Radio Data System (RDS) is a communications protocol standard for embedding small amounts of digital information in conventional FM radio broadcasts. RDS enables FM radio stations to send additional information along with the regular program signal. Radios and tuners with the RDS logo and wording are able to receive and display RDS information, which will often include the station name, current time, or name of a program currently being broadcast. RDS is used on VHF FM radio broadcast transmissions and provides a number of facilities that are of great use to all radio listeners, but particularly to those radio listeners in cars. RDS enables traffic reports to be received more easily and provides many facilities, including enabling the radio station name to be displayed on the radio display. The following information fields are normally contained in the RDS data:

• AF (alternative frequencies list): A list of alternative frequencies for the same station, which can be used to maintain a good signal when driving long distances.

• Program Service (PS): A short name for the station, up to eight characters long.

• Program Type (PTY): A code indicating the type of program being broadcast, such as news, sports, or music.

• Radio Text (RT): A message that can scroll across the radios display, up to 64 characters long, which can include things like sports scores, song titles, artist or album names, even advertisements.

RDS is widely used in Europe and is increasingly popular in the Far East and North America. Over 700 radio stations in the United States, most of them in major metropolitan markets, now broadcast RDS information on a regular basis.