Satellite
TV
In
the next chapter we will introduce you the basics of digital
satellite television and show you the differences with
analogue satellite television.
Digital TV
Digital TV became a part of everyday-life for most of
the Croatian satellite-viewers. Many people thought of
it as just a next step in the transmission of TV and radio
programs via satellite and that the viewers wouldn’t
accept it, since they would have to pay an enormous amount
of money, at least in the beginning, to buy a satellite
receiver without including the peripherals like modules
and cards, which costed a real fortune. Nowadays we can
happily say that this has changed, since digital satellite
receivers and modules and cards lowered their prices,
so that they are affordable for everyone. Digital TV today
dominates in the satellite communications and this will
last for at least the next ten years till the satellite
equipment industry doesn’t come up with something
entirely new.
The first satellite transmission in digital technology
was performed in June 1993 in Germany. They tested the
transmission of ten satellite programs via one transponder.
The transmission took place via the Copernicus 2 satellite,
which is stationed at 28.5°E.
How digital
TV works?
Digital television uses data-compression. Compressed data
need less space and is easier distributed via satellite
and cable networks. In digital technology the picture
and sound data is sent in form of compressed binaries.
This means that the data is first transferred into binaries,
which means they will be expressed in only zeros and ones.
For example 0=0, 1=1, 10=2, 11=3, 100=4, 101=5, 110=6,
111=7, 1000=8, etc. Afterwards this data is compressed
and is ready to be sent to the end user.
Data-compression
Why must the data be compressed? This is done for a simple
reason: compressed data uses less space than the ordinary
analogue sound and picture transmission. In the transmission
of satellite and earth programs in analogue technique
whole picture slide, 25 frames per second that is, are
sent, which delivers a complete picture on the TV. This
is the reason why they can transmit only one program via
one transponder or available channel on the satellite
if the use analogue technique. The second program is transmitted
via another transponder, the third program on the next
transponder and so on. Expert concluded that this way
of transmission uses too much available space. Since frames
that are sent are nearly always the same, what means that
the sent data of following frames are either totally equal
or at least very similar, there is no need to send one
frame after another. Via digital transmission and picture
and data compression the satellite receiver shows the
first picture on the TV set, then it compares it to the
next picture, and if it comes up that it deals with the
same picture it will simply ignore the second one. Otherwise
if the second picture differs only a bit the satellite
receiver will only transmit these details and make the
necessary changes to the first picture. The receiver will
now compare the third picture with the second and will
proceed in the described manner. This is how the receiver
will compare all following pictures, which it receives
via satellite or a ground transmission network that emits
digital satellite TV programs. This is the basic of data-compression:
the more unnecessary repeating picture-parts you delete
the more necessary changing picture-parts you send. This
is how all digital programs via satellite and earth are
sent today in Europe.
For the ability of sending digital programs in this way
there were developed special systems for program transmission.
They are called MPEG and they are the standard for digital
transmission. Today the only system in use for digital
transmission is the MPEG 2 system.
What is the MPEG system?
MPEG means Motion Picture Experts Group. This group is
developing systems for digital pictures since the late
80’s. The first system was called MPEG 1 and was
overall accepted in November 1994 for the use of digital
transmission, but the MPEG 1 system had a picture quality,
which is identical to the picture quality of your VCR
and that means the system was able to present a horizontal
resolution of 250 lines, which is not enough for T transmission.
Therefore they started to improve the MPEG 1 system and
so a few years later they developed the MPEG 2 system,
which fully satisfied the need of digital TV and radio
transmission and was therefore recommended as the new
world standard. This system is used today in the transmission
of digital TV and radio programs whether they are emitted
via satellite or via ground networks.
MPEG 1 is used today in the transmission of ADR (Astra
Digital Radio) and in the transmission of digital radio
programs via ground networks, the so-called DAB (Digital
Audio Broadcasting).
In what ways differ these systems? Basically it’s
about the signal transmission speed and the audio part.
MPEG 2 is capable of data transmission speeds higher than
30Mbit/s. this means that more than 30 million information’s
are transferred during one second. MPEG 1 was capable
of only 1,5Mbit/s. by the way a MPEG 2 receiver is capable
of receiving MPEG 1 signals, but vice versa this not possible.
Another difference is the audio part. MPEG 1 is capable
of emitting and receiving only stereo sound, which means
it is able to use only two sound channels. MPEG 2 is capable
of sending and receiving more-channel surround sound like
for example Dolby ProLogic or the newer Dolby Digital.
Both systems are sound compatible; therefore MPEG 1 can
reproduce MPEG 2 sound but only in stereo sound without
the possibility of reproduction with more sound-channels.
In what ways differs analogue satellite TV from
digital satellite TV?
The main difference is in the digital program transmission
technology itself. The basics are the same. Programs are
recorded in a studio with simple cameras, movies are copied
with telekinos, afterwards the are translated into digital
codes which is given to the TV station, which is sending
it to the satellite, which is emitting it so that you
can sit at home and receive the program. Your satellite
receiver transforms the received digital signals into
analogue signals so that they can appear in form of a
picture on your TV set. Digital pictures need to be transferred
into analogue pictures, since there are no TV sets yet,
which would be capable of showing a digital picture without
transforming it first.
