[Coco] [coco] video signal generation

[Richard Atkinson]

Just one thing I'd check. Are you terminating the video signals properly?
Your filter might be acting partly as a terminator, and without termination
the rise and fall times could be longer.

Richard


On 1/5/07, RJRTTY at aol.com <RJRTTY at aol.com> wrote:
>
> People
>
> I have  been struggling with a problem with my converter for a while
> and I need some  information.
> Does anybody know the details of how the GIME  generates a
> RGB video signal?   The problem I am having is that  while 80 col
> text on the green channel is clear and sharp, 80 col text on the  red
> shows
> some video degradation and 80 col text on the blue channel is  completely
> illegible.
>
> What I am thinking is that the GIME generates the  green channel first,
> the
> red channel second and the blue channel  last.   Is this correct?
> Another
> strange thing is that  80 col text in any color combination that has even
> a
> little green in it shows  up well but if you look at 80 col. text using
> pure
> red or blue as the  foreground or backround you get a wierd kind of video
> smearing.
>
> I  already have a solution.  If a low pass filter is placed in the input
> channels
> the 80 col text shows up well in all color combinations.    In other words
> I
> had
> to DECREASE the bandwidth of the converter in order to  get acceptable
> results.   It seems that the quality of the video  signal coming out of
> the
> GIME in the coco3 is only slightly better than the  old monitors could
> display
> and the high bandwidth of my converter is just too  much for the signal
> showing it "warts and all".
>
> I don't know about the  rest of you but purposely degrading the converter
> to
> approximate the  perfomance of the old monitors just seems wrong to
> me.  The
> image does  soften a tiny bit with the filters but not enough to notice if
> you
> were not  already looking for it or directly comparing it to
> an  unfiltered
> converter.
>
> Does anybody know what is going on with the  conversion process in the
> GIME to cause this?
>
> TIA
> Roy
>
>
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