Reinventing Television, Part II — Dr. Joseph Flaherty on HDTV Standards, the ATSC System, and the DTV Transition

by Dr. Joseph Flaherty, Senior VP-Technology, CBS, Inc.
Sunday, March 8, 1998

The HDTV system would support two, and only two HDTV, scanning rates of 1080 active lines with 1920 square pixels-per-line interlace scanned at 59.94 and 60 fields per second and 720 active lines with 1280 pixels-per-line progressively scanned at 59.94 and 60 frames per second. Both formats would also operate in the progressive scanning mode at 30 and 24 frames/second for the transmission of film programs wherein the low film frame rates had already compromised the motion portrayal - the wagon wheels go backwards.

The Grand Alliance system would employ MPEG-2 video compression and transport systems, the Dolby AC-3 audio system, and 8-VSB modulation.

The Grand Alliance system was built and tested and was verified to be the best-of-the-best. By 1995, the technical work was completed and the digital high definition system was ready for approval. The modern miracle of engineering genius had been achieved! A wide screen, 16:9 HDTV system with five times the picture quality of 480 line SDTV had been developed and compressed into the narrow 6 MHz television channel. After 8 years of single purposed effort, the Country was on its way to a vastly improved high definition television service.

However, this was not to be! At the last minute, in the Spring of 1995, the then FCC Chairman, Reed Hundt, required the Advisory Committee to include several 480 line interlace and progressively scanned SDTV formats in the digital standard, and, without further testing, the SDTV formats we e added. Americans transition to high definition became a transition to 460 line SDTV and liDTV.

The ACATS digital SDTV and HDTV standard, as documented by the Advanced Television Systems Committee or ATSC, was recommended to the FCC by the Advisory Committee on November 28, 1995, but in another last minute change, the scanning formats were privatized, and the ATSC standard was finally approved by the FCC on December 24th, 1996 and its use mandated for terrestrial DTV and HDTV broadcasting.

81 days later, on April 3, 1997, the FCC adopted an initial digital channel allotment and assignment plan and DTV service rules, and these are presently under review.

In its fifth, and final, Report and order in the proceeding on digital television the FCC required, among other things, that the affiliates of the top four networks (ABC, CBS, Fox, & NBC) in the top 10 markets be on-the-air with a digital signal by May 1, 1999, and the affiliates of the top four networks in markets 11-30 be on-the-air by November 1, 1999.

The FCC also set as an important goal in the digital transition, the return of the analog (NTSC) spectrum at the end of the transition period. The Commission set a target of 2006 as a reasonable end-date for the NTSC service with reviews of that date in its periodic reviews to allow for any necessary changes in Commission rules.

Under a separate voluntary agreement made at the urging of the FCC, some group owners, including CBS, agreed to have some top-ten digital stations on-the-air by November 1, 1998, 8 months and 19 days from now. Thus, after 9 years, 3 months and 22 days of study, debate, design, construction, testing, and rule making, America's terrestrial broadcasters have the ATSC digital TV and HDTV system that, if used promptly, and properly, will assure their competitive parity with other 21st century distribution media.

The last major task for the FCC is to ensure that all distribution media accommodate all the DTV and HDTV formats and deliver them all the way to American homes.

This is especially critical for all cable systems since they control the majority of the Nation's television program distribution. They must deliver to all subscribers the full range of ATSC digital program qualities, including HDTV, without modification, degradation, or format conversion.

Moreover, DTV and HDTV program distribution over cable systems must be implemented on the same time schedule as the rollout of the digital TV stations. Lacking this parallel rollout, the availability of DTV and HDTV to viewers will be a hit-or-miss affair at best. Such an undisciplined rollout would certainly delay the sale of digital wide screen receivers and, thus, delay the final transition to all digital television. This, in turn, would delay the shut down of the analog service and the return of the NTSC spectrum.

The Nation's engineers and scientists have devised the World's best digital TV and HDTV system, the government has approved it, mandated it for terrestrial broadcasting, and is assigning the last available VHF and UHF channels in the radio frequency spectrum to broadcasters to implement the digital TV and HDTV service.

The rollout and application is now up to the creative and business communities of broadcasting. What must they consider?

In the past all competition in the TV marketplace was based on the same general technical quality. It was 525 line NTSC from the camera on stage to the receiver in the home. Senior managers never had to make decisions on program presentation quality. Hereafter, there will be a wide range of technical qualities delivered to viewers from SDTV, through HDTV multiplex" programming, to full quality HDTV, and technical quality will become an increasing factor in the competition for viewers.

