The Grand Alliance

In response to this invitation, in May 1993, as an alternative to a second round of intense competitive testing, the proponents of the four all-digital systems formed the Digital HDTV Grand Alliance. The members of the Grand Alliance were AT&T (now Lucent Technologies), General Instrument, North American Philips, Massachusetts Institute of Technology, Thomson Consumer Electronics, the David Sarnoff Research Center (now Sarnoff Corporation) and Zenith Electronics Corporation. After a thorough review of the Grand Alliance's proposal, the Advisory Committee ordered a number of important changes, and the Grand Alliance companies proceeded to build a final prototype system based on specifications approved by the Advisory Committee.

The prototype Grand Alliance system was built in a modular fashion at various locations. The video encoder was built by AT&T and General Instrument, the video decoder by Philips, the multi-channel audio subsystem by Dolby Laboratories, the transport system by Thomson and Sarnoff, and the transmission subsystem by Zenith. The complete system was integrated at Sarnoff. Testing of the complete Grand Alliance system started in April 1995 and was completed in August of that year.

The Advisory Committee testing of the Grand Alliance system was similar to that conducted for the four individual all-digital systems, however, additional tests were conducted to more fully evaluate the proposed system. These new tests included format conversions between the progressive and interlace modes (both directions) and compliance with the MPEG-2 video compression syntax. Subjective audio tests and long form viewing of video and audio programming were also conducted. A second set of field tests was conducted in Charlotte, North Carolina, utilizing the complete Grand Alliance system. (The VSB transmission sub-system had been field-tested alone in Charlotte in 1994.)

Another vitally important organization in this historic process was the Advanced Television Systems Committee, a private sector organization founded in 1982. ATSC is composed of corporations, associations and educational institutions, developing voluntary standards for the entire spectrum of advanced television systems, including high-definition television. All segments of the television industry are represented within the ATSC, including broadcasters, cable companies, satellite service providers, consumer and professional equipment manufacturers, computer and telecommunications companies, and motion picture and other content providers. Working closely with the Advisory Committee throughout the U.S. DTV process, the ATSC was responsible for developing and documenting the detailed specifications for the ATV standard based on the Grand Alliance system. In addition, the ATSC developed the industry consensus around several standard-definition television (SDTV) formats that were added to the Grand Alliance HDTV system to form a complete digital television standard. Among other things, these SDTV video formats provide for interoperability with existing television standards and support the convergence of television and computing devices.

Following completion of its work to document the U.S. ATV standard, the ATSC membership approved it as the ATSC Digital Television Standard (A/53) on September 16, 1995. On November 28, 1995 the FCC Advisory Committee issued its Final Report, providing the following conclusions:

• The Grand Alliance system meets the Committee's performance objectives and is better than any of the four original digital ATV systems
• The Grand Alliance system is superior to any known alternative system
• The ATSC Digital Television Standard fulfills all of the requirements for the U.S. ATV broadcasting standard

Accordingly, the FCC Advisory Committee recommended that the ATSC DTV Standard be adopted as the standard for digital terrestrial television broadcasts in the U.S. After receiving the Advisory Committee'#146's recommendation, the FCC released a Notice of Proposed Rule Making announcing its intention to adopt the ATSC standard. The notice stated:

"We believe that the ATSC DTV Standard embodies the world's best digital television technology and promises to permit striking improvements to today's television pictures and sound; to permit the provision of additional services and programs; to permit integration of future substantial improvements while maintaining compatibility with initial receivers; and to permit interoperability with computers and other digital equipment associated with the national information initiative. It was developed and tested with the unparalleled cooperation of industry experts..."