The Satellite Geosynchronous Orbit Advantage.
(back to top)
With Satellite Television the problem with radio interference,
distance and the circumference of the earth is overcome because
the signal to the home television is received from a satellite in
outer space that is far enough up to cover a full half area circumference
of the earth just like a flash light shining from one direction
can cover the full half of a ball. A Satellite is an object orbiting
another object such as the moon orbiting the earth or in other words
any object repeatedly moving around another object in a circular
fashion. TV Satellites are placed in outer space at a great distance
from the earth of 22,200 miles (35,700 km) up as compared to the
space shuttle which orbits at 200 to 350 miles up or the moon at
238,238 miles up. They are rocketed into a position and a speed
that orbits at the same speed as the spin of the earth (7,000 mph
or 11,000 kph) so they remain stationery in the same place above
the earth. This is called a geosynchronous orbit which obviously
means that signals can be engaged by receiver and sender satellite
dishes on the earth without having to continually move their aim
towards the orbiting satellite. In other words, you only have to
direct the aim of your TV satellite dish once in a stationery position
and from then on it will be able to pick up the stationery signal
hitting it from space.
The Satellite Microwave Signal Advantage. (back to
top)
Satellite Television like broadcast television is a wireless system
that uses radio signals to transmit television programming directly
to the viewer’s house. With regular broadcast television there
is a large powerful antenna which transmits the signals to the home
television antennas which are in the direct line of the TV broadcasting
stations sight. These signals can go around and through small objects
like trees and buildings but they are limited in distance they can
travel by the circumference of the earth which no radio signal can
penetrate. In other words, if your television antenna is on the
other side of the earth or hidden by the curvature of the earth
you will not be able to receive the signal. If the earth was perfectly
flat you could receive the signal from thousands of miles away.
The other problem with direct broadcast television is that the signal
gets distorted even in the viewing area because of large objects
interfering with the radio signal and other reasons so that one
has to be close to the broadcast area to get a clear signal that
is equivalent to cable TV. Also, signals transmitted by Satellite
are very different than television or radio signals broadcast over
the air. They are transmitted by microwaves that do not behave like
the lower frequency radio waves of off air television or radio which
can bounce off obstructions, clouds, and the ground. Micro waves
are direct according to line of sight and therefore it is important
that you do a survey to make sure there are no obstructions that
will block you from receiving your signal or getting a full good
signal.
The Two Types of Satellite Systems. (back
to top)
Once satellites were put up into space there was the need for a
new type of antenna to receive the signals and thus satellite dishes
were innovated to receive these new signals. The first satellite
dishes were large dishes of 6 to 12 feet in diameter and started
popping up in the back yards all over the US in the late 70’s
and early 80’s. This first satellite system came to be known
as TVRO (TeleVision Receive Only) and is still alive and well today
and one of 2 different kinds of satellite systems. TRVO is known
by other words such as C Band Satellite TV, Big Dish TV, Full View
and BUD (Big Ugly Dish). TRVO or C-Band satellite has a large dish
which must be able to move its aim towards different satellites.
In the continental United States it can receive up to 20 C-band
satellites They also now can be upgraded to receive free or unscrambled
programming from the more modern and superior Ku band frequency
Satellites. TRVO systems are more expensive and difficult to install
and require regular maintenance but have the greatest variety of
programming available in satellite television. With a TRVO satellite
system cable TV programming is available, foreign stations, live
unedited television feeds between broadcast stations of things like
news, sports, and NASA activities. For more detailed information
on TRVO click on TRVO basics.
The Superior Technology of Todays DBS Satellite
Systems. (back to top)
More recently the second type Satellite TV system is DBS, Direct
Broadcast Satellite, which is by far the most popular and widely
used. DBS is broadcast by high powered satellites in the microwave
high Ku frequency range of 12GHz to 14GHz compared to the lower
C band frequency in the 3.4-gigahertz (GHz) to 7-GHz frequency range.
This frequency makes it possible for signals to be compressed into
30:1 MPEG-2 compressed video signals which allows far more channels
to be squeezed through without damaging digital clarity so that
there is a large number of up to 200 channels from one satellite.
Further, because there can be a number of satellites received by
one dish, DBS providers, like Dish
Network, can offer 500 or more channels to your satellite dish.
This Ku frequency microwave also made it possible to have High
Definition Television (HDTV). HDTV gives viewers crystal clear
pictures that are equivalent to theater quality sights and sound
with special Dolby Digital 5.1 channel surround sound. Your DBS
programming is transmitted and received with the same quality that
a DVD player can reproduce movies with big screen quality effects.
