Buzz
The Radio Data System showcases the call letters of the radio station. Douglas Sacha / Getty ImagesIf your car radio displays FM station call signs directly on the screen, it means you have the Radio Data System feature. This system was initially developed by Swedish Telecom in 1976 to transmit data to radio pagers. In the early 1980s, the European Broadcasting Union transformed it into the Radio Data System (RDS). The U.S. National Association of Broadcasters (NAB) adopted a standard for it in 1993. The British Broadcasting System (BBC) is also a user of the system.
The Radio Data System (RDS) is widely available in many U.S. cities.
In the United States, FM radio stations are allocated 200 KHz of bandwidth (in Europe, it's 100 KHz). The station doesn't use all of this bandwidth for music. RDS is a completely separate radio signal that fits into the station's frequency allocation. It operates at a frequency of 57 KHz and has a data rate of 1187.5 bits per second (check out this useful diagram of the FM signal for more details). RDS transmits alongside the regular FM stereo (or monophonic) radio broadcast. It can carry data such as song titles, station call signs, and indicate when traffic or weather reports are being broadcast.
RDS was mentioned in this BBC article, which explains how a "pirate" radio station managed to send out a signal that "took over" many radios. On certain car radios, there is no simple way to turn off RDS — the only solution was to drive out of range of the interfering signal.
These resources will help you dive deeper:
- What is RDS?
- BBC Reception Advice: Radio Data System (RDS)
- An Introduction to RDS
- How Radio Works
- How the Radio Spectrum Works
- How Radio Scanners Work
- How Ham Radio Works
- Why do all FM radio stations end in an odd number?
- Why do some radio stations sound clearer at night than during the day?
