International projectionist (Jan-Dec 1945)

U. L. approved . . . eliminates fire hazard. MicroSwitch safety cut-off — when door opens, motor stops ! Motor does not transmit torque to operating parts. Reel-drive Dog... prevents broken keys. Available through Theatre Supply Dealers. GoldE Manufacturing Co. 1220 West Madison St. Dept. R, Chicago 7 Low Maintenance Cost Positive Friction . . . Will Not Clinch Film Modern, Compact Design "Tilt-back" Case . . . Reels Can't Fly Oft STRATOVISION (Continued from page 17) coverage radius of 50 miles is possible, whereas at an altitude of 30,000 feet a coverage radius of 211 miles is possible, and at 50,000 feet about 300 miles is possible. Another very interesting feature of high-altitude operation is the fact that as the station's height is increased, the transmitted power necessary to deliver a usable signal to the line-of-sight distance is sharply reduced. Fifty kilowatts of power will deliver a usable signal at approximately 50 miles from a ground station, whereas only one kilowatt of power will deliver the same usable signal at approximately 200 miles from 30,000 feet. Smaller powers are required from the higher altitudes because the path difference between the direct wave and the ground-reflected wave is increased. The fact that such small powers are required from high altitudes is very inviting for several reasons: 1. The broadcast service area covered is relatively tremendous. 2. The smaller-powered transmitters can be made in sizes and weights which are practical from the standpoint of carrying them in an airplane. 3. Powers of the order of one kilowatt can be generated with tubes which are available today — even for the CBS highdefinition color television frequencies. 4. The small amount of power required to operate the transmitter can be obtained from power plants installed in the airplane. If so desired, the power required to operate the equipment could be taken from generators connected to the aircraft's engines. This power will represent only about four per cent additional load on the plane's engines. If we transmit from one plane to the next plane in the chain, the line-of-sight distance between the two planes is about 400 miles instead of the 35-mile spacing for ground stations. With such large relay spacings a program link from Hollywood to New York is obtainable with only eight airplanes as compared with 100 relay points on the ground. This greatly reduces the technical problems involved by virtue of requiring fewer handlings of the program. With directional antennas and utilizing relay frequencies on the order of 2.000 megacycles, this relaying can be done between airplanes with powers of less than one watt. Tubes readily are available which will generate powers of 5 watts in this frequency range. These relay stations could be designed to carry several television programs and also an abundance of other information such as FM network programs, facsimile, motion picture theatre television, etc. Because the broadcasting service area and relay spacings increase with altitude and the power required to service the broadcasting area comes down as altitude is increased, it is desirable from a standpoint of radio operation alone to operate the plane at as high an altitude as possible. The altitude of operation of the system is limited by the economic and technical problems involved in operating planes at extreme altitudes. A study of the overall combination of radio and airplane operation indicates that an operating altitude between 30,000 feet and 50.000 feet provides a good compromise. (TO BE CONTINUED) S^euSon 6 Cv/ reetinai o all I.A.T.S.E. Locals from LOCAL NO. 619 ALEXANDRIA, VA. 'GOLDIE', OF SIMPLEX, HONORED BY DISTAFF SIDE AT N. Y. LUNCHEON Technically smart and super-efficient ladies of the industry's technical branch recently threw a luncheon party for Dora Goldman, secretary extraordinary for many years to high officials of International Projector Corp. Pictured above (l-r) are: Florence O'Neill, National Theatre Supply; Ruth Entracht, International Projectionist; Betty Connolly, Warner Bros.; Toby Roth, Prudential Circuit; Elizabeth White, RKO; Frances Tannenbaum, RKO; Evelyn Gang, LA. Local 306; Miss Goldman; Lee Schindler, Century Circuit; Clara Schmitt, N.T.S. Co.; Lillian Perlman, Paramount; Lillian Morgan, Loew's, Inc.; Veronica Stock, Loew's Inc., and Margaret Marayno, Local 306. (P.S.: They found time to eat, too.) 34 IAN 2S 1348 INTERNATIONAL PROJECTIONIST