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NTSC and PAL are making me confused!

Discussion in 'Electronic Design' started by Myauk, Jan 8, 2007.

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  1. Myauk

    Myauk Guest

    I am measuring CVBS outputs using NTSC and PAL playback discs with
    Oscilloscope.
    What are the differences between the NTSC and PAL CVBS output signals?
    Will it be possible to say whether the CVBS signal is NTSC or PAL just
    by examing the waveform at the Oscilloscope?
    Regards

    P.S it might be more appropriate to submit this question to
    sci.electronics.repair or sci.electronics.basic but I am getting used
    to be in this group!
    :)
     
  2. Damir

    Damir Guest

    No.The main difference between PAL and NTSC is how the color
    information is coded and decoded.

    Regards,
    Damir
     
  3. One immediate thing you notice is that NTSC has 60Hz frame rate,
    and PAL 50Hz.
    The second thing is that I think NTSC uses a 'setup' in black,
    and PAL does not (you can see that if if you display a horizontal line).
    So black is actually not at blanking level, but a few percent above it.
    Then there is the color burst, it changes 90 degrees phase each line.
    You can see that on a H triggered scope.
     
  4. Ban

    Ban Guest

    Switch your scope to TV-frame/field-sync and measure the time between each
    half_field, 16.7 vs. 20ms
    If your scope doesn't have this trigger feature you probably won't be able
    to determine the format.
     
  5. Damir

    Damir Guest

    NTSC could also be with 50Hz frame rate and 4.43MHz color carrier.
    The difference between NTSC and PAL is in the way U and V signals
    are included in two horizontal lines.
     
  6. Yes. and you can also get PAL at 60Hz.
    The frame rate, is a good 'guide', for where to start looking, but should
    not be taken as gospel.
    This is the best simple test. It is after all, the 'core' of PAL (phase
    alternation by line).

    Best Wishes
     
  7. Eeyore

    Eeyore Guest

    Is NTSC ever 50 fps ? I thought it's always 60.

    And is there ever 60fps PAL ?

    Graham
     
  8. Guest

    Yes, they do have PAL-60 (60 fields/sec) - never seen any NTSC-50 fps
     
  9. "Myauk" () writes:

    And that's the problem, problem posting here because it's their "hang out"
    instead of finding the appropriate newsgroup.

    Up until late 1995 (or was it '96? it's been so long I can't remember)
    there was only sci.electronics and sci.electronics.repair Traffic was
    heavy, at least for some, so some decided to split it up into multiple
    newsgroups. The vote passed, and we have the multiple newsgroups in
    the hierarchy that you see today.

    But all of that goes to waste when some fool decided they should post
    a basic question in sci.electronics.design because "they like it there".
    Likely that fool shouldn't have been posting there in the first place,
    because their questions were basic to begin with.

    If you can only come up with a vague quesiton, then your question belongs
    in sci.electronics.basics Or better yet, start reading some books that
    are the time honored way to learn. Then come up with some detail that the
    book doesn't answer, or doesn't explain well, and use sci.electronics.basics
    to ask a question that will get an asnwer that fills in the missing detail.

    Your question is about laziness, because there is no indication that you've
    done any reading to see any difference between the two systems. If you
    hd, then you'd be specific about what they have in common, or not have
    to ask the question as you realize they aren't really different.

    I should also point out that when you ask a basic question here, you
    often won't get the best answers, because nobody is taking your beginner
    status into the equation.

    Michael
     
  10. [rant with no answer snipped]

    Which PAL or NTSC version (which countries) do you care about? It may
    be as simple as checking the frame rate, as Ban pointed out.

    If you view the color burst on a scope sychronized to and triggered by
    the Hz line rate, you will generally see +/- 90-degrees phase shift in
    PAL (on alternate lines) and 180 degrees on alternate fields. So: 90,
    180, 270 and zero

    In NTSC, you will observe only the 180 degree shift. All this presumes
    sc/hz phase lock at the source, as with a broadcast signal.

    Frank Raffaeli
    http://www.aomwireless.com/
     
  11. http://www.aomwireless.com/

    sonofagun ... the color burst is not +/- 90 degrees wrt the horizontal,
    it's +/- 45 degrees
    Frank
     
  12. Jim Backus

    Jim Backus Guest

    The colour sub-carrier frequency. 3.5... MHz for NTSC, 4.3... MHz for
    PAL My solution would be to look with a spectrum analyser and see what
    frequency the sub-carrier was.
     
  13. jasen

    jasen Guest

    yes. the differences in frequency of the different components of the signal
    should make hint at that.

    othewise you would have to look at the intelligence in the signal
    (if you pick the right encoding you'll see pixels of the similar
    colour clustered together)

    Bye.
    Jasen
     
  14. jasen

    jasen Guest

    stick a NTSC tape in a multisystem VCR and the output will be PAL at the
    NTSC framerate. (no doubt, with significant jitter)

    Bye.
    Jasen
     
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