Chapter 4.14 - Radio Broadcast Data System

Abstract

Radio Broadcast Data System (RBDS) is the official name used for the U.S. version of the Radio Data System (RDS) Standard, which was first adopted in 1993 by the National Radio Systems Committee (NRSC) and revised in 1998 and in 2005. 1 RDS is a standard originally adopted by the European Broadcasting Union (EBU) for transmitting low bit rate (on the order of one kilobyte per second) digital information to appropriate receivers using conventional FM radio broadcasts. The RDS system standardizes several types of information transmitted, including time and station identification. RDS has been a standard in Europe since the mid 1980s. The two standards (RDS and RBDS) are nearly identical, with only slight differences, mainly in which numbers are assigned to each of 31 musical and other program formats. Both use a 57 kHz subcarrier to carry data at 1187.5 bits per second. The 57 kHz frequency was chosen for being the third harmonic (3×) of the 19 kHz 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 utilizes error correction. RDS defines many features, including how private (inhouse) or other undefined features can be “packaged” in unused program groups.