Why is video inverted for transmission?

Discussion in 'Digital Photography' started by Green Xenon [Radium], Sep 20, 2007.

  1. I wouldn't call an LCD a "tube". The other examples you quote are
    devices that create an image or amplify a signal by modulating the flow
    of electrons across a span of vacuum. A LCD has no vacuum and almost no
    continuing electron flow. It's not like the other technologies at all,
    definitely not a "vacuum tube".
    You could equally well say that these days it is nearly completely solid
    state, with a few vacuum tubes here and there, but in insignificant
    numbers compared to the total number of active devices.

    Dave
     
    Dave Martindale, Sep 24, 2007
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  2. Would it have been easier for you if I had said "in his gentle way"
    instead? Did the emoticon not help you interpret my intent?
     
    Gene E. Bloch, Sep 24, 2007
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  3. Green Xenon [Radium]

    Bob Myers Guest

    That's unfortunately been the trend in the U.S. as well, at
    least as far as digital cable/satellite providers are concerned.
    I get horrible compression artifacts on many programs via
    the digital satellite service.

    What does the digital over-the-air broadcast picture look
    like for you, though?

    Bob M.
     
    Bob Myers, Sep 24, 2007
  4. Green Xenon [Radium]

    Allen Guest

    Try "PrognostiCation", or "PrognostiCate". Of course, if you looked up
    the original spelling you would have seen this immediately the blank
    space that you looked at, so you have probably identified yourself as a
    troll.
    Allen
     
    Allen, Sep 24, 2007

  5. Its no joke if it was your job to deliver the best video possible.


    --
    Service to my country? Been there, Done that, and I've got my DD214 to
    prove it.
    Member of DAV #85.

    Michael A. Terrell
    Central Florida
     
    Michael A. Terrell, Sep 24, 2007
  6. Green Xenon [Radium]

    Randy Yates Guest

    No. I still don't know what your intent is or was.
    --
    % Randy Yates % "The dreamer, the unwoken fool -
    %% Fuquay-Varina, NC % in dreams, no pain will kiss the brow..."
    %%% 919-577-9882 %
    %%%% <> % 'Eldorado Overture', *Eldorado*, ELO
    http://www.digitalsignallabs.com
     
    Randy Yates, Sep 24, 2007
  7. Green Xenon [Radium]

    Don Pearce Guest

    It looks soft, bad motion artifacts - the Rugby World Cup coverage at
    the moment frequently verges on the unwatchable. Colours are often
    "painting by numbers" type pastel shades. Flesh tones particularly
    suffer from this.

    d
     
    Don Pearce, Sep 24, 2007

  8. That's why the tube databooks listed those pins and N/C. N/C = DO
    NOT USE.

    --
    Service to my country? Been there, Done that, and I've got my DD214 to
    prove it.
    Member of DAV #85.

    Michael A. Terrell
    Central Florida
     
    Michael A. Terrell, Sep 24, 2007
  9. Green Xenon [Radium]

    Randy Yates Guest

    Allen,

    Is it that satisfying to you to sit behind your computer and write
    nasty little messages like this to total strangers?

    If you would read the adjacent post I made on this very subject
    a few minutes ago, you would see my reasoning.
    --
    % Randy Yates % "Remember the good old 1980's, when
    %% Fuquay-Varina, NC % things were so uncomplicated?"
    %%% 919-577-9882 % 'Ticket To The Moon'
    %%%% <> % *Time*, Electric Light Orchestra
    http://www.digitalsignallabs.com
     
    Randy Yates, Sep 24, 2007
  10. :)

    You should have seen some of my projects, years ago. :) I'm still
    using one of them: An adjustable battery charger build from a RV power
    supply, and a Staco version of a Variac. The output voltage is
    adjustable from zero to about 20 volts, and lets you set the charging
    current. It is built in the aluminum housing of a WWII aircraft RADAR
    receiver.


    --
    Service to my country? Been there, Done that, and I've got my DD214 to
    prove it.
    Member of DAV #85.

