Re: Multinorm TV woes - no NTSC color display

[Linards Ticmanis <ticmanis@gmx.de>]

Michael J. Mahon schrieb:

> I see two possibilities--1) the 14MHz crystal you installed is just
> enough out of tolerance that the monitor does not recognize the burst
> as a color burst, or 2) the monitor is applying some strict criterion
> to the video signal that the Apple does not conform to.  (This is more
> of a problem with monitors that use digital decoding.)

By the way... what criteria are theoretically available for this detection?

A little brainstorming reveals:

1.) Number of lines per frame or per field
2.) Horizontal frequency
3.) Number of color carrier pulses per line
4.) Relative phase shift of color burst from line to line
5.) Number and arrangement of vertical sync pulses

Most of these would need some tolerance but not too much, so that there
are neither too many false positives, nor too many false negatives.

Did I forget anything?

I wonder, which of these would be easiest to implement in a TV set and
to get right most of the time (i.e. the TV would be able to reliably
tell apart all of NTSC-3.58, NTSC-4.43, PAL, PAL-60 and SECAM), but
would fail for the Apple?

-- 
Linards Ticmanis