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117 posts

Master Geek


Topic # 114685 27-Feb-2013 15:47 Send private message

I don't know whether this is the right place to ask or not - but I don't know where else to turn. I'm not technically clued up - and the aerial people and an electrician I approached really can't help any more.

We switched to Freeview when our old TV died. We have a flatscreen (Panasonic) on Freeview and it didn't take too long before I had to switch our VCR for a recorder / blueray (also Panasonic) with two Freeview tuners. The aerial is split between the TV and recorder so it's not greatly weakened like it was when they were on one cable.

Apart from some interference when it rains (we're in a hilly suburb sheltered from the nearest main broadcaster, it works well. I've just checked and today the TV is signal strength 8/10 - and the quality is 10/10. The recorder is the same - although signal strength is 7/10 on some channels. Interestingly the ones that are dow slightly are not the onces that were weak - I assume the result of retuning last year.

So that's our scenario. The problem is that over the last 3-4 weeks we've been having problems with the recorder. My first thought was the machine itself was playing up. But we had the aerial people out - and they found that there was indeed a minor problem to do with the old cable connecting to the new boxes. So they left - and the same problem returned. So they came back and replaced the cable from the aerial to inside the house. And they left - and the problem returned. That was Monday.

Last night it worked fine. When we finished watching what we had recorded, we went to switch off - and noticed that the recorder was showing corrupt pictures - on all channels.

Today the aerial people told us what we'd already concluded - it is almost certainly interference. They added that most interference problems are caused by microwaves (ours might be used at dinner time - but now when we're recording), cordless phones (ours doesn't get used much - and definitely wasn't last night) and wifi.

Now ironically our laptops were being used last night - when the programmes were being recorded - but not when we noticed the recorder was displaying corrupt images. We're not ruling it out - but it does seem unlikely. The faulty image occurs both when we're out and when we're watching another channel at the time of recording.

So does anyone have any tips that might lead us to a better outcome - or can they point us to someone who might solve the problem? Thanks

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  Reply # 771220 27-Feb-2013 19:28 Send private message

Sure sounds like interference.
Basically all you can do is switch off all appliances and see if it goes away.
Computers, modems, refrigerators, freezers, compact fluorescents, cordless phones, heat pumps can all cause harmful interference if just a minor fault is present in any of them.
Touch lamps are really bad. Once you eliminate all your own stuff then start outside.
Street lighting, neighbours equipment and anything else you can think of. Check with your neighbours too if they have same problem.
Interference can be extremely difficult to trace.

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  Reply # 771649 28-Feb-2013 12:15 Send private message

A UHF bandpass filter (or VHF attenuator) may solve your problem. Microwave ovens and WiFi are on 2400MHz whereas Freeview UHF is down at 600MHz, so unlikely to be the cause.

I was convinced my problems were interferrence but it seems it is more likely low digital TV signal strength and too high analog TV signal



117 posts

Master Geek


  Reply # 771675 28-Feb-2013 12:56 Send private message

That's very interesting. Have no idea whether it would work or not. We've had Freeview for some time now (I think 2010 but not sure - my stroke's left me with an even worse memory) and this problems only occurred in the last month or so. The signals were a bit weaker in the past (we're also in a curved hill road that makes cell phone reception marginal) - but haven't checked signal stregth recently. The re-did the frequencies in our area last year, and that coupled with the recent work by the aerial guys has left us with stronger more consistent signals.

So I still thik it's doubtful this would work - but it's the easiest thing to try. The only thing is how do we fit it - can we just plug it in - or does it need to be wired in? And given we've got a cable that splits with one to the TV and one to the recorder, and we only have problems on the two tuners in the recorder, presumably ot needs to go there? Or is it up on the aerial?

BTW these guys call themselves dishtv - but we're on the terrestrial Freeview - not the satellite one. Will it still work?

Thanks

129 posts

Master Geek
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  Reply # 771685 28-Feb-2013 13:15 Send private message

PhilANZ: That's very interesting. Have no idea whether it would work or not. We've had Freeview for some time now (I think 2010 but not sure - my stroke's left me with an even worse memory) and this problems only occurred in the last month or so. The signals were a bit weaker in the past (we're also in a curved hill road that makes cell phone reception marginal) - but haven't checked signal stregth recently. The re-did the frequencies in our area last year, and that coupled with the recent work by the aerial guys has left us with stronger more consistent signals.

So I still thik it's doubtful this would work - but it's the easiest thing to try. The only thing is how do we fit it - can we just plug it in - or does it need to be wired in? And given we've got a cable that splits with one to the TV and one to the recorder, and we only have problems on the two tuners in the recorder, presumably ot needs to go there? Or is it up on the aerial?

BTW these guys call themselves dishtv - but we're on the terrestrial Freeview - not the satellite one. Will it still work?

Thanks


When I got my first DishTV unit-a T1020- I had a new areial installed and had big problems with interference when recording and play back. Being in Hamilton I went straight to the Dishtv guys several times believing it was a box fault. They were very helpful and upgraded the firm ware several times but to no avail. They then suggested an attenuator. I got a 12db one from jaycar and the necessary adapter plugs and it cured my problems. They contacted me a little later and gave me one of their new UHF band pass filters to try and give feed back on. (lucky me as they ain't cheap). It also works fine. I now also have a T1050, I have the filter connected to it right at the box and the jaycar unit is connected to the T1020 at the box. My tv is a Panasonic 42" Plasma and it has never had reception issues.

