Thicknet/10base5 Test Segment: The Cable is In!

[Eric Smith]

On Wed, Jun 27, 2018 at 12:39 PM, Paul Koning <paulkoning at comcast.net>
wrote:

> This reminds me of a research project done at DEC that at one point was
> discussed as a possible product but didn't happen: an Ethernet segment
> mapping device.  It was called "packet voltmeter".  The idea was that you'd
> have one at each end of the cable (it replaced the terminator).  It would
> build a table of source addresses and packet signal amplitude.  You could
> then combine the measurements at the two endpoints, plus the known cable
> attenuation, to make a physical map (with tap placement) of each Ethernet
> node.
>

HP made that, and sold it as the 4990S "LANProbe Network Analysis System",
which consisted of a 4991A "LANProbe" Cable Segment Analyzer, which you put
at one end of the 10BASE-2 segment, and a 4992A "node locator", for the
other end. There was also HP 4990A ProbeView software for Windows 3.0, but
the 4991A and 4992A together could do what you describe, even without the
the 4990A.

I bought a 4991A from a surplus store cheap 20 years ago, but I've never
found the 4992A, and the 4991A offers only a tiny subset of the
functionality if you don't also have the 4992A.

The Internet doesn't know much about the HP 499x products. They are
mentioned in an HP Journal article "Design Challenges for Distributed LAN
Analysis" in February 1992 (vol 43 no 1 page 66 ff.).