Weak signal on BBC channels

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  • chrisjrchrisjr Posts: 33,282
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    figrin_dan wrote: »
    I'm in St Albans today. . .

    It might be a red herring but I notice a huge 4G signal on channel 61 which wasn't there until recently. If the AGC on your tv is seeing it, it could be reducing the signal strength across the whole spectrum (Yes, including the lower frequencies of Crystal Palace).

    It's also very windy.
    If the OP has a wideband aerial and is pointing roughly in the direction of this 4G source that could be a possibility. A Group A aerial would help reduce the amount of signal, unless very close, as would being well off beam.
  • anthony davidanthony david Posts: 14,461
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    chrisjr wrote: »
    If the OP has a wideband aerial and is pointing roughly in the direction of this 4G source that could be a possibility. A Group A aerial would help reduce the amount of signal, unless very close, as would being well off beam.

    He could get a free 4G filter but reading this thread I think the aerial has either blown around in the wind or there is water ingress, either way it's probably new aerial time.
  • grimtales1grimtales1 Posts: 46,685
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    What does ACG mean?
    It is indeed very windy today, and most likely will be tomorrow as well.
    Maybe I could call that at800 helpline (or whatever it is) if it could be being caused by a 4G signal
  • anthony davidanthony david Posts: 14,461
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    Lets go back a bit. You were asked to go outside and look to see if your aerial looked OK and was pointing the right way. All you said was it was high on a chimney pot, they usually are, but you still can easily compare it with a neighbours one to see if it is pointing the right way.

    Secondly, talk to your neighbours, if they aren't having any problems it is down to your system, aerials don't last for ever especially if they are put up by a cowboy. Go to a reputable aerial firm and get a new one fitted if required. There is no quick fix in these situations.
  • grimtales1grimtales1 Posts: 46,685
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    Thanks :) Sorry, I went outside, and found my aerial does indeed seem to be pointing the same way as my neighbours one, it looks all right to me :)
  • anthony davidanthony david Posts: 14,461
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    grimtales1 wrote: »
    Thanks :) Sorry, I went outside, and found my aerial does indeed seem to be pointing the same way as my neighbours one, it looks all right to me :)

    Not been blown around in the wind then. No trees with new leaves in the way by any chance? Have you spoken to your neighbours?

    If the neighbours are having no problems, what chrisjr says in post 35 about water ingress seems the most likely solution to me. If you are in a strong signal area the connection at the aerial may have rotted through and you may be using the cable as an aerial which will give lots of odd results.
  • grimtales1grimtales1 Posts: 46,685
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    I'll speak with the neighbours/support where I live and see what the results are :)
  • grimtales1grimtales1 Posts: 46,685
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    Hey,
    Would anyone recommend trying one of those booster/amplifier kind of things? Something like this:
    http://www.amazon.co.uk/1byone%C2%AE-Digital-Amplifier-Booster-Outdoor-x/dp/B00KV9CBAM
    Its very small so I thought I could just put it on a window (or behind the TV so it looks like part of the TV) and maybe it would make the signal more stable?
  • chrisjrchrisjr Posts: 33,282
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    grimtales1 wrote: »
    Hey,
    Would anyone recommend trying one of those booster/amplifier kind of things? Something like this:
    http://www.amazon.co.uk/1byone%C2%AE-Digital-Amplifier-Booster-Outdoor-x/dp/B00KV9CBAM
    Its very small so I thought I could just put it on a window (or behind the TV so it looks like part of the TV) and maybe it would make the signal more stable?

    A booster behind the telly is in the wrong place. Ideally it should be as close as possible to the aerial so it has the cleanest possible input signal. It then stands a chance of poking a good clean signal down the cable overcoming any losses and interference induced into the cable.

    If the problem is that the signal off the aerial is weak and there is noise and interference getting into the cable then sticking a booster on the TV end of the cable will only boost all the noise and interference along with the wanted signal. It can't magically boost just the wanted TV signal and ignore all the other crap that is causing the reception issue.

    So there is a very real chance it won't make things any better.

    There really is no substitute for getting the cleanest strongest signal possible at the aerial terminals to start with.

