(1) See also HD audio.
(2) (Hybrid Digital RADIO) Digital audio broadcasting (DAB) from iBiquity Digital Corporation, Columbia, MD (www.ibiquity.com). HD Radio provides the digital technology for AM/FM stations in the U.S, while Europe uses the Eureka DAB system for AM/FM (www.worlddab.org) as well as Digital Radio Mondiale for AM (www.drm.org). Digital radio provides an improvement in sound quality over traditional analog radio.
HD Radio simultaneously transmits a digital version of the analog broadcast and also provides a second digital channel, which can be used for alternate radio programming or data services such as song information, weather reports and car navigation updates.
In-Band On-Channel (IBOC)
HD Radio transmits the digital signals in unused portions of the same channel as the analog AM and FM signals (in-band on-channel). As a result, radios are more easily designed to pick up both signals, which is why the HD in HD Radio stands for "hybrid digital," not "high definition." HD Radios tune into the station's analog signal first and then look for a digital signal.
The European DRM system shares channels similar to HD Radio, but the European DAB system uses different frequencies for its digital transmission.
History
iBiquity was formed in 2000 as a merger of Lucent spinoff Lucent Digital Radio and USA Digital Radio. Lucent's progress with radio receivers was combined with USA Digital's advancements at the transmitter side, making an excellent marriage of technologies and a way to avoid a dual standard war. The original iDAB brand was changed to HD Radio in 2001, and on November 11, 2002, Detroit's WDMK was the first radio station to broadcast HD Radio. See iTunes tagging.
Transmitting updates to a car navigation system is one type of data service that HD Radio can provide.
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