By Mark Kalan
Last year the FCC mandated that television broadcasters upgrade to new digital technology. If you had an older television set and were not connected to a cable or satellite system then you needed a decoder box to get the signal. There were many news stories about the change and lots of talking heads whining about it on, where else, television.
Meanwhile many AM and FM radio stations have been quietly upgrading their transmitters to new HD standards. This upgrade was not mandated by the government, as was the upgrade to digital television.
Before I go on, lets talk about what HD radio isn’t; it isn’t HIGH DEFINITION Radio. HD originally stood for Hybrid-Digital but recently the company that oversees HD Radio, iBiquity Corporation, says that the HD doesn’t stand for anything. Also, HD Radio is not satellite radio. HD Radio is free over the air radio while satellite radio is available only through a subscription service. Finally HD Radio is not Internet Radio. There are many Internet Radio stations that stream programming and there are Internet enabled radios but they are not HD Radios. To make it more confusing; there are some stand-alone units that can be connected to the Internet and receive HD, Satellite and Internet Radio.
As with the change from vinyl discs to compact disc and videotape to DVD; digital technology offers improved quality of images and sounds.
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 with near CD-quality sound and AM radio that sounds as good as the FM radio plus multicasting, captioning and tagging.
The digital signal is less vulnerable to reception problems so no more static, hissing, or popping noise. Digital technology allows a radio station to transmit more information in the same radio wave. This means higher quality sound. FM transmissions will sound as good as CDs. Since 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 however AM station clarity will be equivalent to current analog FM stereo radio.
Should you lose the digital signal for some reason (obstructing terrain, nearing the edge of the broadcast area, etc.), your HD Radio will default back to analog mode, similar to the way current radios switch from stereo to mono mode when receiving a weak signal.
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, or the station’s call letters. Stations can also include local and regional information, such as weather updates or traffic alerts.
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.
Being digital only, 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 specialized programming — ultimately giving the listener a greater variety of music and talk to choose from.
Multicasting is a big deal for radio stations and listeners alike. A radio station can now better serve its listeners. For instance, a public radio station can broadcast morning jazz music on one “channel” and morning talk programming on another “channel.” Same radio station, same frequency on the dial, but multiple options for the listener. A commercial radio station could branch out into multiple formats, having rock on the main channel, and country on its HD2 feed, for example.
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 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.
All in all some pretty cool technology!
For those truly technically-minded you can read the Wikipedia entry on HD Radio here.
for a guide to HD radio stations click here.
A truly informative report on HD Radio in Hyundai cars is here.
The link to the HD Radio industry trade group is here.