[vdr] Re: LAN cable length / Streaming Plug-In

[Maarten van den Berg <maarten@ultratux.net>]

On Friday 04 April 2003 14:28, Jörg Knitter wrote:
> > But what most forget, this 100 m are splitted up in 90 m of fixed
> > installation cable between patch panel and wall socket, and 10 m of
>
> the
>
> > flexible cable for connection to the switch and the device. If you
> > use normal patch panel type cable with a length longer than 10 m you

This is not true.  Indeed, sometimes FTP (wich is shielded) instead of UTP 
cable is used in installations. That is to further minimise any possible 
interference, but by NO means a neccessity.  Besides, since a few years 
most have stopped using FTP because of it's high price and little (if 
any) measurable difference.

The trick with cat5 is not the [absense of] shielding; it's making double 
sure that at NO place the twists are 'broken'. Even a short stretch of 
untwisted wire or a loop where the two wires are not snugly together but 
somewhat apart, can (will!) wreak havoc on your connection. This is why 
you should be extra-extra careful when crimping RJ45 plugs; a stretch of 
just 1 (one) centimeter untwisted wire protruding from the plug will 
kill(!) your good signal, (depending on the level of "noise" around). 

Two RJ45 plugs plus an extender / adapter in between accounts for maybe as 
much as 5 cm or more of untwisted wire. Is it really no wonder that that 
gives a LOT of interference. You are relatively lucky to still get a 
signal AT ALL though such a cable. ;-)   And that is no joke.  

> > can expect problems. I assume the OP has only the flexible cable
> > type. And if you crimp the connectors yourself you can make a lot of
> > errors.

Oh yeah. If you have a "split pair" for instance, you are guaranteed to 
have dire problems with your connection. You must be sure of the correct 
wiring when crimping your own cable.

> > The other important point is the connection between both cables. This
> > only works if a CAT5 wall socket is used. Connecting two long cables
> > just with a adapter will cause problems.

You're absolutely right. For the reason, see above.

Maarten

-- 
This statement is either false or a paradox.


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