From twibright at hispeed.ch  Sun Nov  6 14:23:35 2011
From: twibright at hispeed.ch (Karel Kulhavy)
Date: Sun, 06 Nov 2011 15:23:35 +0100
Subject: [Ronja] Distance between Twister2 and DTE
In-Reply-To: <201110302125.04878.mms@max-sievers.name>
References: <201110302125.04878.mms@max-sievers.name>
Message-ID: <4EB69867.2050704@hispeed.ch>

On 10/30/2011 09:25 PM, Max Moritz Sievers wrote:
> Dear developers,
>
> I don't understand why the RJ45 jack has to be plugged directly into the
> computer or switch and why the cable cannot exceed 1 or 2 meters. Would it
> make any difference if I use optical fibers (using a converter at the end of
> this RJ45 jack)?
>    

Thats because normally RJ45 cable interface has filters that prevent 
emanation of higher harmonics of the square wave signal from longer 
cable lengths. For complexity reason this filter was left out in Ronja.

I am also not sure if longer cable cannot degrade the waveform to the 
point it would be decoded improperly without the filter.

So it is for electromagnetic compatibility and maybe reliability.

If you use converter and optical fiber I think it would be likely OK.

Karel