While radio is coming back into vogue, with the acceptance of satellite radio systems from Sirius and XM, another standard appears ready to take the spotlight. HD Radio, using digital signal compression, will give listeners a free alternative to monthly satellite radio fees. Companies like Sanyo and Radiosophy showed off their upcoming HD Radio products at NAB.

HD Radio uses digital technology to compress audio signals. According to Radiosophy, this makes AM stations sound like FM, and FM stations sound like CDs.

HD Radio also offers sound quality on par with satellite radio. Listeners go to their familiar radio stations and the HD Radio will pick up side channels. A subscription is not required, but the downside is that, unlike satellite radio, advertisements are part of the broadcast mix like normal radio.

Listeners tune in to the same frequency of their favorite radio station. The HD band for the station is slightly offset and transmits at 20 db below the main channel's power. FCC mandates that the stations do this in order to maintain the same coverage area of their regular definition broadcasts.

Each radio station is allocated 96 kb of total bandwidth and can choose to split the data between the standard definition and high definition channels. In addition to music, the other channels could broadcast traffic information on another channel, like HDTV, where you go to channel 34, and have 34-1, 34-2, 34-3, etc.