While HD radio increases the quality of AM and FM broadcasts dramatically, this may not be the main reason to buy an HD radio.

You may buy it because of a new concept called HD2.

HD radio is digital radio. It requires less radio spectrum which, in turn, enables a concept called multicasting. In other words, radio stations with HD radio technology will be able to broadcast their primary FM channel in digital while offering up to two additional side channels on the same frequency. These extra channels have been named HD2.

What to expect from HD2

Seven of the nation's largest broadcasters have joined together to form the HD Digital Radio Alliance to promote HD radio and to coordinate the use of HD2. One of the goals of this Alliance is to help create new programming content to put on those HD2 signals. The Alliance intends to coordinate the use of the new HD2 channels to offer variety ¨C music, news and entertainment ¨C across formats. Early next year, it will announce specific HD2 programming and promotional efforts for the country's top 25 markets.

The Alliance also pointed out that HD radio offers more than just entertainment. It can also transmit text messages such as traffic reports, and real-time weather forecasts. It also has an interactive capability. For example, the day may come when you will be able to instantly download or purchase a song you're hearing on your radio simply by pressing a "Buy It Now" key.

Free and commercial free

Alliance members have said that HD2 channels will be free and commercial free, at least initially. Just as important, they will be locally programmed in each market ¨C unlike satellite radio which cannot offer local material. How long these HD2 channels will remain commercial free is hard to guess. However, Alliance members have said that these HD2 channels will remain free to listeners, just like today's AM and FM broadcasts. with the possible exception of premium multicast services such as concerts or traffic updates.

25 stations now with dozens more coming

Last May, Chicago's WUSN became the USA's first commercial FM outlet to multicast. Infinity Broadcasting recently added a second digital channel to Chicago's WJMK. Three Detroit stations have announced a new companion multicast channel, and a number of National Public Radio stations have begun multicasting. It is believed that more than 25 stations are now broadcasting HD2 and dozens more are expected to add these channels by year's end.

In other words, HD radio and HD2 are on the march. Now, all we need are more HD radios so we can actually hear this amazing new technology.

To learn more about HD radio, please go my Web site, http://www.hd-radio-home.com, to get all the buzz.

Douglas Hanna is a retired marketing executive and the author of numerous articles on HD radio, the Internet and family finances.