Table Of ContentContents
How to Install a UK Satellite Sky or Freesat TV System
About this Book
Notes for USA
How Digital TV Works
Which Receiver to buy?
Sky or Freesat?
Where to Buy
Install it Yourself
Elevation Angle
Installation Options
Cable Fitting
LNB Fitting
LNB Adjustment
Trees in the Way
Dish on Pole
Dish in Window
Disguised Dish
Roof Cable
Ladder Safety
Curing Interference
Kinked Cables
Fitting Plugs
Bad Reception
Moving House
Multiple Satellites
Outside UK
Troubleshooting
LNB Reset
Cable Extension
Dish Painting
Large Houses
Apartment Blocks
TV in Bedroom
Other Books
Contact
How to Install a UK Satellite Sky or Freesat
TV System
By Martin T. Pickering B.Eng.
© 2015 Martin T. Pickering
ISBN 1-905964-01-3 -> 978-1-905964-01-7
About this Book
The information in this book applies specifically to the United Kingdom but the basic
principles are true for any region in the world.
This book contains notes about installation to help you to understand what is involved.
Such an understanding will help you to choose what to buy and should help you to save
money and time. You may skip the technical sections, if you wish, but you could read
them later before making a final decision on what to buy.
You need a good understanding of what’s involved, so you can decide what dish and
receiver to buy to suit your particular location/ house layout/ feature preferences.
Otherwise you could end up with a system that doesn’t work properly - picture freezing
and so on - or something that doesn’t do what you want it to do.
Because of the dangers involved in climbing ladders, wiring devices to the mains power
supply and the general risks involved in climbing ladders, working on roofs or in lofts, use
of tools and handling heavy objects or metal parts with sharp edges, we strongly
recommend that you employ a professional to do the actual work.
What programmes can I watch via satellite?
It changes so I won’t list them here. Please refer to www.sky.co.uk and freesat.co.uk
In order for the eBooks in this series to stand alone, there is some duplication of
information in each one. For example, none of these eBooks would be complete without a
description of how to fit a TV plug and how to fit an “F” connector. Omitting it from any
of them would leave the eBook incomplete. However each eBook deals with a separate
subject and such duplication is minimal. If you buy two or more eBooks I make no
apologies for such duplication.
Images: Some images require a colour screen for best understanding.
Installing Sky Digital Satellite TV and Freesat
Introduction
This book is part 2 of the “Understanding Sky Digital and Freesat TV” series. If you
haven’t read that first eBook (which is free to download) please do so.
Most books about satellite TV are aimed at those people who want to fit a motorised
system. Such books are often full of mathematical equations and technical explanations
which even the time-served installer neither uses nor understands.
This book is a MATHS-FREE ZONE. I promise you that there is less maths in this volume
than you would need to count out your beer money!
You will find simple explanations of everything you need to know. In fact you will
probably understand satellite TV installation better than most installers by the time you’ve
read this!
A complete description of how to install a satellite system is included.
In addition, you will find trade secrets exposed: Short cuts and best methods that time-
served installers know from experience, plus examples of what not to do (although some
“installers” still do!)
Most people buy this book reluctantly, without understanding why their questions can not
be answered in a simple two minute reply.
So I want to say “thank you” for your faith in me. I promise you that the information in
this book is worth every penny and more. By reading all the information you will gain an
understanding that will help you to carry out your own successful installation at the lowest
possible cost consistent with getting what you want OR – at the very least – to save money
and time when getting someone else to do the installation and to make sure they can’t fool
you into accepting anything less than the best.
Notes for Installers in the USA
This eBook deals with all aspects of installing a UK Sky Digital system in the UK,
Europe, Scandinavia and a few countries further away.
A lot of the information will be useful to a US installer but some specific information does
not apply to the US systems (i.e. DirecTV and similar).
The main difference is that DirecTV uses a high-band-only LNB with circular polarisation
switching. (In contrast, the UK Sky system uses a “universal” dual-band LNB with
horizontal/vertical polarisation switching and band switching via a 22kHz signal generated
by the digital receiver).
In addition, there is no legal requirement to add a safety-ground connection to a UK
system but in the USA there is.
The references to various European satellites have no meaning in the USA as those
satellites are permanently below the horizon for the USA.
How Digital TV Works
With digital compression, the number of channels from a transmitter can be multiplied by
5, since each frequency that carried one analogue programme can carry five Standard
Definition digital programmes (or more).
Digital programmes are “compressed”. I’ll explain this in simple language because it’s
useful to know how it works. My explanation isn’t technically accurate but it will serve to
give you a good enough understanding. You probably already know that a moving TV
picture comprises a series of still picture “frames”. Each frame is made up from a number
of horizontal lines which scan across the TV screen from left to right, filling the “frame”
from the top to the bottom. (Even an analogue TV picture contained some digital
information. You could sometimes see it as flickering dots or dashes at the top of the
screen. This was the “Teletext” data, which was included in the picture signal).
