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NOTE: This page was written in 1998, several years ago before Digital was introduced. It has NOT been updated since 2000.
FAQ UK Analogue Satellite TV for Beginners
Copyright ©1998 Martin Pickering
Version 1.2 updated on January 4, 2000
This file may be downloaded for private and personal use but NO part of it may be published in any form without the prior permission of the author.
1. How does it work?
2. What is an LNB?
3. What is a satellite receiver?
4. What is a decoder?
5. Do I need a decoder?
6. How do I decide what to buy?
7. What is Astra?
8. What is Digital?
9. What is "Hot Bird"?
10. Can I receive both Astra and Hot Bird?
11. Can I install my own system?
12. Can I receive even more programmes?
13. What is SKY?
14. Should I buy the cheapest?
15. Will my old LNB work with a Pro-Logic receiver ?
16. Is it possible to add a second LNB to my existing equipment ?
17. Should I buy an analogue receiver and LNB or buy digital?
1. How does it work?
A number of satellites have been launched into orbit around the earth. They sit in a circle above the equator at a distance of 36,000km. This position allows them to remain in the same relative position in the sky.
To a viewer on Earth, they do not appear to move.
Each satellite has the ability to receive signals transmitted from Earth and to re-transmit them back to Earth over a wide area. The satellite on-board equipment which does this is called a Transponder. A satellite can have several transponders - typically 16. On the ground, large transmitting dishes are used to "uplink" the programmes to each satellite. Each transponder of each satellite beams the programme back down so that it reaches an area designated the "footprint". This is the area where the signal is strongest. The signal becomes weaker towards the edges of the footprint.
To receive a signal you need a dish. This acts as a curved mirror and focusses (concentrates) the weak signal at a point in front of the dish where an "LNB" sits.
2. What is an LNB?
"LNB" stands for Low Noise Block-downconverter. This LNB often has a horn which collects the focussed signal and feeds it to a tiny aerial inside the LNB. The job of the LNB is to convert the weak microwave signal into a stronger signal at a lower frequency. This lower frequency signal can then be fed down a coaxial cable to the satellite receiver.
3. What is a satellite receiver?
The satellite receiver is able to separate the mess of signal coming from the LNB into several recognisable TV picture channels and soundtrack channels. Normally you will be able to "tune" the receiver so that you get your desired programmes at particular channel numbers.
4. What is a decoder?
Many of the programmes are scrambled before they are uplinked to the satellite. In order to descramble them you need a decoder. The usual type of UK decoder is called "Videocrypt" which is licensed by Thomson plc. This type of decoder is usually built inside a receiver. For most scrambled channels you will also need a Smartcard to allow the decoder to work. Smartcards are generally available by subscription in specific countries. This is because the programme providers are licensed to broadcast programmes only to certain countries for which they pay a fee. Apart from "Videocrypt" the next most common type of decoder is called a "D2MAC" transcoder. This is not really a decoder but simply a means of translating a different transmission standard. (Most European broadcasts transmit using the "PAL" system, but D2MAC, DMAC, SECAM are also used. In the USA "NTSC" is used.) Inside most DMAC/D2MAC transcoders is a "Eurocrypt" decoder as well. This works very much like "Videocrypt" and has its own Smartcards.
If your receiver does not have a suitable internal decoder you will usually be able to connect one externally. You should consider this point BEFORE you buy because some combinations of receiver and decoder will not work. Always get the whole bunch of equipment demonstrated before you buy and make sure that the connecting leads used to demonstrate are the ones you take home (these can give problems as well).
5. Do I need a decoder?
You can watch a lot of "free" analogue programmes with only a receiver. However, only a few of these are English. But do remember that you can receive dozens of "RADIO" programmes from analogue satellite (audio sound tracks without pictures) and you don't need a decoder for these! Some broadcast in stereo and some in mono. Currently, BBC Radio 1 and 3 are in stereo. BBC Radio 2, 4, 5-Live and World Service are in mono.
6. How do I decide what to buy?
Ask several satellite-owning neighbours to demonstrate their systems. Usually they will be pleased to do this. See if you can find somebody with a big motorised dish who will show you the vast choice you can receive from different satellites. Apart from looking at picture quality, performance and price, consider reliability, too. About ten percent of satellite receivers fail within two years.
