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 analogue TV reception in most places. These antennae have between 10 and 18 elements and a single reflector. These are not 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.
Digital High Gain
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. A more expensive aerial is only required where the signal strength is low, but can often provide 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 aerials have been used to improve analogue reception in poor reception areas. They are generally unsuitable for Freeview reception, however some installations may work. Otherwise replace with a digital high gain Yagi aerial.
Indoor aerials are generally not suitable for Freeview reception. In areas of good signal strength it is often possible to receive some transmissions.
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.
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.
Both analogue and digital television is transmitted the same group of transmission frequencies (known as channel 21 through to 68). 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.
Your comments are always welcome. Please use the form below to add your thoughts or questions to this page. We will get back to you as soon as we can.
jb38 Tuesday 30 August 2011 10:25PM
Richard S: I think I may well have misinterpreted what you were meaning in your original posting, insomuch that when you mentioned the TV's on the loft aerial couldn't get COM3, I didn't realise that this was in "addition" to them not receiving PSB2 either, as I assumed it was only COM3 that was the problem on these sets. Anyway the test you carried out of by-passing the distribution amplifier proved interesting by this action having enabled you to receive PSB2, as that could indicate the signal is indeed possibly over powerful, however the puzzling bit of this being, that if it was powerful then I would have expected that the TV's on the loft aerial should have been able to receive PSB2, the fact that they don't suggests that some other factor must be in existence, what Mux Ch23 signal level is shown on them?
I have to say though, that the reception predictor on the post code provided indicates your position as being able to receive from a number of sources, namely Hasland as well as Belmont, although these being indicated as less than the 100% rating seen from Chesterfield on Mux Ch's 26 - 23 - 29 (HD service), although SDN (Mux Ch43) - ArqA (Mux Ch46) - ArqB (Mux Ch40) are all listed as being variable (as you are experiencing) this improving slightly by coming out of variable on Sep11th, then being fully OK from the12th of October.
I would like though if you could try a Mux channel check on a TV that is connected to "each" aerial, the channels to use being Mux Ch25 and Mux Ch60, these corresponding to Belmont and Hasland's PSB2.
Regarding the distribution amp in the loft what model is it?
Richard S: Another addition, could you also verify that the Mux channel numbers in question are actually being seen as these numbers whilst on the signal checking screen, and not just being referred to from the transmitter list.
Hi there. I have recently moved to Stroud from Chester. I was recieving the full 6 Freeview muxes previously including HD channels, and am now only recieving 2 muxes (BBC A, D3&4) but the digital uk website says I should also be recieving the BBC B (HD) mux as well, and with a strong signal at that.
My aerial is in a loft, but the other 2 muxes are recieving at close to 100% signal strength and quality as I am atop a hill facing the transmitter, only 2 miles away.
Would the signal degradation through the roof tiles be sufficient to degrade the HD mux so that my TV doesn't even pick it up during a manual scan of the frequencies?
Ken Moverley. Wednesday 31 August 2011 8:30PM York
Hi, Have old sony tv model No KD28DX40U.
Have lost signal on channels 3&4 tv, when program tv get all signals.
Class 1 aerial installed. have to get signal from bisdale transmitter area,due to tall trees near house.On the fringe of all areas. Is tv too old or do I need better aerial?
Richard S Wednesday 31 August 2011 9:13PM Chesterfield
jb38 - Thanks for your response.
I have gone through the signal detection as you suggested.
On the external aerial all the MUXs were correctly tuned for Chesterfield. The good news with this is when I looked at the amp to find out the model (its a Fringe 4-way masthead) I found the dial where inserting a screwdriver can turn down the gain. I have done this to the lowest setting and now all the channels have returned, all on 100% signal with the exception of ch23 which is at 80% - I don't know how I had missed this when messing around with it before.
With the loft aerial, my last post was possibly misleading. You were correct originally that I am only missing COM3 on ch40 from this aerial - I guess it is probably best to wait for the power increase to see if this fixes it. It just seems odd that pre-switchover MUX2 was on ch40 at the same power as COM3 and it worked fine.