To convert a TV film to digital in the most basic way, a computer scans a picture frame
and represents each coloured dot and its brightness as a number code. In addition, it can
“compress” some of the code. For example, a red line across the screen ……….. can be
represented as the number code for every red dot which might be -05-05-05-05-05-05-05-
05-05-05-05 as many times as it takes to make the correct line length. But this is wasteful
because the same information can be represented as (the number of dots) x (the colour).
So our short line of eleven red dots is represented by [11][05], which is a much shorter
code. This is a simplified explanation of how a coloured picture can be compressed.
But simply compressing the picture information is not enough. The “boffins” figured out a
way to remove information so that even less code needs to be transmitted. Suppose you
are watching a news reader. Most of the time, the only parts of the picture which are
moving are her eyes and mouth. So the
computer scans the first picture frame, converts it to digital code and “compresses” it in a
similar way to the red line explanation.
Then it looks at the next picture frame and compares it with the first. The news reader has
started to open her mouth but nothing else has moved. So the computer sends a code
which means “same as previous except at coordinates x-y substitute the following code”
and then gives the code for the new position of the dots that make up the news reader’s
lips. And it does this for the next frame and the next.
But even this isn’t compressed enough for the “boffins” so they thought up another idea.
The next frame isn’t transmitted at all!
That’s OK because the Digital Receiver also contains a computer. It watches the code for
each frame and converts it into a picture that you can watch. When it sees that a frame is
missing, it looks at the previous few frames and compares the movements. Then it
“predicts” what the next frame will look like and guesses it. Normally you can’t tell but
very occasionally things do go wrong.
For example, if the news reader moves to the right to pick up a piece of paper then moves
back again - if at the point when she begins to move back, the frame is not transmitted,
your Digibox will “predict” that the news reader continues to move to the right. Worse, it
may decide that only her hair continues to move to the right. The result may be that, just
for one fiftieth of a second, the news reader moves left while her hair moves right! These
mistakes are usually so subtle that you won’t even notice.
So, the digital compression technique is not perfect but the resultant pictures should look
perfect. When the Digital TV’s computer “reconstitutes” a picture, it will make a perfectly
“clean” picture with no “sparklies”, no “graininess”, no colour faults, no “ghosting” and
no interference lines. If you see any of these effects, then they will usually be occurring
after the Digibox has passed its picture out to your TV or the TV is faulty.
Multiplexing
Once compression is complete, a typical TV programme or film can be broadcast in about
one fifth of the time it takes normally. However, this is of little use since you don’t want to
watch it five times as quickly!
So the broadcasting computer combines the digital information of typically five different
programmes by a process called “multiplexing”. Simply put, it mixes the data for, say, five
programmes together in such a way that the Digital receiver can pick out the data for the
programme that you want and reconstitute it into picture and sound. Oh yes, I forgot to
mention, the sound is also converted into digital information, compressed, and mixed in
with the rest of the data. Those of you who listen to “MP3” music will be familiar with
compressed audio.
The end result is that each of the transmitting stations receives a data stream containing
picture and sound for up to five separate programmes and retransmits this data stream or
signal so that your aerial can receive it. One big advantage is that it now costs only one
fifth of the price of transmitting an analogue programme which required one frequency to
itself. This opens the door for more programmes to be transmitted.
Your Digital TV works magic by picking out the specific frequency of the channel whose
“multiplexed” data stream contains the programme you want to watch. Its internal
computer takes the data for that one programme out of the data stream and recombines it
to give picture, sound, text and other information as well. It works at incredible speed to
reconstitute each picture frame as well as the sound to go with it, guessing at (roughly)
every fourth frame and receiving a full frame only (roughly) every ninth. When it gets it
right, you’ll have crystal clear pictures and sound. If it gets it wrong, you’ll get lip-
synchronising problems, strange picture effects, picture breaking into coloured squares
and even complete loss of picture (usually only when the signal is weak or interrupted).
The Dish
For Sky and Freesat the dish is usually oval (wider than its height) and charcoal grey.
Paint it if you wish. It will last longer and you might make it blend into the background
better. It needs to be aligned to an accuracy of better than half a degree! This is almost
impossible to achieve without a signal meter, which range in price from £5 to £500. The
dish collects the very weak satellite signal and acts like a parabolic mirror to concentrate it
on the LNB.
The LNB
Sits on the end of an arm, facing the dish. LNB stands for Low Noise
Blockdownconverter. It is so named because its function is to select a block of channel
frequencies, amplify them and convert them to a block of lower frequency signals that will
pass down a coaxial cable (microwaves won’t). LNBs have 1, 4 or 8 outputs with ‘F’
connectors.
The Digibox
Uses a combination of voltages and tone, passed up the coaxial cable, to switch the LNB
to the desired band, according to what channel you select.
Coaxial Cable
Although not as high a microwave, the signals are still very high frequency so the signal
loss in the cable is quite high. Consequently, it’s essential to use only the highest quality
cable, otherwise you could have problems in bad weather.
