Freeview interference

Discussion in 'Freeview & YouView' started by Square eyes, May 27, 2004.

  1. Square eyes

    Square eyes
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    I wonder if any one can help with an annoying problem

    I sometimes get a banging type sound\judder\pixialition through my freeview box

    This happend on my old tv\freeview box

    Ive just changed tv and freeview box(diffrent model) and the problem persists
    although i have a the same fereeview box but diffrent tv in the bedroom and its unafected by the issue


    Both boxes are running through seperate signal boosters and the pictire and sound are very good normally they are also on surge proof extension leads

    I thought it may be a mux problem as itv channels tend to get it more than others but it does happen on other mux's

    I thought it may have been when the hot water\heating\thermosta was on but it happens when its off
    This problem does not happen when i watch dvd's or analougue TV

    Tonight im going remove the booster and see what happens

    any other ideas ?

    thanx
     
  2. LV426

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    If you get occasional glitches like this on an otherwise nrmally good and clean signal, it is indicative of some occasional electrical interference. You are on the right lines considering thermostats etc. It could be a refrigerator or something else; it could be a neighbour's car or passing traffic with badly suppressed ignition.

    Improved screening may help - replacing the aerial downlead with satellite-type aerial cable (has an extra layer of foil screening) and new connectors.

    Signal boosters (if they are in-room types, as opposed to masthead types) will also boost any interference which arises in the cabling so won't solve the problem.
     
  3. Square eyes

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    Thanks i think the boosters are making it worse but without it on the old freeview box the itv MUX was very low signal so i may be worse off without it the connectors are good and as i say the picture upstairs is spot on

    Its also connected with 30 quid monster cables and the surge protectors are brand new

    Will the surge protectors stop interference from Fridges\tumble dryers ?
     
  4. LV426

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    Surge protectors are there to protect the electronics from suden increases in voltage (as might occur, say, if a power cable was struck by lightning).

    RF interference CAN be mains-borne, and I suspect that a simple surge protector won't clean it. But it can also be airborne, which is where ensuring your cables (right from the aerial into your room and equipment) are as screened as they can be.

    It may be (this is all guesswork - can only be resolved by trial and error) that the bedroom setup is further away from whatever the source of the interference is....
     
  5. idhutt

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    Alot of people say that there is no alternative other than to replace all cabling with fully screened versions. But for £9.99, I tried the TVI RF Filter available from Maplin(QT25C). It works very well for me, totally cured a problem that I was having with some low voltage lighting, and all but cured other interference from mopeds, boiler etc. The instructions mention that it must not be used low signal area (it attenuates the signal) or on an amplified signal ~ it doesn't seem to be an issue to me even though I have a mast head booster.

    -Ian
     
  6. Square eyes

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    Excelant i didnt think of the lights and i think the penny has now dropped it does add up as the interference does not seem to occur in the day!!!!!

    I have 3 wallmounted uplighters on a dimmer and one is above the mains switch ....

    i will try 2night with no lights and let you helpfull lot know the results :)

    thanx
     
  7. geeWcee

    geeWcee
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    How did you get on square eyes?
     
  8. chrisgeary

    chrisgeary
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    i bought one of those RFI filters from maplin yesterday. i tried it directly into my freeview box (which has an amplifier ahead of it, mainly for the itv/ch4 mux) and also prior to the amp. i have problems with the thermostat and light switches in my house. this filter changed nothing for me. admittedly, i am in a weak signal area and the freeview post code checkers says i shouldnt be able to receive it. perhaps if the signal was stronger, it might be more effective.
     
  9. Square eyes

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    better but got the odd "judder" without the lights on still.it does not seem to happen on bbc1\bbc2 and alot of the freeview extra channels

    Itv and c4 are the culprits which are i believe on the same mux??

