Television digest with electronics reports (Jan-Dec 1953)

channel allocation structure.8 The signal specifications now under consideration meet this objective. Within the same bandwidth that had been allocated to monochrome alone, the proposed system has succeeded in adding color information, while maintaining compatibility with present monochrome standards. This has been achieved by “interlacing” the color information with the luminance signal when portrayed on a picture tube in either color or monochrome; 8 and by taking advantage of the relative insensitivity of the eye to changes in hue and saturation in small areas. 15. To “interlace” the color information, a color subcarrier within the 6 megacycle channel is used. The location of this subcarrier is critical in that it must be selected so as to minimize color information visible on monochrome receivers in order to maintain to the greatest extent possible the quality of the monochrome picture. In addition, the location of the subcarrier must be well removed fi’om the picture carrier and sufficiently removed from the sound carrier to avoid interference. The objectives with respect to the location of the subcarrier, although not fully attained, have been met to a satisfactory degree. 16. The second technique relied upon in the NTSC system relates to the demonstrated fact that the eye is much less sensitive to changes in hue and saturation in small areas than it is to changes in brightness. The corollary is that as the size of the viewed object is reduced, the eye becomes progressively color blind so that ability to distinguish hue deteriorates. It follows that the color components of a picture can be transmitted over a narrow band of frequencies since resolution of fine detail is a function of bandwidth. In the NTSC system faithful colors are transmitted over a 0.6 me bandwidth while the monochrome or luminance signal is transmitted over a 4.2 me bandwidth. In between is a twilight zone where adulterated colors are transmitted. Thus, faithful colors appear in the coarse areas of the picture, adulterated colors in the medium fine detail and only monochrome in the finest detail of the picture. The saving of frequencies resulting from the use of this technique is obtained at a cost in terms of the adverse impact on picture quality, but as indicated below, the overall result meets minimum standards of acceptability. 17. Quality of the Color Television Picture. The Commission’s second and third criteria relate to the quality of the color television picture in terms of specific characteristics. In the light of the data of record concerning the tests and demonstrations conducted by proponents, and the observations of the Commission at the demonstration in these proceedings and at the Commission’s laboratory we are of the view that the color television pictures transmitted are satisfactory and that the signal specifications merit standardization on this score. We have reached this 8 The amount of picture detail which can be conveyed and the resulting quality of the television picture, Is delimited by the bandwidth allocated for the transmission of the video signal. Each time the scanning beam traverses from a light element of the picture to a dark element and returns, a complete cycle of video electrical energy is generated. For technical reasons the 6 me channel assigned to a television station can only accommodate approximately a 4 me video bandwidth. If the sole objective to be served were a high quality picture, It would certainly be desirable to Increase the video bandwidth to permit transmission of greater picture detail. However, spectrum space is severely limited and the bandwidth of television stations must be determined with a view to the desired number of television stations and the needs of other services. » Color is perceived as a conscious sensation In terms of three major attributes: brightness, hue and saturation. Brightness is a measure of the light Intensity radiated or reflected from objects, i.e., their physical "luminance”, and Is the only attribute exhibited by both colored and non-colored objects. Hue Is the most characteristic attribute of color and determines whether the color Is red or green or yellow, etc. Finally, saturation distinguishes strong colors from pale colors of the same hue, as red and pink. Saturation may be considered as related to physical “purity” or freedom from dilution with white. It Is common knowledge that sunlight Is a mixture composed of all the various colors of the rainbow such as red, orange, yellow, green, blue. Indigo and violet. It has been found that It is not necessary to mix all the colors of the spectrum to form white light. Three colors properly selected and mixed In proper proportions will form white and most other colors. However, It Is not possible to produce colors which are outside the spectrum area Included by the primaries For example, If the three primaries are red, green and blue. It is not possible to produce saturated violet since It Is outside the spectrum area Included between red and blue. Likewise, If a diluted red or orange were selected as one of the primaries, It would not be possible to obtain a saturated red. conclusion despite some apparent deficiencies of the color pictures as viewed on presently available receivers. None of the deficiencies present is sufficiently grave, however, to interfere seriously with the over-all enjoyment which may be derived from viewing the color pictures. Although the color reproduction is not completely faithful, it is sufficiently accurate to be a pleasing reproduction. The loss in resolution, as compared to monochrome, is offset by the greater realism resulting from the addition of color information. The brightness level on present color equipment, while lower than on monochrome receivers, is nevertheless within the range of acceptability for home viewing. 18. Receiver Apparatus. The Commission’s fourth criterion relates to receiver apparatus and is a two-fold objective. First, the receiver apparatus must be simple to operate in the home and must not have critical registration or color controls, and second, it must be cheap enough in price to be available to the great mass of the American purchasing public. 19. Our evaluation of the receiver apparatus with relation to the first of the foregoing objectives is based on our examination of the receivers furnished by 13 manufacturers for use in the demonstration held in these proceedings and the receivers offered by three manufacturers to the Commission’s laboratory and on our consideration of the data submitted in the proceedings. The inherent complexity of the proposed signal specifications is, in large part, reflected in the receiver. The color tube, and the attendant circuitry, is of complicated and intricate design and will impose a substantially greater burden in the servicing and maintenance of the color receiver as compared with monochrome receivers. The viewer controls on the front panel of the receiver apparatus are l-elatively simple to operate in light of the complexity of the equipment, and color controls do not appear to be critical. The reception of color television transmissions on color receivers demonstrated and examined does require a finer adjustment of the tuner control than is necessary on a monochrome receiver, for by moving this control too far in either direction, a considerable change can be effected in the color balance of the picture. This necessity for finer tuning, however, does not add significantly to the complexity of operation; and such adjustment would appear to be well within the competence of the normal home viewer. In addition to the controls required for monochrome reception, all of the receivers have an additional “chroma” control which requires adjustment by the viewer. The chroma control, which is not critical, determines the saturation of the colors. At one extreme position, the colors are fully saturated, while at the other extreme position, the colors are washed out. Some of the receivers also have a hue control installed on the front panel of the receiver for adjustment by the viewer. The hue control permits the hue of the picture to be adjusted to the personal taste of the viewer. 20. The data in the record with respect to the estimated price of the receiver is meager. The cost of the tri-color kinescope and the complexity of the attendant convergence circuitry, deflection yoke, and high voltage supply in the receiver, comprise major elements in the price of the color television receiver. RCA-NBC has furnished estimates of receivers based on the use of a 16-inch envelope tri-color tube which has a measui’ed viewing surface of 8% inches by 11 inches, the equivalent of a 12% inch monochrome tube.10 The estimated cost of the 16-inch envelope tube to receiver manufacturer’s is between $175 and $200. The estimated introductory price of the first color receiver will be between $800 and $1000. We do not believe that the data in the record are sufficient to support the conclusion that the presently available receiver apparatus is “cheap enough in price to be available to the great mass of the American people” as contemplated in our criteria. However, several manufacturers have expressed their conviction that when color 10 No estimates have been furnished on the price of receivers with larger tubes. 3