Electronic Design

Digital Audio Broadcasting: A New Frontier

Traditional radio services in the U.S. are entering a new era of digital audio broadcasting (DAB). Development efforts have been under way for over five years. Now, using the S-band frequency spectrum, two service providers—XM Satellite Radio and Sirius Satellite Radio—are set to launch their signals toward automobiles around the country before year's end.

This is occurring as the terrestrial in-band on-channel (IBOC) specifications backed by iBiquity Digital Radio are expected to become a standard by early 2002. Interestingly, DAB, based on out-of-band frequencies, has been traveling the air space of Europe via satellites for nearly a decade, and an entirely new market is emerging.

The transition to DAB is made possible by powerful low-cost floating-point and fixed-point digital signal processors (DSPs), in conjunction with high-performance, high-speed analog-to-digital and digital-to-analog converters, as well as RF modules. It isn't surprising, therefore, to see major DSP vendors forming strategic alliances with service providers, car-radio makers, and producers of terrestrial receivers.

In fact, a number of vendors have already announced reference designs and chip sets for this emerging space. For instance, STMicroelectronics has unveiled plans to take its satellite receiver chip sets into production. Chips from STMicroelectronics are aimed at XM Satellite's receiver design. Moreover, Agere Systems has readied RF/analog and DSP chips for the satellite-to-car receiver set from Sirius.

Applying SHARC DSPs, Analog Devices is working closely with Visteon's engineers to develop digital radio receivers based on IBOC specifications. Similarly, Texas Instruments (TI) and Motorola have partnered with third parties to provide solutions for this space. TI, for example, disclosed a reference design for Europe's Eureka-147 DAB receivers. The design taps TI's TMS320DRE2000 and RadioScape's software-defined radio.

In fact, XM Satellite is preparing to launch its service nationwide by November. All major equipment makers are hoping to get their DAB receivers into the market before the service commences. Sirius aims to do that as well. This company is serious about getting the signals into car receivers in some parts of the country before the year's end, and about going across the country by the first quarter of 2002.

Both XM Satellite and Sirius plan to offer nearly 100 channels. These include dedicated channels, which have been created in partnership with other radio networks. For example, Sirius and ABC Radio Networks, a subsidiary of Walt Disney Co., have jointly created a channel for the nation's truckers, in addition to sports and entertainment channels.

DAB service providers are promising a lot more in terms of sound quality and a new array of data-rich services. Like cable TV, though, this enhanced sound quality for AM radio and CD-type performance for FM receivers won't come free of charge. Aside from the higher cost of digital receivers, the DAB service will probably cost the consumer around $12.95 per month. Also, separate radio receivers are presently needed for the two competing satellite-to-car broadcasting services. Fortunately, both XM and Sirius see this as a hurdle to their growth. So it is not surprising that they have agreed to develop a unified standard, thereby enabling a single receiver to handle the signals from the two service providers.

Will consumers pay a fee for this improved digital radio broadcast service, or will they continue to use free analog service? Only time will tell. Paid cable TV has survived and is growing impressively. But is the consumer ready to add a paid audio service to an existing paid video service? DAB will surely find its niche. Send me your thoughts on this matter.

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