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stratovision
Stratovision was an airborne television transmission relay system from aircraft flying at high altitudes. In 1945 the Glenn L. Martin Co. and Westinghouse Electric Corporation advocated television coverage of small towns and rural areas as well as the large metropolitan centers by fourteen aircraft that would provide coverage for approximately 78% of the people in the United States This system has been used for domestic broadcasting in the United States, and used by the U.S. military in Vietnam and other countries.
==Technology==
Because the broadcasting antenna for Stratovision is usually hung beneath the aircraft in flight, it naturally has a great command of Line-of-sight propagation. Although transmission distances are dependent upon atmospheric conditions, a transmitting antenna 30,000 feet (9 km) above the Earth's surface has a line of sight distance of approximately .
A Stratovision 25 kW transmitter operating from 30,000 feet (9 km) at 600 MHz will achieve a field intensity of 2 millivolts per meter for a 30-foot (9 m) high receiving antenna up to 238 miles (383 km) away from the aircraft.
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
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