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Technology Stocks : LAST MILE TECHNOLOGIES - Let's Discuss Them Here -- Ignore unavailable to you. Want to Upgrade?

To: DenverTechie who wrote (2353)	11/21/1998 9:33:00 AM
From: Frank A. Coluccio	Read Replies (4) \| Respond to of 12823

Hi Denver, just a minor clarification with some historical perspective, and possibly a correction of something which I think was the result of a typo but needs to be clarified, nonetheless. I know that you are aware of the following facts. I thought that perhaps others would find them interesting. >>Normal telco engineering standards are to limit the wire center (Central Office) to 18,000 feet radius (about 6.5 miles in diameter) from the CO<< Make that the equivalent of 3 to 3.5 miles if 18,000 feet is your point of reference, ordinarily, with today's outside plant wire gages. Although there are cases which extend far beyond this, as reinforced by the introduction of 30,000 ft.+ ISDN BRI and 2B1Q extenders that some vendors have promoted in their repertoires. >> although I have seen several instances of old wire centers being more than 21,000 feet in radius. << I stipulate today's plant, because wire gages have changed, and gage is an important criterion here. Older wire is usually of a lower gage (fatter diameter) which could withstand longer distances. In previous generations of loop plant (much of which is still in use today), prior to transistorized and IC type line elements such as bidirectional repeaters and, and later DLCs and then fiber muxes, 18 AWG and in some cases lower AWG wire were good for transcontinental stretches with the assistance of vacuum tube amplifiers known as V1 and V3 repeaters. The V originally standing for Vacuum tube. Phantom circuits (derived through the manipulation of magnetic flux in the cores of loop isolation transformers of these V type amps) on short and intermediate runs, as well as the long distance runs, were also used to provide "pair gain." They did this in an unmultiplexed four-wire circuit environment (by today's standards, in any event) by supporting the main connection, and a dependent secondary connection in the background, over the same four wires, without the talkers on the primary circuit knowing about it. Other variations of "Phantom Circuit" arrangements extended the number of talk circuits to three and four or more with an additional pair or two. This was very manually intensive work requiring intricate levels of balancing and tuning by a craftsman (no ladies that I am aware of did this at that time, except in Russia and Poland) upon initial set up, aided through the use of a device known as a "Wheatstone Bridge" [no, not the Rock Band called Wheatstone Bridge," rather an electric circuit used for tuning RCL circuits with highly sensitive criteria. See: qub.ac.uk ] The main point of interest here that I'm making is that copper circuit "pair gain" is nothing new. It's been around for about a hundred years or so, in one form or another. Only the means by which it is achieved keeps improving, with each improvement yielding greater efficiencies. FWIW.