7. What is Astra?
Astra is the name given to two groups of satellites, owned by a company called S.E.S., which are located above the Earth (around 19 degrees east of south and around 28 degrees east of south). As far as your dish is concerned, each group of satellites looks like one large satellite because they are so far away and so close together. Each Astra satellite has at least 16 transponders. At present there are six satellites in the 19E group, labelled 1A to 1F. Satellite 1A to 1D transmit mostly ordinary "analogue" signals and E, F transmit mostly digital on a higher frequency band.
8. What is Digital?
Astra 1E transmits mostly digitally compressed signals. This method is more efficient because it allows one transponder to transmit up to fourteen different programmes at the same time! However, you will need to buy a Digital Satellite Receiver in order to receive these new programmes. Such receivers are in use in the UK, parts of Europe, South Africa, Australia, Indonesia and the USA (and other places). They can be more than four times as expensive as current "analogue" receivers. However, analogue transmissions are likely to continue for at least two years and the average life of a satellite receiver is only about five years.
9. What is "Hot Bird"?
Hot Bird is the name of a satellite that is located at 13 degrees east of south. You can point your dish in that direction and receive signals from Hot Bird just the same as you can from Astra. There are some English programmes which are not scrambled but most programmes are foreign language (sometimes English with foreign subtitles). At the same location as "Hot Bird" is another, older satellite called "Eutelsat II-F1". You will see the programs from this as if they came from "Hot Bird" but the signals tend to be weaker in the UK. There are other "Eutelsat" satellites located at 7'E, 10'E and 16'E of south.
10. Can I receive both Astra and Hot Bird?
Yes. You need a slightly bigger dish with two LNBs fitted on a special adaptor bracket. The dish and LNBs have to be aligned very accurately to receive good pictures from both satellite groups.
Switching between two satellites
If you have a fixed dish with two LNBs fitted on something like a LittlExtra™ bracket, you will need an A-B switching box to select each LNB as required. This type of manual switch sits near to the receiver and is fed by two cables from the LNBs on the dish.
The disadvantage is that you have to get off your butt to operate it!
Another type of switch is available. This one goes under various names but the original one is the "Wych Switch" designed by me, Martin Pickering, and marketed by a company called Wychavon (now defunct). It was also sold under the name of "Twin-Sat" switch. (I made the prototype on "Veroboard". The circuit is available for a very small fee if you want it).
It is fully waterproof and clips to the dish arm. Two short cables run from the LNBs to the switch. Only one cable is required to connect the switch to your satellite receiver.
This unit responds when the voltage supply to the LNB goes off then on again fairly quickly (within a couple of seconds). On most receivers this effect is achieved by pressing the STANDBY button twice. On some receivers such as Pace, however, you will need an additional Slave unit which fits at the receiver end of the cable and has a SCART plug which must go to the TV SCART socket on the satellite receiver. (This means that you can't use the SCART socket to feed your video or television).
This type of switch allows you to switch from one satellite to the other from the comfort of your armchair. Of course, if you buy a twin input receiver in the first place you will not need such a switch!
If your receiver is more modern you can use its 22kHz tone system to control a different type of switch. This is called a "22kHz switch".
11. Can I install my own system?
Yes. You don't need any special equipment, although you can not guarantee perfect pictures without the use of a meter. There are lots of books on this subject. *Ref1.
The dish has to point towards the desired satellite(s). It can be mounted almost anywhere, provided that it has "line-of-sight". For Astra analogue you need a clear view at 19 degrees East of South (plus magnetic variation - about 6 degrees) at an angle of about 25 to 27 degrees upwards from the horizon (England). Make sure that there are no trees or buildings blocking this line.
A fine example of an extremely buckled dish. As you look from edge to edge you should see a straight line - but not with this one! Also, the cable is hanging down instead of being secured to the dish arm and clipped to the wall.
This dish is OK but the "installer" used brown TV cable (wrong!) and threw it over the roof. Now, every time the wind blows, the cable gets dragged and wears a hole in the outer sheath. Result - rainwater runs down the cable into both the LNB and the satellite receiver.
12. Can I receive even more programmes?
You can install a larger dish on a "polar mount". This is a special swivel mounting which allows the dish to move in such a way that it tracks the satellite arc above the equator. There are several variations on this theme: another is the "Horizon to Horizon" mount which gives a longer arc of travel. For most purposes, an ordinary polar mount with a linear actuator (motor) is the most cost-effective solution. You will also need a "positioner" (power supply and control unit) to drive the actuator which moves the dish.
