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(詳細はUnited States, the Class D Citizens' Radio Service, or Citizens' Band ("CB"), is one of several personal radio services defined by the FCC's Part 95 rules. It is intended to be a two-way voice communication service for use in personal and business activities of the general public, and has a reliable communications range of several miles, though the range is highly dependent on type of radio, antenna and propagation. Class A and B are no longer in existence (the frequencies were folded in to the GMRS radio service), Class C is a Radio Control ("R/C") model service and is covered further down in this article. CB Radio is most frequently used by long-haul truck drivers for everything from relaying information regarding road conditions, the location of speed traps and other travel information, to basic socializing and friendly chatter. ==Eligibility== There are no age, citizenship, or license requirements to operate a CB radio in the United States, and the service falls under the "License by Rule" part of the FCC rules (basically, if one follows the rules one is considered licensed). Operators may use any of the authorized 40 CB channels; however, channel 9 is used only for emergency communications or for traveler assistance and the higher number channels are almost exclusively SSB modulation. Use of all channels is on a shared basis. However, foreign governments and their representatives are not eligible to use citizens' band radio within the United States. Operation is permitted anywhere within the United States and its territories or possessions; as well as anywhere in the world except within the territorial limits of areas where radio services are regulated by a foreign government, or another U.S. agency such as the Department of Defense. Transmitters must be FCC certified and may not be modified, including modifications to increase output power or to transmit on unauthorized frequencies. Output power is limited to 4 watts for AM transmitters and 12 watts peak envelope power for single sideband (SSB) transmitters. The antenna may not be more than 20 feet (6.1 m) above the highest point of the structure it is mounted to, nor more than 60 feet (18.3 m) above the ground. AM and SSB modulation is used in the USA, some other countries have similar services in their countries that use FM. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「CB usage in the United States」の詳細全文を読む スポンサード リンク
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