Docstoc

Satellite TV- What Is A Satellite-

Document Sample
Satellite TV- What Is A Satellite- Powered By Docstoc
					Satellite TV has been around for decades now and has become a leader in television
delivery technologies.

Most people know that a signal is relayed from the main distribution center up to the
satellite and then bounced back to the dish on your roof in order to deliver TV to your
home.

However, not many people actually know how a satellite works and what is involved
in creating a network of satellites that can provide coverage to an entire country, or
many different countries.

Here, we'll explore a bit of the behind the scenes work that occurs while delivering
satellite television to your home.

Up In Space

By definition, a satellite is anything that orbits the Earth in a circular or elliptical path.
The Moon is, by this definition, a satellite of the Earth. Also, the Earth is a satellite of
the Sun.

As far as modern technology is concerned, a satellite is a piece of equipment that
orbits the Earth and performs a certain function.

Satellites are not mass produced from a factory. Each is specifically designed to
perform a certain task, and this makes for a lot of variety. Some satellites are used to
track weather patterns, others are used form triangulation in the Global Positioning
System (GPS), and some are used for scientific purposes.

For example, the Hubble Space Telescope is a satellite affixed with an array of lenses
and photography equipment that is used to take pictures of space without the
atmospheric interference experienced at land-based observatories.

The satellites that we are most interested in for the purposes of this articles are
communications satellites.

Communications Satellites

Inside communications satellites are a number of important systems. For satellite TV
customers, it is vital that the satellite stay in a geosynchronous orbit, meaning that it is
in the same patch of sky at all times, so the satellite has guidance systems built in to
maintain position.

The most important piece of equipment, however, is the transponder. A transponder is
a device that receives a signal at one frequency and then retransmits it at another
frequency to avoid any interference with the source signal.

Inside each communications satellite are thousands of transponders. The television
provider's distribution center will transmit a signal directly to the satellite. The
satellite's transponders will analyze that signal and then retransmit it on a different
frequency.

The satellite dish mounted on your roof is designed to pick up signals on that
frequency and acts like an antenna. The signal then travels to the set-top receiver box,
where it is decoded and you can watch your favorite programming.

				
DOCUMENT INFO