startling noises on occasions

Discussion in 'Satellite TV, Sky TV & FreeSat' started by davee, Sep 9, 2005.

  1. davee

    davee
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    When viewing digitally, courtesy of a Humax freeview box, I occasionally get a momentary loud noise from the speakers which sounds like someone has thrown a bunch of keys onto a hard surface. :eek: This is sometimes but not always accompanied by a brief freezing and pixellation on the tv. Anyone got any ideas why this should occur?
     
  2. Greg Hook

    Greg Hook
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    Just guessing, but could be some kind of electrical surge?

    Also does this happen during storms etc or all the time?
     
  3. Nick_UK

    Nick_UK
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    You're picking up interference from a household appliance like a fridge, freezer, or boiler. Either because your signal is weak, or because your aerial cable is not the type with a metal foil screen.
     
  4. wormvortex

    wormvortex
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    my tv with the in door arieal connected to it does that, if u flick a lightswitch u hear a bang and a white line appears across the screen
     
  5. davee

    davee
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    Nope nothing to do with atmospheric conditions, the aerial and cables are new properly installed, the coax is top grade screened and terminated with F connectors. The electrical supply to this room is independant of all others to avoid switching interference. This only occurs on the digital input. If I switch the signal direct to the tv without going through the freeview box it doesnt seem to occur :confused: :confused:
     
  6. Bert Coules

    Bert Coules
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    I think what you're describing is a momentary loss of signal lock and the subsequent reinstating of it. On my system, that produces exactly the effect you've seen and heard (and the sound glitch can be quite alarming if you happen to have the volume even moderately high).

    Have you checked the signal strength meters? If they're generally quite low (which could mean a problem with your LNB, your receiver or your dish alignment) it won't take all that much to lose the lock temporarily.

    Bert
    www.bertcoules.co.uk
     
  7. Nick_UK

    Nick_UK
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    He won't have a dish or an LNB, it's a Freeview box :)
     
  8. Bert Coules

    Bert Coules
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    Nick,

    Ah. Thanks for that.

    The silly thing is, I actually went back and added the bit about the LNB and dish alignment because I thought my original answer wasn't full enough. That'll teach me to leave things alone.

    The symptoms do sound exactly like a momentary loss of signal though, don't they?

    Bert
    www.bertcoules.co.uk
     
  9. Nick_UK

    Nick_UK
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    Sounds like a fridge or a boiler causing a temporary loss of signal lock to me too.
     
  10. davee

    davee
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    Thats what I would have thought, but any reason why it would be so pronounced on freeview channels? I'm going to have to experiment with forcing the interference in order to try and identify it. As Bert says even if the sound is moderately loud the sound glitch is quite alarming. Possibly a mains conditioner would help. But again if the spike is so pronounced I'm surprised it doesnt interfere with the computers when theyre on.
     
  11. Nick_UK

    Nick_UK
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    The sound on Freeview is a bitstream (i.e. a fast succession of 1's and 0's) which digitally represent the audio output. If an interference pulse is received, it causes corruption in this bitstream, which can cause a variety of noises like clanking keys, squawks, chirps, bangs, etc. On an analogue channel, you'd just hear a click or a pop. Freeview signals are weaker than analogue TV signals, so interference can have a more profound effect.
     
  12. davee

    davee
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    Now that makes sense. Thanks all. :smashin:
     
  13. Boy Lex

    Boy Lex
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    My freeview does this in the kitchen when I use my electric pepper grinder!
     

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