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Freeview signals: too much of a good thing is bad for you

If you have a high-gain aerial or use signal amplifiers, it is quite common to find that the high-power digital signals provided after switchover will overload your Freeview equipment - and can appear to be "weak signals".

If you have a high-gain aerial or use signal amplifiers, it is
published on UK Free TV

Most people will experience nothing but simplicity and joy with the digital switchover - the process that turns off the old five high power analogue signals, and the existing six low power digital services and replaces them with six new high power Freeview multiplexes.

For those with problems, there are generally three issues.

Eliminating other possible problems first

The first is that very, very old equipment will not function with the digital signals split into 6,817 sub-signals, as it was only designed to work with 1,705 sub-signals. This is known as the "8k mode issue" - see TVs and boxes that do not support the 8k

It is also common that people do not clear out the old channel list (by selecting "first time installation" retune, "Factory Reset" or "Shipping Condition") before doing an "autoscan" for the available broadcast frequencies, and this results in everything from missing channels to no subtitles, programme guide, wrong channel numbers and no text services. If you can't find how to do it see either Freeview Retune - list of manuals or do it this way: My Freeview box has no EPG, is blank, has no sound or the channel line up is wrong .

A third problem is caused by having signals from more than one transmitter - see Digital Region Overlap.

The final very common issue is "too much signal".

Transmitters have much more digital power after switchover

At most transmitters, the digital signals after switchover are considerably more powerful than before. This was because when the analogue and digital services ran together, the digital services were kept low to prevent appearing as snowy interference on television sets using analogue reception.

Here is an example, from Sutton Coldfield, of how the signals change at switchover:



4,000kW of analogue signals are turned off, and the digital services increase in total power from 48kW to 1,200kW - that is an increase of 25 times in numerical terms, also know as +14dB. (The reduction of -7dB from the analogue strength is intended - the digital services require less power to cover the same number of homes).

This large increase in power should cause no effect for most people. A stronger signal does not increase the picture quality (you need Freeview HD for that), sound levels - the only effect should be that more homes that are further away from the transmitter mast can receive a stable digital signal.

High gain aerials and signal boosters

However, many people have been tempted into buying one both high gain aerials and signal boosters.



High-gain aerials were very suitable for places where the Freeview signal before switchover was very weak indeed, but if you have one of these and you are located closer to the transmitter, you will probably now have a signal overload.

Generally speaking, signal booster devices are never really much use for Freeview reception, and much of the time they actually amplify the interference more than they do the signal, causing reception to get worse, not better.

How to tell if you have too much signal

There are almost as many ways for a Freeview box to display the "signal strength" and "signal quality" as there are types of Freeview box. Here are some of them:



Speaking generally, there will be two indicators:

One is signal strength - this shows the power level of the signal entering the Freeview box. Often "0" is the lowest and "10" the highest, but sometimes it can be a percentage, sometimes coloured boxes and so on.

The signal strength should be around 75% - more than this indicates too much signal.

The other measure is the signal quality and this is much more important to high-quality Freeview viewing. Any measures that increase this to the maximum will provide for uninterrupted viewing, lower values will result in "bit errors" that cause the picture to freeze and the sound to mute out.

One problem with over powerful signals is the overload can sometimes show as a low signal because the receiver circuitry will enter a "blown fuse" state to protect itself.

How to deal with too much signal

First, if you have a booster or amplifier - remove it from your system. Don't just unplug the power, as this will result in no signal getting though the device.

If you can't just disconnect the output cable and connect it to the input cable, you might need a coax female-female coupler to connect two male connectors together.



If you don't have a booster or amplifier, you might have to fit an attenuator onto the cable. They come in two types, either a "single attenuator", around five pounds, or a variable attenuator, for around ten pounds. The variable sort has a knob that can be turned to select the required level of signal dampening.

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Comments
Tuesday, 22 October 2013
R
Richard
8:46 PM
Fakenham

Hi,
Thanks for your message.
My post code is NR21 9BZ

link to this comment
Richard's 2 posts GB flag
Richard's: mapR's Freeview map terrainR's terrain plot wavesR's frequency data R's Freeview Detailed Coverage
J
jb38
sentiment_very_satisfiedPlatinum

11:35 PM

Richard: As Tacolneston @ 25 miles away would appear to be your Freeview station then I doubt if an excessively high signal level would be the cause of your problem even although what you have reported could suggest that it is, its a pity that you didn't purchase a booster of the variable gain variety as those types are far more flexible by allowing any suspicion of an excessively high signal level causing problems to be instantly verified or dismissed, and example of a variable gain type seen on the under mentioned link.

