Bell telephone magazine (1922) (14568535508)

Identifier: belltelephonemag00vol2930amerrich (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

Text Appearing Before Image:

the weaker sounds been developed which costs less than are less affected by circuit noise. New extra cable pairs at distances as short circuit components—especially some as 15 or 20 miles. It will not replace which have resulted from the Labora- the older systems on very long routes,but it fully meets Bell System stand-ards of transmission on circuits upto 200 miles in length. These stand-ards permit three or four such cir-cuits to be connected together to pro-vide a conversation path. The system has many novel fea-tures. A device called a compandorconfines the speech currents on thelines within narrower limits than the tones research on semi-conductors—are used in many places where vac-uum tubes would otherwise be re-quired, with a consequent reductionin size and cost, and also in theamount of power used. Special care and much ingenuityhave been exercised to keep the equip-ment compact. Maintenance has beenmade simpler by mounting whole cir-cuits as plug-in units, so that when a

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A recently developed carrier telephone system, compact and efficient, brings the advantagesof carrier telephony to telephone circuits used over relatively short distances i95i Post-JVar Achievements of Bell Laboratories 167 unit needs attention itcan be replaced by aspare as easily as vac-uum tubes are inter-changed. The compact-ness of the apparatushas facilitated this typeof mounting. Althoughlow cost has been a ma-jor consideration, it hasnot been achieved bysacrificing quality oradaptability. The system provides12 two-way circuits ontwo pairs of wires, andincludes every featurewhich is needed to han-dle calls dialed byeither customers oroperators. Moreover,both pairs can be inthe same cable, whichis not usually the casewith the older systems. Thus it will be pos-sible to provide for therapidly increasing vol-ume of toll traffic byincreasing the capacityof cables already inplace, instead of add-ing new ones. This will be of specialvalue in conserving copper during thepresent emerge

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1922

Prelinger Library

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