Fw: HDMI extending

[Gareth Cook <g@xxxxxxxxxx>]

Interesting extract from an article - mebe i can just chop into it and
"extend" the hdmi cable ?

DVI and HDMI, unfortunately, are not so robust. The problem here is the
same as the virtue of analog component: tight control over impedance. When
the professional video industry went to digital signals, it settled upon a
standard--SDI, serial digital video--which was designed to be run in
coaxial cables, where impedance can be controlled very tightly, and
consequently, uncompressed, full-blown HD signals can be run hundreds of
feet with no loss of information in SDI. For reasons known only to the
designers of the DVI and HDMI standards, this very sound design principle
was ignored; instead of coaxial cable, the DVI and HDMI signals are run
balanced, through twisted-pair cable. The best twisted pair cables control
impedance to about +/- 10%. When a digital signal is run through a cable,
the edges of the bits (represented by sudden transitions in voltage) round
off, and the rounding increases dramatically with distance. Meanwhile,
poor control over impedance results in signal reflections--portions of the
signal bounce off of the display end of the line, propagate back down the
cable, and return, interfering with later information in the same
bitstream. At some point, the data become unrecoverable, and with no error
correction available, there's no way to restore the lost information.



Gareth Cook
IT Architect, SWG Sales
IBM SWG Sales - Lotus Park, Staines, TW18 3AG
Office: +44 (0)1784 445166 - Mobile: +44 (0)7980 445166
AIM Chat : TheBoyG - MSN Chat : chat@xxxxxxx
email: g@xxxxxxx


----- Forwarded by Gareth Cook/UK/IBM on 24/03/2006 13:43 -----

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ukha_d@xxxxxxx
Today 13:22

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[ukha_d] HDMI extending
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Here's a question - do you think I could extend a HDMI cable over a length

of cat5 (about 10 metres) ? Without having to go down the HDMI over CAT5
module route

I'm a bit tied for running a cable - but it might be possible to shorten
this run to 5 metres - or even use some STP

G.

Gareth Cook
IT Architect, SWG Sales
IBM SWG Sales - Lotus Park, Staines, TW18 3AG
Office: +44 (0)1784 445166 - Mobile: +44 (0)7980 445166
AIM Chat : TheBoyG - MSN Chat : chat@xxxxxxx
email: g@xxxxxxx