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Radio interference from plasma screen

Discussion in 'Plasma TVs' started by Mikethecautious, Oct 5, 2005.

  1. Mikethecautious

    Mikethecautious
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    I am concerned about radio interference caused by plasma screens and want to know:

    1) whether there is any health risk e.g. for young children from watching plasma screen for a long period of time?

    2) whether there is any easy way to reduce or prevent interference from affecting my next door neighbour?

    Just being 'cautious' as usual, but would be really grateful for any information/reassurance.

    Many thanks
     
  2. MAW

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    ???? There is no RF interference allowed from domestic appliances. They do not emit radiation of any sort apart from light and heat (plenty of that). It sounds like you've heard the myth about sitting in front of the TV with your legs apart LOL!
     
  3. Mikethecautious

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    That's good of you, MAW - thank you. But I have read a lot about plasma creating radio interference on another website, so I am now wondering what to believe! :confused:
     
  4. Drd

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    My dog's turned green!
     
  5. GaryB

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    Not true I'm afraid. All TVs emit RF interference at many frequencies. It would be impossible to make one that didn't - TV Detector Vans work by picking them up. The permitted levels are set by EMC (Electromagnetic Compatibility) regulations and are low enough that they pose no threat to health, even for small childen but they can cause interference to other electrical items. Put a small portable with an indoor aerial near a plasma and see what happens when you switch it on. The JVC LT-37DM6 I'm currently testing causes slight patterning on the portable with indoor aerial in my kitchen about 10 feet away. You can even get stuff like this where emissions have to tightly be controlled.

    Google EMC and interference for more.
     
  6. MAW

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    30 mins of reading shows no references to emissions from plasma displays. Whilst I'll admit all electronic devices have some emissions, plasma is 'low risk' so to speak, EMI is bad in the IR spectrum of course, and often interferes with your remote control, but not much in the radio frequencies, and certainly no high energy stuff. My plasma has no visible or audible effects on any local electronics, I have a lot here. Unlike my mobile, which causes all sorts of problems, even when not in use, just switched on.
     
  7. Badger0-0

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    I concur.
    All tellys emit RF :smashin:
    Because they have transformers and resonant circuits etc.
    But they don't cause interference.
    EU rules say they don't, simple.
    And if they do, they're faulty.
    If it hasn't passed the tests, you can't import or sell it.
    Either that, or the appliance suffering interference is faulty or tripe, which is much more likely.
    I know this because, as a radio ham, I can whack out massive amounts of RF and not get faulted, if your telly changes channel etc.
    The fault is with the appliance suffering the problem, because it's picking up something it's not supposed too.
    It's been that way for 20 years.
     
  8. TeresaTT

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    My PWD6 causes havoc with my digisender. If I don't carefully position my Digisender box, it's IR emitter sends an almost constant IR signal to my TiVo making it very unresponsive to it's own remote control. As soon as I turn my plasma screen off, the TiVo responds immediately to it's remote. I have had to experiment to find a position for the Digisender where it is unaffected. There is defintely interference between the PWD6 and Digisender.
     
  9. MAW

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    Teresa, i refer you to my post above, this is most certainly not 'dangerous', but broad spectrum IR interference, I earn a living put of overcoming this! You need to get the IR recieving window out of line of sight, by reflection offf any flat pale surface, mirror, anyhting that could give the tivo IR except the remote. I have my gear in a closed cupboard with a QED roomlink IR sending kit. The QEED reciever is beyond the 170 degree viewing angle of the plasma, in the side of a bookcase. Works for me, no IR problems.
     
  10. TeresaTT

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    Maw, it's the Digisender box itself that I have the problem with. If I position it so that it is behind my sub woofer which is next to my plasma, I don't have any problems. However, if it is moved slightly out of place, I get the problem again. The other solution is to move the Digisender IR emitter away from the TiVo until I need to use it. But you can guarantee that I forget to move it back before we've gone to bed and want to watch some TiVo programmes in our bedroom.
     
  11. Nick_UK

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    If you're worried about devices emitting RF radiation, look at your PC, not your plasma. The trend amongst kids is to remove the side panels from PC's to make them run cooler. The side panels are there to reduce the RF radiation from the case. This is far more likely to have a detrimental effect on your neighbour's FM reception than it is on your kids, but it's anti-social, just the same.
     
