Labs.

The first use of radio telephony in Europe was documented to be on the first-class passenger trains in Germany between Berlin and Hamburg in 1926. At about the same time, it was also introduced on passenger airplanes for air traffic security. It was also in Germany where radio telephony was introduced on a large scale, for the use of German tanks in the Second World War. Post-war, the German police made use of unused tank telephony equipment to run the first radio patrol cars in the British zone of occupation. . But the use of radio patrol cars service was limited to trained specialists on the use of the equipment. Ships on the River Rhine were among the first to use radio telephony with an untrained end customer as a user, in the early 1950s.

The MTA, which was the first fully automatic mobile phone system, was developed by the Swedish company Ericsson and was commercially released in the country in 1956. It was the 1st system that didn't need any kind of manual control, but was at the heavy side of 40 kilo's. A leaner upgraded version, at 9 kgs was introduced in 1965, called the MTB, which was with transistors and utilized DTMF signaling. It had 150 customers during its initial launch, up to 600 when it shut down in 1983.

In 1967, the use of a mobile phone neccessitated staying within the cell site all throughout the phone call is made, which was serviced by one base station. Because of the stand-alone design of each cell site, this did not provide continuity of automatic telephone service to mobile phones moving through several cell areas. Continuity of calls while moving through several cell sites was made possible in 1970 with Amos E. Joel, Jr., another Bell Labs engineer’s invention of an automatic call handoff system, which allowed this process.

AT&T, in December 1971, submitted a proposal for cellular service to the Federal Communications Commission (FCC). In 1982, 11 years after AT&T’s proposal submission, the FCC gave its approval for an Advanced Mobile Phone Service and allocated frequencies in the 824-894 MHz band. In 1990, Analog AMPS was replaced by Digital AMPS.

 

 

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