Radio Data System
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Radio Data System, or RDS, is a communications protocol standard from the European Broadcasting Union for sending small amounts of digital information using conventional FM radio broadcasts. The RDS system standardises several types of information transmitted, including time, track/artist info and station identification. RDS has been standard in Europe and Latin America since the early 1990s, but less so in North America.
Radio Broadcast Data System is the official name used for the U.S. version of RDS, though the "RDS" name seems to be at least as common in usage. The two standards are nearly identical, with only slight differences, mainly in which numbers are assigned to each of 31 musical and other program formats the RBDS system can identify. RBDS was approved by the NRSC, RDS by the EBU.
Both use a 57kHz subcarrier to carry data at 1187.5 bits per second. The 57 kHz was chosen for being the third harmonic (3×) of the pilot tone for FM stereo, so it would not cause interference or intermodulation with it, or with the stereo difference signal at 38 kHz (2×). The data format utilises error correction. RDS defines many features (see below), including how private (in-house) or other undefined features (such as differential GPS) can be "packaged" in unused program groups.
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[edit] Content and implementation
The following information fields are normally contained in the RDS data:
- AF
- Alternative Frequencies This allows a receiver to re-tune to a different frequency providing the same station when the first signal becomes too weak (e.g. when moving out of range). This is often utilised in car stereo systems.
- CT
- Clock Time Can synchronise a clock in the receiver or the main clock in a car. Due to transmission vagaries, CT can only be accurate to within 100 ms of UTC.
- EON
- Enhanced Other Networks Allows the receiver to monitor other networks or stations for traffic programmes, and automatically temporarily tune into that station.
- PI
- Programme Identification This is the unique code that identifies the station. Every station receives a specific code with a country prefix. In the US, PI is determined by applying a formula to the station's call sign.
- PS
- Programme Service This is simply an eight-character static display that represents the call letters or station identity name. Most RDS capable receivers display this information and, if the station is stored in the receiver's presets, will cache this information with the frequency and other details associated with that preset.
- PTY
- Programme Type This coding of up to 31 pre-defined programme types – e.g. (in Europe): PTY1 News, PTY6 Drama, PTY11 Rock music, – allows users to find similar programming by genre. PTY31 seems to be reserved for emergency announcements in the event of natural disasters or other major calamities.
- REG
- Regional This is mainly used in countries where national broadcasters run "region-specific" programming such as regional opt-outs on some of their transmitters. This functionality allows the user to "lock-down" the set to their current region or let the radio tune into other region-specific programming as they move into the other region.
- RT
- Radio Text This function allows a radio station to transmit a 64-character free-form textual information that can be either static e.g. station slogans or in sync with the programming such as the title and artist of the currently-playing song.
- TA, TP
- Traffic Announcement, Traffic Programme The receiver can often be set to pay special attention to this flag and e.g stop the tape/pause the CD or retune to receive a Traffic bulletin. The TP flag is used to allow the user to find only those stations that regularly broadcast traffic bulletins whereas the TA flag is used to stop the tape or raise the volume during a traffic bulletin.
- TMC
- Traffic Message Channel Requires an RDS-TMC enabled decoder, and appropriate license-paid software.
[edit] RDS support
As far as implementation is concerned, most car stereos will support at least AF, EON, REG, PS and TA / TP.
- More expensive car stereos will offer TMC, RT and / or PTY, perhaps with "NEWS" override.
- Home systems, especially hi-fi receivers, will mainly support functions like PS, RT and PTY.
