OT: Network Cable Tester

[David Curtis]

On Thu, 24 Sep 2009 15:04:23 -0600
drew einhorn <drew.einhorn at gmail.com> wrote:

> On Thu, Sep 24, 2009 at 1:37 PM, Roger Neth Jr <baypos at gmail.com>
> wrote:
> > I have used a Fluke 620 for 8 years and works great for what your
> > needs are, look on ebay also.
> 
> Definitely can't afford a new one.
> Might be able to afford a used one on ebay.
> 
> Looking at the specs.  How do they do that?  I can see some of it.
> But, without something connected at the far end, how do they tell
> there isn't an open circuit at the connector on the far end of the
> cable?

http://en.wikipedia.org/wiki/Time_domain_reflectometry

and

http://en.wikipedia.org/wiki/Time-domain_reflectometer

Not exactly sure what improvements have been made over the years, but
in the late '90s we would send PCBs to get 'TDR' tested to measure the
impedance of certain copper traces that carried either high frequency
signals or were part of differential circuits. Same principles apply.

Dave