By using much higher frequencies (gigahertz, compared to terrestrial televisions megahertz) more transmission channels called transponders (the satellite equivalent of multiplexes) can be provided. For example, there are only six Freeview multiplexes, but Sky or Freesat users can access two hundred satellite transponders.
Aside from exceptional weather conditions (very heavy rain for example) digital satellite provides stable pictures and audio. Where Freeview transmitters are no more than 732 metres above sea level, the geostationary satellites used for television are 35,800,000 metres above the equator so reception is possible even where buildings, trees and hills make terrestrial reception impossible.
The downside of the transmitters being 22,300 miles up in the air is that the signals are very, very weak - so standard TV aerial is of little use. When the signals are sent to the satellites, huge dish transmitters are used to uplink the signal to the satellite. These are tens of metres from side to side, and feature an emitter that generates the signal, which is first bounced of a mirror (called a reflector) and then off the surface of the parabolic dish.
There are many satellites in the sky over the equator. Often these are in clusters over a particular position, for example there are four used for UK television are at 28.2 degrees east. There is another cluster over the 19.2 degrees east positions that are used for German television.
To receive these very weak signals from the satellite, it is necessary to use a dish for reception too. By using a reflective dish, this concentrates the signals onto a small device called a LNB. This is held in front of the dish by a metal arm.
The size of dish for reception is typically much smaller; often 60cm to 100cm in diameter, but the exact size depends upon the transmitting satellite transponder. To keep the transmission power levels down to levels that can be powered by the satellite's solar panels, each beam is focused on a particular area of the Earth's surface. If you are trying to receive the signal at the centre of this zone, a small dish is required. At the outer edges, you may need a 5 metre dish. Maps of these zones are provided by the satellite companies, and are called satellite footprints.
When the dish is installed it must be aligned carefully as the signal is very weak. The installer needs to know the inclination and the azimuth from the ground location to the satellite. If you install yourself you will find that there are markings on the dish that are used to point the dish in the correct position. It is important that the view of the satellite will not be blocked, so must take into account leaves growing on trees and potential building works.
For many people the LNB will have a single cable connected to it, however if you have Sky+ or a multi-room installation the LNB package will actually contain four receivers a quad-LNB. Unlike terrestrial television where you can split the aerial cable to feed more than one Freeview box or television set, with satelite reception you cannot. So, a Sky+ box with two receivers (so you can watch one thing and record another) has two cables connecting the box to the dish.
The cable that connects the dish to the receiver must be satellite grade cable. Whilst this looks superficially like the cable used to connect and aerial to a television, a higher grade cable is required for satellite reception.
Here is an image of a co-axial cable. This sort of cable is used to connect any type of receiving aerial to the reception equipment.
RG6, PF100 and PH100 are all types of coax cable that are suitable for the very weak signals that are received by a satellite dish. (The power is the same as you would receive from a one-bar electric heater on the moon).
The conductor in the centre passes the signals received from the dish to the set-top box. This is made from steel in RG6 cable, and from copper in the RF100 and PH100 types. This makes RG6 less suitable in the UK where rain can damage the cable.
The shielding is responsible for keeping unwanted external interference from damaging the signal. In the cheaper cable this will be a foil wrap, in better specified cables this is a braid (or mesh) of copper wires. The sheild in the RF100 covers 58% of the cable.
The non-conducting layer between the shield and the conductor is called the dielectric. This can be either a solid (RG6), foam (RF100) or air-spaced (PH100) dielectric. This makes the cables progressively more flexible (ie bendy without damage).
Roger Fitzpatrick Wednesday 3 December 2008 4:22PM Lowestoft
We have just bought a new Panasonic 42" Plasma TV with integrated Freesat tuner.
We have a Sky minidish with Skybox. If we connect the Skybox to the TV it works OK If we disconnect the Skybox and connect the dish cable directly to the TV and then try to configure Freesat reception we get a message that says " Can't connect to Freesat check the dish & cable"
We've exchanged the Panasonic and get the same resulton the replacement. Freesat, Comet and Panasonic all say that it should work but it doesn't. Even the Comet engineer hasn't been able to enable Freesat.
Any ideas ?