You need a HDTV receiver to receive these channels and companies
like VMC Satellite offer these an all their
equipment free with a life time warranty. These Ku frequency waves
also made it possible to use a very small satellite TV dish of only
18 inches across. Also, the dish can be stationery without the need
to move or aim at the satellites because the satellites for DBS
systems have a geosynchronous (stationery) orbit and are also close
enough together in outer space for the signals to be sent from a
number of satellites towards the stationery aim of one small dish
with good reception. It is all of these extra features like small
dishes, the offer of large numbers of channels in packages and the
ability to have high quality digital television and sound that has
caused Satellite TV to be exploding in growth and converting many
cable users to satellite TV.
The major DBS systems available in the US are DIRECTV
and Dish
Network which both offer a small 18 inch dishes. DIRECTV
picks up signals transmitted by 3 satellites made by Hughes
Electronics Corporation which make up the primary orbital location
or slot at 101° degrees for channel reception in space. These
3 satellites in this primary slot are so close to each other that
the small 18 inch receptor dishes for television viewing do not
have to move to pick up all three satellites. DIRECTV
has 2 more orbital slots with additional satellites at 110°
and 119° degrees over the equator which provide additional TV
channels to those available on the primary orbital slots including
Spanish and HDTV (High Definition TV) channels.
DISH
Network through its parent company EchoStar Communications has
2 EchoStar satellites that make up its primary orbital slot or location
in space for signal reception by its 18 inch dishes for television
viewing. These satellites are at 119°W over the equator and
send most of the programming choices with DISH Network. Again these
satellite dishes also do not have to move because the 2 satellites
are so close together. DISH Network has additional satellites at
61.5°W, 110°W and 148°W that provide HDTV (High Definition
TV) channels, local network programming, International channels,
Spanish and data services.
The Overall Processing TV Signal Path To TV Viewing.
(back to top)
Direct broadcast satellite providers (DBS) such as Dish
Network and DIRECTV
buy television programs like HBO or ESPN from the broadcasters who
charge them a fee for these rights. In other words DBS providers
buy wholesale from the broadcasters and resell them for a profit.
Because of this arrangement the basic path of the radio signals
containing television programming starts from programming source
(broadcaster) to the satellites, then back to the DBS broadcast
center, then back to the satellites, then to the viewers satellite
dish and LBN filter, to the receiver and finally the television
set.
Details on How A Satellite Dish Operates. (back
to top)
The sending satellite dish and the viewers receiving satellite
dish consists of a bowl shaped dish and a central feed horn known
as a “low noise block down converter” (LBN) aimed just
in front of the dish at the dish. Both sending and receiving dishes
work in the same way except in the opposite direction. The viewers
dish catches the waves from one or more closely placed satellites
in space and these waves deflect off the dish at an angle that focuses
them on the feed horn (LBN) just like light focused through a concave
glass focuses on a particular point. One LBN can pick up waves from
2 or 3 satellites if they are placed close to each other in space
in a stationery (geosynchronous) orbit. This allows for a great
number of channels. However, the quality of signals is somewhat
compromised in this set up because the horns are not aimed as directly
as they can be at any particular satellite. There are now some newer
dish systems that use 2 or more horns to pick up a more direct aim
from each satellite to increase the signal strength and quality.
The LBN amplifies the TV radio signals and filters out all the radio
waves or noise not carrying television programming. This then travels
down the cable attached to the LBN to the Satellite TV receiver.
Details on How a Satellite TV Receiver Works. (back
to top)
The Satellite TV receiver is the last processing mechanism before
coming to the viewing television. Its first function is to de-scramble
encrypted digital signal from the Satellite TV provider. The receiver
unlocks the signal by a special decoder chip for a particular programming
package which can be updated to another package because the provider
can communicate with the chip through satellite signals to make
any adjustments and can also send special signals known as electronic
counter measurer (ECM) to disrupt viewers using illegal descramblers.
This is why you cannot get free DIRECTV
through piracy. Secondly it takes the digital MPEG-2 signal and
converts it into an analog NTSC format that a standard television
can recognize or into a HDTV signal for High Definition Television.
Thirdly, it takes from the satellite signal and splits out just
the channel you have selected which is why you cannot have 2 Televisions
viewing different programs from the same receiver like you can with
Cable TV and also why you cannot tape one program while watching
another at the same time. However, DISH Network provides up to four
receivers free with life time warranty and free installation when
you sign up for one year. A Satellite TV receiver is far more complex
than the cable TV receiver because it has many more functions beyond
just descrambling. They can continually up date programming information
so that you have a fully interactive TV guide the comes up from
any channel that shows you what has been on and what will be on
every channel up to 2 weeks in advance. They also keep track of
what you have watched like pay per view movies and automatically
signal to the satellite this information plus automatically phone
a computer at the providers headquarters to pass on billing information.
They include digital video recorders (DVRs), which have the ability
to pause and record up to 100 hours of live television onto a hard
disk. Some even give you TRVO functions and HDTV accessibility.
Now that you have read this you have all the basic satellite TV
knowledge in order to make an intelligent choice that you will be
thankful you made.
