Posted by Richard Crowley on 10/09/06 23:40

"Radium" wrote ...
> What is the color sub carrier frequency in SECAM video?
>
> http://www.high-techproductions.com/pal,ntsc.htm
>
> The above site shows the color sub carrier frequency for
> NTSC [3.579545 MHz] and PAL [4.433618 MHz].

While Wikipedia claims that SECAM is, historically, the "first"
European color standard, my understanding is that today it is
produced and recorded as PAL, and "converted" to SECAM
only upon transmission. I'd bet that the SECAM color
subcarrier is the same as PAL, 4.53 MHz. The WorldWide
Web (according to Google) seems strangely mute on the topic
of "SECAM subcarrier"

> Of the video frequencies described [horizontal frequency, vertical
> frequency, color subcarrier frequency], the color subcarrier is the
> highest? Why is this?

A simplistic explanation would be that there are many pixels
in each video line (which is why the subcarrier is larger than
the horizontal rate). And there are a many lines for each frame
(which is why the horizontal rate is larger than the vertical rate).

> How would the picture quality look like if the color sub carrier
> frequency was only 1 hz?

The entire black and white screen would change to a different
color every 15-20 seconds. (Assuming two 8-bit values for
I & Q are required per color :-) The picture would look like
those old hand-tinted prints from 100 years ago before they
had color film. Where one scene would be tinted blue, and
the next one orange, and the next one green.

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