Ken Moverley.: Bilsdale is yet to switch over, this will happen some time next Autumn. While that TV will not work after switchover, that may not be the source of your current problem.
The Belmont transmitter has just switched over in the last few weeks, so it's possible that signals from that are strong enough to confuse your TV. Some equipment does support 8K mode but can't handle a combination of both modes. In this case, you would have to add a Freeviewbox.
The prediction for Bilsdale is pretty good, so you should check that the aerial is intact and still pointing the right way. Problems on the lowest channels (and you don't get lower than C21) usually indicate a problem with the reflector, the elements at the back of the aerial.
The TV is also on Digital UK's list of equipment that can't handle a larger Network Information Table at http://www.digitaluk.co.u…tnit , but since that says the TV software would freeze when you retuned, I assume you had the software update that corrected that problem.
Assuming that "slightly better off" will be worthwhile, there may be two problems in changing:
1. I have two aerials, one of which points to somewhere in the East Mids( I assume Waltham but I am too far away according to the map although E Mids news comes in strongly) and the other to Sandy Heath.
In analogue days the aerial fitter pointed the aerial N.E. based on a line of high trees quite close to the property interfering with the signal from the S Coldfield area(W Mids).
If I had the aerial moved to point to S Coldfield would the same problem apply to digital?
2. If I want to hear local news for N'pton and Daventry area I need Look East but I take it that as I currently get good digi reception on BBC East then I could simply find the BBC Look East channel when needed?
Essentially my problem was Film 4 and ITV4 reception and todays re-tune based on Sandy Heath has made no difference but there is another re-tune on 14 Sept and then on 23 Nov.
Will these two further re-tunes improve both channels?
There are no reported engineering works or problems for Emley Moor however for the last 4 or 5 days but I have experienced pixelation and signal dropout on all HD channels - this after 2 months of trouble free reception following acquisition of new TV
Last night signal quality was shown at less than 5% and signal strength about 22% for HD channels, whilst standard definition is more or less 100% quality and 90+% strength
The Oxford transmitter is changing to digital this month and there's a message to re-tune our boxes on 14th and 28th. I've noticed though that the ITV channels are freezing a lot more than normal this week and wondered if this is likely to be something to do with the change over?
More seriously, they might be moving equipment, cabling, aerials, etc. though they should be reporting low power if applicable. Have a look at the page of rthe Oxford Tx, which will show any announcements due to Brian's many links!
Geoff - Brian is a bit fundamentalist about the (undoubted) superiority of rooftop aerials; but depending on location and what the roof is made of and direction to transmitter youu MAY be OK with a loft aerial - or even a set top.
Geoff: At 25km from Mendip you'll probably be OK with a loft aerial, though you do have to ensure it's aiming through tiles rather than brickwork, and avoid reflective surfaces in the loft. I'd go with a 40-element log-periodic, see Online TV FM DAB Aerial sales .
QI have sky multlroom in louge and three other rooms. Is
There a cheaper opn. Also if when you record wlth skyplus you get interference on playback such as picture freeze and sound breakup, is box at fault or bad dish alignment
alan: As you are only 4 miles away from Crystal Palace, I would be inclined to use a standard log periodic type aerial in the loft, provided that is that you dont have to face it into a water tank to obtain the correct angle for the transmitter, and also that it isnt facing through the adjoining walls of other properties, as if it is, then gutter mount it. (Fixings permitting!)
Jb38 one thing to remember when instaling an aerial in the loft if you have foil insulation mounted to the beams this will block all the signal no matter how strong, i have come accross this and it is a pain every bit of information helps have a great night
alan: If you must really use a loft aerial, and I would suggest you use a rooftop aerial if you possibly can, the official advise is to make sure you use satellite-grade coaxial cable to connect it to the TV set, to offset the losses caused by putting the aerial in an unsuitable location.
steve.t Thursday 15 September 2011 9:12PM Dartford
hi am in dartford have low signal strength on itv,channel 4 and some others so bought a Mux Magician ultra high gain group w aerial because it said it was good for bad digital reception.when looking online for a direction to point it came across this site,saying it would be better to have a group a because it may avoid inteferance from other masts.is this right because it would be agro trying to send it back but dont want to put it up if its gonna make things worse.thanks for any help.
