When a subscriber requests
an Internet page from a distant Web server, the computer sends
the request to the satellite modem (indoor unit) which converts
and delivers the request to the microwave radio transmitter
in the satellite dish (outdoor unit).
•
The radio transmitter then
sends the request up at the speed of light to a geostationary
satellite, which immediately relays the message down to the
central network operations center (NOC). The NOC is connected
directly to a Tier 1 Internet provider (the Internet backbone)
via high-capacity fiber optic lines and thus is able to instantly
route the Web page request on to the Web server of the requested
Internet page.
•
When the request is received
by the Web server, the server immediately begins sending out
the Internet page to the satellite NOC in the form of many individual
packets of information. The NOC employs sophisticated data acceleration
technology that relays the various information packets, which
travel at the speed of light to the geostationary satellite
and down to the remote subscriber site. The acceleration technology
maximizes the delivery efficiency of the satellite network and
greatly enhances the speed at which Web pages arrive at the
end user.
•
At the remote subscriber
site, the burst of Internet data is received from the satellite
by the outdoor dish and instantly relayed via coaxial cable
to the satellite modem inside. The data is then converted and
sent through an Ethernet cable to the Subscriber’s computer
where the Internet page is displayed on the monitor. Incredibly,
this process from start to finish takes only a fraction of a
second.
Because of our enormous coverage, network capacity and direct access
to the Internet backbone, we can place any site in the continental
U.S. – no matter how remote its location – directly on top
of the Internet backbone and deliver to it high-speed access to the
entire World Wide Web. Agristar Global Networks can provide high-speed
connectivity to homes and businesses to which DSL and cable cannot
reach, connecting all of rural America to its broadband communications
network.
Satellite Network Infrastructure:
Agristar Global Networks
Subscriber Sites.
All subscriber sites have a satellite system that is comprised
of two primary components: the outdoor unit and the indoor unit.
•
The outdoor unit
is comprised of a small dish antenna (approximately 2ft
x 3ft in size) with transmit-and-receive electronics attached
to its front.
•
The outdoor unit
is connected via coaxial cable to the indoor unit, which
is a small box (approximately 8” x 8” x 2”)
that houses the satellite-computer interface electronics.
The indoor unit communicates with the subscriber’s
personal computer through a basic Ethernet connection.
Geostationary
Satellite.
Agristar Global Networks' space segment utilizes a type of satellite
called a “geostationary” satellite to relay information
to and from subscriber sites. Most communication satellites
in use today are geostationary satellites, which orbit the earth
directly over the equator at a distance of approximately 22,300
miles in space. It is at this distance that one complete orbit
around the earth takes 24 hours, thus these satellites are able
to stay over the same spot on the surface of the earth (geo)
and so appear to remain at a fixed point in the sky from the
surface (stationary). The advantage of geostationary satellites
is two-fold:
1)
Geostationary satellites
can provide communications service to an enormous area,
with a single geostationary satellite able to provide
coverage to approximately 40% of the earth's surface.
2)
Subscriber Sites
do not need complicated tracking systems to maintain a
signal as they would for satellites that do not remain
in a fixed point in the sky. With geostationary satellites,
an installer needs to point the dish only once.
Each satellite is comprised of 32 transponders, which are the
part of the satellite that perform the actual signal relay back
and forth to Earth. Modern transponders are able to handle huge
amounts of data traffic – a single Ku-band transponder
is capable of handling approximately 100 million bits of information
per second. With this capacity, if one transponder is accessed
for only 2 minutes per day, it could transmit the equivalent
of more than ½ million single-spaced typed pages. This
immense data capacity makes today’s communication satellites
a highly-effective technology for transmitting and receiving
all types of content, from simple Web pages to software applications
to high-resolution audio and video programming.
Network Operations Center.
The satellite network operations center (referred to as the
NOC) is the primary uplink and downlink facility. Agristar Global
Networks is arranged in a point-to-multi-point architecture
with Internet information routed from the Web, through the NOC,
up to the geostationary satellite and then down to any one of
the thousands of subscribers on the Network.
The NOC has multiple large uplink and downlink satellite antennas,
each capable of handling an immense amount of data traffic to
and from space. The NOC is also connected directly to the Internet
backbone via high-capacity fiber optic pipes – in effect
placing the subscribers directly on the Internet backbone no
matter how remote their rural home or business.
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