DTV Defined at Last: CEA Issues Guidelines

What's in a name? If it's a "Digital Television," no one has been quite sure, and the resulting confusion over basic nomenclature has been one of many factors inhibiting market acceptance of the new format. Now, the Consumer Electronics Association (CEA) has decided that clear definitions are needed to cut through the fog.

On August 31, the CEA published an extensive set of definitions intended to clear up the issue of what is and what is not a digital TV. The definitions will help retailers and consumers gain a clear understanding of the many similarly named features and capabilities available on a wide range of equipment.

As the CEA has it, there are now three distinct classes of DTVs: High Definition, Enhanced Definition, and Standard Definition, with corresponding classes for tuners and monitors. A "television set" or "television receiver" is a device that includes both a display screen and an inboard tuner; a "monitor" depends on an outboard tuner or other source to create an image. A "tuner" receives radio-frequency signals and converts them to forms usable by video displays and audio processors.

According to the new guidelines, HDTVs will offer the following capabilities:
• Receive ATSC terrestrial digital transmissions and decode all ATSC Table 3 video formats
• Display vertical scanning lines of 720 progressive (720p), 1080 interlaced (1080i), or higher
• Display an image in a 16:9 (width:height) aspect ratio
• Receive, reproduce, and/or output Dolby Digital audio

HD monitors will be capable of displaying 720p, 1080i, or higher-level images. An HD tuner must be capable of receiving and decoding all ATSC Table 3 radio-frequency formats, may also output HD formats converted to other formats (including those at lower levels of resolution), and should output a Dolby Digital audio signal. It may also output a digital datastream with the full resolution of the original signal, for decoding by an external processor.

Enhanced Definition televisions (EDTVs) will be capable of:
• Receiving and decoding all ATSC Table 3 formats and ATSC terrestrial digital transmissions
• Displaying vertical scan lines at a level of 480p or higher
• Receiving, reproducing, and/or outputting Dolby Digital audio signals

There is no specified aspect ratio for EDTV. An ED tuner must receive and decode all ATSC Table 3 formats, must output 1080i/p at a minimum resolution of 480p, and may output 480i as 480i. An ED tuner must also output Dolby Digital audio, and an ED monitor must be capable of 480p or higher.

Standard Definition Television sets will receive and decode all ATSC Table 3 formats, and will produce "usable audio" and images at lower levels of resolution than ED equipment. No aspect ratio is specified for SDTV sets. SD tuners, interestingly, must output Dolby Digital audio, even if SDTVs do not.

The CEA has created logos that will appear in the next few months on equipment meeting the various definitions, so that salespeople and consumers will no longer be confused about what they're discussing on showroom floors. "This new terminology . . . will give consumers a 'good–better–best' choice when shopping for digital TV products," said CEA president Gary Shapiro. "Consumers can buy with confidence, knowing that the DTV products they purchase do indeed have DTV capability and are upgradeable to a specified level of DTV performance." With the CEA's new program in place, the "definition" of HDTV and all its derivatives should be better than ever.