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Home :: The Electronics Integrated in to your Satellite TV System :: You Are Here
The Electronics Integrated into your Satellite TV System
Satellite television has long seemed like magic. Most people know that
satellites orbit the Earth, bouncing signals to and from our planet. The
electronics integrated in to your satellite TV system is much more complicated.
Today, satellite television providers broadcast their programming in digital,
rather than analog, signals. The outcome is a much higher quality picture and
sound over original satellite reception.
Initially, satellite television was broadcast in 3.4 to 7 GHz frequency range,
also called C-band radio. Current digital satellite broadcasts are transmitted
in 12 GHz to 14 GHz frequency range, also called the Ku frequency. In addition
to more rapid signal transmission, the higher gigahertz permit many more signals
to be broadcast and picked up at once.
There are five essential elements to your home satellite television system. The
first is the programming source. This is the station where the broadcast
originates from.
HBO, USA and other national channels each create their own lineup, broadcasts
and provide their own advertising (commercials.) These programs are transmitted
to an orbiting satellite that they control. The radio waves containing
programming are then reflected from the satellite to a DBS provider broadcast
center.
Local stations typically transmit their programming, like news and show line
ups, to the broadcast center via fiber optic cable. It is not cost effective for
localized programming to be sent to satellites only to be sent back down to a
broadcast hub in the same area.
A broadcast center is a ground based hub run by the satellite service provider.
This is where programming is lined up so there is no interruption of service and
television programs begin at the appropriated time. Broadcast centers are also
responsible for converting programming into high quality digital streams. Before
the programming is sent back to an orbiting satellite, it is compressed to
MPEG-2 format – the same formatting that DVDs use – and encrypted to prevent
theft.
Radio signals containing the MPEG-2 information are sent from the broadcast
center to satellites in orbit around the Earth’s equator. Besides providing
television shows, we use satellites to facilitate communications, weather
forecasting and scientific research. With so many satellites orbiting the Earth,
it is a very exacting task to send the proper signals to the correct satellite.
Once the signals have reached the satellite, the signal is transmitted back down
to Earth. This transmission finds a satellite dish, usually attached to a home,
to receive it. Most dishes contain a bowl-shaped surface as well as a central
feed horn.
The satellite dish can only receive signals, it cannot transmit. As the curved
dish receives a signal from the orbiting satellite, it reflects the signal to
the central horn.
The feed horn contains a low noise blockdown converter, or LNB. This converter
strengthens the signal and filters out radio signals that do not carry
television programming. From the LNB, the stronger, filtered signal is sent to
the receiver box inside the home.
The receiver box is usually a black or gray box a little smaller than a VCR.
There is a place for video in (signal from the LNB), video out (to the
television) and a power cord. Some boxes are integrated into a digital video
recorder (DVR), like TiVo.
The receiver unscrambles the signal and holds the key to unlock the encryption.
The unlocking mechanism is provided by a decoder chip, supplied by the satellite
service provider. Without the proper decoder, no television shows will appear.
Illegal descramblers are often disrupted by the satellite service provider. The
service provider is able to send an electronic counter measure (ECM) that will
knock receivers without the proper coding off their system.
While some televisions are able to output digital quality television (HDTV),
most televisions require analog signals. In the US, that analog format is called
NTSC. If a viewer has an HDTV, settings on the receiver can be changed to output
in digital format.
With so many components involved in receiving satellite television channels,
there are a multitude of places your service can be interrupted. The functions
and electronics integrated in to your satellite TV system must all be reliable
and compatible.
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