🚀 go-pugleaf

Al Peterson wrote:
> 
> "Jeff Brady" <jeffbrady@dmait.com> wrote in message
>
> > Any cable w/ a ferrite core should do the trick.
> 
> Not true.  The purpose of a ferrite core on the cable is to help
> in reducing radiation to meet FCC Part 15 rules requirements.
> 
> As the cable gets longer the capacitance between the video leads
> and ground increases and will degrade the video response if the
> cable exceeds a critical length.
> 
> Depending on the cable construction, usable lengths will differ. 
> I doubt if you will find any commercially available cable that
> will allow acceptable performance at 30 meters.

Good cables are actually several coax lines, with a characteristic
impedence (which is related to the ratio of inductance to
capacitance per unit length) and look resistive, usually around
100 ohms.  A line will attentuate higher frequencies, but the
losses will not be significant at medium lengths.  It is important
that such lines be driven from a matching driver, and terminated
in their characteristic impedance, otherwise you will get ringing
and other nasties.

At frequencies below the cutoff frequency the principle effect of
the line is to delay a signal, and it will also attentuate it
(depends on the resistance per unit length).

So the effects depend highly on the quality of the cable.  You
could probably replace the chroma carrying portions (three colors)
by lengths of RG58, or whatever is the right match to the end
impedances, and function perfectly well over fairly long
distances.  Small dimensions (such as the multiple lines in your
cable) generally mean poorer quality lines.

The important thing is matching impedances.

-- 
Chuck F (cbfalconer@yahoo.com) (cbfalconer@worldnet.att.net)
   Available for consulting/temporary embedded and systems.
   <http://cbfalconer.home.att.net>  USE worldnet address!