Hi Roger, If the lnb on your dish is faulty on the band that the freesat epg network id & transport stream are on the panasonic may think that the dish is not connected, as the skybox uses a different epg, transport stream & network id on a different band(which may be working) the sky box will see the dish. I cant be sure but its my best guess ! Mark Aberfan Aerials
Paul O'Neill Wednesday 3 December 2008 10:28PM Askam-in-furness
Briantist. Having done a fair bit of research into Freesat (including the great comprehensive coverage you have on this site) I do realise the need for a clear line of sight between the dish and the satellite. My point really was that the engineer installing the dish obviously wasn't as clued up. Maybe when he returns on Friday I should suggest he looks at this site!
freesat on the costa blanca you will need a minimum of a 1.9m dish as it runs from the same satellite as sly does @ 28.2 and 28.5 deg .Now if i remember on a 1.9 dish in alicante you will loose itv and bbc2 and a few more around 2 or 3 every day due to your location..
Keith Thacker Thursday 4 December 2008 7:15PM Burnham-on-crouch
Brian. Brilliant site! My postcode is CM0 and said to be a good satellitereception area. Even so, might it pay me to fit a 60 cm as opposed to a 43 cm dish? Secondly, I want to be able to get all the BBC and ITV channels (incl. HD) plus Channels 4 and 5 and News 24. Which is the best satellite to point my dish towards?
Hi Keith, A 60CM solid dish (like a triax td 58) or a zone 2 sky dish are always better than a std 43cm dish, we always use larger dishes on commercial jobs & you will find most riggers have a 60cm dish at their own homes ! You should point your dish at astra 2 at 28.2"e to recieve the channels you seek. Mark Aberfan Aerials
Paul O'Neill Friday 5 December 2008 5:13PM Askam-in-furness
Briantist. I'll suggest it if he ever turns up. Today was cancelled. "The engineer had no authority to tell you when he was coming back, that's up to the office". They also used the weather as a excuse (It's been a lovely dry windless day and well above freezing...I've been gardening) then it was because it had to be a 2-man job, well, that's what they were saying until I reminded them this is a bungalow. Next Tuesday is the day to watch!
Hi Derek, thanks for your comments, they tend to confirm my thoughts about the lnb being faulty on one band. Good thinking on keeping the skybox as you then retain access to sky3 fiver & five us.
Mark Aberfan Aerials
I have a 70cm Metronic sat dish with Sat Receiver " Touch BOX3"on which I receive "HOT BIRD".Just purchased Panasonic Flat screen HD TV with Built in " Free Sat",I Want to receive "ASTRA 2A"28.2*E Can you sugest Type of LNB to use, & can I use my 70cm dish
Hi Frank, you can use the metronic dish & lnb if you focus it on 28.2 e & lose hot bird, i dont think a dual feed arangement device is available for this dish . if you want to keep hotbird it will probably be cheaper & a lot easier to have a sky dish fitted & set to 28.2e for your freesat service.
Mark Aberfan Aerials
Eric Muir Saturday 6 December 2008 7:53PM Dumfries
if I wish to change from free Sky to freesat will my dish be pointing at the correct sat. and if so, will I need a second lnb and cable to use twin record on a Humax?
sorry if this has already been asked but I just recently found this site.
Hi Mark thanks for your sugestion of using sky dish to receive " HOT BIRD" & my 70cm Metronic dish for ( ASTRA 28.2) I visited MAPLINS & was told they can order me a Bracket on which I can fit two LNB,s & use my 70cm Metrinic dish & adjust the LNB to receive HOT BIRD 13.0 & ASTRA 28.2 is it possible would like your comment please
Hi Frank, If a multi lnb bracket is made for your dish you will need to find out you will need to find out if it will do two satellites 15" apart (not all do !) also if the bracket gives two side feeds & not one centre & one side. if the bracket has two side feeds, i would line the dish up on the original centre feed on astra 1 @ 19.2e tighten it up & then fit the multi lnb bracket & the line up the hot bird & astra 2 lnbs, that way both feeds "see" around 45-50cm of dish, it is harder to do it this way but give better results ! Please avoid "universal type" brackets as they are often best discribed as "bits of metal" & are not very good ! however if metronic make one for their dish then it might be worth a go ! I would not undertake this sort of job without at least a sat meter that identifies the different satellites. Mark Aberfan Aerials
can anyone advise me on what is required to enable me to receive 28.2 19 and 13 sats, i have a fixed 80cm dish and a sky digibox, i live in Snowdonia and reception is sometimes bad hence the 80cm dish.