The one thing that I did notice though was that the tall BT building with aerial array on top of, is not terribly far away from Tacolnestons signal path, and if any form of high powered RF radiation was emanating from that source then a booster would make the effect on a Freeview TV or boxes tuner worse, but though its really a case of whether or not you have checked as yet with any of your neighbours to find out if they are also experiencing similar problems to your own, because should they be then the problem is outwith your control and as such its pointless wasting time experimenting with your installation in the hope of finding a solution.

Two points I would like to know, 1: what model of "one for all" have you purchased? - 2: where is your aerial mounted (loft or roof)

Buy Plug-In 1 Way TV Aerial Signal Booster at Argos.co.uk - Your Online Shop for TV aerial boosters.

link to this comment
jb38's 7,179 posts GB flag
Thursday, 31 October 2013
M
MMcIntyre
10:55 AM

Hi,

I have a BT broadband and a freeview box. I had problems with signal a few years ago but for the last 2 years the signal has generally very good. The last week the signal keeps getting lost and an error message appears saying "freeview signal" too low.

We recently purchased a Roku player and that has probelsm connecting to the Internet as well. I don't know if this is relevant. In addition the actual built in freeview on my television keeps losing signal.

Do you guys have any idea what could be causing this?

link to this comment
MMcIntyre's 2 posts GB flag
M
MMcIntyre
10:56 AM
Glasgow

Oh sorry I forgot my postcode is G11 5DT.

Thank you so much.

link to this comment
MMcIntyre's 2 posts GB flag
MMcIntyre's: mapM's Freeview map terrainM's terrain plot wavesM's frequency data M's Freeview Detailed Coverage
M
MikeB
sentiment_very_satisfiedPlatinum

11:47 AM

MMcIntyre: the roku is simply a streamer, and its problems are more to do with broadband speed, and has nothing to do with tv reception.

If you are getting low or no signal, either three is a problem with transmitters (which is unlikely for more than a short time), or you have a problem with your aerial. Check the signal chain back from the box/tv. Could just be a loose cable, but it possible you have a loose, corroded or frayed coax somewhere.

link to this comment
MikeB's 2,579 posts GB flag
Monday, 18 November 2013
S
sandy goodchild
12:31 PM

LG advise me to get a vairable attenuator as my signal from crystal palace is too strong. I've looked on amazon but the reviews for each are contradictory. For each the reviewers say best with freeview and also worst with freeview. Which one is best with freeview?

link to this comment
sandy goodchild's 1 post GB flag
J
jb38
sentiment_very_satisfiedPlatinum

7:11 PM

sandy goodchild: All of those variable attenuator devices come into the category of "hit and miss" as far as just how effective they are at alleviating the problem being complained of, and so I wouldn't pay too much attention to that said by users of such devices as the reports made by users of same can be as variable as the attenuator itself.

Taking that said into account its not really worth spending a great deal of money in the off chance that it might cure the problem, that is "if" indeed its being caused by excessive signal strength! therefore the one seen on the undermentioned link is quite sufficient for most requirements.


TV Aerial Attenuator Variable 0-20Db Freeview Digital | eBay


link to this comment
jb38's 7,179 posts GB flag
Monday, 25 November 2013
S
Sam
11:19 AM
Brighton

Hiya,
BN1 3AN, communal roof ariel but no signal at all. Currently relying on rubbish indoor ariel. Should I pay to get a new rooftop ariel myself (tall building so will need scaffolding...£££££'s) or is there another way> Don't want cable....

link to this comment
Sam's 1 post NL flag
Sam's: mapS's Freeview map terrainS's terrain plot wavesS's frequency data S's Freeview Detailed Coverage
M
MikeB
sentiment_very_satisfiedPlatinum

11:54 AM

Sam: if your not getting any signal, perhaps others have the same problem. There might be a fault either within the cable to your own tv, or one coming down from the main aerial. If its the latter, then you can share the cost, get the management company to put it right, etc.

So ask other people first, if only to find where the problem lies.

link to this comment
MikeB's 2,579 posts GB flag
Monday, 2 June 2014
A
A McGrath
2:25 PM
Grantham

Hi,
I live 4 miles from the Waltham on the Wolds mast in Leicestershire . My TV picture was breaking up while the set diagnostics showed I had a strong signal of poor quality. Fitting a variable attenuator fixed the problem until I had to buy a new (Panasonic) HDD. Now, even with the attenuator, all I can get is CITV!
Is it possible to fit 2 attenuators in series or is there another way of dealing with this? Our only access to TV now is iPlayer through the Wii on a very poor broadbandwidth.

link to this comment
A McGrath's 1 post GB flag
A's: mapA's Freeview map terrainA's terrain plot wavesA's frequency data A's Freeview Detailed Coverage
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