created this page to give a basic introduction on how Satellite
first section of this web page will explain how to get
Satellite TV in the UK - either by paying a monthly subscription
to Sky or by paying nothing at all (except for the receiver
box and dish) for programmes from FreeSat
Just read the bits that interest you! ***
you wish to make suggestions. correct problems and/or errors,
offer advice or simply want to have a chat then please e-mail
is the Digital Switchover?
2012 the UK will have completed the change from analogue to
digital television. This is known at the Digital Switchover
here for more details) and is being done region
by region following a government timetable. When it is complete
viewers will have three system options to get their favourite
channels. These are Freeview
(the land based-terrestrial service) which needs a normal
TV aerial and Satellite TV which uses a dish pointed at a
cluster of satellites in space. A third option, only available
in certain areas, is Cable TV.
you live outside a Freeview coverage area (click
here to check using your postcode) and cannot see
the extra programming available, an alternative is to get
a satellite TV system.
Read on to learn what you need to do ....
a short introduction:
TV and radio programming aimed primarily at the UK comes from
a group of satellites located at 28° east of South. They
are called 'Astra-2A, Astra-2B, ..., etc, and EuroSat'. The
main provider of satellite television for the UK is Sky and
virtually all their channels are scrambled. To unlock Sky
channels a dedicated receiver-box and a special viewing card
are needed. The viewing card contains special electronic codes
which unlock the channels you pay for each month. Getting
these Sky programmes can be expensive (starting at about GBP17+
can you get for free from Satellite?
Sky is primarily a subscription-based service offering several
hundred channels of TV and Radio. The actual monthly cost
depends upon the subscriber's selection of channels and equipment.
A special 'viewing card' is required to be inserted into a
dedicated Sky receiver box to unscramble the programmes subscribed
to. However some channels are not scrambled and can be viewed
on a standard satellite TV receiver box (often called a Free-to-Air
receiver) connected to a correctly positioned dish.
about Freesat and FreesatfromSky?
Freesat is a joint venture between BBC and ITV to provide
free TV viewing across the UK without the need for any subscription
charge. All you need to do is buy a receiver and and have
a dish installed (either by youreslf, a friend or a recognised
aerial company). A dedicated Freesat receiver has a comprehensive
Electronic Programme Guide (EPG) built-in making programme
selection for up to 7 days ahead very easy.
FreesatfromSky operates in a very similar way, but
requires the use of a dedicated Sky box and a 'viewing card'.
The FreesatfromSky service requires a one-off payment for
the installation of receiver and dish. This gives all the
free channels plus a selection of subscription channels for
a few months. If the additional channels are NOT cancelled
within the specified time period the viewer will have to give
at least 30 days notice to cancel the subscription. Viewer
about HD TV channels?
HD programmes are only available (at the moment) via satellite.
Freeview HD channels are expected to become available during
the latter stages of the Digital Switchover roll-out. The
BBC and ITV programmes are free to view. Freesat HD compatible
receivers are available to buy (starting at about GBP95).
Sky offers a wide selection of HD programming but a special
HD receiver and an additional subscription is necessary.
Astra-2D footprint by courtsey of SES-Astra
Sky on 08442 410 595
more info on programme choice, visit www.freesatfromsky.co.uk
read the Q&A section.
Freesat on 0845 313 0052
- If you have your own Sky Digibox, dish and LNB and can install
it yourself (or have a mate to do it), then ask Sky to send
you a FreesatfromSky viewing card - a modest fee may be payable.
Or buy a Freesat receiver and enjoy all the free channels
and free HD !
created this part of the page to give a general introduction
on how Satellite Television works.
broadcast satellites are placed in orbit directly above the
equator at a height of about 36000km. They travel through
space at the same speed the earth's rotation - so to us on
the ground the satellite appears to be stationary. This is
known as a geo-synchronous (or geo-stationary) orbit.
controllers fire on-board jet thrusters occassionally to keep
the satellite in the specified position in space. This is
the major factor in determining the 'life' of a satellite.
Europe the orbital location of a satellite on the Clark Belt
is given by the number of degrees to the East or West of due
South (for example: Astra 1 = 19.2°E, Hispasat = 30°W).
This is the Azimuth.
