Electronic Design

Marconi's Legacy Lives On: Digital Radio Comes Of Age

A week at the beach might seem the ideal time for a bit of a respite from technology. But when I ended up at Marconi Station on Cape Cod, my surfside relaxation turned into both a historic and a philosophical reflection on the communications revolution.

In January 1903, radio pioneer Guglielmo Marconi transmitted the first two-way transatlantic communication from this beach in South Wellfleet, Mass. Marconi had convinced President Theodore Roosevelt and England's King Edward VII to participate in the historic Morse code messaging exchange. The Cape Cod station later served as Marconi's main "ship-to-shore" communications station, allowing passengers on the Cunard liners to receive and send "Marconi-grams."

Today, all that remains of the four 210-ft wooden towers Marconi built are some 10-ft sections of the wooden tower beams bolted to their concrete slabs. The National Parks service maintains a scale model of the broadcast towers in a seaside pavilion at the site.

But what a legacy! Marconi's work remains the essential building block for so many of today's wonders, and it seems to me (to quote Roosevelt's transatlantic message) a true "wonderful triumph of scientific research and ingenuity."

Marconi's broadcasts a century ago continue to reverberate, in ways both direct and indirect. In talking with you readers, it seems a whole generation of you was pulled into electronics via the lure of building and broadcasting via your own shortwave radios.

In your personal lives, I'm also betting that many of you are the early adopters of today's new radio technologies. Somehow I was not too surprised by a recent market study from International Demographics that showed that approximately 63% of satellite radio listeners are men, with 55% having at least one college degree. The survey also revealed that 76% of listeners are over the age of 35 and 48.5% are over 45. (Go to elecdesign.com to take our QuickPoll about radio use.)

Suddenly the world of radio is a hotbed of new technology. Satellite radio has been touting its vast array of programming and its digital-quality sound to lure listeners away from traditional broadcast radio. In response, broadcast stations are moving to HD Radio, using existing AM and FM radio bands, and adding digital transmission capability—not only improving music quality but also allowing for simultaneous transmission of station information, song/artist information, news scrolls and traffic reports, and other data. Future features will include "buy now" buttons and integration with hard-disk recorders.

HD RADIO
The HD Radio (a.k.a. In-Band On-Channel Digital Audio Broadcasting) system widens the bandwidth of assigned AM and FM channels, permitting digital signals to be broadcast using orthogonal frequency-division multiplexing (OFDM) with multilevel modulation schemes. HD Radio eliminates static, hiss, pops, and fades and offers backward and forward compatibility with traditional broadcasts.

The sole developer of the technology, iBiquity Digital Corp., says that AM digital gains FM-like audio quality while FM digital has CD-equivalent audio. This quality boost is achieved by eliminating multipath distortion (which occurs when part of a signal bounces off an object and arrives at the receiver at a different time than the main signal) via the reassembly and synchronization of the multiple OFDM data streams.

A recent New York Times article spotlighted the first crop of home HD receivers hitting the market this summer, including component units from Yamaha, a tabletop from Boston Acoustics, and an all-in-one CD/DVD/satellite unit coming from Polk Audio—-plus a flood of new products in the pipeline. The Times says 450 U.S. stations currently broadcast in the digital format, with 2000 more stations planning to convert.

ABI Research stats show that tens of thousands of HD radio car tuners have been sold since the first products hit the market last year. Kenwood, the first HD Radio manufacturer, offers 40 models that work with an HD Radio car adapter.

Marconi helped start a revolution, and you readers are keeping that revolutionary force rolling with today's radio innovations— "wonderful triumphs" in their own right!

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