  12. Mikethecautious

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    Just to say thanks for the replies on this - very helpful (or amusing if not helpful - thanks Drd)!
     
  13. Keyman

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    I believe the CE is a self certify process, reponsibility lies with the EU manufacturer or the importer. Part of the CE is the EMC, which is to do with the electromagnetic interference.

    If the appliances are CE, they should not have a significant effect of EM interference.

    However with mass tv manufacturing, individual tests are not possible and therefore the approach to solve the problem is by good design and statistical check.

    If your set is showing significant effect on other appliances, you may want to contact the manufacturer to see if there is possibly any chance that your set is faulty.

    This is also a reason why PC bulit with a large see through window will not usually be legal (a solid case is usually earthed and therefore shielded). Whoever build one for sale can be breaking the law and be fined and as far as I am aware, there can possibily be jail sentence (although no one I know of yet).

    I think enough info for you for the day. LOL
     
  14. degrangier

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    Plasma screen are well known by radioamateurs. When a neighbour buy one of them, then the HAM receiver noise is increased to such a level that any reception is possible.

    Plasma screen use quite a lot of energy, and emit a good proportion of these energy in large spectrum electromagnetic noise. In addition, quite large surface of these devices tend to make an efficient antenna, due to a large number of electricial connections. The level of electromagnetic waves is increaded with the inverse square of the distance to the screen, tending to be infinite close to the screen. (electromagnetic Maxwell laws)

    I will NEVER buy a PLASMA screen. No thanks.

    Stay on the safe side and buy a TFT or LCD screen instead.
    In addition these plasma screens could be forbiden to use in the future, electromagnetic noise is standing out the EMC regulations.
     
  15. ian_m42

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    Which is just the opposite of an article in a EMC magazine I have read recently the EM interference from plasma's is significantly less due to the presence of a conductive layer on the front of the glass (to remove excess charge from the plasma) compared to LCD's which don't have this conductive layer and emit much more EM interference due to the presence of high frequency powered fluorescent tube back lights.

    I know when we had some equipment EMC tested I had to turn my portable off (and stop playing games !!!) as the LCD screen interfered with the test equipment.
     
  16. degrangier

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  17. ian_m42

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    Nope, just one who has had plenty of experience EMI sheilding LCD screens for using in kiosks, studios etc. Backlights often main cause. No experience on plasma, probably too big for the market we are in.

    The article was about new plasma screens being sold today, in that they don't generate so much EMI, possibly implying old screens did.
     
  18. curlydog

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    I have a Panasonic TH-42PW6 plasma which I've had since about 2003. I've noticed recently that there is no way you can listen to Long Wave radio in the house when the screen is on - the interference prohibits it.
    Also at the weekend I hooked up my mac laptop to the screen for the first time and plugged the sound into my surround system from the mini jack output to the amp. The buzz was horrendous and made watching impossible.

    I would like to know how this RF can affect ones health. It is only in the past year or so that I have started to watch every evening for a few hours at a time and I'm finding that I get really bad head aches and my husband has been complaining that it makes his eyes water and sting for years now. Does anyone know of any tests regarding these emissions?

    Thanks

    curlydog

    :eek:
     
  19. GaryB

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    If you look at my post No.5 above you'll see that although electrical items emit interference, the levels are strictly controlled by EMC regulations and are in no way dangerous. Unless your set has a fault causing it to emit very high levels of RF, your symptoms will have another cause.
     
  20. curlydog

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    Thanks GaryB, I suppose I'm more concerned since I've become aware of it having upped my watching hours tenfold recently.
    It probably doesn't help that I live next door to the telephone exchange, in the shadow of a huge mobile mast. So I'm becoming more aware of new technologies that we really haven't tested in the long term. A bit like the early days of x-rays, asbestos or smoking etc.
    We could be those poor guinea pigs that the next generation will look back at in amazement thinking how badly informed we were.
    squeak squeak.

    In the meantime I don't suppose I have a hope in hell of getting quiet hum free audio playing back from my laptop into my surround system, with the pic going to the plasma.
    :rolleyes:
     
  21. Bumtious

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    Err I'd be more concerned about the mast you live by rather than your plasma screen.

    Your hum problems are more likely to be caused by poor quality cables that are picking up RFI (radio frequency interference) from that mast.
     