Clark Belt viewed from northern Europe
idea of geo-stationary satellites was first suggested
by Arthur C Clarke in an article written for Wirless
World magazine in October 1946.
The region in space occupied by these satellites is
commonly referred to as 'The Clarke Belt'
signals to and from the Satellite
and radio programme signals are sent from the various originating
studios to an Earth up-link station. From there the gathered
'bouquet' of programmes is transmitted into space using a
dish aimed at the orbiting spacecraft. This is known as the
'up-link'. The frequency is about 14GHz (in Europe)
The satellite receives these signals, amplifies them and transmits
them back towards earth on a different frequency. This work
is done by a transponder.
This 'down-link' operates at about 11GHz (in Europe), in the
so-called Ku microwave band).
A group of satellites in the same orbital position (such as
Eutelsat's 'Hotbird') may have a combined total of more than
70 transponders. A transponder rebroadcasts 1 analogue TV
channel or as many as 14 digital TV channels (this depends
on the digital compression techniques used:- lower compression
= less channels = better pictures).
kind of broadcasting is known as DTH (Direct-to-Home broadcasting).
satellite has a massive array of solar cells. Some satellites
are cube-shaped and have huge wing-like solar cell arrays
extending from the main body, while others are cylindrical
and have their entire surface coated with solar cells. The
cells convert sunlight into electricity to operate the satellite,
providing power for the transponders and to maintain the charge
on the standby batteries for the times when the satellite
is in the shadow of the Earth.
Up-link station at Leuk, operated by Swiss PTT
satellites used for radio and television broadcasting are
not usually owned by the broadcasting companies.
Broadcasters lease the technical facilities from the satellite
owner. In Europe the two major satellite providers are Eutelsat
The earth stations required to send the programmes up to the
satellite (called the 'up-link') are provided by a variety
of organisations in many many different countries. Some of
these are commercial organisations (eg BT in UK) and some
are government agencies (eg national PTT authorities).
This is the actual signal strength map (or Footprint) of the
Astra 1G and 1H satellites (as published by the owners of
the satellites, SES-Astra). Both 'birds' are located in the
same orbital position in space at 19.2°E.
The antenna on the satellite directs the signal down to a
specific land area.
Just as the beam from a flashlight gets wider and weaker over
distance so does the satellite radio signal.
Contour lines on the map show the required dish size for satisfactory
that these satellites have a signal beam dedicated to covering
the Canary Islands. This arrangement is known as a 'spot-beam'.
into Satellite TV and Radio ...
tune in to satellite TV some specific receiving equipment
most obvious item is the dish. The dish is the antenna
(aerial). It works like a curved mirror to collect, reflect
and concentrate the radio energy from the satellite and focusses
it into the throat of the LNB (Low Noise
LNB amplifies these very weak signals and converts
them to a lower frequency (from about 11GHz down to about
2GHz), the so-called intermediate frequency. This signal
travels along the coaxial cable to the Receiver unit in the
home. It is very important to use the correct
type of coax cable - ask your supplier for CT-100, or better.
Receiver (often called the set-top box, STB)
performs all the electronic signal processing that is required
to recover the TV signal. In addition it sends power and control
signals up the cable to the LNB. The Receiver is connected
to the TV set either by an antenna (aerial / RF) lead or SCART
cable. Operation of the receiver and channel selection is
normally done with an infra-red remote control unit.
basic principle of getting the satellite TV signal is the
same whether an analogue or digital system is being used.
However, the electronic processing of digital and analogue
signals is very different indeed.
Digital signals comply with the DVB-S (Digital Video
Broadcasting - Satellite) protocol. Look for the DVB logo.
For an analogue signal, the signal strength is very important,
but for digital reception as much care must be paid to maximizing
signal quality (the higher the quality number the less bit-rate
errors the receiver will have to cope with).
Dishes, More Satellites
a greater choice of programming it is possible to 'look' at
several satellites. This can be done by using a motorized
dish or a combination of several fixed dishes and LNB's.
use multiple dishes a simple switching system called DiSEqC
(Digital Satellite Equipment Control
- developed by Eutelsat) is all that is needed, but the receiver
must be DiSEqC compatable. The DiSEqC switch is usually fitted
near the dishes and a single cable feeds to the Receiver.