HDTV may become the primetime and sports medium of choice by producers, programmers, and the viewing public. Some broadcasters, cable, and DBS programmers have already declared their intent to provide HDTV program services. In the competition for viewers, full, wide screen, high definition will be available, and high definition will always be just a "channel click" away.

In considering the importance of high definition, it is vital understand that wide screen, high definition is not just pretty pictures for today's small screen TV sets. Rather, it is a wholly new digital platform which will support the larger and vastly improved displays in development toy commercialization. HDTV viewed on such large wide screen displays will create an entirely new viewing experience and will finally make the home theater a practical reality.

As to DTV and HDTV formats, the 480I and 480P formats, with only 236,000 and 304, 000 displayable pixels respectively, are SDTV formats. They were added to the DTV standard as SDTV formats, and they are not, and never will be, HDTV.

Moreover, it may be more important to note that the two HDTV formats are not of equal objective quality.

The resolution of an image is finally determined by the number of displayable pixels in each frame. Pixels are the smallest picture elements that compose a picture, and the 1080I, 60 field HDTV format is composed of 1,451,000 displayable pixels, while the 720P, 60 frame format is composed of only 830,000 displayable pixels, or 43% fewer pixels.

In the 30 and 24 frame film transmission mode, the 1080P HDTV format has 1,866,000 displayable pixels against the 720P, 30 and 24 frame formats with only 830,000 pixels, or 1,000,000 fewer displayable pixels than the 1080P, 30 and 24 frame formats.

Today, however, viewing HDTV is a bit like Mark Twain's comment that "Wagner's music is better than it sounds". Today HDTV is better than it looks! The display devices are the limiting quality factor. While improvements are being made by the month, as of today, no display has achieved the full quality potential of America's HDTV system. Last week, Fujitsu announced a new 42 inch, 16:9 wide screen, flat panel display with 1024 pixels per line - approaching full HDTV quality.

This display development is as it should be! The new wide screen HDTV
system needs to provide the headroom and challenge for further near term
development.The full potential of any new standard should never be
fully encompassed by the existing state-of-the-art, nor should it be so futuristic as to not have its potential achievable in a foreseeable time. America's HDTV standard is beyond the present quality of displays, but not beyond the scope of rapid development.

Subjectively, like many things, beauty is in the eye of the beholder, and some will prefer one DTV format over another, the objective quality of each notwithstanding. Nevertheless, full HDTV quality will rapidly improve and will continue to widen the gap between it and all lesser formats.

On November 21st, 1985, with apologies to Arthur C. Clarke for plagiarizing his title, I delivered a lecture entitled, 112001, A Broadcasting Odyssey." In that lecture I said:

"As we evaluate tomorrow's TV and HDTV and plan for its implementation, we must bear in mind that today's standard of service enjoyed by the viewer will not be his level of expectation tomorrow. Good enough is no longer perfect, and may become wholly unsatisfactory."

"Quality is a moving target, both in programs and in technology. Our judgements as to the future must not be based on today's performance, nor on minor improvements thereto."

Today, twenty five years after NHK began its pioneering work, High definition as defined by the CCIR and SMPTE is, and will be, a system employing at least 1000 active lines, interlace or progressively scanned. Lesser formats may be improvements over NTSC, but are not "High Definition"

The digital era has begun, and every segment of the television business will feel the impact of this digital revolution. Digital technology will radically change television's means of communication, its quality, its flexibility, the conduct of the business, the scope and effectiveness of the service, and every aspect of the medium. While some may still consider this historic invention unfortunate, its application is, at the same time, inevitable.

Historian Elton Morrison suggested:

"It is possible, if one sets aside the long-run social benefits, to look upon invention as a hostile act - a dislocation of existing schemes, a way of disturbing the comfortable bourgeois routines and calculations."

This, in turn, led Secretary Adams to write:

"Inventions, especially visionary ones that disturb established patterns, rarely diffuse rapidly and success fully of their own accord. Centralized, bureaucratic managers and industrial giants are alike in too often being obstacles to, rather than sources of, broader perspectives. Enmeshed in present constraints, higher echelons fail to notice that most future problems and their solutions lie outside their sphere of influence."

NANBA broadcasters will be the digital TV and HDTV "sphere of influence," for, as was noted by Erwin Duggan during his term as an FCC Commissioner:

"You and we, finally, need to treat broadcast television as more than a business, or it will become nothing more than a business."