Freeview signal on Sony Bravia TV too strong?

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• chrisjr Posts: 33,282

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  20/11/14 - 12:48 #2

  It is quite possible for a strong signal to cause problems. You can get so much signal that it overloads the front end of the tuner which can corrupt the data on the mux concerned and also generate spurious signals that interfere with the other muxes.
  
  Though if it was OK previously that does suggest something has changed recently. It would be unlikely (though not impossible) for the transmitter you are receiving to have had a boost in power. Aerial and cable faults tend to go in the other direction, ie reduce signal rather than boost it.
  
  So there could be some other cause. One possibility that does get reported a few times here is interference from HDMI cables onto the aerial cable going into the TV. If you have the usual tangle of wires behind the telly it is possible this could be the cause. Easily checked simply by untangling the mess and keeping the aerial lead as physically far away from the other cables as possible.
  
  It is also possible something has happened to the aerial cable to allow in more interference. So might be worth changing the lead if you have one. I assume the aerial goes into the Humax then a link from the Humax to the TV? If so then one test could be to plug the aerial direct to the TV. That would eliminate the link lead and Humax from the equation. If that works fine then either the Humax or the link lead are faulty. Which can be tested by changing the link lead.
  
  If it proves to be the Humax output causing the problem and plugging the aerial directly into the TV is OK then you could simply split the aerial feed and send it separately to Humax and TV, effectively bypassing the dodgy Humax output. Won't make a jot of difference to how anything operates doing that.

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• [Deleted User] Posts: 4

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  20/11/14 - 13:21 #3

  Hi Chris, thanks for your reply. I have tried a retune with the aerial going straight in to the tv (bypassing the humax) and the problem is still there. I do have some HDMI cables back there so will give that a try tonight. I guess one thing I don't really understand is the difference between signal strength v signal quality. I will post any progress I make.
  
  thanks

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• Colin_London Posts: 12,714

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  20/11/14 - 13:46 #4

  Bravias have an in built LNA controllable via settings - have you tried switching this off?

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• Dr.OliverTwich Posts: 1,580

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  20/11/14 - 15:18 #5

  Check cables and connections used. Re-make any hand-made plugs. What does the Humax report for each mux for signal level and quality?
  
  Double check you are tuned to the correct transmitter frequency... most likely Black Hill and some distance away - but Darvel can come in quite well in parts and may be found first in an auto tune? Manual tuning may be preferred in that case. http://www.digitaluk.co.uk/coveragechecker/main/trade/G1+1NQ/NA/0/19ca31sf6aeku071s81rque5n7 is a prediction for the City Halls & Old Fruitmarket... click on <change address> to get one for your home.

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• chrisjr Posts: 33,282

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  20/11/14 - 15:34 #6

  jack_garnethill wrote: »

  Hi Chris, thanks for your reply. I have tried a retune with the aerial going straight in to the tv (bypassing the humax) and the problem is still there. I do have some HDMI cables back there so will give that a try tonight. I guess one thing I don't really understand is the difference between signal strength v signal quality. I will post any progress I make.
  
  thanks

  
  You should not have retuned. That should be the last thing you do after every other possibility has been eliminated.
  
  Signal strength as the name suggests is how strong the raw UHF signal is. Unfortunately there are next to no standards for how this is measured. So there is no agreed value of signal level that corresponds to 100% on all TVs and PVRs. So 100% on one make of TV could correspond to 50% on another!
  
  Signal Quality is usually a measure of how error free the signal is. In this case 100% means no errors. So 27% means a lot of errors getting in.
  
  You can have low signal strength and high quality with digital. The signal tends to stay perfect over a wide range of signal levels then as it gets down to a certain point the signal quality starts to drop off and then quite rapidly quality falls to zero.
  
  If the TV does have a built in signal booster (what Colin_London means by LNA) then it might be worth seeing if that is turned on and see what effect turning it off has. Nice easy fix if it does work.

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• [Deleted User] Posts: 4

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  20/11/14 - 15:37 #7

  thanks so much for your replies, I will heed your collective advice this evening after work & post tomorrow, how I get on.
  
  cheers again

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• [Deleted User] Posts: 4

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  20/11/14 - 18:46 #8

  Thanks everyone, I believe it was a question of manual digital tuning. (Which I don't really understand). I found my transmitter - it was blackhill as DR.OliverTwitch suggested. I then tried all of the channels that came up and the last channel 51 L-GLW? came up 100% signal quality, and everything is back to normal. Although I just checked the signal quality and even though I have a perfect picture with no break ups, it still shows signal quality to be very low (around 20%)....?
  
  But all the channels are working so I'm gonna leave it...
  
  Thanks again,
  
  Jack

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• Zenith Posts: 3,873

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  21/11/14 - 11:40 #9

  I wouldn't be surprised if your picture starts to break up again though, with Q that low.
  
  You mention that you noticed that one of the channels showed 100% Q.
  
  Have you checked the Q of all the MUXes to see how much variation there is between them?

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