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! :)
On a sunny day (8 Jan 2007 02:20:05 -0800) it happened "Myauk" wrote in :
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.
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.
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.
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.
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.
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.
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Jim Backus running OS/2 Warp 3 & 4, Debian Linux and Win98SE
bona fide replies to j backus jita
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)
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