Television digest with electronic reports (Jan-Dec 1953)

traps and any other known methods to minimize the radiation. The ultimate answer to whether the additional interference susceptibility of color receivers will be a serious impediment to the establishment of a successful color television system will be furnished in the performance record of receiver manufacturers and the manufacturers of transmitters and other electronic equipment. 30. Transmissions over Inter-City Relay Facilities. The Commission’s seventh criterion is that the signal specifications must be capable of transmitting color television programs over inter-city relay facilities presently in existence or which may be developed in the near future. 31. It is our view, based on the data in the record and the observations of the Commission at the demonstration in these proceedings and at the Commission’s laboratory that satisfactory color television pictures can be transmitted over existing inter-city relay facilities. Moreover, it appears that improved systems of inter-city relay facilities now under development will provide for the transmission of a more satisfactory color television picture in accordance with the signal specifications under consideration. 32. Long distance television transmissions are generally provided by use of the microwave relay system and the coaxial cable system. Existing microwave circuits have a bandwidth of somewhat more than 4 me and require no special equipment to transmit color pictures using the proposed signal specifications. The bandwidth of the coaxial cable currently in use, however, is limited nominally to 2.7 me. Since all the color information in the proposed signal specifications is transmitted on the 3.58 me subcarrier, special provision must be made for confining the color signal within the 2.7 me bandwidth. This is accomplished by the use of cable conversion equipment which heterodynes the color information down to a frequency band within the cable pass band for transmission at the sending end of the circuit and restores it to the original frequency band at the receiving end. The resulting signal is limited to a bandwidth of 2 me for the luminance channel and .3 me for the color signal. 33. Color television pictures transmitted in accordance with the proposed signal specifications over the microwave system currently in use results in negligible observable degradation and provides a highly acceptable color intercity transmission service. Transmissions over the coaxial cable system currently in use results in appreciable degradation. Although the degradation is appreciable it is our view that the over-all quality of the pictures presently meets minimum standards for acceptability. Moreover, although it appears likely that the coaxial cable currently will continue to be used for a number of years to provide network service in some areas, it appears that commercial and audience pressure may result in replacing this equipment with improved cable carrier and improved microwave equipment. The Bell Telephone Laboratories, Inc., which participated in the activity of the NTSC, stated that it has under development improved systems of intercity television transmission to provide for the satisfactory transmission of a color signal in accordance with the proposed signal specifications. 34. Compatibility. The term compatibility in its usual sense l-efers to the satisfactory reception of black and white pictures from signals broadcast in color on monochrome receivers without alteration. There is, however, another aspect of compatibility, sometimes referred to as “reverse compatibility,” which relates to the satisfactory reception of monochrome signals on color receivers without alteration. 35. The first aspect of compatibility is a factor of critical importance in view of the fact that there are at the present time more than 27 million sets in the hands of the public. No change is required in existing monochrome receivers for the reception of a black and white picture from color transmissions on the proposed signal specifications. It appears, however, that the black and white pictures suffer some degradation. At distances from the receiver where the line structure is evident there is also a dot structure visible. Beyond this critical distance there appears to be no significant deterioration in the picture. It appears that the degree of degradation is not substantial, and we do not believe it will interfere seriously with the public’s viewing of color programming in black & white. 36. With regard to the second aspect of compatibility (i.e. reverse compatibility) no test data has been submitted. A number of parties commented favorably on the ability of present color receivers in this respect, but the statements were of a general nature unsupported by data. Our own observation indicates that the monochrome picture suffers a noticeable loss of definition when received on a color set. 37. Convertibility. The term convertibility has been used to describe the changes necessary to enable existing receivers to receive color transmissions in color. No practical converter has been demonstrated nor does it appear that proponents of the proposed signal specifications have any current plans for the production of converters. Ill — CONCLUSIONS 38. Field Sequential System. In our consideration of specifications for the broadcast of color television in the 1949-50 proceedings in Docket 8736 et al., we concluded that of the three systems under consideration only the field sequential system met minimum standards of acceptability. These signal specifications were, however, incompatible in the sense that receivers outstanding in the hands of the public could not receive color transmissions in monochrome without adaptation. The limited amount of commercial color broadcasting on these standards was short-lived, and color television broadcast equipment for the field sequential system has never been produced in quantity and is not now being produced, nor are color transmissions in accordance with the field sequential standards being broadcast or contemplated. Three years have passed since that decision, and there are now more than 27 million television receivers in the hands of the public, all of which are incompatible with our present color television standards. That circumstance serves to nullify those rules and standards completely. We have concluded, therefore, that our present rules for the transmission of color television should be deleted. 39. Proposed Signal Specifications. The proponents of the color television signal specifications proposed in this proceeding have been of the view that a color television system in order to prove successful must be compatible. With this premise in mind, petitioners have cooperated in an industry-wide, intensive program of study, research and experimentation, lasting over a period of more than two years, in an effort to evolve and formulate satisfactory compatible color television signal specifications. To this end, petitioners have expended millions of dollars and have employed thousands of man-hours of the most highly skilled engineers and scientists in the electronics and related fields. 40. The accomplishment of a compatible color television system within a 6 me bandwidth is a tribute to the skill and ingenuity of the electronics industry. The proposed color television signal specifications produce a reasonably satisfactory picture with a good overall picture quality. The quality of the picture is not appreciably marred by such defects as misregistration, line crawl, jitter or unduly prominent dot structure. The picture is sufficiently bright to permit a satisfactory contrast range under favorable ambient light conditions and is capable of being viewed in the home without objectionable flicker. Color pictures can be transmitted satisfactorily over existing inter-city relay facilities and improvements in inter-city relay facilities may be reasonably anticipated. 41. It has long been recognized that compromises are necessary when an attempt is made to compress within a 6 me channel as much information as is required in a color television system. The achievement of a compatible system within a 6 me channel has been accomplished only by the utilization of extremely complicated and intricate equipment. It relies on a system of circuitry involving the most advanced techniques in optics, mechanics and electronics. The complexity and intricacy of the equipment and circuitry is reflected in the following: 5