TV screen freezing - help

[obmcfc]

Most nights my TV keeps freezing and get message on screen digital service - now its an old TV connected up to decent freeview recorder (using indoor ariel)

I bought a filter cable at weekend as thought someone on road may have a CB radio (or similar) as there is a large mast/ariel type thing at back of some of the houses on the street - but was still doing it this morning. I could be watching film for couple of hours and TV fine then all of a sudden problem just starts.

Happens on various channels and at any time of day/night (mainly evenings) just seems really random. Intend buying new TV but don't want to waste money if going to be crap reception.

I have moved ariel, rebooted and scanned freeview box but still happens. Also checked and no transmitter work taking place.

When I check signal it jumps from 0 to 75% then back down again constantly during the problems

Any help greatly appreciated

 

[ChrisFrost]

Your problem is simple. Your aerial sucks! That's it in a nutshell.

The solution is equally simple: Get an outdoor aerial, professionally fitted.


The reason the aerial sucks is partly geography (it's inside your house where the aerial signal is at its weakest), and partly to do with atmospherics. There are certain times of the day where the earths atmosphere is good for radio transmissions (which is what all TV aerial signal are) and there are times when it's bad. When you lose your signal then those are the bad times.

"So, why does the signal go from 75% to 0?" is probably your next question. The answer is it is the nature of digital transmissions.

There's a threshold level below which the signal corrupts completely. At that point you get no picture at all. When the signal level drops very close to the threshold point then the TV shows you a picture freezing and blocking. There's a very narrow margin to go from an okay picture to blocking to nothing at all. That's how digital TV reception works.

Without wanting to get too technical, you'll find that when the picture is freezing on some channels then it might still be okay on others. That's because digital channels are broadcast in groups (called 'muxes') and the strength of these muxes varies. The muxes for the BBC and ITV channels are the strongest. The muxes for the shopping and minority channels are generally weaker.


Okay, now some good news....

The fact that your indoor aerial works at all bodes well! It means that you live in a reasonably strong signal area or that your aerial is on a side of the house that faces the transmitter. So, even a modest outdoor aerial fixed outside your window is likely to solve your problems.

If you are doing this DIY then go to the Satcure web site and buy a Vision 10-040 Log Periodic aerial, and whatever type of brackets are required for your house. Buy a length of coax (WF100) and the appropriate plugs. If you are unsure then just give the Satcure boys a ring and they'll sort you out.

Simple - Job done

If you go for an aerial installer then the same type of aerial and coax will be perfect. You're unlikely to need a ultra high gain "digital" aerial that looks like it could beam signals from Mars. Most of the time they're seriously OTT and just cause problems with movement and broken pointing later on because they're fitted on undersized brackets.

 

[obmcfc]

Thanks for prompt response, live in block of flats hence the indoor aerial and was hoping you wouldn't say need outdoor one.

It usally affects main channels BBC and ITV channels more so than others such as Dave, Film4 etc etc

Will speak to the landlord.

Thanks again

 

[rjm2k]

Could be that your box picked up more than 1 transmitter and chose the worst one, do you have the same channels but in the 800 range. If so you can manually search on the frequencies used by the better transmitter

 

[obmcfc]

Have had that issue before with an older and cheaper freeview box.

I am very close to Crystal Palace transmitter (only few miles)

and checked postcode on here

http://www.wolfbane.com/cgi-bin/tvd.exe?DX=L&HT=10&OS=sm6+0bb

 

[Sam Gangee]

When I check signal it jumps from 0 to 75% then back down again constantly during the problems

That's usually symptomatic of a signal which is far too strong.

I am very close to Crystal Palace transmitter (only few miles)

That supports my theory.

Yep, a whopping 86dBuV/m signal. Probably still at least 80dBuV/m indoors. Looks like you need at least a 12dB attenuator and maybe higher.

 

[obmcfc]

sorry to sound dim but what will this do Sam

 

[ChrisFrost]

What he mean is a device to reduce the signal level. The reason for such a device is that too much signal is just as bad as too little. It overload the tuner.

This thread highlights the problem associated with fault diagnosis via the net versus on site. When I visit a site theres lots of clues as to possible cause of problems. I can also use a signal meter to assess the strength and quality of the signal. Just basic info that a customer might not think important can be vital. In your case it has emerged that you are very close to the countries biggest transmitter. There may be other info as yet unknown that helps further.

Doing s remote diagnosis is a little like doing a jigsaw with most of the lid missing.

 

[obmcfc]

Thanks for all your help guys, really appreciate it and will give this a go

 

[obmcfc]

I turned down amplification on ariel and also got new TV - hasn't frozen since.

Thanks for all suggestions and help