Audio Video News

Other than cable companies' refusal to carry digital television signals, the biggest obstacle to growing the DTV market has been reception problems.

On January 2, researchers from Royal Philips Electronics, News Corporation, and Australian National University announced a new design in indoor antennas that they claim will improve reception in fringe areas and make DTV accessible to far more people than is now possible.

Three years of research went into development of the antenna, according to a joint announcement from Philips Research and the Fox Group engineering team. They had studied DTV reception problems in Los Angeles and metropolitan areas, and had concluded that the major problems were on the receiving end, not at the transmitters. In particular, they discovered that digital receivers have problems distinguishing between original signals and reflections (or multipath signals) from hills, buildings, bridges, and other structures.

In analog receivers, multipath causes "ghosting," or noise, in the picture. Digital receivers facing similar conditions may not produce a picture at all. In weak signal areas, analog receivers will produce weak pictures; digital ones will produce no picture at all once the signal strength drops below a threshold level.

Researchers analyzed thousands of reflected signals in multiple locations and incorporated their findings into recommendations for new microprocessors that will have vastly improved abilities to filter out weak signals. Fox president of engineering Andrew G. Setos told reporters that much of the original engineering for DTV reception was based on "bad assumptions."

Fox and Philips researchers say they have achieved an 85% success rate with their new antenna, a rate similar to the 88% claimed by Linx Electronics Inc. with its new digital receiver. The best receivers available now have a 50% success rate with signals in difficult areas.

Reception problems had prompted many complaints from early adopters to the Federal Communications Commission, and have long been considered one of the major roadblocks in the transition to a fully digital television system. Approximately 3 million DTV-capable sets have been sold in the US, most of them for use with DVD players. Fewer than 1% of American households have purchased the digital receivers needed to pull in over-the-air digital programming.