    I think the ariel points at Bedmond so would be intrested to see if anyone else has the problem although the channel strength for all channels is 9 and i say the picture is very good normally
     
  10. Crocodile JD

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    Hi All

    I am also experiencing signal interferance, but strangely it's only started happening recently and only on certain channels. I installed a Pioneer DBR-TF100 about 8 months ago and was so impressed. I got a near perfect reception on all the freeview channels. The only glitch being for a couple of seconds when my boiler kicked. Now suddenly I can't keep a signal at all on some channels. The biggest problem is with Sky Sports News and Sky News, but I also get problems with UKTV History and a couple of others. BBC 1 to 4 and News 24 seem OK as do ITV 1 and 2.

    If it was a cable problem why suddenly start now? I have had a new washing machine recently but the problem persists even if this is off. I can't think that anything else has changed.

    Any help or advise much apprieciated as I'm well frustrated with it. :mad:

    Cheers

    Croc
     
  11. LV426

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    It was certainly always the case that, from time to time, (and often without any overt announcement) a given analog channel on a given transmitter would operate on reduced power for a few days, while some engineering maintenance was carried out. And this manifested itself as an increase in grain or noise.

    It seems entirely likely, then, that the same thing will happen with the freeview muxes.

    So - if you are in a less-than-ideal reception area, with, perhaps, a less-than-ideal aerial and/or cabling, (but enough to work reasonably well with a strong signal) and it so happens that a given mux is running on temporarily reduced power - you may get more errors and hence glitches.

    If it is transmitter-related - it will cure itself in due time.
     
  12. Crocodile JD

    Crocodile JD
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    When I first set the box up, I set it to down load new firmware during the night. I haven't left it on over night recently, certainly not since the problems started. So the first thing I tried has to leave in on over night to do a hardware update and hey presto it worked :D All channels spot on again.

    Therefore, to anyone experiencing problems, make sure you've got the latest firmware before anything else :smashin:

    Croc
     
  13. Crocodile JD

    Crocodile JD
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    Aggggggh :mad: spoke too soon. It was great for 2-3 days then suddenly back to square one! why the hell is this happening?

    BTW I live in Tamworth from where I can virtually see 2 transmitters, Sutton Coldfield and Hints. Are they analogue only or does the digital stuff get transmitted from the same place??

    Interestingly though, dispite being reasonably close to the transmitter, I was never able to get a decent picture on channel 5 until I installed freeview, but it is perfect now on digital, even when the other channels are playing up.

    Any help greatfully received :lease:

    Croc
     
  14. LV426

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    New aerial? According to the DTG website, the Sutton Coldfield transmitter requires a Group B aerial for both (pre-digital) analog AND for the Freeview digital muxes. Oriented horizontally.

    So - is yours pointing to Sutton Coldfield, and are the elements horizontal? And (less easy to confirm) is it Group B?

    If you are in line-of-sight to the transmitter, you shouldnt be experiencing problems. Unless the aerial is pointing the wrong way, wrong orientation, wrong type (group) and/or there is a fault in the cabling.

    Oh......and the first thing the aerial cable should go into, afterr it enters your house, is the set top box - not a splitter, your TV, VCR or similar.
     
  15. Crocodile JD

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    Thanks for the suggestions Nigel

    ... Ah well it does go into a spliter which I think is a booster as well? At least the spliter box (which is in the loft) is plugged into the mains. Assuning that it is a booster, is that a good or bad situation. I guess if I can get a coupler, I could try by-passing the box.

    TBH the arial was in when I moved into the house. I haven't a clue what type it is. It is not so cleverly suspended in the roof braces in the loft at about 10 degrees off horizontal. I'm willing to accept that it could be wrong and I've put no effort in in trying to do any better. But the reason is that I never had to before. As I said since installation of freeview (which consisted of plug it in and off you go) and for about 8 months since it's been perfect. Why would it suddenly go now if the arial was wrong all the time?? Haven't moved the arial in that time either AFAIR

    I'll definately have a mess about and see if it does the trick though.

