TI-99/4A Comments

From: Philip.Belben_at_powertech.co.uk <(Philip.Belben_at_powertech.co.uk)>
Date: Fri Jun 13 12:05:29 1997

In my previous message I wrote (re: meanings of video signals),

> The other two signals are the quadrature components of chrominance.
> They are derived from Y by subtracting red and blue, and are normally
> called U and V (in some order).
>
> The colour telly receives U and V phase modulated onto a subcarrier (I
> think). The hue control on American tellies sets the baseline against
> which phase is measured here. (In Europe, the PAL system reverses the
> phase each line, so any hue errors should cancel out)

Before someone like Tony jumps down my throat, U and V are _amplitude_
modulated onto the subcarrier, in quadrature with one another. Thus the
phase of the subcarrier gives the hue, and its amplitude the saturation.

I hope you are not any more confused than before :-)

Philip.
Received on Fri Jun 13 1997 - 12:05:29 BST