Re: [stella] Re: [Fpga2600] Where am I going wrong?

Subject: Re: [stella] Re: [Fpga2600] Where am I going wrong?
From: "Eric Ball" <ericball@xxxxxxxxxxxx>
Date: Thu, 2 Jun 2005 23:34:39 -0400
In the active video is too long.
There should be at least a  1.5uS "front porch" of blank before the 4.7uS
sync pulse.  I also don't like the glitch during the sync pulse (which is
also in

> I've found different references for various voltage levels.  One source
> says black at .3, another .4, and another says "blank" at .40 and black
> at .48, while some don't mention "blank" at all!

Note: with Japan NTSC blank = black, which may be some of the confusion.

140 IRE = 1 volt

sync  0 IRE = 0.000V
blank 40 IRE = 0.286V
black 47.5 IRE = 0.339V
max white 140 IRE = 1.000V
colorburst 40 IRE peak to peak (0.143 - 0.429V)
max white with colorburst 120-160 IRE = 0.857-1.143V

You may want to make COLU=0x?E 0.857V so you don't overdrive the video.
Most TVs will do some AGC based on the sync pulse and colorburst, so if your
voltages are off a little (but your ratios are correct) you should end up
with a decent signal.

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