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Question on Analog vs. Digital Signals for Plasma TV

Discussion in 'Electronic Repair' started by buck, Mar 30, 2006.

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  1. buck

    buck Guest

    If there is a better forum for this question please direct me. I currently
    have a regular RCA 32" television that is hooked up to cable TV via "analog"
    signal. My question is.... If I buy a plasma TV and stay with analog (not
    digital) will my picture be an improvement over my older TV just due to
    different technology??

    thanks for any help!
     
  2. Arfa Daily

    Arfa Daily Guest

    As far as I've seen so far, the simple answer to that is " no ". On some
    picture content, the image produced by either plasma or LCD is superb. A
    nice stationary bowl of flowers, or a properly lit studio shot of a
    newsreader, for instance. But switch channels to the motor racing, and you
    will be able to count the number steps it takes the car to get across the
    screen. You'll also wonder why the paint appears to be coming off the body,
    and trailing along behind ... Ok, perhaps not quite that bad, but
    nevertheless, you will get clearly visible motion artifacts on a flat panel
    TV of any type, compared to a CRT set, no matter whether you feed it with a
    digital or analogue signal. If you are serious about buying a plasma, get
    the salesman to show you it working on a large variety of content.

    The effects are at their worst when you are watching a programme that is
    originated digitally, broadcast and received digitally, and reproduced on a
    pixel addressed display. I currently have three different models of LCD set
    in the workshop, and personally, I wouldn't have any of them in my house as
    anything other than a second set.

    Arfa
     
  3. As far as I've seen so far, the simple answer to that is " no ".

    A good explanation follows.........
    It's also important to note that a conventional TV set "blurs" the image so
    that it looks smooth. Since plasma and LCD TV sets have discreet pixels, there
    is a much more noticable space between them. 42 inch plasma TVs used to be so
    bad that you could see the spaces between the lines at over a foot away.
    Hopefully you won't sit so close to the set, but you get my point.

    Digital signals are the worse offenders, the analog signal is broken up into
    discrete pixels before being recorderd or transmitted. This has nothing to
    do with the connection method of your TV set, DVDs, and anything that is
    encrypted (digital cable, satellite TV, etc) all are digital and have
    a specific number of pixels.

    When you play the signal back on a device with a different number of pixels,
    some sort of conversion has to take place to map the image from one set of
    pixels to the other. Converting the signal to analog and back again has its
    charm, it will give you a smoother looking picture.

    For example, an LCD TV may have a resolution of 1280 pixels across. Now if you
    have a usual DVD, it has the image chopped up into 720 pixels across. If you
    display the picture properly, one pixel on the screen to one pixel in the
    image, you will see black bars on the sides. DVDs are usualy 520 pixels
    high, so a TV with 1280x1024 resolution will "adjust" the horizontal and
    just display every vertical pixel twice. This may look odd, but the human
    brain can compenstate.

    If you get a "widescreen" TV with a horizontal resolution of around 1440 pixels,
    then a DVD playes quite nicely by doubling every pixel. This may require a
    digital input to the TV because of the high frequency range (bandwidth)
    required to carry so many pixels.

    The problem with plasma and LCD TVs is the manufacuring of the display. There
    is no such thing as a color display, they are really combinations of three
    single colors, called primary colors, red, green and blue. You brain
    sees combinations of these colors as the entire range of color, but it
    is not really there. Each pixel requires three real pixels one of each
    color on the display.

    Therefore a single 1024 line of pixels is really 3,072 pixels, with 1024
    groups of three. This is difficult to produce in high resolution. OLED
    (organing light emiting diode) technology will replace this. OLEDs still
    have discrete pixels, but the process of putting them on a screen is similar
    to an inkjet printer. While a three inch 800x600 pixel LCD screen is almost
    impossible to manufacture a 800x600 OLED screen is relativly easy and
    cheap.

    Since computer processing power is also easy to come by and cheap, in a
    few years, a high resolution OLED TV will be availble at a price far
    lower than a plasma, DLP or LED screen which will automaticly convert
    almost any picture into one that looks good and it will be fast
    enough to show motion without artifacts.

    Of course, the first OLED TVs will cost around $10,000 but in 20 years
    you will see them on cereal boxes.

    Living in Isreal brings me an interesting point of view, the TV standard
    is PAL, but most of the programs on satellite and cable TV are from the
    U.S. in NTSC. NTSC signals have a faster frame rate (30 versus 25), but
    a lower resolution (525 lines versus 625). Obviously these have to be
    mathematicly converted to fit the taller screens and less frames per
    second. The quality of the conversion varies and you see all sorts
    "problems" with the picture.

