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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
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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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Monday, 2 June 2014

2:38 PM

A McGrath: Yes, you can get ba couple of attenautors (pretty cheap from the the net), and put them in series - you just need some cheap aerial leads to connect them together.

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MikeB's 2,579 posts GB flag
Tuesday, 1 July 2014
Susan Moon
7:38 AM

Hi I have the same problem with too much signal strength. The aerial installer came out and used an attenuator on my digital box. This worked, but it was 20d that worked. He's taken it back now, and told me to take my recorder freeview box back ( I've had three boxes in a month, all Goodmans boxes) the attenuators I've seen online are usually about 6d . Do you agree, and would another type box work. Mine is a Goodmans box and I understand from some websites that they tend to interfere more with signals...

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Susan Moon's 1 post EU flag

8:52 PM

Professional TV engineers always used to carry a selection of attenuators, from 3 dB up to 48 dB and they can simply be connected in series. Good ones can be bought online quite cheaply so a small selection might halp - else you would need to get a variable type that you can adjust for best results.
It's not the box causing any 'interference' but the way they react to signals that are too strong or too weak - neither are a good thing! Whilst the 'Goodmans' branded boxes are inexpensive they are not the best on the market, nor the worst probably. It's said to be true that they don't react well if there is too much or too little signal. The need is to get the right balance between strength of the signal and quality of the resulting pictures. Hence selecting the right level of attenuation is important if your signal is too strong.

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MikeP's 3,056 posts GB flag

10:38 PM

Susan: Since I have a Goodmans box, I can agree with MikeP's description ' they are not the best on the market, nor the worst probably'. Its not as sensitive as my Sony recorder by any means.

Changing the Goodmans box isn't going to solve the problem - its your signal strength. You dont give a location, but its probably pretty close to a transmitter.

To kill the signal on my Sony, I did exactly what Mike P said - put some attenuators in series (I had a variable one, but it really didn't work well). You'll find loads of attenuators of different strengths on Amazon - there is a 12db one for £1.59, which is what I got - I used this seller…ator .

You can connect them via short lengths of aerial lead, but using couplers is neater (although you can end up with the 'Camberwell Carrot' effect). At least you now know what the problem is, and when you come to replace your system for a TV with an inbuilt digital tuner or PVR, you can take appropriate action.

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MikeB's 2,579 posts GB flag
Wednesday, 2 July 2014

9:27 PM

MikeB & Susan:
If you buy coaxial in-line attenuators they have a male connector at one end and a female at the other - you just plug them together one after the other if you need more attenuation. One possible is at 12DB COAX PLUG INLINE ATTENUATOR: Electronics Note that these have standard coaxial connectors so you can plug them in without needing any extra cabling. They are available in various degrees of attentuation, the normal range is 3, 6, 12, 18, 36 and 48 dB attenuation and that other suppliers are available.
Note that these are only intended for use with the UHF TV signals such as Freeview - they do *not* work with connections to satellite dishes!

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MikeP's 3,056 posts GB flag
Thursday, 31 July 2014
Simon Dale
11:07 AM

I am currently running my TV on my original aerial used before digital. When scanning for new channels I get 10 for signal quality but zero on signal strength. HD works fine and I have no picture break ups. Should I consider an aerial upgrade and if so do you recommend the Labgear 28-Element Log Periodic Aerial. My post code is OL6 9AS

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Simon Dale's 1 post GB flag
Simon's: mapS's Freeview map terrainS's terrain plot wavesS's frequency data S's Freeview Detailed Coverage

9:37 PM

Simon Dale

I'm not sure about the necessity to upgrade at the present time, but if you do consider it I would advise selecting a good quality log-periodic aerial. These cover the whole spectrum likely to be used for TV broadcasting now and in the foreseeable future. But do not fall the scam of a 'digital' aerial, *all* UHF aerials will receive both digital and analogue broadcasts equally well and some are charging a premium for a 'digital' aerialm when it is not required technically.

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MikeP's 3,056 posts GB flag
Monday, 15 September 2014
10:04 PM

My TV with freeview built in always hangs / freezes on ANY BBC channel.
I suspect it is due to it being a cheapy model but scouring around 'the net' it appears a too strong signal will possibly do this.
I did try a variable attenuator with no success. Only 3 miles from Olivers Mount in Scarborough and have a booster fitted purely to get a second tv signal up to the bedroom. I have tried with no booster. Loft aerial which has been there during the analogue days.
The cheapy tv does not have a signal strength / quality indicator so I am relying now on advice before throwing the said TV out of the bedroom window.
Maybe some more attenuators?? although I did try holding the coax plug just close to the a signal just...and it still blooming well froze.
Only BBC though....bizarre.

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Chris's 2 posts GB flag

10:31 PM

Chris: If your TV is a Goodmans/Bush (or, since you say its a 'cheapie', perhaps with the same software), then there is a decent chance you've got the same problem as the rest of us. See this thread: My ITV/C4 Freeview channels have disappeared - what can I do? Is it my SCART ca

We are hoping for a solution soon.

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MikeB's 2,579 posts GB flag
Tuesday, 16 September 2014
7:48 PM

Mike B:
Its a Logik TV which probably falls into the same category. I will hold on from discarding it into the garden....for now.

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Chris's 2 posts GB flag
Chris's: mapC's Freeview map terrainC's terrain plot wavesC's frequency data C's Freeview Detailed Coverage
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