Clear Channel Radio announced Friday that all of its 350 HD2 stations are ITunes Tagging-compatible. This makes it easier for listeners of those stations to identify songs they want to buy through iTunes later. Clear Channel announced in April that all of its primary HD stations were iTunes Tagging-compatible. The company is using HD Radio to make the new function work.

Developed by Ibquity, HD Radio is a new radio transmission technology that enables AM and FM radio stations to broadcast their programs digitally. FM stations feature CD-quality sound, according to the manufacturer, without any audio distortion or fuzziness. Because HD Radio stations broadcast a digital signal, they can embed additional information in their carrier waves -- including track information.

Using an HD Radio-equipped receiver with iPod dock that supports iTunes Tagging, users can click a button to identify songs they'd like to buy. The next time you synchronize the iPod to your Mac or PC, iTunes builds a playlist of those songs, which you can then purchase through the iTunes Store. Polk Audio's I-Sonic Entertainment System 2 and other devices feature the capability.