    Not to mention that my bull manure filter kicks in when I see an item described as a "digital" amplifier when it isn't and mentions a HDTV aerial which of course is a mythical beast whose existence lives only in the minds of unscrupulous aerial fitters to relieve the gullible of an extra 20 quid to fit exactly the same aerial as their "standard" one.
  • daisydeedaisydee Posts: 39,393
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    I wish I could find out just where the problem lies with the poor reception on my TV. It's so bad, I have to watch online. Could it in fact be the TV set or Freeview top set box wearing out? I can get completely interference free channels on about 3 channels, if it was the aerial, surely it would affect all channels? A new problem is sudden loss of sound, I have to switch channels to get the sound back. scanning through the channels, I've noted that pixiliation/hiccupping sound occurs when the reception is 80% , it is reasonably good when reception is 82%. None of the channels are higher than 82%.
  • chrisjrchrisjr Posts: 33,282
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    daisydee wrote: »
    I wish I could find out just where the problem lies with the poor reception on my TV. It's so bad, I have to watch online. Could it in fact be the TV set or Freeview top set box wearing out? I can get completely interference free channels on about 3 channels, if it was the aerial, surely it would affect all channels? A new problem is sudden loss of sound, I have to switch channels to get the sound back. scanning through the channels, I've noted that pixiliation/hiccupping sound occurs when the reception is 80% , it is reasonably good when reception is 82%. None of the channels are higher than 82%.

    You should not be getting any problems at 80% signal strength, assuming you are reading strength and not quality? If it was 30% strength then that would be more understandable. Anything above 50% or even 40% should be pretty rock solid. Though you can get problems with too much signal which can cause overload in the first stages of the tuner leading to all sorts of undesirable effects.

    So either your kit is failing or is suffering from interference.

    What TV and set-top box are you using? Does this mean you are using an old analogue TV set with a Freeview box or do you mean you have a Freeview TV and a Freeview PVR (recorder). If the latter if both TV and PVR are showing similar problems then that does indicate an interference issue. If the former then it could be simply a failure of the set top box.

    If you could beg steal or borrow another Freeview box that you know works perfectly and try it on your aerial, or alternatively take your box to somewhere you know works perfectly, that would give you an idea whether it is the box or something else causing the problem.

    How is the aerial connected to the box/TV? Do you have a wall plate with a short lead from that to the box/TV? If so try another lead. Some of the really cheap leads you can buy in the likes of Tesco are really badly screened and let in all sorts of garbage so swapping for a better made properly screened cable may help. As can keeping the aerial lead as physically separate from all other leads as possible. There have been several threads here on DS about HDMI leads causing interference with aerial leads for example.
  • anthony davidanthony david Posts: 14,461
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    There are always questions like this at this time of year, as others have pointed out it is usually due to leaves appearing on trees which have a bad habit of growing taller every year. If the problem is worse when it is rainy or windy, trees are the most likely cause and a better aerial, fitted by someone reputable, is the only solution.

    Everyones first move should be to ask their neighbours if they are having problems. If not then ask here but follow the advice and report back your findings. If possible try your TV or STB on a friends known good aerial to eliminate it as a source of your problem.
  • [Deleted User][Deleted User] Posts: 435
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    figrin_dan wrote: »
    I'm in St Albans today. . .

    It might be a red herring but I notice a huge 4G signal on channel 61 which wasn't there until recently. If the AGC on your tv is seeing it, it could be reducing the signal strength across the whole spectrum (Yes, including the lower frequencies of Crystal Palace).

    It's also very windy.
    It won't be the AGC.
    THE AGC reference signal is detected after the signal has been demodulated after it has passed the SAW filter at the IF frequency and if even if the channel you are tuned into is 60 the SAW filter will remove it.
    Incidently the demodulated reference voltage via a comparator connects to a pin diode (electronic variable attenuator ,for the benefit of call me Dave) at the tuner input .

    What a high signal level could do ,if strong enough is to overload the first amplifier and or mixer in the TV tuner .
    If the highest channel used is 59 a simple notch filter will reduce the interfering signal by > 30dB ( 1000 times for the benefit of call me Dave) fitted on the aerial input to the telly.
    If the highest channel used is 60 ,then this is a problem as no ordinary filter can remove a interfering signal at channel 61.
    Of course our wonderful planners employed by Ofcom don't know this little technical gem
  • figrin_danfigrin_dan Posts: 1,437
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    chrisjr wrote: »
    You should not be getting any problems at 80% signal strength.
    This is not good advice!
    Firstly 80% of what? The "measurement" is meaningless without knowing scale. Some receivers use 45dBµV as 100% some use 100dBµV.
    Secondly, ignoring the signal quality that could be 80% of noise and interference.
    It's only worth looking at signal strength if quality is at 100% and you still have problems.
  • MartinPickeringMartinPickering Posts: 3,711
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    Here's a page which discusses ALL the possible causes of Freeview reception problems:
    http://www.satcure.co.uk/tech/freeview_problems.htm

    There's no point in guessing or wasting money on a "booster". Eliminate the possibilities, one by one. Make a list and cross off each one as you eliminate it.

    Whether or not a "booster" will help is discussed on this page:
    http://www.satcure.co.uk/tech/amps.htm
  • grimtales1grimtales1 Posts: 46,685
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    Theres an interesting bit here:

    'If your reception is worse at night then your signal may be too strong or you may be suffering from local electrical interference.'

