[Arm-netbook] HDMI High-Frequency Layout: Recommendations--Taper

Luke Kenneth Casson Leighton lkcl at lkcl.net
Tue Dec 5 01:49:02 GMT 2017


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On Tue, Dec 5, 2017 at 12:30 AM, Richard Wilbur
<richard.wilbur at gmail.com> wrote:
> The goal of the taper is to minimize the reflection coefficient involved with
> changes in impedance caused by changes in transmission line geometry.
> In essence we are trying to make the changes so gentle that we don't scare
>  any electrons.  The scared electrons reflect at the point of abrupt changes
>  in impedance(flee back in the direction they came from) which weakens
>  the signal delivered to the HDMI cable and, finally, the display.
> (Forgive the anthropomorphization of the electrons--it is purely for illustrative purposes.)

 i get it.  and it's fun, too.  reminds me of "B.O.B" from Monsters
for some reason.

Dr Cockroach: "Look out, here comes..."
Susan: *pause*... "Susan".
B.O.B.: "SuuUuuusan... oo that does sound scarey.  i scared myself"

 btw i miiight be able to do a pair of arcs on each side of keepout
area, in "S" format, where it needs to narrow / widen.

 are you able to take a closer-up photo or a higher-res version, don't
worry about the file limit to the list i'll "approve" it when i see
it.  the image is 320x240 and it's too blurry to make out the writing
and notes.  not too hi-res btw! :)  some of these iphones... dang.
what i do is: use GIMP, convert to JPEG, set it at "35% compression",
that's a good compromise on quality and size, then you can get away
with even as high as 1000x1000 @ only... 80-200k or so depending on
complexity.  i also tend to select "Image | Mode | Greyscale" on
pencil-drawn pictures.

l.



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