Broadcasting is mainly used for the distribution of traffic and travel information. The Radio Data System (RDS) is a standard for sending small amounts of digital information using conventional FM radio broadcasts. RDS uses the technique of adding data at a bitrate of 1187.5 bps on an existing stereo transmission in a way that the data is carried inaudibly. The Traffic Message Channel (TMC) is a service of the RDS which provides traffic information coded according to the ALERT-C protocol. TMC messages are processed by in-vehicle RDS-TMC receivers which use this information to give route guidance considering the current traffic and weather conditions.
Digital Audio Broadcasting (DAB) is a technology for broadcasting audio in digital form. DAB was developed within the Eureka 147 Project and is now standardised by the European Telecommunications Standards Institute (ETSI). DAB uses the frequencies 47-68 MHz, 174-240 MHz and 1452-1492 MHz. The gross data capacity for the entire DAB signal is approximately 3 Mbps, of which approximately 2.3 Mbps can be used for data transmission. Considering redundancy in channel encoding, a net useful payload in the range of 0.6-1.7 Mbps is available. As the bitrates are magnitudes higher than those available with RDS-TMC, more sophisticated traffic and travel information can be broadcasted using DAB.