13. What is SKY?
SKY is the nickname of a company called BskyB, which provides most of the English-language programmes broadcast from Astra. At the time of writing, only Sky News can be watched without the use of a decoder. The other analogue SKY programmes require the use of a VIDEOCRYPT decoder. The "QVC" shopping channel is the only one of these which does not require the use of a smart card. To get a SKY smart card you have to obtain an application form (ask your nearest satellite shop for a form). Decide what you want to watch and how you want to pay. Fill in the subscriber agreement form and post it to the SKY address. You can speed things up by faxing a copy. As soon as your card arrives, phone SKY, give the card number, and ask to have it turned on. They will tell you to switch your receiver on, stick the card in the slot then wait till they broadcast your turn-on signal. Obviously this will only work if the receiver is getting a SKY channel. No need to leave the TV set on but the receiver and dish system MUST be working to receive the signal. It's all very exciting! The cheapest "multichannel" package costs £12.95 per month (at the time of writing) and gets you everything except the Movie channels and Sports channels. A similar situation applies to Sky Digital but please read the specific page about this.
14. Should I buy the cheapest?
This is the question which nobody likes to answer. The cheapest systems are fine if you don't need the best picture and sound quality. Even the lowest price systems can be expected to give better pictures than ordinary terrestrial TV. If not, there is something wrong so don't accept it. However the price tends to reflect the build quality and, therefore, the reliability. The installation cost also tends to reflect the quality of materials and workmanship.
How can an installer save money? Easy: by using a low-quality cable which does not carry the signal as well as good cable (but you won't see a problem till it rains) and which does not last as long outdoors (ultraviolet light from the sun cracks the plastic and water gets in). By skimping on the length of cable and on brackets and clips (eg. install it on the front of the house instead of round the back out of sight). By skimping on other items (connectors, LNB noise-figure, Dish quality). By joining lengths of short cable (never!)
For the best quality equipment and workmanship it pays to find out about specialist installers. There are some but they take a lot of finding. They won't do a low-cost job but they'll be happier to come back to sort out any problems because this cost will be built-in to the price. You get what you pay for. Ask yourself if your thousand pound widescreen Nicam Stereo TV really deserves a 99 pound satellite system! Check with your friends to see if they can recommend an installer. Look at the workmanship.15. Will my old LNB work with a Pro-Logic receiver ?
Yes. The LNB simply converts the microwave frequencies to lower ones that ANY receiver will use. The LNB does not care what kind of receiver you connect. However, you may not receive ALL available channels if you use an older LNB with a new receiver (or vice-versa). Read the LNB FAQ page.
16. Is it possible to add a second LNB to my existing equipment ?
If you add a 2nd LNB you will need to put it on a 2nd dish! Much easier is to swap the existing LNB for a "twin output" type which will feed two receivers. This could lead to problems however because the new LNB will probably be an "Enhanced" or "Universal" type which will not directly match your existing receiver in terms of frequency range.
If, however, you are adding a second LNB to watch programmes from a second satellite then you may be able to fit it to the same dish by using a special bracket (but you will probably need a larger dish). Read the LNB FAQ page.
(See question 10).17. Should I buy an analogue receiver and LNB or buy digital?
Digital Sat TV is certainly here but whatever you buy now will be obsolete in a few years (apart from, possibly, the LNB). However, that will always be true. In five years time the satellite systems on sale will still be obsolete a couple of years later. How long do you want to wait? Manufacturers are making "improvements" all the time in order to sell new equipment. Buy what you want now. There are many good deals around for both used analogue receivers and for new digital systems. Digital systems are inherently more expensive to manufacture and you might find your programme choice is limited if you like to watch foreign broadcasts and buy a dedicated Sky receiver.
STANDARD DISCLAIMER: Information is given in good faith. No responsibility will be accepted for any loss, damage or injury which occurs directly, or indirectly, as a result of your use of this information. It is your responsibility to check the facts.
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Copyright ©1998 SatCure
Version 1.2 updated on January 4, 2000
This file may be downloaded for private and personal use but NO part of it may be published in any form without the prior permission of the author.Send this page address - CLICK HERE - to a friend !
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