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Hd radio

The meaning of «hd radio»

HD Radio (HDR)[1] is a trademarked term for the in-band on-channel (IBOC) digital radio technology. HD Radio is used by AM and FM radio stations – mostly in the United States, Canada, and Mexico, with a few implementations outside North America. The system transmits additional digital data associated with an existing radio station's standard analog signals, re-broadcasting the same signal in a digital format, with less noise. The digital data may also include up to three additional digital radio signals, which can be used to broadcast other stations within the same frequency allocation.

HD Radio allows for an all-digital mode. Three AM stations use it, one under experimental authorization, the other two under new rules adopted by the FCC in October 2020. All other AM radio and FM radio stations that use HD, simulcast both digital and analog audio on the same frequency (a hybrid digital-analog signal) as well as to add new subchannels and text information. HD Radio broadcasting's content is currently free-to-air, although prospective listeners still must purchase new receivers, in order to hear the digital content of the transmission.

iBiquity developed HD Radio™, and the system was selected by the U.S. Federal Communications Commission (FCC) in 2002 as a digital audio broadcasting method for the United States.[2][3] It is officially known as NRSC‑5, with the latest version being NRSC‑5‑D.[4]

iBiquity was acquired by DTS in September 2015 bringing the HD Radio™ technology under the same banner as DTS’s eponymous theater surround sound systems.[5] The HD Radio™ technology and trademarks were subsequently acquired by Xperi Holding Corporation in 2016.

HD Radio™ is one of several digital radio standards which are generally incompatible with each other:

By May 2018, iBiquity Digital Co. claimed its HD Radio technology was used by more than 3,500 individual services, mostly in the United States.[6] This compares with more than 2,200 services operating with the DAB system.

The bandwidth required for HD FM is increased to 400 kHz, for analog-digital hybrid transmission with extra sidebands. This makes adoption outside the United States problematic: In the United States, the FM channels are spaced 200 kHz apart, as opposed to the spacing elsewhere, which is normally 100 kHz. From long-standing FCC licensing practice, stations assigned to geographicly overlapping or adjacent coverage areas will be assigned frequencies separated by (at least) 400 kHz, in order to provide a further degree of protection against interference between stations on adjacent frequencies, than could be achieved with the 200 kHz spacing alone. Hence the wide 200 kHz U.S. spacing in combination with geographical separation means that the needed 400 kHz spacing already exists; the only impediment is the extent of cross-station interference can be prevented by the digital technology and / or tolerated in practice.[7] The extra space is used for the digital sidebands; outside the U.S., spacing can be 300 kHz, which causes problems with some of the sidebands.

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