404 Electronic Communication and Data Systems
Satellite TV
Arthur C. Clarke first introduced the idea of launching
satellites to improve communications. He did this in an
article in the fall, 1945 issue of Wireless World magazine.
He stated that if satellites could be launched high enough
(35,880 kilometers or 22,300 miles) above the equator,
they would be in geostationary orbit. Geostationary orbit
means an object rotates with the earth.
The first communications satellite, Telestar I, was
launched by the National Aeronautics and Space Admin-
istration (NASA) in 1962. It was a small, experimental
satellite that only operated a few hours each day. This
satellite made communication between the United States
and Europe possible. In April, 1965, NASA launched the
first commercial satellite, Early Bird. This satellite was
owned by the International Telecommunications Satellite
Organization (INTELSAT), a group created in 1964. Now
there are many satellites in orbit allowing for television,
telephone, radio, data, and other communications
messages.
Rockets and space shuttles place satellites into space.
There they are deployed and the circuits are activated,
Figure 23-23. Figure 23-24 shows an SBS communica-
tions satellite now in orbit. This satellite was designed to
provide voice, video teleconferencing, data, and elec-
tronic mail services to U.S. businesses.
From its geostationary, or synchronous, orbit 22,300
miles above the equator, AUSSAT, Australia’s first
national communication satellite, links that entire country
and Papua, New Guinea, through an advanced telecom-
munications system. See Figure 23-25. When the satel-
lite is in orbit, the antennas point south, making the
spacecraft look upside down if viewed from earth.
Refer to Figure 23-26. It shows the inside of a satel-
lite. A traveling wave tube amplifier increases the
strength of the communication signal for its broadcast
back to earth. It is being adjusted by an engineer. The
amplifier is onboard a communication satellite. This
satellite is built to carry both standard traveling wave
tubes and solid-state power amplifiers. This type of satel-
lite is reliable and has a long life.
The diagram of the parts of a satellite are shown in
Figure 23-27. Figure 23-28 shows satellites in orbit over
North America.
Figure 23-23. The launching of the Hughes communica-
tion Leasat 4 satellite. (Hughes Communications, Inc.)
Figure 23-24. A Satellite Business Systems (SBS)
satellite being prepared for launch.
(Hughes Communications, Inc.)