[thelist] [OT - Kinda] Internet Access

Norman Bunn norman.bunn at craftedsolutions.com
Thu Oct 16 15:58:12 CDT 2003


> ><snip>
> >
> >Since we have moved to a new neighborhood, Time Warner Cable has not
quite
> >validated service to our area due to the lack of customers. More will
show
> >up. They've agreed? to reassess the situation in January 2004. No cable
and
> >no cable modem.
> >
> >SBC Yahoo DSL has really made me angry. To get DSL access you need to be
> >within the three-mile, or 18,000-18,500 ft radius of the station. My
> >neighbor, who happens to be even further away measures at a nice 15,000
ft.
> >We, close to the station, measure at a horrid 20,000 ft. Our houses are
> >about 40 ft apart. So, somewhere in the ground, there's an extra 5,000 ft
of
> >telephone cable in 40 ft of distance... Yah I know, really stinks.

As a former phone company engineer, let me explain that it is not just the
distance, but the configuration of your phone circuit that can cause
problems.  The issue at hand is that a single pair of wires serves your
home.  These wires are twisted together and build up capacitance over
distance.  This capacitance is manageable out to about 18000 feet.  Circuits
beyond 18KF require the installation of load coils to add inductance to
counter the excessive capacitance.  The first of these coils is placed 3KF
out and each subsequent one at 6KF intervals.  You can quickly see that it
is possible to have a "loaded" pair of wires and a non-loaded one within the
18KF limit (though this is not encouraged due to cost considerations and the
fact that circuits used between load coils have unacceptable transmission
characteristics).  It is even possible within the same cable on your street,
so that one person had service via a loaded pair and the next door neighbor
via unloaded.  The problem as far as is that load coils  destroy the high
frequencies necessary to provide DSL, so a loaded pair cannot support DSL.
This could be a reason you cannot get DSL on your line.

Another possibility is that you and your neighbor may be served from
different cables routed from different directions, one of which has taken a
more circuitous route (OK, I'll admit a 5KF discrepancy is hard to stomach
and would reflect some pretty bad planning in the engineering office).

A final possibility is one I ran into when getting DSL.  This is where more
than one prefix is served in a given area (not that uncommon these days),
with some of them served by one set of switching equipment, say a Nortel DMS
and the others by another, say an old AT&T ESS.  In this case, one set of
prefixes has been programmed to accept DSL and has compatible DSL
terminating equipment installed, while the other does not.  Over time the
issue is resolved.

I know none of this solves your issue, but maybe it can help you understand
the possibilities for the problem.

Norman
www.CraftedSolutions.com




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