File:Bell telephone magazine (1922) (14569631157).jpg

Identifier: belltelephonemag4344amerrich (find matches)
Title: Bell telephone magazine
Year: 1922 (1920s)
Authors: American Telephone and Telegraph Company American Telephone and Telegraph Company. Information Dept
Subjects: Telephone
Publisher: (New York, American Telephone and Telegraph Co., etc.)
Contributing Library: Prelinger Library
Digitizing Sponsor: Internet Archive

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possible to reduce our rates materiallyover the years. Today, 70 per cent of all Bell Systemcircuits used for long distance service areprovided by means of broadband facili- 20 ties, and for the Long Lines Departmentthe figure rises to 90 per cent. More thana quarter of all Bell System long dis-tance services flow over a coaxial cablenetwork—and the future will see this pro-portion greatly increased. About 13,000 miles of coaxial cablesnow criss-cross the country. Between1965 and 1972, it is expected that an ad-ditional 10,000 miles will be placed inservice. In the Long Lines Department—which uses about 95 per cent of the co-axial cable manufactured by the WesternElectric Company—expenditures for newcable of all types were only $1.77 millionin 1959. In 1964, due to stepped up con-struction of coaxial cable routes, thisfigure reached about $40 million, an in-crease of almost 23 times. (In contrast,in the same period, total Long Lines con-struction increased about three and-a-half
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Scene above shows a coaxial cable beingspliced. The cable has been laid in a deeptrench in section of hardened route. times.) Five years from now it is expectedthat annual expenditures for constructingcoaxial systems will be at least doublethe present rate. Broadband Transmission In principle, broadband systems—using either cable conductors or a radiorelay channel—transmit a band of fre-quencies several million cycles in width.Then, with terminal equipment at eachend, this broadband is subdivided intohundreds of narrower bands, each usedfor one high quality long distance voicecircuit. (The frequency bands used fortelevision programs or high speed datatransmission are much wider than thoseused for voice current.) Broadband circuits produce betterquality transmission than earlier typesof cable circuits. An important reason forthis is speed—broadband transmissionapproaches the speed of light. Echo ef-fects—whether in a transmission medium,a room, or a hall—only become bother-so

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