Terrestrial tunes
Earthbound digital radio gets chip support
Maury Wright, Editor-in-Chief -- CommVerge, 8/1/2002
Satellite digital radio has debuted to mixed reviews, and many people still think that terrestrial digital radio will be more compelling because listeners will receive their favorite existing stations in pristine digital quality. Expect the IBOC (In Band On Channel) technology that will occupy the same frequency space as existing stations to begin rolling out around the Consumer Electronics Show next January.
STMicroelectronics just became the second chip vendor to announce support for IBOC. The company has announced a two-chip IBOC design that consists of the TDA7515 analog front-end, which downconverts the incoming signal to a 10.7-MHz intermediate frequency (IF), and the DSP-based TDA7580, which directly digitizes the IF and handles digital and analog radio-processing tasks.
By working directly with the IF signal, the DSP code in the TDA7580 can implement equalization features that combat multipath interference, greatly improving reception of weak signals. Moreover, the software approach will allow receiver manufacturers to design a fallback mode in which the radio can swap from digital to FM at the edges of the digital signal range. ST jointly developed the digital radio software with Bose.
ST has been the sole source of digital radio chips for XM Satellite Radio's network and now joins Texas Instruments as a supplier to the IBOC community. TI built the multichip IBOC prototype implementation shown at CES last year, and at the same show announced a single-chip implementation of the DSP section of the design.
