From: rsiatl!turner@rsiatl.UUCP
Newsgroups: comp.dcom.telecom
Subject: Re: St. Louis Cable Thefts
Date: 15 Aug 92 22:11:00 GMT
Organization: TELECOM Digest
X-Submissions-To: telecom@eecs.nwu.edu
X-Administrivia-To: telecom-request@eecs.nwu.edu
X-Telecom-Digest: Volume 12, Issue 633, Message 8 of 10

> Also, neither in the above nor in the TV news did anyone ask or
> address one possible solution and prevention of this situation --
> replacing copper with fiber. I'm surprised the telco doesn't take the
> opportunity to replace the aerial cable with fiber in these areas
> where the cable was stolen. (Or would that cost a vast amount more,
> requiring some sort of powered fiber-to-copper converters at every
> line drop? 
 
They will steal fiber just as readily as copper, only to latter 
discover that is is worthless.  I have been told by a MCI fiber
tech that they have had fiber stolen, only to have the criminal
return to cut even more of it because they felt they were cheated.
When I installed some fiber in downtown Memphis we had to close
up the hand-holds every night to protect the fiber (normally
you could figure 8 the cable and leave it out.)
 
Several telcos I know of have gone to using insulated grounding
wire instead of bare bare copper, as it reduces the value if it is
stolen.
 
If you want to talk about really bad vandalism, one of the power
companies in either New England or the West had a problem with people
climbing high voltage transmission lines towers and stealing aluminum
crossmembers off the pole.  They had experienced several failures
(read 360 kV line fell to the ground) and a lot of costs replacing the
missing parts.  An education program targeted at the scrap metals
dealers in the state solved the problem.
 
> Just how does a telco handle the transition from fiber strung between
> the poles to copper pairs going into a house? What happens to
> telco-line-powered devices in this circumstance? How is ring current
> generated? Are there separate fiber-to-copper convrters for every
> drop, or still a copper multi-pair cable for the neighborhood with one
> central fiber-to-copper unit up a pole somewhere, with its own
> electric meter and hooked to electric lines, mainline fiber, and
> neighborhood copper distribution? Does having fiber-to-copper, or even
> fiber to the home, mean that your phone service dies when electric
> power dies? Or is the fiber paralleled with current-carrying wires to
> provide CO battery to the drops?)
 
Fiber in the Loop right now uses DLC (Digital Loop Carrier) such as a
SLC-96 (tm AT&T) to convert hicap digital lines to analog or 2B1Q
lines for either ISDN or digital pair gain.  A SLC is usually provided
with local mains power as well as battery backup.  The SLC contains
line cards like those used in a D4 channel bank to interface to the
analog subscriber loop.  These cards can be anything from loop start 2
wire POTS to various flavors of E and M to BRITE (Basic Rate Interface
Terminal Equipiment) cards for delivering ISDN.
 
The SLC can do some concentration or it can give every subscriber a
digital bit stream back to the CO.  Without concentration, it will
deliver 96 loops from 5 T1s.  The T1's can be fed from a colocated
MUX, from a distant MUX or from a CO.  The SLC can be pole mounted,
located on a concrete pad or in a CEV (Controled Enviroment Vault), or
located at the customers premise.  Fiber terminating at a customer's
premise can also be used to delever DDS service with a very low BER.
 
Fiber is also used to connect to remote switches in rural and very
populated areas.

 
Pat Turner  KB4GRZ  turner@dixie.com.


[Moderator's Note: This message appeared earlier in the Digest but due
to technical errors had portions mixed up. It is repeated here as it
should have appeared the first time -- I hope!  PAT]