Casual observers of technical progress often assume that the basic forces at work are merely those of new science and improved technology.  But seasoned veterans of the technical wars know that many other forces are also at work.  Prominent among them are the pride and prejudice of technical, industrial, and political leaders; the pursuit of power and profit; the rivalry for command of patents and markets; as well as the forces of government: inertia, misunderstanding, and, occasionally, foresight. The development of television in the United States is a prime example of the conflicting interplay of these forces and their ultimate resolution for the public good.  The body on which these forces were principally brought to bear was the National Television System Committee. 

Its initials "NTSC" are the hallmark of American television practice and, for that matter, the hallmark of much worldwide practice.

Two Previous RMA Committees

The first NTSC reviewed in 1940 and 1941 the existing arts of television and brought forth standards which were thereupon promptly adopted by the FCC (Federal Communications Commission) as the basis of the black-and-white service.  Most of the new science and technology involved had been worked out previously by two committees of the RMA (Radio Manufacturers Association - now the Electronics Industries Association).  In 1935, RCA had demonstrated a fully electronic 343 line television system.  This event raised the ambitions of many in the radio industry to open a new market, and a spirited industrial contest was thereby joined.
The FCC presided over the arena and its then Chief Engineer, Commander T.A.M. Craven, set forth the ground rules: frequency allocations had to be agreed upon, and standards written which would insure a high quality service, one permitting every receiver in the hands of the public to derive pictures from every transmitter licensed by the Commission.  Thereupon, in 1936, the RMA Television Allocations Committee, one of the two RMA groups, made the most basic proposal of them all: that the channel should be 6-MHz wide. This was a very wide channel indeed for its time, and it was chosen with the explicit understanding that double sideband amplitude modulation would be used for picture transmission, permitting no more than 2.5 MHz of video bandwidth.

Aside from the cited important correction of the previous work, the first NTSC made no significant changes in the recommendations of the RMA Committees, and it was able to complete its work in nine months.  Why then was the NTSC necessary?  Did it serve a purpose?  The second question is easily answered.
The review of prior work by the NTSC was conducted thoroughly and across the board, by competent and devoted engineers having conflicting Opinions and company positions.  So, when the standards were approved by this diverse group, they were on immeasurably sounder ground than were the RMA standards.
 

The other question--Why an NTSC?--requires a more complex, but largely nontechnical answer. What happened - as has so often been the case in the history of applied technology - was a conflict between powerful men bent on capturing for themselves and their companies the lion's share of a new and potentially massive industry: television broadcasting and receiver manufacture.

The industry responded promptly and well.  Indeed, it had no choice, if the television industry was to resume its growth.  In all, the first NTSC had 168 committee and panel members, it devoted 4,000 man-hours to meetings and left a record of 60,000 words.  By the time it finished its work, in March 1941, it had reviewed and endorsed the NTSC standards.  They are still in use today in the United States, Canada, Mexico, Japan and some ten other countries.  The only present change is their narrower tolerances on the scanning rates to accommodate color television.  The net effect on the industry was, of course, that the field was opened up to all comers on a more even-handed basis.  RCA continued to maintain its preeminent position, but there is little doubt that the market was greatly extended by the presence of many powerful competitors.

Incompatible Versus
Compatible Systems

The first NTSC explicitly disavowed the possibility of compatible color (if indeed it ever imagined that compatibility was possible).  At the insistence of CBS representatives, NTSC proposed to the FCC that field tests of color systems be encouraged, using the NTSC monochrome standards in all respects except the number of lines and the field and frame frequencies.  This was early evidence of CBS's long, hard and costly battle, ultimately unsuccessful, to put across adoption of its incompatible field-sequential system.  As a matter of fact, the coming of color television was marked by an epic battle between , two strong personalities: David Sarnoff, Chairman of RCA-NBC, and William Paley, Chairman of CBS.  During the meetings of the first NTSC in November 1940, Peter Goldmark of CBS presented to it an impressive demonstration of field-sequential color, using 343 lines, 120 fields per second and a video channel of 6 MHz.  Later proposals to use two or three contiguous 6-MHz channels for higher definition and/or lower flicker, were dashed by the fact that, in 1948, the FCC, dismayed by the shortage of channels for the burgeoning monochrome service, had ordered a freeze on the licensing of further stations that did not end until July 1952.

