What you need to know about HD Radio™
The new sound in radio
Ralph Graves is one of Crutchfield's blog editors, and part of the company's social media team. He writes about home audio/video gear, specializing in Apple-related and wireless technologies. Ralph holds a master's degree in music composition, and his works have been released on various labels. He's served as product manager for an independent classical and world music label, produced several recordings, and worked extensively in public broadcasting. Since 1984 he's hosted a weekly classical music program on WTJU, and is also active as a blogger and podcaster.
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Robert Ferency-Viars is the managing editor for the Crutchfield car A/V learning content, and has been with the company since 1999. A Virginia native from the heart of the Blue Ridge Mountains, he loves spending time with his wonderful wife and sons, listening to music, writing, and playing games with friends. Robert's love for car audio began at 16 when he installed his first car stereo.
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What is HD Radio?
HD Radio technology allows broadcasters to transmit a high-quality digital signal. For listeners who have an HD Radio receiver, the benefits are:
- FM radio that sounds almost as good as a CD
- AM radio that sounds as good as traditional FM
- No more static, pops, crackles or fades
- Transmission of additional information, such as song titles and artists
- Increased listening options with multicasting
- Tagging songs for later purchase through the iTunes® Store
Let's take a look at each of these in turn.
FM radio with near CD-quality sound
Digital technology allows a radio station to transmit more information in the same radio wave. Primarily, this means higher quality sound. So much more so that FM transmissions can sound nearly as good as CDs, and definitely much better than the hollow sounds of old analog FM. How much better the music sounds will depend on your local stations and your radio gear.
AM radio that sounds as good as FM Stereo
AM radio uses smaller sections of bandwidth than FM. There is not enough bandwidth for HD Radio to give AM stations the same CD-quality signal as FM stations. But there is enough room to give AM stations clarity equivalent to current analog FM stereo radio. This boost in sound quality is expected to make AM radio a viable alternative to FM, which means more options for listeners.
No more static, pops, crackles or fades
The digital signal is less vulnerable to reception problems. The radio tuner's digital processors eliminate the static, pops, hisses, and fades caused by interference. You hear only clear, clean, rich sound. Should you lose the digital signal for some reason (obstructing terrain, nearing the edge of the broadcast area, etc.), HD Radio technology defaults back to analog mode, similar to the way current radios switch from stereo to mono mode when receiving a weak signal.
Transmission of additional information
Another benefit of digital radio is the radio station's ability to transmit additional information along with the music signal. This can take the form of scrolling text on your receiver's display, such as a song's artist and title, station call letters, and so on. Stations can also include local and regional information, such as weather updates or even traffic alerts. HD Radio also supports Artist Experience. With compatible receivers you can view album art, logos, and more, when provided by the station.
In addition to duplicating their analog programming with an HD Radio broadcast, stations can subdivide the digital portion of their signal. This allows a station to "multicast" — that is, broadcast two or more programs simultaneously. Listeners might have a choice of, say, a sports game or music. These additional channels can only be received on an HD Radio tuner. But just as cable TV allowed specialized networks to flourish, multicasting provides the potential for stations to offer more niche programming — ultimately giving the listener a greater variety of formats to choose from.
Some stations are broadcasting a tag-enabled HD Radio signal, which let you select a song for purchasing at a later time simply by "tagging" it. To take advantage of this feature, you need three things: an iPhone or iPod, an audio/video component that includes an HD Radio tuner, iPod dock and "Tag" button; and a local radio station that's broadcasting an HD Radio signal that has enabled tagging.
As you're listening, just press the "Tag" button when you hear a song you'd like to buy. The component saves the song information in its memory (but not the song itself). When you dock your iPod to the device, the information automatically transfers to your iPod. The next time you sync your iPod to your computer, a list of the songs you tagged will appear, giving you the option of purchasing them through the iTunes Store. The tagged songs you elect to purchase are then downloaded to your PC's iTunes library, and copied to your iPod.
The technology behind HD Radio
A company called iBiquity Digital has created the technology to make this happen. They license this technology to radio stations and consumer electronics manufacturers.
Unlike the conversion to digital television, consumers have a choice of whether to participate in the upgrade. In contrast to the television industry, where the analog signal was turned off by Federal decree, radio stations will continue to broadcast the analog signal along with the new digital signal. If we choose to not upgrade our radios, we can still listen to analog AM and FM radio — although we'll be missing out on the digital-only features and multicasting channels.
How does it work?
HD Radio technology works pretty much just like traditional analog radio transmission:
- The radio station sends out the analog and digital radio signals, along with a third signal for text data.
- The digital signal is compressed before being transmitted.
- The three-layered signal is transmitted from the radio station's upgraded digital transmitter.
- Multipath interference, caused by the signal reflecting off of buildings, is ignored by the digital radio, which is able to discern the true signal and ignore interference.
- Your radio receives the signal and, depending on your equipment, you hear either the digital or analog feed.
What HD Radio technology is not
HD Radio technology is not a subscription service, like satellite radio. It is the same free, over-the-air broadcast radio that we've always known. Only better. It is not something that consumers have to buy into. Everyone can choose to continue listening to their current radios, but eventually all AM/FM radios will incorporate digital technology. It is a natural evolution of the medium.
HD Radio is not the same as satellite radio. Rather, it's an improvement to terrestrial AM and FM radio. Satellite radio, on the other hand, is an alternative to broadcast radio, in the same way that cable or satellite TV are alternatives to broadcast television. Even if you do have satellite radio, there are often times when you want to listen to your local station — and that's where HD Radio comes in.
Hear it for yourself
If you want to join the digital radio world, it'll mean spending a little more for a new HD Radio compatible car stereo system or a home stereo HD Radio component than for comparable systems without the HD Radio option. But prices continue to decrease as more manufacturers enter the HD Radio receiver market. HD Radio receivers are being offered as optional equipment in an increasing number of new automobiles.
Find the new sound in your town
You can go to hd-radio.com to see the stations in your area that are on-the-air with HD Radio, as well as those stations that have licensed the technology and will eventually be broadcasting with it.
Now that HD Radio tuners and receivers are commercially available, more radio stations are investing in the upgrade. They want to keep up with the enhanced sound quality of digital radio. And whether we upgrade right away or wait until our next vehicle has a built-in HD Radio receiver, we, as listeners, win.