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Radio Data System (RDS) is a communications protocol standard for embedding small amounts of digital information in conventional FM radio broadcasts. RDS standardizes several types of information transmitted, including time, station identification and programme information. The standard began as a project of the European Broadcasting Union (EBU), but has since become an international standard of the International Electrotechnical Commission (IEC). Radio Broadcast Data System (RBDS) is the official name used for the U.S. version of RDS.〔(【引用サイトリンク】url=http://www.nrscstandards.org/SG/nrsc-4-B.pdf )〕 The two standards are only slightly different. Both carry data at 1,187.5 bits per second on a 57-kHz subcarrier, so there are exactly 48 cycles of subcarrier during every data bit. The RBDS/RDS subcarrier was set to the third harmonic of the 19-kHz FM stereo pilot tone to minimize interference and intermodulation between the data signal, the stereo pilot and the 38-kHz DSB-SC stereo difference signal. (The stereo difference signal extends up to 38 kHz + 15 kHz = 53 kHz, leaving 4 kHz for the lower sideband of the RDS signal.) The data is sent with error correction. RDS defines many features including how private (in-house) or other undefined features can be "packaged" in unused program groups. ==Development== RDS was inspired by the development of the Autofahrer-Rundfunk-Informationssystem (ARI) in Germany by the Institut für Rundfunktechnik (IRT) and the radio manufacturer Blaupunkt. ARI used a 57-kHz subcarrier to indicate the presence of traffic information in an FM radio broadcast. The EBU Technical Committee launched a project at its 1974 Paris meeting to develop a technology with similar purposes to ARI, but which was more flexible and which would enable automated retuning of a receiver where a broadcast network transmitted the same radio programme on a number of different frequencies. The modulation system was based on that used in a Swedish paging system and the baseband coding was a new design, mainly developed by the British Broadcasting Corporation (BBC) and the IRT. The EBU issued the first RDS specification in 1984.〔 Enhancements to the alternative frequencies functionality were added to the standard and it was subsequently published as a European Committee for Electrotechnical Standardization (CENELEC) standard in 1990.〔 In 1992 the US National Radio Systems Committee issued the North American version of the RDS standard, called the Radio Broadcast Data System. The CENELEC standard was updated in 1992 with the addition of Traffic Message Channel and in 1998 with Open Data Applications〔 and, in 2000, RDS was published worldwide as IEC standard 62106. 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「Radio Data System」の詳細全文を読む スポンサード リンク
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