Local FM radio stations KSSK FM, KUCD, KDNN and KIKI will launch next-generation digital broadcasts next spring, becoming the first Hawai'i stations to offer so-called high-definition radio.

High definition, or digital broadcasts use the same language as computers — a series of on and off electronic pulses — to modernize the medium with better sound and new features. Digital broadcasts won't increase a radio station's range, but digital signals can be cleaned up, removing garble and uneven reception.

Such radio programs will remain free, however consumers will need to buy a special HD-radio receiver to listen to the new digital broadcasts. In addition to offering CD-quality FM sound, the technology allows listeners to receive information on their radios such as song titles and artist names.

Unlike the government-mandated conversion to High Definition TV, the switch to HD radio is market-driven. That means the nation's 12,000 or so radio stations are free to convert to digital broadcasts when they wish. (For television, the federal government will require all broadcasts be in HD by February 2009.) So far 969 radio stations in the United States have converted to HD radio, according to iBiquity Digital Corp., a consortium of radio broadcasters and equipment makers.

Currently no Hawai'i stations are broadcasting HD Radio programming. However, San Antonio-based Clear Channel Communications Inc. has announced plans to begin offering HD radio in Honolulu beginning with KUCD in March, followed by the company's remaining local stations in subsequent months.

Atlanta-based Cox Communications Inc., which owns KCCN, KINE, KPHW and KRTR, said it expects to have its Honolulu radio stations converted to HD radio by mid-2008, according to Neil Johnston, vice president and chief financial officer for Cox Radio.

The big issue for radio stations is deciding when to make the switch, said Clear Channel's local general manager Chuck Cotton. Radio stations don't want to invest in the technology until there's an audience ready to buy HD radios. Consumers won't buy HD radio receivers unless stations broadcast HD radio programs.

"It's a little bit of a chicken and the egg thing," Cotton said. "It all takes time" to sort out, but "HD radio is coming."

The effort to upgrade radio is meant to keep listeners from migrating to competitors such as satellite radio, which is not available in Hawai'i, and Internet music sources. However, Cotton said there will always be a need for radio broadcasters.

"We provide something that no one else can provide — local news and information," he said. "Nobody is going to have the financial wherewithal to do that."

In the future HD Radio also could generate additional revenue for radio broadcasters from alternative advertising, transactions on sales of advertised goods, and subscription fees for information services.

Unlike the subscriber radio services offered by Sirius Satellite Radio and XM Satellite Radio Holdings, digital broadcasts will be free. However, HD radio can transmit a separate stream of data at speeds of up to 48 kilobits per second, or slightly slower than a typical dial-up Internet connection.

The radio-broadcasting industry has yet to decide just how it plans to use this extra data capability, but in the future stations could offer continually updated news on a subscription basis, which could be displayed or read aloud. Future radios also could allow listeners to pause and replay music.

Digital radio relies on what's called in-band, on-channel broadcasting technology that can transmit AM and FM analog signals simultaneously with high-quality digital signals. Clear Channel initially plans to use that technology to simulcast programming on its Honolulu stations.

For example, KSSK FM's analog station will continue to feature adult contemporary music, but the digital version will feature mainstream country music. A listener using an HD radio could select either the adult contemporary broadcast in analog or the country music in HD. Similarly, KUCD will continue to air alternative rock, however the digital version will feature smooth jazz.

Fortunately for consumers, there is only one technology standard in the HD radio industry, unlike the two standards for satellite radio. That means consumers won't have to worry about investing in a technology standard that may become obsolete. Digital-radio ready receivers cost about $100 to $150 more than standard analog receivers.

HD radios are available online now and should be available in stores locally once local stations begin broadcasting in HD.

So far BMW is the only automaker to offer HD radio as a factory-installed option, though nine other brands have announced plans to follow suit, according to iBiquity.

Reach Sean Hao at shao@honoluluadvertiser.com.