    Michael A. Terrell
    Central Florida
     
    Michael A. Terrell, Sep 24, 2007

  11. The glass is green from the lead, used to reduce Xray emissions.


    --
    Service to my country? Been there, Done that, and I've got my DD214 to
    prove it.
    Member of DAV #85.

    Michael A. Terrell
    Central Florida
     
    Michael A. Terrell, Sep 24, 2007
  12. But even "regular glass" appears to have a greenish tint.
    Like the mirror in my bathroom. If you look at it from an
    acute angle, you can seee the greenish cast from the glass.
     
    Richard Crowley, Sep 24, 2007
  13. Green Xenon [Radium]

    Jerry Avins Guest

    No wonder Thunderbird's spell checker flagged it. I assumed the word was
    just too big. Silly me!

    Jerry
     
    Jerry Avins, Sep 24, 2007

  14. Sigh.

    --
    Service to my country? Been there, Done that, and I've got my DD214 to
    prove it.
    Member of DAV #85.

    Michael A. Terrell
    Central Florida
     
    Michael A. Terrell, Sep 24, 2007

  15. Don't forget that a tube based sync generator could fill almost half
    a relay rack in the early days. (The power supply chassis took the rest
    of that half rack space.) A TV station I visited in Fairbanks Alaska
    was still using one in 1974. The military TV station I worked at at
    that time had a state of the art RTL IC DUAL sync generator, with an
    automatic transfer that didn't use all of three rack units. (5.25")
    Even with two power supplies, there were still a few empty slots.


    --
    Service to my country? Been there, Done that, and I've got my DD214 to
    prove it.
    Member of DAV #85.

    Michael A. Terrell
    Central Florida
     
    Michael A. Terrell, Sep 24, 2007

  16. Like the 50 year old 17" Philco portable I picked up on Saturday.
    Those were never stable, and I doubt this one will be, unless I modify
    the sync circuit.

    --
    Service to my country? Been there, Done that, and I've got my DD214 to
    prove it.
    Member of DAV #85.

    Michael A. Terrell
    Central Florida
     
    Michael A. Terrell, Sep 24, 2007

  17. True, but if you could look at the edge of a flat CRT faceplate it
    would be almost black.


    --
    Service to my country? Been there, Done that, and I've got my DD214 to
    prove it.
    Member of DAV #85.

    Michael A. Terrell
    Central Florida
     
    Michael A. Terrell, Sep 24, 2007
  18. Green Xenon [Radium]

    Jerry Avins Guest

    ...
    NC meant "no connection" and one was advised not to use them because
    voltage withstand was not assured. Pin 1 was listed NC on the glass
    versions of the 6L6, but it was intentionally connected to the metal
    shell (and usually grounded) in the metal version.

    Jerry
     
    Jerry Avins, Sep 24, 2007
  19. Green Xenon [Radium]

    Joerg Guest

    Ok, sorry, Michael. I just can't find any joy in watching people beat
    each other up, the umpteenth rerun of Letterman's show, divorcees
    screaming at each other or some never-ending ballgame that pushed away a
    nice classic movie. Most annoying these days is the number of times
    where a movie in the programming guide ain't showing at all.

    Also, OTA transmitters appear to lack the TLC of yesteryear. I can't
    count the times when the image froze or the audio went and nobody at the
    station seemed to care.

    And yes, I've done video projects myself and tried to deliver the best
    video signal possible. Designed my own sync separators and so on. But
    that was for industrial applications where there are no ladies wrestling
    in the mud and stuff.
     
    Joerg, Sep 24, 2007
  20. Green Xenon [Radium]

    Jerry Avins Guest

    Iron impurities are the source of most of the green color you see in
    glass, but high-purity glass isn't so expensive that CRTs couldn't be
    made of it. I find lead giving a greenish tint counterintuitive. There
    is certainly no green in lead "crystal" tableware.

    Jerry
     
    Jerry Avins, Sep 24, 2007
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