When you read today where someone writes about, "back in the eighties...," you naturally think of 1980-something. This 1949 advertisement by Bell Telephone Laboratories mention of "back in the eighties" was referencing 1880-something. The picture juxtaposes a telephone pole massively populated with cross poles, insulators, and wires, with an engineer holding up a section of coaxial cable that was in the process of replacing the poles and wires. Thanks to Bell Labs' relentless R&D efforts, those early single-channel, short distance twisted pairs were obsoleted by 1,800-channel coax. Fiber optic cables today typically support more than 30,000 voice channels.
Bell Telephone Laboratories Advertisement
They Packed a Pole Line into a Pipe
Back in the eighties, telephone executives faced a dilemma. The public demanded more telephone service. But too often, overloaded telephone poles just couldn't carry the extra wires needed, and in cities there was no room for extra poles. Could wires be packed away in cables underground?
Yes, but in those days wires in cables were only fair conductors of voice vibrations, good only for very short distances. Gradually cables were improved; soon every city call could travel underground; by the early 1900's even cities far apart could be linked by cable.
Then Bell scientists went on to devise ways to get more service out of the wires. They evolved carrier systems which transmit 3, 12, or even 15 voices over a pair of long distance wires. A coaxial cable can carry 1800 conversations or six television pictures. This is another product of the centralized research that means still better service for you in the future.
Bell Telephone Laboratories Exploring and Inventing, Devising and Perfecting, For Continued Improvements and Economies in Telephone Service
Posted January 18, 2017