Frequency Allocation

My husband is looking for the following information about HD TV:?

What are the individual channel allocations for HD TV, i.e. Ch4 uses frequency A to B.

Is this what he is looking for?

US Television Stations
Digital Channel Allocations & Status

If so, click this link

http://www.hdpictures.com/stations2.htm

Frequency Allocation Chart $14.95

The history of mobile phones traces the development of handheld radio technology for your two-way radios attached to vehicles handheld computer and cell phones.

Two-way radios began to be used in motor vehicles such as taxis, police cars, ambulances, etc. That were not yet classified as mobile phones, which were not yet connected to the telephone network. That said, it was not possible to dial numbers your two-way radios. Later, a growing community of mobile phone users, who were known as the mobileers, popularized the technology that ultimately lead to the early mobile phone.

The first mobile phones were permanently installed in vehicles, but the versions that followed, known as transport or "bag phones" were equipped with a cigarette lighter plug so that it could also be transported, so it could be used as mobile or as two portable radios. In the 1940s, Motorola has designed two of backpacker two-way radio, walkie-talkies and later developed a large hand held two way radio for use by the U.S. military. This battery "Transmitter-Talkie" (HT) was great as a man's arm.

In December 1947, engineers at Bell Laboratories, Douglas H. Ring and W. Young Rae recommends hexagonal cells for mobile phones. Philip T. Porter also suggested that the towers at the corners of the hexagons rather than at the centers and have 3 directional antennas that receive in 3 adjacent hexagon cells. But the technology did not exist then and still does not exist any frequency allocated. It was not until the 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 has documented that in the first passenger train of its kind in Germany between Berlin and Hamburg in 1926. About the same time, also first introduced on passenger aircraft for traffic safety. It was also in Germany where the radio telephony was introduced on a large scale for the use of German tanks in World War II. Post-war German police use of tank telephony equipment used to run the first radio patrol in the British zone of occupation. . But the use of cars patrol radio service was limited to trained in using the equipment. Boats on the river Rhine were among the first to use radio telephony with an untrained end customer as a user, in the 1950s.

The MTA, which was the first fully automatic mobile phone system was developed by Swedish company Ericsson and was commercially launched in the country in 1956. It was the 1st system that does not require any manual control, but was on the heavy side of 40 kilos. An improved version, more agile, at 9 kg was introduced in 1965, called the MTB, it was with transistors and use DTMF. He had 150 customers during its initial launch, up to 600 when it closed in 1983.

In 1967, using a mobile phone neccessitated stay within the site cell throughout the phone call is made, which was attended by a base station. Due to the independent design of each cell site, this does not guarantee continuity of automatic telephone service to mobile phones moving through several cell areas. The call continuity while moves through various cell sites was possible, according to BBG Communications, in 1970 Amos Joel., The invention of another Bell Labs engineer an automated calling system relay, allowing this process.

AT & T, in December 1971, presented a proposal for cellular service to the Federal Communications Commission (FCC). In 1982, 11 years after presentation of the proposed AT & T, the FCC gave the adoption of advanced mobile services and allocation of frequencies in the 824-894 MHz band in 1990, analog AMPS was replaced by Digital AMPS.

About the Author:

Broderick Booth Goran

BBG Communications

Article Source: ArticlesBase.com – Bbg Communications: History of the Mobile Phone