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radio signal. In addition to
amplifying the signal, a
communications satellite
also typically converts the
radio from one frequency
to another so that the
signal getting sent down is
not confused with the
signal being sent up.
People communicate to a
satellite using an antenna
on the ground, which
called an "earth station" in
technical terms. The earth
station sends up radio
signals to the satellite.
These signals are called
"uplinks."
The satellite receives these
signals, makes them
stronger, and then retransmits them back down
to the Earth. These signals
Joy feelings magazine
back to the Earth are
called "downlinks."
Sometimes the uplink and
downlink earth stations
perform various
specialized functions. For
example, some uplink
stations deliver - or "feed"
- video or audio
programming to the
satellite, which is then
retransmitted to users all
over the United States or
world. These links are
called "feederlinks." Other
uplink stations are used to
control the satellite. Such
uplinks are called
"control" links. Downlink