Possible Tetra Mast TV interference

[Taffycat]

We have a bit of a conundrum going on here and, I'm wondering if anyone can offer any guidance please?

We have a roof aerial which supplies the signal to two LCD TVs, which are in two separate rooms. (The signal was switched fully to digital (Freeview) last year, so no analogue signals at all now.)

One TV has a built-in Freeview tuner, the other one receives Freeview via a scart-gizmo (which takes the place of a set-top box) and works just as well as the built-in receiver. Normally, a very good picture/sound and, very neat.

Anyway, quite recently, we have begun to experience "interference" on all channels, but, only on ONE of the sets, and then only at certain times of the evening - usually just after 8 pm. The picture and sound begin to break up and distort (on the "gizmo" set only.) There is pixellation, bright lines and the only answer is to switch off.

The other set however, is completely unaffected. No problem.

It happened last night, but at 10 pm I switched it on again and watched the News - the picture/sound was perfectly fine.... but immediately afterwards, around 10:35-ish, the interference began again. When I popped my head around the door to see if the other set was reacting, it was absolutely fine.

So..... after a bit of Google-sleuthing, it looks as if the problem could be a Tetra mast (and I have discovered there is one situated about half-a-mile-or-so from here. But I'm a bit puzzled. Why is only one set affected - if the mast is responsible?

From what I understand, interference would be more likely to happen if we were using a signal booster - which we are not. So, is there any definitive way of telling what is actually going on, do you think? Or a test of some kind that we could easily carry out?

Sorry this is a bit long-winded, but thank you if you've managed to read this far.

 

[Ian]

Does the TV with a built-in freeview receiver have a scart socket? If so, you could switch the gizmo over to that one temporarily and see if it does the same thing - just to rule out a problem with the TV.

I don't know much about this sort of thing, but I think it may be worth checking the above as I would have thought that digital interference would cause a very sharp drop off - i.e. you'd get no picture/sound rather than just degraded quality like you would on analogue.

Again, I could be barking up the wrong tree, but if you turn the scart gizmo off and let it cool down, does it tend to work once it turns on again?

 

[floppybootstomp]

If the 'scart gizmo' is switched on at around the same time each day it could be taking time to warm up and show a fault. If possible delay switching on until the time the interference usually starts (around 8pm) and see if the interference is present. If it isn't but starts after a given time, it's likely the 'gizmo' is faulty.

The other likelihood is the more modern TV with the built in digital (Freeview) tuner is better screened and/or built and thus not affected by something that may be causing the interference. If that is the case I'm afraid the only solution would be a similar TV to the unaffected one with built in digital tuner or an external digital (Freeview) tuner for the older TV.

The external tuner would have to be tried before purchase preferably as it may be the TV causing the interference to be displayed.

 

[Taffycat]

Hi Ian and Flopps, thank you both for the speedy replies and suggestions.

I think we can rule out a problem with the gizmo itself, because having left the TV on for a few hours today - by way of an experiment - nothing has happened at all. (So probably not an overheating problem.) The picture is fine (and the sound would be, if we had it turned up..... but sorry, can't stand the daytime offerings )

The gizmo, incidentally, is one of these - not meaning to advertise, but at least you will know what I'm banging-on about.

We wondered whether a different external tuner would be any better than the Konig gizmo, or if getting another set with Freeview built-in would be the best option. Right now, I'm thinking the latter(?)

Pity really, the "old" TV is still in very good nick - a slightly chunkier flat-screened Panasonic Viera, maybe 5 or 6 yrs old and not used much - but I guess technology has moved-on a fair bit since we originally bought it, so possibly time to replace it.

 

[floppybootstomp]

Good luck TC, at least 5 or 6 years down the line you get a lot more telly for less pounds now.

Just to verify a small point, I didn't actually mean the external tuner was overheating but some electronic faults don't happen until the electronic device has reached it's normal operating temperature.

Using this situation I used to fault find using a can of freezer spray by spraying suspect components and seeing if a fault went away. Very nifty

Freezer spray is also sold with a different label for three times as much, only then they call it 'bubble gum remover'

 

[Taffycat]

Thanks Flopps and yes, looking around, I can see what you mean about getting more features for less pounds.

Thanks also for clarifying the overheating/normal operating temperature point... I've got-it now

Brilliant idea re the freezer spray! Have to say that we hadn't heard of that one before... looks like it could be useful stuff to have in the tool chest though.

Appreciated the help muchly, Thanks again.

 

[crazylegs]

Right after reading your post TC I think I have the answer to your problem!

I have a flatscreen LG TV with built in HD freeview tuner and it gets a fantastic picture all of the time..
about 2 months ago I purchased a Freeview box that had recording functionality built in so I could record programs, So I duly swapped my inbuilt tuner for this box and I noticed my signal was weaker through the box than my inbuilt tuner and the picture would pixelate on certain channels and break up, this would happen intermittently and when it felt like it but if I swapped back to my inbuilt tuner it was perfect...
Bear with me..
My inbuilt tuner in my TV had an inbuilt booster for the signal and I noticed the freeview box I had bought did not, I came to the conclusion over time and a fair bit of testing that the signal I was receiving was good but not super strong, but with my inbuilt tuner with the booster built in I never had a problem..
The box without a signal booster showed up my weak to good signal for what it was!

Remember some multiplex signals on the digital tv network are stronger than others, so certain channels normally the main ones BBC, ITV etc have a stronger signal, others like QVC, Quest, etc sometimes broadcast with a weaker signal and so that multiplex will be slightly dodgy depending on location weather conditions etc etc..

