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Military Communications Satellites

As soon as the possibility of placing a man-made satellite into an Earth orbit was recognized, speculation began as to the feasibility of using a radio repeater (transponder) for intercontinental communications. The use of geostationary satellites for this purpose was suggested by Arthur C. Clarke in an article in "Wireless World", 1946. The advantages of the geostationary orbit for general communications and for broadcasting was apparent, although there was much speculation about the acceptability of satellite links for telephone channels in view of the long echo delay of some 540 milliseconds. A public offering of satellite voice channels was not made until sixteen years later at which time they were found to be acceptable as had indeed been predicted by simulated tests.

There are four segments to the military satellite communications (MILSATCOM) architecture. First, ultrahigh frequency (UHF) satellites are the workhorses for tactical ground, sea, and air forces. Second, the superhigh frequency (SHF) Defense Satellite Communications System (DSCS), first deployed in the 1970s, supports long-distance communications requirements of military forces that cannot be met by groundbased communications systems. The DSCS system satisfies the majority of DoD's medium- and high data-rate communications requirements. Milstar will soon be integrated as the third segment of the MILSATCOM architecture. It will provide a worldwide, secure, jam-resistant communications capability to US civilian and military leaders for command and control of military forces. The fourth segment consists of commercial communications satellites, which are used to support DoD's MILSATCOM capabilities where jamming protection is not required.(1)

In 1945 British scientist and science fiction writer, Arthur C. Clarke, published a technical paper in which he suggested that communications satellites were feasible.

The Syncoms were three experimental, active satellites. The name, coined from the first syllables of "synchronous communications," referred to their orbits. Each Syncom satellite weighed about 85 pounds. Syncom I was launched February 14, 1963, but did not reach synchronous orbit and communications failed. Syncom II, launched July 26, 1963, was the first satellite placed in synchronous orbit. It was active in many successful intercontinental communication experiments. Syncom III, launched August 19, 1964, was the first stationary Earth satellite. It demonstrated the practicality and effectiveness of stationary, active communication satellites. In orbit near the International Date Line, it was used to telecast the 1964 Olympic Games in Tokyo to the United States, the first television program to cross the Pacific.


References

1. Department of Defense, Report on the Bottom Up Review, October 1993, page 65.


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