HD Radio is a broadcast technology that digitizes radio signals and sends them over the same frequencies that currently carry analog broadcast radio signals. HD Radio broadcasts can transmit sound that is practically CD-quality, without any static or hiss.
The way it works is the bundled analog and digital signals (the latter signals are compressed) are sent to a digital broadcast antenna. The digital broadcast antenna then broadcasts the signal over a large area so that it can be picked up by homes and vehicles that are equipped with HD Radio receivers. The reason the signals are hiss-free is because the HD Radio receivers are designed to weed out any distortion, hisses and other forms of static that tend to plague analog radio signals.
One nifty feature for HD Radio recipients comes thanks to the digital signal being, well, digital. The digitized signal can pack with it all manner of text data -- anything from song titles and artist information to stock market quotes and traffic updates. HD Radio listeners, then, don't have to wonder who sang the song they just heard and loved, or hope in vain that the disc jockeys might actually imagine that not everyone already knows the song.
The broadcasts themselves are free to listeners, so long as they have an HD Radio receiver. The receivers can be ordered factory-installed from more than a dozen automobile manufacturers and they can otherwise be purchased at thousands of U.S. retail outlets, at prices starting as low as around $40 [source: HD Radio.com].
Ironically, readers would be remiss to think it's just "high definition TV for radio." Technically, the initials in HD Radio do not stand for high definition. "HD Radio" is instead a trademarked name belonging to iBiquity Digital Corp. that represents the company's IBOC (in-band on-channel) digital audio broadcasting technology [source: Crutchfield Advisor].
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