Radio Data System

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 program 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. The two standards are only slightly different, with receivers able to work with either system with only minor inconsistencies in the displayed data. RDS is only used on analog stations. The HD Radio equivalent is Program-associated data (PAD), now called Program service data (PSD). Both versions carry data at 1,187.5 bits per second (about 1.2 kbit/s) 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 38 kHz + 15 kHz = 53 kHz, leaving 4 kHz for the lower sideband of the RDS signal.) The data is sent with an error correction code, but receivers may choose to use it only for error detection without 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. Of the three broadcasting partners of the EBU, the BBC were reportedly pursuing the application of RDS technology most enthusiastically and sought to attract bids from manufacturers to make a "BBC-accredited radio" supporting RDS features. Having received no manufacturer interest, however, the corporation engaged designers at Kinneir Dufort to produce a prototype showcasing these features. This prototype, unveiled in 1989, incorporated a liquid-crystal display capable of showing images such as weather maps, accompanied by "a light pen with which the radio can be programmed from barcodes", these barcodes encoding programme information, and supported detachable modules, of which a cassette player module and a printer module were developed. Despite reluctance to develop screen-based functionality that might bring RDS into competition with television, the utility of being able to print out information such as weather maps or even advertising was regarded as potentially interesting to both radio and television manufacturers alike. 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 U.S. 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.

RDS2

The RDS-Forum (Geneva/CH) decided at its annual meeting (8–9 June 2015) in Glion/Montreux to bring the new standard RDS2 on the way. The standard will be created in close collaboration with U.S. colleagues from NRSC RBDS-Subcommittee and should offer a unified platform for FM broadcasting and data services worldwide.

Key features

Seamless support for frequencies from 64 MHz to 108 MHz (AF, EON) New character coding: UTF-8 (old EBU Charset remains for compatibility mode for the old 0A/2A Groups). New ODA (Open Data Applications) handling, "B" groups are assigned as signalling group to the "A" groups. Long PS-Name, up to 32 byte with UTF-8 character set. (Indian, Chinese, Arabic, and more) RadioText (eRT) 128 byte long with UTF-8 character set. Increased capacity from 11.4 up to 57 "A"-groups per second. (2,109 bit/s. net capacity with the single modulation-type multiple subcarriers (SMMS) technology) Graphical RadioText – supports HTML/CSS templates (for smartphones, car radios, computers/tablets) Supports return channel over gRT if the receiver has IP or SMS capability. Broadcaster's graphical logo – a maximum 4 kilobyte picture (JPEG, PNG, or GIF) Hybrid Radio feature (partly based on Radio France development)

Content and implementation

The following information fields are normally contained in the RDS data:

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