The Receiver box sends control signals along the cable to
the DiSEqC switch to automatically select the correct combination
of dish/LNB and satellite.
Upgraded versions of the DiSEqC protocol allow for control
of motorised dishes (DiSEqC 1.2 and 2.0).
detailed spec of DiSEqC protocol go
different type of motorized system is the horizon-to-horizon
(H-H) method. Here an electrically operated screw-jack
pushes and pulls the dish which pivots on a special mounting
bracket. This makes the dish accurately follow the position
of the satellites along the Clark Belt. Receivers incorporating
this type of motor drive will usually have 'Positioner' included
in the name/description.
even greater flexibility LNB's are available with single,
dual, quad or octo (8) outputs. Each output is totally independent
from the others. This allows multiple receivers (living room,
bedroom, kitchen, etc) to connect to a single dish/LNB.
'looking' at two closely spaced satellites (eg Hotbird [13°E]
and Astra-1 [19E°]) it is possible to use one dish and two
LNB's mounted on a special extension arm. The dish and one LNB
is focussed on the weaker of the two satellites. The second
LNB is moved along the extension arm until a satisfactory signal
from the second, stronger satellite is received (this picture
shows a single output LNB 'looking' at Hotbird and a quad output
LNB 'looking' at Astra-1 - note that one output from the quad
LNB is not in use).
is a view of uncletony's
The garage roof is used as a base for the various dishes.
The LNB's are connected to a 4-way DiSEqC switch. The
output of the switch is a single cable connected to 'free-to-air'
analogue and digital receivers.
The Sky (Astra-2) system is a completely separate installation
for family entertainment.
receive a strong and reliable signal in all weathers the dish
must be pointed directly at the satellite.
Select a position where the path to the satellite is clear
and unobstructed (for example a tree without leaves in winter
will cause no problem - but in summer virtually no signals
will get through to the dish).
"Pointing the dish" means setting the Azimuth
and Elevation correctly.
is the angle between horizontal and the satellite in orbit
on the Clarke Belt.
(In the UK this ranges from about 21° in the far north
of Scotland to about 27° in the south of England [for
is the position (east or west of south) where the satellite
is located (19°E, 1°W, etc).
(or polarization offset) is the final little tweak required
to get the strongest possible signal from the satellite.
Instead of having the LNB fixed vertically in it's holder,
a few degrees of clockwise (right) or anticlockwise (left)
twist from the vertical is applied to compensate for the
position of the satellite being either east or west of due
south (in the northern hemisphere). The skew applied in
northern UK for Astra-1, 19°E, is 10° clockwise.
This increases to 16.5° for viewing Astra-2 at 28°E
setting up your dish it is important to take into account
the difference between true North and magnetic North.
This is called the Magnetic Declination (or Variation)
this useful FREE
program from Pangolin
Comms to easily calculate the Magnetic Variation
at your location anywhere in the world.
you've got a dish you've gotta have this .... download
SWMLink from Swedish
Microwave. Among the many things it can do,
this useful application is probably the best there is
for calculating dish Az, El and Skew
from any location on the globe for any
satellite on the Clarke Belt. And best of all it's for
find your Latitude and Longitude go to
and enter your UK postcode.
the map is displayed then click on 'Click here
to Convert/Measure coordinates...'.
Your location details will be shown in a new table. Dead
worldwide locations go to www.heavens-above.com
to find your Latitude and Longitude
to satellite Transponders
Transponders are interleaved using opposite polarity
Adjacent transponders are transmitted with alternate polarity.
This allows more transponders to be used within the frequency
band(s) allocated to satellite DTH broadcasting. The LNB is
capable of switching between signal polarity.
transponder on a satellite has a typical bandwidth of 27MHz.
A single analogue channel will occupy this whole space. Up
to 14 compressed digital TV channels can be fitted into the
signal is 6 MHz wide. Main Audio carrier is at 6.60 Mhz
Additional audio sub-carriers at 180kHz spacing are used for
stereo TV sound, alternate languages and/or radio stations
Rate represents the data rate (typically 27500Kbps) - see
FEC is the Forward Error Correction factor inserted by the
broadcaster. The data stream can include TV, Radio and/or
analogue system uses FM (Frequency Modulation).
digital system uses QPSK (Quadrature Phase
Shift Keying) modulation.