    DVDs are not a problem, almost everyone here who has a DVD player has a
    multisystem TV set (PAL tuner, NTSC or PAL via the video in) and the DVD
    players switch frame rates automaticly. "Zone free" players are the norm
    here, if they were only zone 2 no one would buy them.

    Geoff.
     
  4. LCD displays all suffer from lag like you are describing, whether the source
    is digital or analog. This is not the case with PDPs. Digital signals that
    are overcompressed may look pixelated on a PDP, but display lag is a far
    greater problem with LCD. What one will find with any new set with digital
    processing is that much of the analog cable will look worse on the new set
    than it did on an older analog crt. There are two reasons for this. One is
    that the newer set likely has higher resolution and will reveal the
    limitations in the original material. The other is that many systems do a
    poor job of upconverting the signal to higher display rates. This latter
    problem involves both inadequate filtering of the analog signal before
    conversion, and unsophisticated upsampling schemes in the digital.

    The solution is simply to watch the material that you plan to view on the
    set before buying it. Products vary greatly within and between
    manufacturers and technologies.

    Leonard
     
  5. buck

    buck Guest

    Hey..... Thanks to everyone for some great comments. Now I am totally
    unsure about whether to get a plasma or not.... :~)
    I will take your advice to see different content at the store before I make
    final decision. What to do? What to do?
    -thanks again!
     
  6. Since you are in the U.S. (I assume), I would go to Sam's club and buy the
    cheapest widescreen TV with an S-Video in jack and the cheapest DVD player
    with an S-VIDEO out.

    Get a membership in the cheapest DVD rental place you can find and if
    you can get CBS and FOX with an antenna, the cheapest antenna that
    will let you do this.

    Relax, watch the content matched to the TV and consider in two years, you
    spent about half a dollar a day on entertainment. After two years things will
    be so different that you will probably want to get rid of what you have
    anyway.

    Higher resolution over the air digital TV is coming. Digital is
    available in most places in the U.S., but the resolution will improve,
    DVDs will be replaced with something better and large screen TVs will be
    cheaper. OLED one inch screen video players are out now, large screen
    ones can't be too far behind.

    On the other hand if you have $5000 to impress your friends with, or have
    a large disposable income and no life, you can get a DLP TV set, a
    DBS satellite dish and a progresive scan DVD player and see the state
    of the art video.

    In two years when the bulb goes in you DLP TV, you will find that it's
    all obsolete anyway. :-(

    Geoff.
     
  7. JANA

    JANA Guest

    The answer can be complicated or simple. As for your old analog set, the
    Plasma or LCD will have a much nicer picture. The technology of the new sets
    are far ahead of the older sets. But, if you don't feed them the proper
    signal in the proper mode, they will not work to the optimum.

    The new displays work best in their native mode. This has to do with that
    they are using pixel addressing rather than a more simple scanning of the
    image. If the signal sent to the LCD or Plasma screen is not in the native
    mode, the system has to do some complicated interpolation to be able to
    display the picture. The image will then look softer.

    There will be a time that everyone who wants to watch TV will have to be up
    to date. Most likely over the next 10 years, analog broadcast TV will be no
    longer in service.

    As for the new TV display technology, it is true that there are some bugs
    with it. This is especially so, with rapid moving objects. As time goes on,
    the manufactures are finding ways to make these sets have higher contrast
    ratios, and have faster response times. There are some newer LCD monitors
    out there now that are faster than the older CRT ones. The prices are still
    very high for a very good monitor, but these will come down.

    Eventually the stores will no longer be selling CRT type monitors. Most of
    the manufactures have stopped making the picture tubes, and are not
    interested in selling CRT type monitors, or TV sets.

    --

    JANA
    _____


    If there is a better forum for this question please direct me. I currently
    have a regular RCA 32" television that is hooked up to cable TV via "analog"
    signal. My question is.... If I buy a plasma TV and stay with analog (not
    digital) will my picture be an improvement over my older TV just due to
    different technology??

    thanks for any help!
     
  8. Arfa Daily

    Arfa Daily Guest

    I'd love to agree with you on all that, but most of the stores that I do
    work for, which sell flat screens - both LCD and plasma, won't place them
    side by side with CRT sets, because these show up the flat panels for what
    they are - generally inferior.

    With a good signal going in, a CRT set looks good under all circumstances,
    from a full dark night-time shot, to a brightly lit studio shot - and if
    we're talking digital here, then let's say a high bitrate source such as
    QVC. On the contrary, flat panel sets of either variety will struggle to
    handle this high dynamic range of brightness and contrast with anything like
    the same fidelity as a CRT, no matter what fancy tweaking software and
    hardware has been incorporated.