This interruption of the progress of the industry had an immediate and powerful effect on Sarnoff and Paley.  Sarnoff then decided that a wideband color service would never be authorized and that a compatible system, which would preserve the existing black-and-white service, had to be invented.  Paley, for his part, ordered an all-court press in favor of the CBS field-sequential approach.  This resulted, in 1949, in a CBS petition to the FCC for immediate authorization of a field-sequential system employing 405 lines, 144 fields per second and a 6-MHz channel.  The FCC in July had requested information on the practicability of all color systems planned for the 6-MHz channel.

Meanwhile, back in 1949, it was clear to Dr. Baker that the time had come for a second calling of the NTSC to provide industry wide agreement on a set of standards for compatible color.  This second incarnation began in January 1950.  At its last meeting, in March 1953, the NTSC approved unanimously the present compatible color standards, and Peter Goldmark of CBS seconded the motion to approve.
Here was an example of what can happen in a free society.  Despite vigorous government opposition, the truth or falsity of counter claims could be worked out, painfully, but worked out to the satisfaction of the many contesting parties.  The new science and technology of compatible color were laid out in all their confusing glory before 315 NTSC Committee, Panel, and Subpoena members.  After 32 months (nearly four times the time taken by the first NTSC), it reached agreement, leaving behind a record of 18 mimeographed volumes totaling 4,100 pages and the better part of a million words.

The dot-sequential system of RCA was the starting point for compatible color, but refinements from other sources proved essential and these were introduced after lengthy discussion and field tests.  Perhaps the most significant of these improvements was the constant luminance principle invented by Loughlin, of Hazeltine, and his proposal to bypass the luminance signal around the color-sampiing circuits.  These techniques removed the dot-interference effects that had been the principal shortcoming of dot-sequential systems.  Other work by the second NTSC included the comprehensive study of the color subcarrier modulation system, the choice of angles and modulation method, and sideband distributions for the I and Q subcarrier signals.  Extensive field tests included a confirmation of the ability of the color synchronizing burst to withstand the effects of severe noise.  Many other proposals were discussed, tested, modified, and accepted or rejected.

As can be imagined from this re-call of history, the second NTSC was not welcomed by the FCC.  One of the Commissioners, R. F. Jones, went so far as to assert that the engineers testifying in favor of a compatible system were in a conspiracy against the public interest.  In fact, the FCC pointedly ignored the NTSC for two years after it began work, at the end of which time FCC engineers were permitted by the Commissioners to attend NTSC meetings and demonstrations.  By that time, 1952, the general embarrassment in Washington over the earlier incompatible color fiasco had subsided.  By 1953, industry wide agreement had been obtained on the NTSC standards, and the FCC authorized their use effective December 23, 1953.

Thereafter Mr. Paley had to follow in General Sarnoff's footsteps, but this disadvantage was tempered by the ensuing history.  It was not until ten years later, in 1964, that the public finally took the bait and began to buy color receivers in substantial numbers.  During that decade, Mr. Paley had time to catch up, while General Sarnoff presided over a total investment by RCA in excess of $100 million before the tide turned.  Sarnoff's faith and perseverance, without which color television service would have been longer delayed, were recognized at a banquet commemorating his 70th birthday, at which the CBS President served as toastmaster.

Difference between NTSC, PAL, and SECAM

It can fairly be claimed that the second NTSC was the most effective operation in the history of technical standardization.  The standards it set up have been adopted by the rest of the world in nearly all major respects.  The most widely used system of color television, PAL, employs a chrominance subcarrier, frequency interleaving of luminance and chrominance components, the constant luminance principle - all taken from the NTSC scheme.  The major differences are that, in PAL, the phase of the color components is reversed from line to line, with corresponding reversal at the receiver, and that simple color-difference signals are used in place of the NTSC I and Q signals.  The effect is to achieve more accurate color values in the presence of multipath and some other types of interference and to reduce quadrature crosstalk.  The SECAM system (considered by most engineers not practicing in France, Russia or their dependencies to be inferior in design to the PAL system) requires the receiver to memorize the content of each line, successive line signals being transmitted in the two color components.  The color signals are sent on a chrominance subcarrier by frequency modulation, thus precluding the use of frequency interleaving.  Both PAL and SECAM require somewhat more complex receivers and have somewhat lower vertical color resolution, but highly satisfactory reception is achieved by each system.

