Freeview reception - all about aerials
Updated 8th January 2014.
Your ability of receive all the Freeview transmissions depends on the suitability of aerial
- the design style,
- the "group", and
- its physical location.
Standard type - Yagi aerial
The standard type of TV aerial is known as the Yagi aerial. It is mounted on a pole, and consists of a rod with a reflector (shown green) at the back and many spiky elements (in grey) at the front. The connecting cable connects to the element nearest the reflector, known as the driver (shown in blue).
These Yagi aerials are directional and so pick up signals best from a transmitter that the rod points towards. The more elements the aerial has, the better it picks up a signal and becomes more directional.
A standard-type aerial is all that is required for digital TV reception in most places. These antennae have between 10 and 18 elements and a single reflector. These are recommended for new installations for good digital television reception, but will more often than not function perfectly in good reception areas.
Typically these aerials are designed to receive only some transmission frequencies - see "groups" below.
High Gain aerials
These aerials are designed for poor digital reception areas, and have two reflectors. For maximum signal strength, some digital high gain aerials have up to 100 elements. Since the switchover to digital-only transmissions back in October 2012, most UK households now have good quality digital TV signals.
A more expensive aerial is only required where the signal strength is low, but can often provide the whole Freeview reception where it might otherwise be impossible.
The CAI (that represents aerial installers) has four standards for digital TV aerials. The highest standard "1" is for homes on the fringes of coverage areas, intermediate standard "2" is suitable for use within the coverage area; minimum standard "3" is for good coverage conditions.
These aerials can be either wideband, or receive only selected frequencies - see "groups" below.
Grid
You may haved used a 'Grid aerial' for analogue reception, but as they are generally unsuitable for Freeview reception, they have now generally been replaced by the Yagi type. However in some places a Grid aerial installation may work for Freeview: otherwise replace with a standard Yagi aerial.
Indoor
Indoor aerials are generally not suitable for Freeview reception. In areas of good signal strength it is often possible to receive some transmissions. Even where an aerial works, people often find that may get interruptions to their viewing (or recording).Loft mounted
Loft mounted arrivals are not generally recommended for Freeview reception, as the roof tiles and plumbing will degrade the signal. Some compensation for this loss of signal can be made by using satellite-grade cable to connect the set top box to the aerial.Positioning
The best position for a TV aerial is mounted outdoors, as high from the ground as possible, pointing directly at the transmitter. The signal can be blocked by hills and tall buildings. It should be positioned away from any other aerials.Horizontal or vertical?
The transmitter will either use vertical mode which requires the elements of your aerial to be up-down, or horizontal mode which requires them to be level with the ground.Groups
Both analogue and digital television is transmitted the same group of transmission frequencies (known as channel 21 through to 60). A coloured marking on the aerial shows the group.To create the best possible analogue picture, TV transmissions from adjacent transmitters have been designated to several different groups of frequencies. By using an aerial that receives only the channels in the correct group, the analogue picture can be kept free from interference.
To receive Freeview transmissions from the same transmitter it has been sometimes necessary to use frequencies that are not part of the transmitter's normal group. When this has occurred, the aerial will need to be replaced with a "wideband" aerial (also known as group W) - one that covers every group.
As Ofcom is planning to move the TV frequencies again - perhaps as soon as 2018 - it may be wise to use a wideband aerial if you can to ensure you can keep viewing Freeview for many years to come.
Help with Television sets?
Monday, 11 April 2011
A
Adey7:11 PM
Briantist - with regard to Wendi's problem with CB radio. when she mentioned old cb ,i immediately thought Aunty Mary (AM).If this is the case then as far as i'm aware it was totally outlawed years ago and you can be prosecuted.I'm not sure if it affects digital signals though. Might be worth checking it out Wendi.
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Tuesday, 12 April 2011
Adey: Yes, you get this investigated using the above link.
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R
R Simpson1:35 PM
My tv now suffers from picture freezing and asynchronous sound now that I have retuned my digital channels - what can I do ?
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Saturday, 16 April 2011
J
John5:06 PM
Aylesbury
I live in an HP21 (Aylesbury) postcode area and usually get my signal from the Oxford transmitter. Today, however, I changed my main arial cable (arial on the roof) to the better quality coax with the copper armour and when I put the arial back up I can only get a signal from the Sandy Heath transmitter which is almost in the opposite direction to Oxford.
I re-installed the arial facing the same way as it has always done so I can't think what has happened?
I made one small change when it was down and that was I noticed the arial was not tight in the clamps that hold it to the U shape support the attachs to the pole so I drilled a small hole through one clamp, through the arial centre arm to add a bolt to keep the clamp tight. I don't know whether that would make any difference though.
Anyone got any ideas? Thanks a lot. John
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John's: mapJ's Freeview map terrainJ's terrain plot wavesJ's frequency data J's Freeview Detailed Coverage
S
sabria6:13 PM
I have just bought a new tv with inbuilt HD tuner. I live in central oxford and was wondering when the HD chanels become available in september will I have to upgrade my aerial?
For some reason im assuming to recieve HD chanels a 48db aerial wont be enough? I have tried to find some clear information on this, for just the ordinary person who isnt technically minded and havent been able to. Any enlightenments would be great?
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J
John6:51 PM
Aylesbury
I think I've realised what the answer might be to my problem above..the Sandy Heath Transmitter has just completed the digital switchover and, therefore, become my strongest signal until September 2011 when the Oxford transmitter does the changeover. When re-tuning my freeview box after doing my arial job it automatically locked onto the the stronger signal.
Thought I would post this as many other people may notice the same thing if they do a re-tune.
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John's: mapJ's Freeview map terrainJ's terrain plot wavesJ's frequency data J's Freeview Detailed Coverage
M
Michael O'Pray11:45 PM
Daventry
I am in Daventry which is probably just in the green area( yellow being the strongest signal) However after a few hiccups for a day or so after the original changeover on April 1 the BBC signals have been quite good. However since the total changeover on 13 April ITV has consistently been a strong signal whereas in the last 48 hrs BBC1, BBC2 and BBC3 have all been unwatchable although BBC4 is OK
Why has the BBC signal dropped in strength and quality and will this be permanent?
The Sandy Heath transmitter is reporting no problems. So why this difference between ITV and BBC?
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Michael's: mapM's Freeview map terrainM's terrain plot wavesM's frequency data M's Freeview Detailed Coverage
Sunday, 17 April 2011
sabria: No aerial upgrade is required to receive Freeview HD.
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