Multicasting

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 more niche programming — ultimately giving the listener a greater variety of formats 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.

iTunes Tagging

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.