International projectionist (Jan-Dec 1946)

The Stratovision System for Television, FM By C. E. NOBLES INDUSTRIAL ELECTRONICS DIV., WESTINGHOUSE ELECTRIC CORP. PART II THE Glenn L. Martin Co. studied the operation of an airplane of the type required for Stratovision operation. The airplane they have designed tentatively is for operation at 30.000 feet. Forty thousand foot operation seems feasible and is more desirable, but since we have at present more knowledge of the airplane design and operating costs at 30.000 feet, the Stratovision system is based on operation at the latter figure. In the future, higher altitudes may be possbile. In the early stages of thinking about airplane operation of broadcast stations, it was felt that the operating costs for maintaining an airplane at high altitudes would be so great as to require that several transmitters be operated from one airplane, thereby realizing income from several paying advertisers. The operation of several transmitters seemed entirely feasible since the smallerpowered transmitters could be small in size and weight. At the same time many of the larger fixed and operating costs remain essentially constant whether the plane is broadcasting one or more than one program. Operating Sequence It was decided that the airplane design should be large enough to accomodate four television transmitters, five FM transmitters, monitoring equipment, and sufficient relayint 'quipmen' to carry four television programs ana five FM programs, and also system communications channels. The airplane proposed is designed on this basis. The sequence of events in the operation of one airplane transmitter is as follows: It is assumed here that the airplane is simply broadcasting and is not operating as a part of a program distribution network. The television and FM studios are located on the ground in the normal fashion. The program is fed into a small ground-to-plane link transmitters, picked up in the plane by a ground-link receiver, fed into the broadcast transmitter, and re-broadcast over the plane's line-of-sight area by means of the broadcast antenna. If this plane were also functioning as part of a program distribution network, the signal from the ground-link receiver would also be fed into a small networklink transmitter and beamed to the next successive plane by means of a directional antenna. For an airplane operating at 30.000 feet with one kilowatt of broadcast power, the metropolitan areas of many large cities are within the service range of this one airplane. A few such cities are: Pittsburgh; Baltimore; Washington; Charleston, W. Va.; Columbus; Toledo; Cleveland; Hamilton, Ontario; Detroit; Buffalo, and all of the smaller urban and rural districts inside this circle. This coverage represents a potential audience of 16.285.000 people. One airplane, therefore, will deliver a service of four television programs and five FM programs to more than 16 million potential listeners. This one plane thus has the capacity to receive revenue from nine advertisers instead of one. Operational Areas Each plane has a broadcast service range of approximately 200 miles in every direction and relaying can be accomplished between two planes which are approximately 400 miles apart. By operating planes over New York, Pittsburgh, Chicago, Kansas City, western Nebraska, western Colorado, Salt Lake City and Los Angeles, a program distribution network from Hollywood to New York is established. These two cities are considered to be the main sources of television program material except for sports events and special events which •night take place ar~~vhe. n the cor ry. A very small amount of equipme... in the plane will establish this link. At the same time each of these planes broadcasts television and FM programs to an area of 103,000 square miles around its operating point. By adding six more stations to this established network — these six flying over Durham, Atlanta, Memphis, Dallas, Sacramento, and Portland, Ore. — approximately 51% of the area and 78% of the population of the United States is brought within the primary coverage area of the 14 stations. The fact that such national coverage is possible and that large program relaying distances may be used is very inviting from a viewpoint of obtaining program material. Almost any event in the country may be put on as a nationwide telecast with proper pickup facilities. Variety of Program Material Sports events, national elections, symphony concerts, Indian ceremonial dances, local disasters such as floods or hurricanes, and a great variety of other program material could be fed into the network quickly by a small "pickup" plane, equipped with television cameras and relaying equipment, stationed at each Stratovision base. Such a plane could fly quickly to the desired scene and relay the program back to the main relay link for broadcasting nationally. This source of program material will not be so readily available to coaxial or ground-relay systems because of the relative inflexibility and small coverages of these systems. Another advantage realizable from such large transmitter coverages and such an easily set up relay link lies in shortening the "build up" time for na> tional television. Under present planning for f1evir'"n, the hroadcaster and the listen £ puolic a? ■ an economic dead Stratovision coverage would blanket an area 4 2 2 miles across, as indicated by the large circle in this sketch. Coverage by a groundlocated station is limited to a 100-mile diameter, shown by smaller circle. 24 IIVTERNATIONAL PROJECTIONIST