The main difference is technically that digitally transmitted
programs need less space on a transponder, what allows
to transmit up to ten (and even more!) programs with one
transponder.
If you compare a picture transmitted with digital technology
with the same picture transmitted with analogue technology
you will see the difference at once. The digital picture
is sharper, has good contrast and there are no lines or
corns in the picture neither are the colours blurred.
In contrast to this the analogue picture is less sharp
and has often dull black and white stripes, what is an
outcome of a weaker signal or equipment with lower quality.
Digital receivers
These receivers do not differ by their outer appearance
from today’s analogue receivers. The main difference
is in inside the device; it’s about a newer technology.
All digital receivers are small computers, which use memory
chips to process the pictures and save data. Today’s
satellite receivers have up to 32 MB RAM memory, which
is, as you’ll have to admit, equal to memory used
in most PC throughout Croatia, even though we are getting
used to 64 and 128 MB too!
Some digital receivers include a built-in communication,
a modem that is, for the connection to the Internet (only
some of them, since most of the receivers with a built-in
modem use the modem as a connection between the receiver
and the provider, who enables so the ordering of special
events- PPV system (Pay per View)) and allows so a fast
changing of information.
About the basic characteristics of digital receivers read
the chapter about satellite equipment.
Now we’ll only mention that all digital receivers
build today have to full-fill the requirements of the
DVB group (Digital Video Broadcasting group, which standardizes
the digital video transmission).
The possibilities an future of digital TV
Digital TV is a new and big technology, which has a lot
to offer in the future. Its possibilities have practically
no boundaries. Only digital TV enables real interactive
watching of TV programs in the comfort of your home. We
will name only a few possibilities.
Internet
We have already mentioned the option of connecting the
digital satellite receiver to the Internet. Today’s
upper-class models with a built-in modem already have
this option. By using such a receiver you have totally
new possibilities of communication what is very important
today, because it is most important to have the right
information in the right time. To use the Internet with
such receivers you have to connect to the phone line and
configure the connection in the same way as you do it
on your PC.
This has to be done, since most of the receivers send
queries to the Internet via the phone line and receive
data via the satellite network. This way the communication
is instant without waiting for results of the Internet-query.
The same never-ending possibilities of communications
has the Internet via satellite, which is established by
connecting your computer to the digital satellite network
in case of which you get your information through the
“sky”.
EPG
Digital TV introduced the term EPG, which stands for Electronic
Program Guide. This enables us to see anytime, during
watching the satellite program, what’s on now and
what will be on next. You can also see the content of
today’s program and some receivers, like for example
the Duo Master 4, allow you to see the program content
for the next 4 days. Today there exist special EPG’s,
which are emitted by some TV stations, for example the
Swedish Viasat emits an interactive EPG, which enables
you to get the freshest news, to play games, listen to
the radio, to watch the timeline of programs, to watch
sport event, to order films, products, merchandise, etc.
British Sky emits an interactive EPG with similar options!
Interactive program watching
Digital TVs main attraction is the interactive program
watching. Mostly it’s about sport or documentaries.
Interactive program watching means that you can interact
with your favourite program, which enables you to create
your own program. The best example is the transmission
of Formula 1 races: you can choose the cameras, change
the ankle of view, etc. Such transmission of races are
provided by some Italian and German TV stations. A completely
different story is the British Sky Sports Extra program,
which is a fully interactive program, which enables you
to watch nearly all important sport events. Most impressive
is the watching of football games, which allows you to
change the ankle of view, to choose the camera, to repeat
scene from the game and repeat arguable details. At any
time you can get the names of all players, statistics,
the biography of a player, etc.
Automatic loading of new software for the digital receiver
Automatic loading of new software via satellite is an
option exclusively for digital satellite receivers. Since
there are today many manufacturers of digital satellite
receivers the upgrading has become more important, because
even the most luxurious digital receiver won’t be
luxury without new software. New software is sent via
satellite only for a few receiver types like for example
Nokia, Force, Samsung, Humax and others, many other manufacturer
don’t offer such a service. Receivers mad by the
manufacturer Force recognize by themselves if the new
software is installed and if necessary they download and
install the software by themselves. After resetting the
receiver will be ready to use the new software.
Other manufacturers however enable software upgrading
by linking the satellite receiver to a computer via the
RS 232 port. Then you have to download the new software
from the Internet (mostly on the websites of the manufacturer)
and install it in the receiver. Afterwards the receiver
will use the new software. If you should have trouble
with newly installed software you can always install the
old software and afterwards try again installing the new
software.
Automatic program search
A digital satellite receiver makes finding programs for
you easy, since it downloads all available programs on
the satellite, which the antenna is adjusted to, when
you use it for the first time and even afterwards during
the everyday usage of the receiver. This means you don’t
have to enter new frequencies, names and other data. The
receiver does it himself if you want him to do it. You
can do this everyday or once a week just to see whether
there have been made some changes to the frequencies of
satellite programs or whether some programs have stopped
their transmission or whether there are some new programs.
