Electronic Design

Digital Broadcast Radio Ready To Take The Airwaves

CD-Quality audio for AM and FM broadcasts is on its way. The formal implementation of iBiquity Digital's HD Radio technology is set to launch. Approximately 100 stations covering 40 major U.S. radio markets are expected to adopt iBiquity's new digital standard and begin transmitting this quarter. More stations will adopt this system later this year.

Formerly known as In-Band On-Channel (IBOC), HD Radio uses digital modulation and multiplexing techniques to add digital transmission to radio stations within the existing FCC-assigned bands. Radio stations will be able to continue transmitting conventional analog signals to listeners who don't have the new HD Radios. The Federal Communications Commission formally approved the HD Radio system back in October 2002 so the U.S. could finally take advantage of digital audio broadcasting (DAB), a technology that European consumers have enjoyed for several years.

The HD Radio system uses DSP audio-compression techniques, orthogonal frequency-division multiplexing (OFDM), and quadrature amplitude modulation to squeeze multiple channels of audio into sidebands above and below existing analog AM and FM sidebands. In addition to its simultaneous analog and digital transmission and improved signal quality, the HD Radio system includes data channels that let stations transmit auxiliary information, such as song title and artist, news, weather, traffic, and stock quotes, that's displayed on the consumer's radio LCD.

At the heart of the HD Radio lies the DSP chip, which performs all of the necessary baseband operations. Texas Instruments claims to be the first to market with a chip that covers all necessary functions. Known as the DRI200, this custom chip is based upon TI's TMS320C6000 DSP technology. It performs the filtering, OFDM demodulation, forward error correction, decompression, and other functions required by the HD Radio standard.

Manufacturers Kenwood and Visteon already have HD Radios on the market. Many others are expected to have consumer home products this year and auto radio products next year.

The iBiquity Digital HD Radio system gives consumers one more digital radio option. Last year, XM Satellite Radio and Sirius Satellite Radio both introduced digital 2.3-GHz satellite radios and subscription services that provide over 100 channels of car radio from coast to coast, thanks to blanket U.S. coverage by their satellites.

iBiquity Digital Corp.

Texas Instruments Inc.

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