Glossary definition of RDS

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.

Phones tagged with RDS