    And motion artifacts, and shading artifacts *are* a problem with these
    displays. Some displays are signally better at reducing the 'unwanteds',
    than others. If I was really intent on buying myself one, and had the money,
    then I would definitely buy a Pioneer plasma.

    As far as the technology getting better is concerned, I'm not so sure about
    that. About 5 years ago, I was called in by a colleague to sort an audio
    problem with an installation of multiple large plasmas in a bar. They were
    NEC professional types, and I will admit to the picture on them being
    excellent. But then it should have been at over 6 grand UKP apiece ...

    I'm not sure what actually represents an LCD monitor that's *faster* than a
    CRT one. I guess that you must be talking about refresh rates, because the
    response times of CRT phosphors are very very short, and I'm pretty sure
    that there is not the LCD panel made, that can come close to them in pure
    pixel on/off response time, but I could be wrong on that one.

    I do absolutely agree with you on them looking best in native mode, though.
    However, "best" is the operative word here ...

    I know a few people who have bought both LCD and plasma displays, and
    ultimately been less than satisfied by them. But, by the same token, I also
    know people who have bought them and been absolutely delighted. I think it
    is a case of those people being the same ones that you used to call on for a
    CRT set fault, and when you got there, the picture was bright green. Then
    the customer walks in the room and says " It's the sound that I've got a
    problem with, mate ! "

    I'm sure that there's still lots of life in this thread yet !! I guess that
    the poor old OP is now well confused, but he's at least got the idea now
    that he needs to look at plenty of content typical to what he watches before
    making a decision. Oh, and don't be fooled by those fancy Sony demo rooms,
    with a top of the range model, shown in the dark ... d;~}

    Arfa
     
  9. buck

    buck Guest

    JANA...... Thanks for answering my original question. I knew there would a
    debate on which technology is better too. I have learned some things.
     
  10. buck

    buck Guest

    Arfa..... thanks.... All good stuff from you.
     
  11. Guest

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    Our online address is:
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    PMBBAY
     
  12. Ken G.

    Ken G. Guest

    I work around these tvs where i work ( salvage outfit ) its my job to
    see if all the stuff works before its sold .
    I notice the plasma & lcd sets are getting better in the last 2 years .
    I have a 36`` sharp lcd and like it better than the old tube set . I did
    notice some lag at first but soon after dont notice it anymore and dont
    care I also got used to the stretching at the sides & just dont notice
    that anymore either .
     
  13. Arfa Daily

    Arfa Daily Guest

    No problem. As a slight aside, I was in one of the stores that I do work for
    today, and I was discussing this thread with the owner, and I was saying
    that about the only plasma that I would possibly entertain, would be the
    Pioneer. I was very surprised when he said that the Daewoo series 3 models
    use Pioneer drive electronics, with a Samsung screen. The only bit that
    Daewoo make themselves, is the analogue tuner board. He went on to say that
    in his opinion, the picture produced by this set actually equalled that of a
    CRT, and was better even than the Pioneer itself, and was the first he had
    seen that he could actually say this about.

    That left me a bit non-plussed, I have to say, because from a professional
    repairer's point of view, I've always considered Daewoo gear to be pretty
    poor stuff, from their cars to their HiFi's, but I'm gonna have to look into
    this, because this guy is a reliable source of opinion, and not an
    hysterical " believer ".

    Another thing that he said, that set me thinking. He has himself, at home,
    got a plasma TV. The only reason that he has it is because he came by it as
    a refused-quote repair. Once he had fixed it up, he took it home, and
    replaced his regular TV with it. Now he tells me, that he spent the next
    month agonising over whether to keep it, or just put it back up for sale, as
    in his opinion, the picture was crap. However, over that month, he says that
    he got used to it, and not having another CRT set in the house to compare it
    to, started to ignore its shortcomings. He has now had it for over a year,
    and he says that although the picture is still crap, for all of the reasons
    that we've been discussing here, he no longer notices, and loves it.

    So there you go. Just maybe, you need to go for the best looker that you can
    afford, put it in, and get used to it ...

    Arfa
     
  14. John-Del

    John-Del Guest

    I currently

    Easy answer. With basic analogue signals, your RCA (or any properly
    operating quality TV) will have a better, more detailed picture than
    any digital technology TV. Digital TVs just aren't designed to convert
    analogue 24 fps to digital.

    But on true HD sources, HD TVs (plasma, LCD, DLP, CRT, whatever) look
    spectacular. However, these true HD channels are but a small
    percentage of what most people receive and watch. I have several
    customers who have already worn out a plasma without ever seeing a
    decent picture on it.
     
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