I receive my programmes from Sandy Heath and have previously mentioned poor reception from Film4 and ITV4. I think I recall getting a reply to the effect that in Aug/Sept the further re-tuning that was required on 31 Aug and 14 Sept should transfer the two channels mentioned above to a stronger group and reception might then be fine
Well I did both re-tunes and the two channels are still basically unwatchable for almost all of the time. It may be that the Aug/Sept retunes have still not transferred these two channels to the max signal strength of course
Will the re-tune in Nov cure the problem or can I now assume that my standardaerial needs upgradng and without an aerial change my reception of these two channels will remain probematical?
I have the standard aerial on the roof and it is pointed at Sandy Heath.
I have had the chance to check what Mike Dimmick said when I wrongly posted on the Sutton Coldfield tramsmitter forum
His advice was to stay with Sandy Heath.It appears from his reply that Film4 and ITV4 have moved to their final resting place on Sept 14th so it looks as if their signal strength and quality is all that it is going to be unless it is still powering up. How many days does it take to get to max power?
I am unsure if Des Collier is replying to my post of 5:35pm but if he is, can Des or any other knowledgeable person explain in simple what his reply means after the word aerial on line two. Specifically what is it that I need to do? Belmont and diplex group A with a group C/D to get all multiplexes means nothing to me.
I looked into my accounts today and after seeing the £50pm I'm paying for virgin thought it was time to return to freeview!
I live in Portsmouth and my setup used to work fine, but now it says no or bad signal and comes back with a 20% signal strength at best. Even the analogue signal
isn't anywhere near crystal, which isn't a great start. Looking at this article my aerial is a class 2 high gain which I've attempted to line up with Rowridge. Elements forward facing vertically with the reflector
on the rear edge. This was is the loft working ok and I've pointed out the windows in the loft with no improvement. I was going to mount it on the roof but it's
not looking worth it at the moment. The set top box is a Humax Fox F2 which I got in 2005. All was ok a couple years back but now absolutely nothing.
I've had the aerial out and redone the contacts, added a (old) booster but still no go. Any help much appreciated?
I'm trying to reduce costs but stuck with my virgin for the mo.
Mike O'Pray Sunday 18 September 2011 12:15AM Daventry
Steve P I take it that you mean two different types of aerial. I have two aerials which are the same but pointed in different directions although there is only one wire into the room. So does this indicate a diplex?
My post code is NN11 4HL
When I switched on tonight at about 7:30pm and tuned into ITV4 and Film4 the reception seemed better on both although the picture occasionally froze and there were small blocks in the picture also.
However I then connected the TV to the HDD box and switched to the SCART connection to connect the HDD.
The reception on both ITV4 and Film4 then became perfect and has remained that way all evening.
So is the signal strength still powering up to explain why ITV4 and Film4 were better although not perfect and will the powering up continue until the reception is perfect via the TV alone and if so in how many more days?
Secondly why does connection via the HDD improve the reception to what seems to be a perfectly satisfactory standard?
So via the HDD the problem may be solved but if I connect via the television only will the powering up eventually solve the problem in the next few days?
I hope I can now assume that the channels giving me ITV4 and Film4 will now stay at the strength I am now receiving today because I am now getting a good picture on both channels via the TV alone without connection to the HDD
So it would seem that since yesterday the signal strength has risen and this is confirmed by the figures that appear under the channels to indicate strength and quality.
However I am still curious about the apparent beneficial effect of the HDD last night.
Weak signals may well be the case but what is it about the HDD that improves things? Last night for instance the signal strength via the TV had regressed and ITV4 and Film4 were not really watchable but were fine via the HDD
PS I just tried both channels in the last few minutes and exactly the same thing happened. Blocky and jerky via the TV and perfect via the HDD
I can only conclude that the HDD makes a difference but how?
Finally and just to repeat once more a question I asked on my first post a couple of days ago, is the signal strength still increasing since 14 Sept or is it at max and if so will the further change on 23 Nov make things any better for the two channels in question?