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Reply #139: Here's a good article on how NTSC video works.... [View All]

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Flatulo Donating Member (1000+ posts) Send PM | Profile | Ignore Mon Nov-24-08 10:02 PM
Response to Reply #94
139. Here's a good article on how NTSC video works....
http://www.maxim-ic.com/appnotes.cfm/an_pk/734

Note that the description of NTSC vertical resolution does not mention the concept of 'pixels'.

If I scan one complete frame (or 2 fields, for interlaced signals) in 1/30 of a second, and do that 525 times (horizontal lines) in that same 1/30 of a second, I need a carrier signal with a frequency of 1/(1/30*1/525) = 15.75 kHz. This signal then gets amplitude modulated during the scan.

To the extent that this scan signal has a period of 63 usecs, this can be thought of as resolution. But it's not a pixel, because it's dependant on the ability of the output device to have the bandwidth to display it.

This may be nit-picking, but I think it's important to be accurate when discussing this stuff.

BTW, I am not a broadcast engineer, but I used to work with a guy who lived and breathed this stuff.
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