  22. Scooby2000

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    I'm not an expert like many of you but I recently tested my V20 as it makes the most annoying high frequency electrical buzz. There seems to be a lot of interference at the back of the set, especially in the three areas where the buzz is emanating from, a tech friend of mine says its a large electro magnetic field?
    Preper to laugh, we used his hearing aid to pick it up :laugh:
     
  23. Inferno

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    I was preparing to laugh but it didnt cut it :laugh:

    But the only electromagnetic field would come from the power supply and surley it wont have that much footprint unless its badly screened that or your friends hearing aid is.
     
  24. curlydog

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    I've been generally concerned about the mast for years now.More for general health reasons. But it doesn't seem to cause much interference with sound/radio - I guess its in a different frequency range - LW radio is 30-300kHz whereas mobile phone frequencies are either 900MHz or 1800MHz. Also one has to bear in mind the inverse square law - I only sit 10 feet away from the plasma screen where as at a guess I might be 95ft away from the mast and possibly in it's shadow.

    But it was definitely the plasma causing the hum on the audio from the computer - as it stopped when I turned the screen off. In normal use, my sound system doesn't suffer from hum. But on this occasion one is forced to use the mini stereo jack out from the mac going to 2 RCA phono's into the video Aux input on the front of the amp. This would be unbalanced and prone to picking up any interference. Mind you, saying that, I'm thinking that all the inputs to the surround amp are on RCA phono too.
    Mmmm....
     
  25. Marcuss

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    This article is worth a read. It clearly demonstrates the RF that emitted from a Plasma TV.

    Plasma TV -- Mother of All RFI Producers

    We installed my sons Soniq here last week. A crazy thing. I am hearing an increase hissing in my ears and my HP laptop receives interference via the mouse pad. Sitting in front of the TV about 2meters roughly the mouse pad barely responds. Moving off to the side or further back, it works again.

    There is something definitely going on here, and the TV is virtually brand new.
     
  26. Chelsea_Fan

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    Funnily enough I've got a spectrum analyser sat a few feet from my Pioneer 5090 and I suppose I could plug in an antenna to the analyser.

    However, I don't have a pukka EMC antenna so I'd just use a long bit of wire or maybe I can knock up a small active antenna because I think the worst radiation will be in the 1-30MHz region.

    I already know the TV is a dirty beast wrt RF radiation because it wipes out my MW AM radio.


    It's probably the other way around :)
    After a while the % odds of them throwing something destructive at the TV screen must approach 100%

    Slip them some sleeping pills?
     
    Last edited: Nov 14, 2011
  27. Chelsea_Fan

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    Here's a couple of analyser plots (taken with a camera)

    This is 0 to 50MHz with the TV off. You can see lots of shortwave signals around 3 to 10MHz even though the RBW of the analyser is set to 30kHz.

    Note that I've used the max hold feature on the analyser and this tends to pump up the noise level between the peaks.

    [​IMG]


    Here's what happens to the reception when the TV is turned on. Note the broad spectrum of mushy noise.

    Note that I've again used the max hold feature on the analyser. This is because the interference from the TV appears to be centred on 482kHz but is pulsed on and off rapidly and this gives lots of interference spread across the whole of the 50MHz span pictured. So to see it fully I have to use the max hold function.


    [​IMG]


    Obviously, these tests are only casual and really should be done using a known EMC antenna in a test chamber rather than a random length of wire in my front room!

    The spectrum analyser is a very good one BTW and is a bit wasted on this test as it can go up to 22GHz.
     
    Last edited: Nov 14, 2011
  28. 55brianb

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    Sorry, but that's not true.

    I'm over at my parents' place for Christmas and always bring a small Eton E5 radio with me. Two nights ago I put it on and couldn't get anything on the lower shortwave frequencies (up to about 12MHz) apart from a mush and heavy RF noise. MW was the same with only the strongest signals getting through (eg BBC Radio Ulster - I'm in N Ireland). My parents live in the countryside, the nearest other dwelling being about a quarter of a mile away. No pylons/overhead power lines or similar, no interference or receiving problems before this visit.

    It turns out that they have bought a 43" Samsung plasma tv since my last visit, and it IS this which is causing the interference - tv on=intereference to a distance of approximately 80-90 feet away from it, tv off=no interference. Simple. The bedroom I was using the radio in was about 50 feet away from the living room which has the tv in it.

    Also, don't forget about the HUGE amounts RF interference being thrown out by approved PLT devices, so saying that there is no RF interference allowed from domestic appliances is simply wrong.
     

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