menuMENU    UK Free TV logo Archive (2002-)

 

 

Click to see updates

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.

Help with Freeview, aerials?
How do I get a test card with Freeview1
I would like to know if it is possible to receive UK terrestrial Freeview servic2
I have been told I would receive too much singal from my Freeview tansmitter as 3
Can my Freeview box receive more than one BBC and ITV region?4
Is it true that my 87 year old mother is entitled to a FREE upgrade when the ana5
[][][
In this section
Should the UK close down the TV networks to allow for more mobile broadband? 1
UK Digital switchover ends - Northern Ireland completes on 24th October 20122
The last day of analogue television in the UK - goodbye PAL3
2 days left of analogue television - goodbye teletext4
3 days of analogue to go - goodbye to NICAM 7285
Changes to Saorview frequencies and power levels, 24th October 20126

Comments
Friday, 16 September 2011
Ian
sentiment_satisfiedGold

6:31 PM
Hinckley

Well as I'm not having any problems at the moment I ain't going to worry. It's defiantly the TV and not fly lead as I have tried several, Mum & Dad have the same model and it dose the same, switching a light or other electrical device on or off sometimes brakes the picture up or makes the sound drop.

link to this comment
Ian's 497 posts GB
T
Thomas
sentiment_satisfiedBronze

9:53 PM
Leeds

As well as a masthead, I have a distribution amp that sends the signal to 3 TVs in 3 separate rooms, and have got these results for Emley Moor's new BBCA:
Panasonic Viera: shows 10/10 for both strength and quality, though I do have that issue with it starting out as 'red' 1/10 the first time I tune to it.
Samsung: 85-88 (out of 100) with Bit Error Rate of 0
Lowry set top box: 55% strength, 95% quality.

My Panasonic TV (the only one with a Freeview HD tuner) shows the HD Mux strength as 9 out of 10, with the quality fluctuating between 4 and 5 out of 10.

Does it sound like I'm getting too much signal? Should I try adjusting the attenuator on the distribution amp?

link to this comment
Thomas's 61 posts GB
Saturday, 17 September 2011
M
Mazbar
sentiment_satisfiedGold

6:44 AM
Ormskirk

Thomas be careful where you put your attenuator, do you know how your masthead gets it power from? If it gets its power from your distribution amp the attenuator coul nock out the masthead and you will have no signal at all what you could try is buy a variable attenuator for each tv and wait for the switchover and if after then you have to much signal you can put them on each tv if you are ok leave them off

link to this comment
Mazbar's 382 posts GB
J
jb38
sentiment_very_satisfiedPlatinum

8:19 AM

Ian Grice: A small point I wondered about is why you are using Waltham at 31 miles away whereas Sutton Coldfield is only at 19mls?

I ask this because the trade predictor on your post code indicates good reception across the board being possible from Sutton Coldfield, (especially high powered BBC1 Mux Ch43) whereas Waltham indicates either poor or no reception being possible, (on SDN Mux Ch29) with this not really improving at any time.

As for the TV that is susceptible to interference, what model is it?

link to this comment
jb38's 7,179 posts GB
J
jb38
sentiment_very_satisfiedPlatinum

10:26 AM

Ian Grice: Further to what I mentioned regarding you stating that Waltham is being used, carry out a signal test whilst on BBC1 and note what Mux channel number is shown, if its Waltham is Ch61, whereas if its Ch43 then its Sutton, which although maybe wrong, I suspect it might be! this being based on your reported signal strength.

If looking at the aerial it should be facing roughly West (actual 283degrees) for Sutton, Waltham being slightly to the North of East. (actual 53degrees)

Regarding the aforementioned signal strength, if you get almost 100% signal / quality before it reaches your "first" splitter amp, then although this is maybe inconvenient to arrange, but I would alter your set up whereby the aerial goes directly into a six way splitter to feed the various rooms, thereby doing away with the two way splitter presently used.

The only reservation I have over what Dave Lindsay has suggested is that I would keep the use of a powered splitter for this purpose, as you aren't exactly that close to a main station, and it has to be remembered are presently receiving a high powered Mux from wherever (BBC1) without a problem, that is even although you are using two powered splitters, which as said in my original posting doesn't in reality give that much of an amplification to the signal, this no matter what fanciful claim might be printed on the label.





link to this comment
jb38's 7,179 posts GB
Ian Grice
sentiment_satisfiedGold

2:53 PM
Hinckley

I use Waltham because I live in the East midland and want East midlands news. Even though I mainly watch via SKY there are some times I use freeview. I know the set up is a bit weird but it would be such a hassle to change it. Aerial is on the back of the house, lead goes through the loft to Sky box at front of house then RF2 feed from sky box goes to bedroom directly above into 2 way splitter 1 feed for TV other then goes up into loft to the back of the house into 4 way splitter and that feeds other bedrooms, kitchen and dinning room. Changing it would mean re routing cables (some behind plaster) and as I said I don't have any freeview problems so if it ain't broke don't fix it. Set up also means we can watch and control sky from any room.

TV is a 14" CRT with built in freeview made by Orion model TV14DT1, also seen then branded as Bush and Goodman's.

link to this comment
Ian Grice's 497 posts GB
Ian Grice
sentiment_satisfiedGold

2:57 PM
Hinckley

Forgot to say have always had very good reception from Waltham even though loads of people have told me I shouldn't? just one of those things.

link to this comment
Ian Grice's 497 posts GB
J
jb38
sentiment_very_satisfiedPlatinum

3:35 PM

Ian Grice: Well I have to say that I really do feel that you must reside in a "chosen spot" for reception from Waltham, as being a long standing engineer (not necessarily aerial) I know that even a trade predictor can have elements of inaccuracy built into its forecasts, as its impossible for any predictor to cater properly for localised conditions, with DUK's usually always giving an element of a "rose tinted glasses" type of prediction, something I usually allow for, but using the post code provided it shows Waltham - Lark Stoke - The Wrekin as being totally out of the question for any form of reliable reception at any time, and this across the whole range of the multiplexes, this being why I doubted if it was Waltham being received.

Just out of interest, can you receive Mux Ch29 from Waltham? as that causes difficulty to many including myself, and will do until October 12th.

link to this comment
jb38's 7,179 posts GB
T
Thomas
sentiment_satisfiedBronze

5:50 PM
Leeds

The masthead is in fact a splitter with four outputs, two of which are unused (but kept for possible future use). The masthead PSU is in the kitchen, also feeding a fourth Freeview set. This one reports 98% signal strength and no errors for BBCA.

It's one of the other masthead outputs that go into the aforementioned distribution amp.
Perhaps I'm already getting too much signal and attenuating it at the amp?


link to this comment
Thomas's 61 posts GB
Ian
sentiment_satisfiedGold

8:21 PM
Hinckley

yes I get channel 29 no probs, also got all the channels before switch over with no problems.

link to this comment
Ian's 497 posts GB
Select more comments

Your comment please
Please post a question, answer or commentUK Free TV is here to help people. If you are rude or disrespectful all of your posts will be deleted and you will be banned.







Privacy policy: UK Free Privacy policy.