On Thu, 7 Feb 2013 21:35:38 -0000, "Ian Field"
wrote:



"Tilmann Reh" wrote in message
...
Michael A. Terrell schrieb:

80's vintage German printing equipment (offset press industry) uses a
video
plug-in card (made by the manufacturer of this equipment) to generate
parameter display for the operator. The display is a standard baseband
video
tube monitor. (It is possible, being German and sold in the USA market,
that
the video may be NTSC or PAL.)

If it's monochrome, we don't need to talk about NTSC or PAL and their
particular color carrier frequencies...


In PAL & NTSC; the colour carrier was a multiple of the line rate.

You mean fractional multiplier ?

The B&W contains spectral peaks at multiplies of line and field rate.
For (stationary) images, there is no energy between the spectral
lines.

The whole idea of both NTSC and PAL (but not SECAM) is to code the
chrominance signal into these "empty" spaces and thus the subcarrier
must be at some submultiple of the line rate. In PAL there is an
additional 25 Hz frequency shift, thus the same phase relationship
occurs every 4th field.

While this spectrum interleaving works pretty well for stationary
images, any movement will spread the spectral lines and luminance and
chrominance can no longer be perfectly separated, causing cross
chrominance and cross luminance problems. For this reason ties with
small details should not be used in TV studios if it is expected that
the signal could be transported through NTSC/PAL, since a tie with
only small B/W stripes would cause a quite colourful result :-).