File:Bell telephone magazine (1922) (14754252254).jpg

Identifier: belltelephonemag22amerrich (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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ng. A typicalunit of packaged equipment, the TypeC carrier terminal, is shown In thephotograph on page 243. This unittakes three separate telephone con-versations and bundles them togetherfor transmission over the wires. Asimilar unit sorts them out again atthe far end. Carrier Telephone Epuipment On a pair of open wires It Is cus-tomary to transmit one two-way con-versation at voice frequencies: that is. 1943-44 Packaged Carrier for the Signal Corps 241 the speech sounds are converted intoelectrical impulses in the telephone setand are sent over the toll circuit atthese so-called voice frequencies.One or more additional two-way con-versations can be handled over thesame pair of wires by employing thecarrier technique. With this means demodulated to the original voicefrequencies. Naturally, the Signal Corps wantedpackages of carrier equipment be-cause fewer shiploads of wire will berequired than would be needed ifcarrier were not used. Two types ofcarrier equipment are being used, the
Text Appearing After Image:
Signal Corps men are removing the packing case from one unit such as is shownon page 243 before up-ending it onto the base which has been prepared at the left to receive it the voice frequencies of the separateconversations are changed or modu-lated, to use a technical term, bydifferent amounts, so that in effectthey are piled on top of each otherfor transmission over the toll circuit.At the distant end filters are used tosort out the separate conversationsand they are changed back again, or first providing one circuit and anotherproviding three circuits (Type C).By using repeaters every 100 to 150miles, the length of these latter cir-cuits can be extended to great dis-tances. The Type C carrier system involvesseparate packages for an East termi-nal, a West terminal, a repeater and 242 Bell Telephone Magazine WINTER a test package. The equipment willbe mounted in cabinets seven feethigh. Spare vacuum tubes, wire,tools, concise installation and operat-ing instructions, drawings and mis

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