thanks Brianist for your reply I was rather hoping to go down the road of multi lnb's but I dont no how i would change channels, I dont understand all the jargan as I'm new to all this, but I have put up my own dish and have a grasp of the basic's. Disquets?/urals? all a bit much for me at this stage!! Any help advice would be greatly received. Thanks hillman
Hi Hillman, You could leave your sky system as it is, (a sky box is not much use for other satellites) you could then get a cheap receiver & a second dish with a 6" monoblock lnb to get 13" & 19" Mark Aberfan Aerials
Hi Mark Thanks for your advice At present I have a 43cm sky dish feeding 1 skybox, then my second dish 80cm feeding another sky box, so I could put two onto one via a quad lnb which would release the big dish for 13 and 19 via a fresh s/hand receiver, I dont want to spend a lot in case it does'nt work, doe's this make sense or am I totally of the mark!! thanks hillman
to Mark Aberfan Aerials/Briantist thanks for your advice, I'm now thinking of going motorised with the following items
Geotrack SG99 H to H mount
Fortec Star Lifetime Ultra receiver My question is do you think these would do the job and also is this all thats require to get me motorised, your comments would be greatly received
Hi Hillman, Yes a quad on your sky dish will serve your skyboxes, & your 80cm should be ok for 13/19 as long as you can get a decent monoblock or dual feed bracket. Your motorised plans seem ok but require a good amount of skill setting up or a lot of time ! please dont be tempted to waste money on a second hand receiver, new ones are so cheap its a false economy ! Mark Aberfan Aerials
Hi Brianist/Mark thanks for your continued support, at the moment my dishes are 80mtrs away from the house so I have a long cable run, I get good results on sky incorporating an in line amp, my worry is will the disequ be able to send a signal of sufficient strenght to the motor over this distance!! also could you recommend a receiver thats not to pricey that would be suitable. thanks hillman
Hi Hillman, How about this receiver Maplin from a reputable manufacturer (fortec star ) who have a uk office based in Sheffield, they should be able to tell you if it can power a motorised dish over 80m & if you need a line amp with it. I have done much longer runs & have never used a line amp. Mark Aberfan Aerials
Hi Mark/Briantist I have just purchased a Panasonic TV with Freesat fitted. I was advised by the seller that all I would have to do is purchase a twin LNB and connect it to my current satellitedish. The dish that I am using with a DiSEqC 1.2 is a Metronic 80cm with a single LNB. My box is a Technomate 1500 CI Would you please advise me what is the best LNB and cable to use so that I can continue to watch all the foreign FTA channels as well as Freesat. Many thanks Andy Lees
A twin lnb would not be suitable with you diseqc setup which appears (from what you said ) to be pointing at different satellites with foreign channels on ! Most tv shop staff would not understand about diseqc etc . A far better option would be a second dish, A standard freesat install is all that is required. (around £80) this has the added bonus that if one system goes down you still have the other !
If you are doing the install yourself a zone 1 (43cm ) or zone 2 (60cm) sky dish will work fine, if you want something a bit better a triax td 54 with a mti lnb is a good combination, use ct100/h109/pf100 benchmarked cable & you should fine.
Don,t know if this is the forum to ask but we have skyhd (I know, costs a fortune and is a waste of time etc etc.) As we have more money than sense would like to get ITV hd on freeseat for some of the sport. Read about a splitter for the satellite wiring. Anybody know what we need??
What I have seen is a little cheap device that takes one lead from the satellite cable after it has come into the house and forks so that two come out one to sky and another lead to freeseat box.(a little adapter in fact)This has a switch so you can choose which device receives the signal. This is near to the sky box and tv. I understand about the lnb thing but this seemed simpler even if a bit fiddly assuming you have to switch from sky to freesat.
jtw: You can't split the lead from the satellite - indeed you risk damaging everything if you attempt it - but you can fit a four-output "quad LNB" to the dish and run in a cable from it for a Freesatbox.
Hi Thanks for advice. Was looking for a simple free(ish) solution that does not involve me on the roof. Could I just pull out the lead from the sky hd box and stick it in the freesat box when needed. Would this hurt anything?
I have recently purchased a Freesat HD digitalbox. I already have a working sky dish and cabling. When I connected the Freesat box to the existing dish the signal strength is zero. Please can anyone post a possible cause and solution to this problem?