http://www.airspacemag.com/issues/2007/august/oldies_and_oddities.php
Broadcast Bomber
By Margaret Moen
Stratovision had one brief shining moment: On June 23, 1948, the system’s airplane-borne TV transmitters rebroadcast the Republican National Convention in Philadelphia to the nine-state area around Pittsburgh, with a demonstration for reporters in Zanesville, Ohio. “Stratovision is a reality with future unlimited,” cheered the Martin Star, a publication of the Glenn L. Martin Company, which, in a partnership with Westinghouse, had backed the system.
Westinghouse electrical engineer Charles E. Nobles developed Stratovision as a way to transmit television and FM radio programs to a wide audience. The underlying problem, the Martin Star explained, was that waves in the very-high-frequency bands used by TV and FM travel in a straight line from the transmitting tower and, unlike AM signals, do not conform to Earth’s curvature. Therefore, the horizon as viewed from the tower was the limit at which TV or radio could be heard—50 to 100 miles in diameter, depending on antenna height.
Nobles, a radar expert, told Westinghouse that he realized “the possibilities of television and FM radio operation, since both have characteristics similar to radar, from an airplane,” particularly given an airplane’s altitude, flying in “lazy circles” high above Earth. Nobles said that an airborne signal could extend to 211 miles in one direction, compared with 50 miles from a transmitter atop the Empire State Building.
Nobles predicted Stratovision would deliver TV and FM to “small town and farm homes.” Thus the focus on Zanesville, population 38,000, with the nearest TV service at Cleveland and Cincinnati, both 100 miles distant.
Three years of flight testing had preceded Stratovision’s debut, with some early tests using a Lockheed PV-2. Before its Zanesville triumph, the system underwent several test flights and broadcasts from a Boeing B-29 Superfortress. Results showed a good signal could be broadcast from 25,000 feet to an area up to 525 miles in diameter. A Youngstown, Ohio viewer wrote to Nobles: “Reception was good, contrast excellent, sound excellent, and a slight shakiness in picture.”
For the June demonstration, Westinghouse and Martin flew reporters to Zanesville. They watched the broadcast at the Zanesville Country Club, where TV sets had been installed for the occasion.
A B-29, orbiting 25,000 feet above Pittsburgh, rebroadcast the Republican convention directly from WMAR-TV in Baltimore, 9 to 10 p.m. EDT. The bomber was outfitted with an eight-foot mast on its vertical stabilizer to receive programs; the signal was sent from the antenna to the cabin, and on to the broadcast antenna. The antenna, stored horizontally in the bomb bay, projected 28 feet down when operating.
After the convention transmission, Martin and Westinghouse representatives trumpeted Stratovision’s future. They foresaw a nationwide Stratovision network, with programs beamed from one airplane to the next. Fourteen airplanes could bring TV and FM radio to 78 percent of the population; a comparable ground installation network would require more than 100 relay points, Westinghouse estimated. A fleet of 60 Martin 202 airliners would suffice.
A January 1949 Martin press release declared Stratovision “ready for commercial development,” but its stellar prospects were dimming. In August 1948, Westinghouse had petitioned the Federal Communications Commission for a permit to launch the first Stratovision station, operating near Pittsburgh. The following month, the FCC, wanting to examine signal interference between stations, put a freeze on new permits.
In 1949, AT&T set up a coaxial cable network to connect the East Coast with the Midwest, largely through underground wiring. Westinghouse dropped Stratovision in 1950.
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Phil K.
Yankee Air MuseumSystems Admin / Ramp Crew / Professional Photo Ruiner
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