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  Reply # 771694 28-Feb-2013 13:40 Send private message

PhilANZ:  how do we fit it - can we just plug it in - or does it need to be wired in? And given we've got a cable that splits with one to the TV and one to the recorder, and we only have problems on the two tuners in the recorder, presumably ot needs to go there? Or is it up on the aerial?

Just plug it in before the the recorder. If you don't watch analog TV on your TV tuner, then plug it in before it splits. I think the filter has F-Type connectors on it, so you will probably need to buy 2x F-type to Belling-Lee (aka PAL) adaptors ~$2 each.
PhilANZ:
BTW these guys call themselves dishtv - but we're on the terrestrial Freeview - not the satellite one. Will it still work?

Yes, the neighbour has one on her TV. Don't know why they are called DishTV.

An attentuator will only work if you have a strong digital signal (and too strong undesired signals eg analog TV)

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  Reply # 771709 28-Feb-2013 14:10 Send private message

You haven't said what type of antenna you are using. It should be a UHF only and good quality co-ax.
Was the old VHF removed?



117 posts

Master Geek


  Reply # 771713 28-Feb-2013 14:14 Send private message

Yes - we had the old aerial removed - and the cable has just been replaced with a better quality one - that's what the aerial guys did the second time they came.

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Ultimate Geek
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  Reply # 771731 28-Feb-2013 14:30 Send private message

Phil,

It may not neccessarily be interference , the fact you have issues when it rains suggests you are not that much above threshold , rain is not really a factor with DVB-T.
Panasonics report 10/10 S&Q even when the signal is quite weak , it is only really a guide.
You could always ring your aerial man & ask him what the dB & BER readings are , that would be a good start.




117 posts

Master Geek


  Reply # 771735 28-Feb-2013 14:39 Send private message

Thanks - I've learned so much through this - stuff that I'm not sure I want to learn - but it's quite interesting.

The rain of course hasn't been an issue for a while - and the signal's at least as strong - if not stronger (according to the Panasonics) than it was a couple of years ago - when we last had the aerial people in.

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  Reply # 771883 28-Feb-2013 19:13 Send private message

PhilANZ: Yes - we had the old aerial removed - and the cable has just been replaced with a better quality one - that's what the aerial guys did the second time they came.


So did the antenna people use a spectrum analyser to attempt to diagnose the problem??




Ross
ADSL2+ sync (Kbps): 11577/945, attenuation (dB): 33.0/16.9, Noise margin (dB): 11.5/11.5

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Ultimate Geek
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  Reply # 771894 28-Feb-2013 19:35 Send private message

Had a similar problem with our FV receivers a year or so back, every evening the picture would go all blocky, like a poor signal, as it was affecting all the FV receivers at the same time. So got on the roof the next weekend, checked out all the aerial connections and all the connections at the splitter under the house, found some moisture inside the di-plexer/booster on the roof and was sure that was the problem.

Anyway that evening the blocky picture was back.

Fast forward to the next evening staring out the window just on dusk with the TV going in the background....See the street lights come on and at exactly the same time the picture goes block!!! Just so happens that the TV aerial was pointing in the direction of a vandalized street light, and the light bulb in the fitting trying to strike, but not been able to because of the damage was causing the intereference.

A call to the council and a few days later it was fixed and the problem solved.


So, keep tabs on what time the intereference starts, observe your surroundings, maybe there is a street light nearby that is damaged or flickering on/off.



117 posts

Master Geek


  Reply # 771902 28-Feb-2013 19:49 Send private message

Had no idea there were so many things that could be involved. I've sent a message to the aerial guys - see what they think. But I'm suprised they didn't give us all this info from their sources. So we'll see what happens - and if we find an answer report back here.



117 posts

Master Geek


  Reply # 782633 16-Mar-2013 12:05 Send private message

Hi there

Well the bad news is our aerial folk appear to have given up the hunt - haven't heard back from them - despite reminding them.

The good news is we haven't had a problem for a week. Previously we'd have the odd day with no problems - but a week is unheard off.

Now at first we thought it might be the transformer down the road abd around the bend from our place. It was faulty, but following it's replacement we had problems that night. We noticed them working on it again next day and thought maybe that's it. But we had problems again that night.

Then we had no more problems (so far). But we also have identified simething else as a factor. A neighbour (who's certainly more line of sight) rang to let us she'd be overseas for six weeks. She also said she'd talked to a guy in TV and they concluded our unit needed cleaning. But since she went we've had no problems. We nervously await her return.

The factor we think (perhaps naively) might be relevant is that she's deaf. She can't even hear the telephone ring - she has to see a light flashing. So we also assume she has some sort of audio signal so she can hear on the phone.

So if the problems return when she does, we'll at least know where to start looking - hopefully we can do something about it.

Just thought I'd let people here know of this latest development and say thanks for all the ideas I got - just glad it's not my job to track down such problems - there are more possible answers than I'd ever dreamed.

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  Reply # 782649 16-Mar-2013 13:02 Send private message

Interestingly our problems have all but disappeared too. Only one program about a week ago had minor problems. It's going to be difficult to know if I've fixed anything if I shift or replace the antenna now.

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