There are a growing number of RDS implementations in portable and navigation devices thanks to lower priced, small footprint solutions. The Apple iPod's Radio Remote accessory is one such device. Others include Griffin Technology's iTrip AutoPilot, Navigon 5100, Magellan Maestro 4250, Microsoft Zune, Insignia NS-8V24, NS-4V24, NS-2V17, Garmin Nuvi360, Sony Ericsson K600i,K550i, K750i, K790i, K800i, K810i, W200i, W300i, W380i , W600i, W610i, W660i, W810i, W830i, P990i, W850i, W890i, W950i, W700i, and Z550i, Motorola L9, E6, E2, W375,W230,W270, L6i and W220, Nokia 6500 slide, 5310, 5610, N96, 6220 classic and 6300i, LG Viewty, LG KS-20, O2 ATOM LIFE,Samsung SGH-F330, SGH-G800, SGH-L170, SGH-E950 and SGH-U900.
[edit] Program Types
The following table lists the RDS and RBDS Program Type codes and their meanings:
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PTY code RDS Programme type (EU) RBDS Program type (USA) 0 No programme type or undefined No program type or undefined 1 News News 2 Current affairs Information 3 Information Sports 4 Sport Talk 5 Education Rock 6 Drama Classic Rock 7 Culture Adult Hits 8 Science Soft Rock 9 Varied Top 40 10 Pop Music Country 11 Rock Music Oldies 12 M.O.R. Music Soft 13 Light classical Nostalgia 14 Serious classical Jazz 15 Other Music Classical 16 Weather Rhythm and Blues 17 Finance Soft Rhythm and Blues 18 Children’s programmes Language 19 Social Affairs Religious Music 20 Religion Religious Talk 21 Phone In Personality 22 Travel Public 23 Leisure College 24 Jazz Music Unassigned 25 Country Music Unassigned 26 National Music Unassigned 27 Oldies Music Unassigned 28 Folk Music Unassigned 29 Documentary Weather 30 Alarm Test Emergency Test 31 Alarm Emergency
[edit] Example RDS Usage
The following three images illustrate how RDS can be used on an FM radio station, the latter two were taken when the radio was tuned to Nottingham radio station 96 Trent FM. All the images are of the display on the Sony XDR-S1 DAB/FM/MW/LW portable radio.
It should be noted that the use of scrolling PS is not recommended, given the potential of distracting drivers on the road.[citation needed] This has, however, become common in the US.
[edit] FM subcarrier usage
In addition, RDS is being proposed as the data transmission protocol in California's pioneering "programmable communicating thermostat" (PCT) program. This would allow signals from the state or utility to offset temperature settings during grid "price events" or completely override occupant temperature setpoints during "emergency events." The technology can be extended to other home electricity consuming devices such as hot water heaters, clothes dryers, dishwashers, pool pumps, etc allowing extensive state or utility control of residential and business electricity consumption as part of energy efficiency "demand response" programs. The hope is that consumption of electricity can be thus rationed as an alternative to building more generation capacity.
RDS sub carrier use for the control of peak power has been in development in Australia since early 2000. ETSA the South Australia Electricity Trust and Saab Systems Australia a local South Australian company pioneered the idea after Trent Ryan a Saab engineer developed the idea in late 1999 and brought it to Saab for further refinement.
[edit] RDS chipsets
Companies such as Silicon Labs in Austin, Texas and NXP Semiconductors (formerly Philips) offer single chip solutions that are found in these devices. The Silicon Labs part supports PS, RT, PTY, TMC, and all other RDS types in a single 3x3 chip and its intended purpose is portable usage (such as mobile phones and MP3 players). NXP also has solutions in this field, and has some automotive chips.
[edit] References
- The Directory of European FM Broadcasting, European FM Handbook 2002-2003, 13th edition, published July 1st 2002, B5 format, ISBN 951-98733-1-7 [1]
- Dietmar Kopitz, Bev Marks, RDS: Radio Data System (Mobile Communications Library), ISBN 0-89006-744-9 [2]
[edit] See also
High-level RDS APIs
- Advanced Multimedia Supplements (JSR-234) (in Java programming language)
- OpenMAX AL (in C programming language)
Related technologies
Related topics
[edit] External links
- The RDS Forum is the professional association of the users of the Radio Data System broadcast technology
- BBC factsheet - Radio Data System (RDS) in HTML format
- RDSList.com
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