Bell telephone magazine (1922) (14569208828)

Identifier: belltelephonemag23amerrich (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:

ions. One could tune In this sta-tion or that by adjustment of theradio receiving device. The radiotransmitters likewise were tuned tosend their signals on certain frequen-cies, much as one tunes the stringsof a musical instrument to sound cer-tain notes of tlie musical scale. This 1944 A Bridge for Speech Across Chesapeake Bay ZS radio technique of separating chan- and thus to transmit a number of nels for communication by tuning them on a single wire circuit. These was applied to wire systems, and carrier systems are now extensively made possible multi-channel opera- employed to obtain additional tele- tion of the present-day carrier sys- phone channels over wires, tems. Among these carrier systems is one It is fairly obvious to us now, be- known as the Type K.* This sys- cause of our own experience with tem was first put into commercial use radio broadcast receivers, that by on telephone cables near the close of means of tuning, any one of a num- 1938. It is capable of transmitting

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At East Ocean View, on the lower side of the Bay, only the radio equipment isinstalled. The conversion equipment is housed in the Norfolk toll office ber of communication channels can beselected from the programs pickedup by the antenna. In this way, then,a single wire circuit may have a num-ber of communication bands sent intoit, and at the other end these bandsmay be separated by tuning—as isactually done in carrier systems. De-velopment has made it possible toput these bands very close together, twelve telephone conversations simul-taneously without interference be-tween them. It seemed that twelvetelephone channels would be aboutthe right number to provide for theimmediate need for circuits acrossChesapeake Bay and to allow for ex-pected future growth. Consequently, * See Twenty Years of Carrier Telephony,Bell Telephone Quarterly, October, 1938. 36 Bell Telephone Magazine SPRING ; it was decided to undertake the de-velopment of a radio system thatwould be capable of transmitting

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1922

Prelinger Library

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