By all odds, the major difference in performance among NTSC, PAL, and SECAM is the superior horizontal resolution of the latter systems.  This arises from two causes: more fundamentally from the wider channels (7 and 8 MHz) used, with correspondingly wider video bandwidths (variously set at 5.5, 6, and 6.5 MHz); less fundamentally from the lower frame rate (25 frames per second) which in turn has the deleterious effect of increasing their susceptibility to flicker problems.  These comparisons prompt a strictly personal view of the ways in which the NTSC standards could be improved, if we had it to do over again.

Clearly, we would have been better advised to choose a wide channel width, say 8 MHz.  This choice would have cut station allocations in the ratio of 8 to 6, but on balance the improvement in the service would have been, in the author's opinion, well worth it.  The NTSC field rate of 60 fields per second is clearly the right choice, agreed upon throughout the world as the proper base for future high definition standards.  With an 8-MHz channel, the 525-line image could have been properly chosen at a considerably higher value, say in the vicinity of 700 lines.  Finally, the NTSC I and Q components which have served us so well are now considered to, have no particular advantage over the simple color-difference signals of PAL, and have some disadvantages indicated by experience with the PAL system.

Despite these minor faults showing that the NTSC system (which preceded the others by ten years) is not perfect in all respects, it remains a system having far more potential than we currently extract from it.  Troubles with cross-color effects in the overlap regions between the luminance and chrominance spectra, have forced designers to limit the luminance bandwidth of receivers produced to date to less than 3 MHz.  This results in a loss in luminance resolution compared to that permitted by the 4.2 MHz offered in the NTSC standards.
Only recently has the announcement been made that comb filters are available in some top-of-the-line receivers, with substantial increase in luminance resolution.  Also, the earlier introduction of the vertical interval reference (VIR) system, which constrains the receiver settings of chroma and luminance to follow the values set at the studio, is now increasingly popular.  So it is that many of the problems of the NTSC standards are being solved by new technology.

Fortunately, also, the problem of program exchange between originations on different standards has been solved by the digital video frame store, at a cost that only large networks can afford.  It is very effective indeed.

The frame store is, in fact, the occasion for asking whether, in the not too distant future, the call may arise for a third NTSC, hopefully under international auspices.  If and when frame stores are so reduced in complexity and cost that they can be incorporated in receivers, then narrow band transmission of television may be in prospect, among several other attractive possibilities.  The eye, as we well know, cannot consciously respond to information clues at any rate faster than about 50 bits per second.  A whole audience, reacting in different ways to different aspects of the presentation, probably could be satisfied with a rate of information clues not greater than a few thousand bits per second.  To achieve such low rates of information transfer in television, we must eliminate the redundancy in scanning by concentrating only on the changes between frames.  Total scene changes will, in this case, require time for full-store accumulation, much indeed as does natural vision.  To adopt this approach requires the digital storage of whole frames and adroit changes in the storage to follow the significant information clues and ignore all else.
This possibility has been understood in its essentials throughout the history of television engineering, and it is still far from practical reality.  But when we consider how much digital processing and storage can now be bought in a hand calculator priced at $7.50, we need, perhaps, not be too discouraged about future possibilities.

If the experience of the two NTSCs is any guide--and I believe it is--we need not only to practice new science and economical reductions.  We must also deal with the human factors of ambition, foresight, strong drives for profit and power, and knowledgeable coordination by government and within the industry.  That such human factors are at work in the world today, pushing for a new day in television, no one among the readers should ever doubt.  The only question is from whence and when will the great push come.