From: "Niels Petersen" 
Reply-To: NielsP{at}bigfoot.com, Fidonet AVtech Echo 



Hi John

> JT> It was an el-cheapo time domain reflectometer, one signal
> JT> generator, one cro. Leave the other end underminated, (or
> JT> shorted) and look at the reflections. We estimated distance
> JT> going on the time of the reflection. Worked quite well. Saved
> JT> us from reterminating the whole network.
>
>  Waht did the pulses look like, unterminated by the break? Did they
> ring like a bastard, or where they still reasonably clean?

  Going on memory (it was a few years back) there was significantly more
ringing and spikes at the point where it was shorted  or open.

  We noticed a few weirdo waves at some points, (not quite as sharp as our
test
shorts and open-ended cables), before we found out we still had one of the
BNC's plugged into a card...

> JT> Naw, the longer the better. If you have t-pieces inbetween, you
> JT> can experiment and progressivly remove each one and look at how
> JT> it effects the reflections.
>
>    To see the ringing, look at the end that is unterminate (or
> broken).

  Think about it Bob.  We don't know where this broken end IS.  That's why
we
were doing this to find out in the first place...

I use a spare terminator and work my way through the computers from 1 end.
This usually pinpoints the break reasonably quickly.

Cheers
Niels

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