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aerial' for analogue reception, but as they are generally unsuitable for Freeview reception, they have now generally been replaced by the Yagi type.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?
Saturday, 25 August 2012
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john hunt11:02 AM
Blandford Forum
I thank you both for your advise, I feel much better in formed,The origional TV FITTER
that came here will only return for further payment,I will post the results next week.jh.
link to this comment |
john's: mapJ's Freeview map terrainJ's terrain plot wavesJ's frequency data J's Freeview Detailed Coverage
john hunt: Can you shed any light what the two boxes with printed circuit boards in are for? What do they look like? Maybe you were given an invoice which describes them.
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Stephen P4:43 PM
... or no paperwork perhaps?
ANY decent fitter would come back and look for no extra charge.
Where did you get him from? Do you have address and real phone number?
I would be tempted to get a new one to come and comment. With a local address.
If you tell us about the existing aerial and wiring it may help know what is up.
Which channels can you receive?
I am presuming you know how to retune/scan?
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jb386:27 PM
john hunt: If I could just add to what has already been said, if your TV person was local then when he changed the items concerned over and "must" found that there was no immediate difference by doing so, then the usual procedure would be for the engineer(?) to accept payment on the understanding that should the same fault occur within 14 days or so that the original items would be refitted and a refund of the payment made minus maybe £5.00 or so for diesel or whatever.
My reason for saying this is, that I suspect that your problem is possibly being partially caused by atmospheric reasons albeit that you still "might" have a deficiency in your aerial system such as a slightly corroded connection where the coax joins into your aerials termination box, but as you specifically mentioned the BBC was involved and its generally always the best then I would think it prudent for you to enquire locally with a neighbour if they are experiencing similar problems, of course only neighbours whose aerials are observed to be mounted and pointing in exactly the same direction as yours or they wont be receiving the same BBC.
The only point I was curious about regarding the aforementioned items that were changed, are you referring to a mast head amplifier and separate power unit associated with?
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Sunday, 26 August 2012
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john hunt12:02 AM
Blandford Forum
TWO 5 to 6inch diameter boxes,both containing printed circuits were removed,when shown to me they appeared to be
dirty and old,each was joined together with a length of co-axial cable.my neighbours in one case had the same problem,some time ago but his was ok on completion..nb:he has two aerials on his bungalow chimney,[as in my case]I have been to see a local reputable tv co..THEY are fully booked for two weeks..
I HAVE a small 12volt electric unit,connected to the rear of tv ,into the aerial,this was fitted 3yrs ago..Ihad it checked out it is ok...it sends millie amps up to the aerial from its transformer.?
link to this comment |
john's: mapJ's Freeview map terrainJ's terrain plot wavesJ's frequency data J's Freeview Detailed Coverage
J
john hunt12:51 AM
Blandford Forum
I have as far as I know been re tuning the set correctly,it takes a few minutes on automatic to go through the channels ,giving a total of 91.jh
link to this comment |
john's: mapJ's Freeview map terrainJ's terrain plot wavesJ's frequency data J's Freeview Detailed Coverage
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Stephen P12:52 AM
So he removed two whole boxes connected by a length of coax? And allegedly replaced them?
Sounds credible but I am confused why TWO.
You say neighbour has TWO aerials on chimney? And you two or only one?
Are his/your two pointed in different directions? Or differently polarised H/V?
The unit you mention probably sends power up the coax to the box(es) you refer to - which is fine though could be the source of the problem if wrong/inoperative. Some TVs can do this for you. RTM ?
How do the aerial cables run, starting from your TV set and working up?
Can you see how the boxes fit in?
Is just one room supplied?
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jb387:26 AM
john hunt: The device you have behind your TV is a power supply unit, this meaning that one of the other devices you referred to must be an aerial amplifier, and if you have two aerials then the second device is suggestive of being a diplexer for purposes of matching / combining the feeds from the two aerials into one and then to the input of the aerial amplifier.
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Monday, 27 August 2012
J
john hunt12:53 AM
Blandford Forum
THANK YOU AGAIN,With all the information I will be able to sort somthing during the coming week,as I am in my late seventies too much info could do more harm than good.jh
link to this comment |
john's: mapJ's Freeview map terrainJ's terrain plot wavesJ's frequency data J's Freeview Detailed Coverage
D
Dee10:23 AM
Northampton
I have just moved into a cottage in NN7,I got an aerial man to put two upstairs sockets in so I now have Freeview in bedrooms and living room.
My question is I am getting Look East which deals with Essex, no where near here, I want nearer news etc. He has tuned it to Sandy Heath, I want more Warwickshire as I live near to the border. I'm a bit old so do I do it or do I need the aerial moved. That's also a bit old
link to this comment |
Dee's: mapD's Freeview map terrainD's terrain plot wavesD's frequency data D's Freeview Detailed Coverage
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