I would say your little Gizmo probably isn't that sensitive and is intermittently dropping out on some of the multiplexes..

 

[nivrip]

Similar problem.

My signal comes into an aerial, then goes to a HD recorder and then to the TV with inbuilt Freeview. If I watch TV via the HD recorder ( usually just to set the timer ) there are times when the picture pixellates or is very poor but as soon as I go back to the TV the picture is perfect, even though it is using the same signal as the HD. Is the signal boosted by the Freeview?

I concluded that perhaps the tuner in the HD recorder was not as efficient as that in the TV, which is several years newer. I have to admit that there are a few occasions when the TV is not perfect but I felt that was probably just a weak signal from the local transmitter at the time.

Before I had HD recording I used a similar system with a VCR, (Aerial > VCR > TV) and I never had a problem with the picture via the VCR even though the VCR was fairly ancient and presumably had ancient technology within it.

Is there any way of improving things? Life is never simple.

 

[Taffycat]

Hi CL and Niv - thanks for the additional input

Re the Konig Freeview-tuner gizmo... we have been using it ever since Wales went digital (May last year...if memory serves.) The reception from it has always been great and trouble-free 'til now. The interference prob is very recent - and, as mentioned, always at the same time of the evening.

But I would have to agree that, reception on the TVs with tuners built-in, is probably stronger here. Even our kitchen set, (which is just a small, cheapie "Alba" model, hooked-up to an indoor aerial,) is interference-free.

Seriously thinking of investing in a set which has Freeview and HD on-board now.

 

[crazylegs]

Hi Niv

You could try a booster just before it goes into the HD Recorder, But I never tried that as my recorder went faulty after a month and started missing recordings so I returned it for a refund.
But yes the TV freeview Tuners do seem far more sensitive and most TV's do have boosters built in and are turned on by default, you should be able to find this in your tv settings, try your TV manual it should be in there..

But yes on reading lots of posts on forums on the intamaweb the general consensus is that most freeview boxes regardless of being standard freeview or HD freeview do have quite poor tuner chips built into the boards, its the recording chips that cost the money and is where the quality is in these boxes..

Hope that helps..

 

[crazylegs]

TC

Could be that someone is using something that is interfering with reception but then that would also interrupt your other TV too, so I don't think it could be that..

I reckon then that your Gizmo is faulty and is playoing you up intermittently when it feels like it or even when it gets a bit warm perhaps!

 

[Silverhazesurfer]

I lived in a place here in the states that at one time (before the digital switch), and I ended up receiving cable TV channels via rabbit ears. I wish I could explain this. An associate of mine suggested that the signal had been boosted in the apartment above me and I was picking up the signal via the bleeding over signal. I connected the TV to the cable jack on the wall and did not get those channels anymore. Once the TV was removed from the cable line and conected to the rabbit ears, it worked just the same.

I also used to use citizens band radio and used an amplifier in my mobile setup. Blastint 250 watts of power out of the antenna caused the signal to play over electronic devices. Again, I do not understand exactly what caused the ability to do this, but now that the more refined electronic devices have been built, it doesn't happen.

I truly don't know if this helps, figured I would drop it here as something that I know firsthand.

 

[nivrip]

Rabbit ears ?????

Not familiar with this term. Is it some North Americanism? Or have I just missed something.

Any explanation would be welcome, SHS.

 

[crazylegs]

Rabbit ears ?????

Not familiar with this term. Is it some North Americanism? Or have I just missed something.

Any explanation would be welcome, SHS.

An old indoor tv aerial!

 

[nivrip]

Hey, thanks CL. You can learn something every day.

I've never heard that term before. Sad life I must lead.

 

[Silverhazesurfer]

Sorry for being unclear. I forget sometimes that the English to English translation isn't exact.

 

[Taffycat]

Yesterday evening, I switched on just after 8 pm and waited for the screen to go crazy as has been usual recently. Hmmm.... time passed, but....nothing happened! Not a hint of pixelation, or whizzy bright zig-zaggy lines, just a good picture/sound.

We left it on, popping back to check now and then, but all remained well throughout the evening!

Then we Terry and I remembered that something similar occurred last year. "Interference" starting up at a certain time each evening, etc. At the time, being new to the digital switch-over, we probably thought it had something to do with that, so we accepted it as teething problems. At that time, it went on for a few weeks before seemingly clearing, and, all remained well until a week or two ago. (As explained in my first post.)

I have tried to find out if something different has been going on in the area, but apart from a flower festival, (is there a rampant dahlia on the loose somewhere...?) there doesn't appear to be anything "obvious."

Thank you Silverhazesurfer for your interesting input. The closest thing we've experienced to that, was back in the days of the old analogue CRT TVs. Occasionally, we would pick up broadcasts by a local cab company.

 

[nivrip]

Hmmm....... but still no explanation as to why one TV was fine and the other had a problem when both received the same signal.

Just like my scenario.

 

[crazylegs]

An easy explanation is what mr Flopp's has already mentioned and interference on the gizmo is because your newer inbuilt tuner has a better filter and so your internal tuner doesn't suffer whereas the Gizmo has no filter and of course picks up interference from electrical devices like drills and spark plug caps in older cars as they drive by!

 

[Silverhazesurfer]

I cannot help but laugh. Could it be solar flares?

http://news.nationalgeographic.com/news/2011/06/110608-solar-flare-sun-science-space/

I have heard of such things. We had a cell phone outage here in the States a few years back that was blamed on solar flares. Again, only speculation, but I imagine that it is possible.