There's a huge change looming in the future for radio broadcasting. It will affect every broadcaster, legitimate or not. It is Digital Audio Broadcasting (DAB) - and if darker theories about its future hold true, it could mean the death of local radio as we know it.
The technicalities and regulatory concerns surrounding DAB are quite complex, as it's an entirely different way to broadcast radio. Here's a short primer:
All radio broadcasting that
takes place today is analog. The audio signal is converted into a radio
signal for transmission, then back again at the receiver. The source
input is, for all intents and purposes, the audio coming out from the
Digital radio, however, would first convert the audio signal to bits - strings of 1s and 0s - before transmission. The radio signal itself would be unlistenable without a receiver equipped to decode the bit strings first.
DAB will work much like streaming audio over the Internet - radio receivers will have to buffer enough program information to play it back to you. Static on the FM band will essentially cease to exist, but any potential interference will result in a complete loss of signal, much like what happens today when you play back a streaming file and net congestion interrupts the stream.
Because most radio stations
now employ digital methods of programming (CDs, DAT, computer automation),
DAB is also supposed to improve the audio quality of radio markedly
- proponents of DAB claim listeners will enjoy "near-CD quality"
sound from this new system, because the signal won't have to be degraded
to analog transmission levels before broadcast.
How DAB Works
In the United States, the radio industry is backing a form of digital audio broadcasting called In-Band On-Channel (IBOC) DAB. Essentially, this system allows for radio stations to make the jump from analog to digital transmission without having to switch frequencies - your favorite station on 95.1 would still be on 95.1 in the post-digital world.
The rest of the industrialized world (with the exception of Japan) will use a form of DAB called Eureka-147. Eureka 147 systems use superior technology - providing a higher-quality signal with less risk of interference to other stations.
However, Eureka-147 uses another section of the radio spectrum not available to stations in the U.S., currently reserved for military uses. The military was asked to give up this piece of the spectrum, but has refused, citing "reasons of national security."
Any DAB technology will require listeners to invest in totally new radio receivers - you will not be able to pick up a digital radio signal on an analog receiver. However, the IBOC DAB system will allow stations to broadcast a "hybrid" signal - allowing those with either analog or digital radio receivers to hear the station - until the entire DAB system is in place and functioning properly.
Looking at IBOC DAB from the spectrum standpoint, one thing is abundantly clear: Big Broadcasting will come out of the transition to digital with twice as much real estate on the radio dial for the same amount of stations.