🚀 go-pugleaf

From postnews Sun Nov 10 21:47:18 1985
> 	A short follow up to the net on the article I posted concerning Fiber
> 	Optic Repeaters for Ethernets. 
> 
> 	Another vendor has come on the scene :
> 	Fiber Com

The strategies used by Fiber Com differ considerably from those used by
Codenoll and Siecor.  The FiberCom network is really a ring in which
a single uni-directional fiber connects all xcvrs into a ring.  The
maximum distance between xcvrs is something like 1 or 1.5 km (my literature
is at work).  If an xcvr fails, a relay couples the input and output
fibers.  I havn't had the pleasure of opening one up so I can't say how
it's done.

The Codenoll and Seicor products both use transmissive
star couplers at the center of a star configuration.  Codenoll's product
is totally passive.  The optical signals must be within 4db for collisions
to be detected so detailed flux budgeting must be done.  Maximum
arm to arm distance is 1.5Km with either a 4 or 8 port star available.
Seicor goes one step further in that they use an active sensor
at the star to sense collisions and then broadcast a collision signal
(increasing the probablity of sensing a collision.)

Fiber Com probably does well in point-to-point stuff and the others
in places where several buildings need to be interconnected.
I'm in the process of installing the Codenoll stuff here.  I should know
more in another couple of weeks or so.
	-tcs
	Terry Slattery	  U.S. Naval Academy	301-267-4413
	ARPA: tcs@brl-tgr.arpa
	UUCP: decvax!brl-bmd!usna!tcs