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Loft aerials

One of the most common problems people have with Freeview reception relates to the use of "loft" aerials.

One of the most common problems people have with Freeview recep
published on UK Free TV

One of the most common problems people have with Freeview reception relates to the use of "loft" aerials.

Because the analogue TV transmitter network uses very high power transmissions (the total ERP for the UK is 64 megawatts) many people have installed their TV aerial in places such as lofts, or have used other Indoor Aerials.

The effect on that roof tiles and walls have on analogue TV signals is that the picture will degrade slightly. Making the signal slightly weaker will add a 'snow' element to the picture which is mildly irritating. The picture quality drops, but it is usually possible to make out the picture, as demonstrated here:



Many people have preferred this slight loss in picture quality for the perceived benefits of a loft-mounted aerial. Loft aerials are much easier and somewhat safer to install, and the aerial is shielded from wind and rain that can cause damage to rooftop aerials. In some places (such as New Towns) TV aerials have been previously banned from rooftops.

However, the BBC and others state that Freeview reception demands a roof-top aerial. The existing (pre Digital Switchover) Freeview signals are at very low power levels. The use by ITV, Channel 4 and five of "64QAM" mode for their transmission multiplexes to provide more channel choice results in a very lower chance of reception of these channels (multiplex 2 is ITV1, ITV2, ITV3, ITV4, CITV, Channel 4, More4, E4, Film4+1; multiplex A carries five, five Life and five US) with a loft-mounted aerial.

By comparison with the image above of how analogue signals look as the signal grow weaker, digital TV reception will continue to give perfect pictures and sound as the power level drops off, until suddenly the level drops below what the COFDM system can cope with. At this point the picture will become blocky and freeze whilst the sound will appear to come and go. Another tiny drop in signal level will result in no picture or sound and a message saying that "no signal is being received". As the signal can vary with weather conditions, people often find that a loft aerial will work when installed and then suddenly stop some months later.

After switchover

After switchover new digital signals will replace the existing analogue and digital ones. The new digital signals will be at much higher levels that the current ones (for most people) and this will help with reception. However, all six multiplexes will switch to the 64QAM mode that causes the problems indicated above.

Due to our Climate Change commitments (Kyoto Protocol), the signal levels for these new digital will not be as high as those currently used for analogue. For this reason you should not depend on the increase in power levels after switchover compensating for having a loft aerial.

Wherever possible you should use a rooftop aerial. If this is impossible, you may find that connecting your aerial to your Freeview box or integrated digital television using satellite-grade coaxial cable will compensate for the loss.

Help with Television sets?
Why are all TVs on sale not digital?1
Do I still have to pay for a TV licence?2
I had perfect channel 5 reception - until I got a digital TV box!3
I Have a Pocket Tv For taking out so I can keep up with news and sport. Will thi4
The pictures from my digital box are all green!5
In this section
Do I need to buy a booster?1
How to receive Freeview on your PC2
Indoor aerials3
Whole house digital TV4
Connecting it all up5
Now and Next6

Comments
Sunday, 16 January 2011
L
Lorraine
6:00 PM
Coventry

I have purchased a Logik L19DIGB10 TV which comes with integrated Freeview. The TV shows sky & terrestial TV fine but when viewing a freeview channel the picture flickers with the image appearing in small blocks. What can i do to fix this?

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Lorraine's 1 post GB flag
Lorraine's: mapL's Freeview map terrainL's terrain plot wavesL's frequency data L's Freeview Detailed Coverage
Monday, 17 January 2011
Briantist
sentiment_very_satisfiedOwner

7:05 AM

Lorraine: Is the TV aerial on the roof?

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Briantist's 38,910 posts GB flag
Sunday, 23 January 2011
C
chris f
6:48 PM

Ihave been using a freeview set top box on my existing set up outside aeriel and it has worked fine but since purchasing a new metronic box with top up tv will not pick up most freeview channels could i need a new aeriel

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chris f's 1 post GB flag
Monday, 24 January 2011
Briantist
sentiment_very_satisfiedOwner

8:04 AM

chris f: I would suspect the receiver you have bought, rather than your aerial. I would return it to the store for a replacement.

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Briantist's 38,910 posts GB flag
Tuesday, 25 January 2011
M
Mark
11:47 AM
Colchester

Hi Brian

I tried retuning my TV's yesterday to see if the Mux 2 channels appeared...still none :(

Do you know if that power boost at Sudbury happened yesterday?

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Mark's 3 posts GB flag
Mark's: mapM's Freeview map terrainM's terrain plot wavesM's frequency data M's Freeview Detailed Coverage
Wednesday, 26 January 2011
Briantist
sentiment_very_satisfiedOwner

8:05 AM

Mark: The next change at Sudbury is 6th July, the last 16th November.

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Briantist's 38,910 posts GB flag
Saturday, 29 January 2011
D
Denver
12:27 PM

I have just installed a digital airier in the loft to run my 2 girls digital tv from. I first connected one tv and got all the free view channels and a perfect picture. However when I then plugged the airmail into the second tv using a 2 way splitter I got a perfect picture but not all the channels. If I use a booster on the second tv will this remedy the problem? (5PE2832.3815,-0.0056) 

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Denver's 1 post GB flag
J
jb38
sentiment_satisfiedBronze

3:09 PM

Denver: An unpowered two way splitter should never be used where freeview is involved as these type of devices reduce the signal strength, the very last thing that's wanted!

You should really use a powered booster / splitter in the loft as this amplifies the signal before any interference can be picked up in the downlead.

There are lots of different types about but for safety reasons don't go for the cheapest when it will most likely be kept permanently powered by the mains, as some of the cheaper "obscure branded" types available from sources such as e-bay etc can run rather hot if left on for lengthy periods of time, that said though there is nothing whatsoever to worry about where it involves well known brands such as Antiference or Labgear, to name but a couple of Brands.

Most people have these type of devices powered year in year out and are never switched off.

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jb38's 81 posts GB flag
Sunday, 13 February 2011
L
luebeck
3:49 PM

Greetings All
I live 8 miles north of Sandy Heath and never have any problems with Loft aerials. I can get good reception with a wire coat hanger. However the exterior aerial I had installed pointing at Sandy requires an amplifier to get a good signal! Digging out my trusty Digifusion a couple of days ago I found that I couldn't get any 7/14 day epg no matter what aerial, why?

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luebeck's 3 posts GB flag
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