This works by changing the phase of the In-phase (I)
carrier from 0° to 180° and the Quadrature-phase (Q)
carrier between 90° and 270°. This is used to indicate
the four states of a 2-bit binary code. Each state of these
carriers is referred to as a Symbol.
diagram showing how four different
binary codes can be transmitted
to Encryption (Scrambling)
television and radio programmes which can be watched by anyone
with a basic receiver are known as Free-to-Air (FTA).
Many broadcasters charge a subscription for their programmes,
prevent unauthorized viewing the signals are scrambled (encrypted).
There are several digital encryption systems - for example
Cryptoworks, Conax, Irdeto, Mediaguard, Viaccess, etc. In
Europe the majority of the few remaining analogue encrypted
channels are beamed towards Scandinavia. These services use
the MAC TV standard, and the scrambling system is Eurocrypt.
unlock a channel the viewer needs a Receiver with a Conditional
Access Module (CAM) that matches the encryption system being
used. On payment of a fee the programme provider will supply
the viewer with a viewing card containing special codes (called
keys) to unlock only the subscribed channels. Copyright and
other legislation normally does not allow the purchase and
viewing of programmes in one country which are intended for
another country (for example: it is not permitted for viewers
in Spain to watch encrypted programmes 'aimed' at the UK by
Receivers are dedicated to one television network and one
encryption system (for instance in the UK, SkyTV can only
be picked-up on a receiver with an embedded (built-in) Videoguard
CAM). In this case the subscriber's viewing card is linked
electronically to one specific receiver.
Receivers are available with a common interface (CI). This
is a single or double 'slot' into which one or more CAM's
can be inserted. Once the CAM is in the receiver the necessary
viewing card is inserted into the CAM.
CAM has been designed to have the same physical format as
a PCMCIA Card (which are extensively used in lap-top computers
the satellite enthusiast a wide range of experimental CAM's
are available (Magic Module, Axas-II, Matrix Reloaded, Dragon,
etc). Many reportedly operate on several of the encryption
systems. Various models of these CAM's are advertised in hobby-related
are a few Receivers on the market which have an embedded experimental
CAM (so-called UCAS - Universal Conditional Access System).
These Receivers usually have at least one additional slot
for another CAM.
Access Module (CAM)
External and Internal views
with built-in hard disk drives are becoming very popular.
When combined with the appropriate CAM and viewing card it
is a simple matter to record any TV programme to disk ready
to be replayed at a later date. Most have twin tuners which
allows the recording of one channel while viewing another.
Dreambox receiver operates very much like a computer. It uses
an IBM 'Power-PC' processor and uses the Linux operating system.
Because of the open access of Linux code many Dreambox enthusiasts
create and modify software to continually improve the receivers
operation. For an introduction
or three manufacturers offer PCI-style Satellite Receiver
cards that fit inside a computer (regrettably only operating
on MS Windows). Not only do these cards receive the programmes
and store an unlimited amount of channel data, some versions
of these cards can make the computer hard-disk operate as
a personal digital video recorder (a 'PVR'). Also available
are USB satellite Receivers for PC's and Mac's which connect
to the computer with a USB cable .
support the hobbist there are a few monthly magazines and
several Internet Forums/newsgroups. By using appropriate search
parameters on 'Google' (or other search engines) you will
readily track these areas down.
of the most respected sources of up-to-the-minute listings
of satellite transponders and programme providers are at:
the very best in technical info about digital and analogue
satellite TV go to Martin Pickering's very own site:
store for e-Books about satellite TV and terrestrial
up-to-the-minute stuff about all aspects of Satellite TV visit
the 'What Satellite Magazine' daily update pages at:
loads of up-to-date stuff about technical and political apects
of UK satellite and terrestrial Digital TV visit:
info about installation of dishes (for Sky) and aerials (for
Freeview) visit the Confederation of Aerial Industries Ltd:
a very technical discussion of terrestrial and satellite DVB
ex-pats who need info about receiving Astra-2D outside the
normal footprint go
uncletony's page about
UK analogue and digital television go