Author: Robert Hyatt
Date: 08:24:32 03/30/01
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On March 30, 2001 at 11:10:52, Wayne Lowrance wrote: >On March 30, 2001 at 10:41:28, Brian Richardson wrote: > >>I have had reliable (hour or so outages every 3/4 months or so) cable modem >>service for more than 2 years. It is always very fast (typically >1Mpbs and >>never slower than 100K, often >2Mpbs, peak >4Mbps). Download speed now is >>almost always constrained by other sites. Last time I looked I could not get >>DSL, but from the horror stories of others, I can't imagine why I would bother. >>I think DSL has some potential bottlenecks too, just further up the line. > >Yes your very right about DSL bottenecks. I have DSL for about one year. PacBell >has agressivly been advertising. For the first 3 month my speed was terrific >then it started to slowly erode. >Now it is very inconsistant at times slower than a 28 k modem and very difficult >to surf the Web at times, other times it is reasonable fast. >I am unhappy with PacBell. From what Bob has said this behavior should not >happen. I do not understand Bob's comment though about two dedicated copper >lines. It is just the standard telephone lines and when the copper wires get to >the telephone pole it is all common wires after that, or is it ? (: > >Wayne No. You have a pair of copper wires from your home to the local switching office. From there data is multiplexed over faster connections that may include fiber. however, if you were to yank your wire out of the wall and follow it, it would go to one of the small green junction boxes you see scattered around the neighborhood, from there it is connected to another dedicated pair of copper wires that go to the larger junction boxes usually seen at the entrance to a subdivision. From there it is connected to yet another pair of dedicated copper wires that go to the local switching office. There are exceptions in areas of rapid growth, where sometimes 40 or 80 pairs of copper run to a multiplexor that is connected to the local switching office. But these are usually replaced as larger cable bundles are strung. You _really_ do have a dedicated circuit back to your local switching office, however. And you could take an ohmmeter and measure resistance from your home to the local office if you wanted. Our local data people have some on-line test equipment that they use to measure the various electrical properties of a pair of wires, and can even tell you (based on timing info) exactly how far you are from the local switching office, "as the copper runs". I am at 16,000 feet, roughly, which is beyond DSL/ADSL range. I am stuck until they build a new switching office that is closer, or until they start to multiplex many local pairs onto fiber back to the local office. 16,000 feet of real copper has too much resistance, capacitance and inductance for fast frequencies.
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