    This seems to be the case with me at the moment, but only on a select number of channels/Muxes. BBC1/2 arent quite at full strength but OK during the day (80% quality) but drop again about this time to 50% and seem variable - same with Dave, Pick etc. Ch33 (BBC4) is not there at all now (bad picture break up) :(

    Could be either one.
  • daisydeedaisydee Posts: 39,393
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    daisydee wrote: »
    I wish I could find out just where the problem lies with the poor reception on my TV. It's so bad, I have to watch online. Could it in fact be the TV set or Freeview top set box wearing out? I can get completely interference free channels on about 3 channels, if it was the aerial, surely it would affect all channels? A new problem is sudden loss of sound, I have to switch channels to get the sound back. scanning through the channels, I've noted that pixiliation/hiccupping sound occurs when the reception is 80% , it is reasonably good when reception is 82%. None of the channels are higher than 82%.

    Sorry, this is actually on my spare TV upstairs which is hardly used nowadays. I bought my Technika TV about 5 years ago and it included Freeview - there's a small box which connects to the TV. The 80% is signal strength, I have been through all the channels and they flicker between 80% & 82%, but there does not seem to be one factor that explains the poor reception as it varies daily and from hour to hour even. One morning I was getting no interference on any channel, but by early evening most channels were unviewable. The next morning, most channels were suffering from pixilation and hiccupping sound. If there is something I really want to watch, I bring it up on the computer as a standby in case interference occurs during the TV program - as often happens. I'd rather watch the TV, and even the computer suffers from buffering!
  • grimtales1grimtales1 Posts: 46,685
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    For me today - Quality on BBC1/2 has gone down to about 40% :confused: Same with Dave, Pick etc :confused:
    Most other channels show a full bar (green), HD channels only show half strength/quality :mad:
  • grimtales1grimtales1 Posts: 46,685
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    I've noticed the signal on my TV finally seems more stable now, and quality has improved on the previously "weak" channels but there will be engineering on the CP transmitter this week... it says "Possible weak signal".
  • daisydeedaisydee Posts: 39,393
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    I finally got around to checking my spare TV which has a Freeview Topbox and I can't get any TV channels on it. DVD & Video tapes play fine and the operating light comes up on the Freeview box, but no sign of any Tv channels. I have checked all connections to no avail. I was wondering about getting in the people who installed the ariel in my loft some years ago, or could it be a local transmitter problem as others on this thread seem to be having similar problems. My main Tv which has 'built in Freeview' ie a small connecting box, still suffers from pixillation, but it is all so random. I just can't work out where the fault lies.:confused:
  • [Deleted User][Deleted User] Posts: 435
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    daisydee wrote: »
    I finally got around to checking my spare TV which has a Freeview Topbox and I can't get any TV channels on it. DVD & Video tapes play fine and the operating light comes up on the Freeview box, but no sign of any Tv channels. I have checked all connections to no avail. I was wondering about getting in the people who installed the ariel in my loft some years ago, or could it be a local transmitter problem as others on this thread seem to be having similar problems. My main Tv which has 'built in Freeview' ie a small connecting box, still suffers from pixillation, but it is all so random. I just can't work out where the fault lies.:confused:

    The cause of the problem is having the antenna as in the loft.
    It's that simple.
    Fitting it outside will lift the single ,typically ten times .
  • grimtales1grimtales1 Posts: 46,685
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    Still having similar problems myself, though not on the same channels as before.
    BBC1/2 etc (CH23) - fine
    ITV/C4/Pick/Dave - fine
    London Live - shite (yellow/red banner) :confused:
    BBC1 HD/ITV HD - average (should have a full green banner, its only half full)
    BBC4 HD - not there :confused:
  • daisydeedaisydee Posts: 39,393
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    The cause of the problem is having the antenna as in the loft.
    It's that simple.
    Fitting it outside will lift the single ,typically ten times .

    But why should it suddenly start giving me problems? It has been fine up until a few weeks ago.
  • chrisjrchrisjr Posts: 33,282
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    daisydee wrote: »
    But why should it suddenly start giving me problems? It has been fine up until a few weeks ago.

    All it takes is something to have been moved or added to the loft or the aerial to have had a slight nudge if you were up there looking for something.

    Because the signal in the loft is reduced to start with and there can be loads of reflections bouncing about causing all sorts of problems you don't have to do very much to alter this situation, often to the detriment of reception of one or more UHF frequencies.

    Being outside has a different set of problems but in most cases it is a better place for your aerial.
  • grimtales1grimtales1 Posts: 46,685
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    Perhaps I'll check my 'loft' and see if the aerial is up there soon (I didnt even know we had a loft in the flat lol) :blush:
    Sorry if I hijacked the post, I could try that (get it moved outside?) but also noticed there seem to be big 4G signals in the 800Hz band as well (I looked at all the channels on the manual tuning DVB menu), so that could be something too.
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