    Cheers

    Croc
     
  16. LV426

    LV426
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    From your description, there are a number of factors that might make the aerial less than optimal; and, if it so happens that the relevant mux(es) are temporarily on reduced power, the two things together may give rise to your issue.

    Boosters are of limited value. They will increase the strength of the signal, so whatever follows the booster in the chain will be less liable to be disrupted by any interference. However, any disruption arising before the booster in the chain will be boosted along with the wanted signal. Strength isn't everything; cleanliness is more relevant.
     
  17. Crocodile JD

    Crocodile JD
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    Thanks Nigel. I've identified that it is MuxC that is the culprit. All the channels that I have problems with are on it I think. I'll start working through my system and try to eek out more/better signal.

    Croc
     
  18. LV426

    LV426
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    Mux C from Sutton Coldfield is on Ch 52, which is in between other digital muxes, so, if the rest is OK (esp. Mux B & D, either side of it at 51 & 55 respectively), it's unlikely to be a problem with aerial group/type.

    One other thing occurred to me: I have heard reports of this type of problem arising when some other device (either a VCR or similar), or the Set Top Box itself, is set to output an RF signal on the same channel number as one of the muxes. So - check anything else you have, with an RF output, and set it well away from the range covered by your transmitter.
     
  19. Crocodile JD

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    ..well the other Muxes are fine.

    Our house is detached, but could equipment from a neighbours house interfear, because again AFAIR nothing has changed equipment wise since well before the problem started.

    There is a guy across the road from us has always had large antennas on the side of his house, could be radio ham type stuff. Maybe if he's added some kit recently, could that do it or is that a totally different frequency?

    Croc
     
  20. Crocodile JD

    Crocodile JD
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    Nigel

    Your absolutely correct. The arial is fine but as you pointed out earlier, it needs to be horizontal and pointing in the right direction. I went up the loft last night and repositioned it, fixing it more permanently this time having optimised the position. I got the signal strength from below 20% to around 70% on Mux C and the BBC channels went from 70% to 90%. Brilliant picture now. Thanks for the advice :smashin:

    Croc
     
  21. idhutt

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    Nigel

    Where can I find information as to what aerial I need? My transmitter is Crystal Palace, quite a distance and certainly not line of sight. The original aerial was replaced to reduce ghosting on my analogue picture and was dramatically better, but it was still installed before DTV became available. The one that I have works fine 99.9% of the time, but I want to check that it is optimal for my use.

    I may also bite the bullit and upgrade my downlead as it must be years old and subject to the elements. Does anyone have definitive information on what downlead I need and where I can purchase it - preferably a retail outlet.

    -Ian
     
  22. LV426

    LV426
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    http://www.dtg.org.uk/

    On the menu, click on retailer/installer, then transmitter channel information. The details in there tell you which UHF channels are used for which analog programmes and digital muxes, and tell you also which aerial type and orientation.

    For a new downlead, just use satellite TV cable - similar to regular UHF cable, but has an extra layer of foil screening inside. Get it from Maplins (for example).
     
  23. Stevejones

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    The problem that I am having is all to do with the spark igniter in the boiler. When viewing terrestial tv, lines come across the screen for a couple of seconds when the boiler fires up. On freeeview (digital) the picture and sound go altogether for a couple of seconds. What could I do to stop this interference (without changing my heating system!)?

    Steve
     
  24. SamRadford

    SamRadford
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    If the interference is mains-borne, you need to add a mains filter as close to the spark igniter as possible. If it's airborne, you need to improve the metal shielding around the spark igniter. If the interference is actually coming from an old thermostat, you need a suitable capacitor connected across the thermostat contacts.
    See http://www.satcure.co.uk/accs/page5.htm#suppressor


    and http://www.ce-mag.com/archive/2000/janfeb/armstrong.html
    .
    .
    and http://www.tnt-audio.com/clinica/filter.html
    .
    .
     

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