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Freesat reception - all about dishes

Satellite reception has both advantages and disadvantages compared with terrestrial (aerial) reception.

Satellite reception has both advantages and disadvantages compa
published on UK Free TV

Satellite reception has both advantages and disadvantages compare with terrestrial (aerial) reception.

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).



Help with Free satellite?
What can I do when my Sky Digibox says 'No Signal' or 'Technical fau1
Can I receive UK TV in Ghana?2
What is a CA module?3
My box says "No Satellite signal being received"4
Is there any way I can get free channels via satellite and have the kind of hard5
In this section
Show me the 55 TV channels have moved to the new Astra 2G satellite 1
Good news for Freesat? Astra 2E satellite launched2
No satellite signal? Check your dish for snow!3
New satellite footprints page4
BBC satellite changes: radio, BBC ONE HD, Red button reduction 12-15 October 2015
Changes to BBC HD transmissions on Astra satellites on 20 September 20126

Comments
Wednesday, 16 February 2011
Briantist
sentiment_very_satisfiedOwner

1:40 PM

LOCHNER: There are no UK services on analogue, and have not been for about nine years.

Please see "Where can I receive it?" for details of the dish sizes required on the All about Freesat | ukfree.tv - independent free digital TV advice page.

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Briantist's 38,915 posts GB flag
Saturday, 19 February 2011
D
Davyblue
12:57 PM

I have bought a Fortec Star digital receiver box which picks up mostly German tv on 19.2 E I have a old sky dish will I be able to pick up Freesat on 28.2 E on this receiver.

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Davyblue's 1 post GB flag
Briantist
sentiment_very_satisfiedOwner

1:26 PM

Davyblue: You can pick up the free-to-air channels, but Freesat also includes an EPG and MHEG5 services, which your box will not provide.

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Briantist's 38,915 posts GB flag
Mark Aberfan Aerials
sentiment_satisfiedGold

1:48 PM

Hi Davyblue,

I've been told that recent fortec star HD receivers when loaded with the right software will not only pickup free to air broadcasts fron Astra 28.2 but will also decode & display the full freesat epg, & even allow you to set recordings from the freesat epg if you have a usb stick / hard drive attached to the receiver.

Mark Aberfan Aerials

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Mark Aberfan Aerials's 1,059 posts GB flag
Briantist
sentiment_very_satisfiedOwner

1:59 PM

Mark Aberfan Aerials: That's very good to know - do you know which models are the "recent" ones?

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Briantist's 38,915 posts GB flag
Mark Aberfan Aerials
sentiment_satisfiedGold

2:38 PM

Hi Brian,

I found this on their website, it mentions the passion+hd & the innovation hd.

"Firmware PASSION+ HD receiver ( January 07, 2009) Click Here to Download

Fast Download of 7 day Electronic Program Guide
New recording and searching options from info display button. (Passion+, Innovation)
Full updated Freesat Channel List (including numbers) Fixed timer recording option for powered HDD's (Passion+, Innovation)"

I can also report that my technomate tm-5402 can access a different 7 day epg on astra 28.2 & can also set recordings from the epg.

Mark Aberfan Aerials

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Mark Aberfan Aerials's 1,059 posts GB flag
Briantist
sentiment_very_satisfiedOwner

3:07 PM

Mark Aberfan Aerials: That's all good to know. I wonder why they don't get the official "Freesat" branding too?

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Briantist's 38,915 posts GB flag
Mark Aberfan Aerials
sentiment_satisfiedGold

3:18 PM

Hi Brian,

If they went for freesat branding they would have to kneecap the usb recording by encrypting the files on the hard drive, there would also be fees & cmpliance testing costs.

Mark Aberfan Aerials

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Mark Aberfan Aerials's 1,059 posts GB flag
Briantist
sentiment_very_satisfiedOwner

3:24 PM

Mark Aberfan Aerials: Yes, that is true. On the other hand there is quite a considerable marketing push for the brand.

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Briantist's 38,915 posts GB flag
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