Some receivers like FORCE’s analogue and digital
receivers have the option of independent registering of
new programs. This means that the receiver by himself
enters new and erases old programs every day at a prior
given time of day, so you don’t have to think about
this at all and you can fully concentrate on watching
satellite programs.
Pay per View programs
All film-lovers are cheered by the fact that only in Europe
you have over 200 movie-programs, which are all naturally
encoded. These programs are emitted as a part of paid
packages, a vast number of them are pay per view programs.
They are based on the concept of emitting only a few shows
with a time delay of approximately 15 minutes. They emit
movies and sport events in such ways. If you want to watch
a show or movie you just order per phone at what time
you want to see it or you can do this by pushing a button
on your remote control as it is the case with the British
Sky Digital package.
Teletext
Teletext of digital TV programs, which emit this service,
can’t be watched on TV like any other ordinary teletext
emitted by analogue satellite TV programs, like HTV (Croatian
national TV) for example. The digital receiver has the
ability to show the teletext emitted by digital programs
on your TV set.
The main advantage of digital teletext is its speed. You
don’t have to wait to get the information you wanted
to see. The basic functions of teletext are: double sized
letters, watch, fast text and showing hidden text. It
has to be stated that some digital receivers can store
up to 3000 pages of teletext.
Now we can say that teletext has reached its purpose by
being emitted with digital technology.
Shopping via satellite
Digital technology has made interactive shopping from
the comfort of your house become reality, you just have
to turn on your TV, tune in a shopping channel, choose
the merchandise you want and order it. Some digital packages
offer the option that you can buy and pay directly with
your satellite receiver. For example the Sky Digital package:
The satellite receiver for receiving these programs, the
so called Sky DigiBox has not only slot for the inserting
of the subscriber card but also a slot for a credit card.
If you want to buy something you like you just have to
insert your credit card into the credit card slot. The
transaction is completed and in a few days you’ll
receive the ordered stuff at home. Paying your merchandise
like this shopping has just become watching and choosing
the products on the shopping channel. This form of payment
will certainly attract many customers.
The possibility of watching encoded programs
Digital receivers introduced a new term: CI, which stands
for Common Interface, which describes a replaceable module,
which is used as an interface to link the receiver to
a digital recorder. These decoders are no to be connected
through a scart-connector, but through this interface
in the front of the receiver. Decoders for digital satellite
TV don’t even look-a-like analogue satellite TV
decoders, which are independent units, which are not small
at all.
More about digital encoding systems and available program-packages
can be read in the chapter about encoded programs.
What should I choose? Analogue or digital?
Despite the fact that everyday TV and radio stations are
stopping to emit their program in analogue technology,
you can still watch nearly 100 TV programs emitted through
Astra and HotBird, and you don’t even have to pay
a big amount of money for it. Digital satellite receivers
are no longer a curiosity in our homes, the reason for
that is that their prices are lowering each day. There
are more and more receivers, day-by-day newer and more
sophisticated models are on the market and therefore older
models are becoming cheaper. Now you can buy a digital
satellite receiver for just 200€, which is still
more than 100€ for an analogue satellite receiver,
but it’s a start. Receivers for this amount of money
will satisfy any TV viewer, who is not interested in watching
encoded TV programs. The more a viewer wants the more
he’ll have to pay for such a sophisticated digital
satellite receiver, since their prices start at 30kn up
to 5000€, as much as costs a SCT Classic (a analogue-digital
receiver with decoders) for example. Such a receiver has
a lifetime guarantee and many options to upgrade it.
Advice for
buyers!
Most of buyers, who aren’t able or who simply don’t
want to inform themselves about the capabilities of digital
satellite receivers, their prices, options and upgrading
simply buy the cheapest available model, which includes
an antenna, a receiver and a LNB. After they buy the equipment
and it is already installed they simply sit down and watch
the program, but soon they are disappointed, since they
can’t watch the programs they wanted too. It’s
getting worse if they visit a friend with a better receiver,
which enables him to watch more programs. The situation
is getting even more tense, since they want to watch more
programs and start to call everybody they know and ask
how to watch these encoded programs and they’ll
always end up with the answer: “It’s impossible
since your receiver isn’t designed to do this!”
Therefore I advise you to inform yourself, since the price
isn’t the only issue that matters, but also your
wishes and the capabilities of the receiver. So you’ll
maybe spend more money in the beginning, but you won’t
have to buy a new receiver simply just to be able to see
the programs you wanted to see from the beginning on.
Before you are buying a digital satellite receiver inform
yourself. Don’t be ashamed to ask questions you
will often see that you already know more than some of
the people that want to sell you the satellite equipment.
The most important thing is to make sure that you can
upgrade your receiver so you can later watch encoded programs
otherwise you can stick with your analogue receiver.
If you aren’t interested in digital technology or
you simply don’t want to spend money to watch TV
just stick with your analogue receiver, since he will
suit you at least the next 5-6 years.
Signals emitted with digital technology are sent in the
form of bits, which is one sign. The more complex a transmitted
program is the more it will require a higher transfer
rate.
