Bell telephone magazine (1922) (14569377498)

Identifier: bellvol25telephonemag00amerrich (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:

gathered, their suc-cessors began to think along the samelines. When the Laboratories en-tered the SONAR program, the great-est need was for precise methods ofmeasuring underwater sound, a fieldin which little quantitative work hadbeen done. Yet this was an impor-tant aspect, for precise measurementis a fundamental factor in good de-velopment and design of any equip-ment. With their broad experience in the measurement of ordinary soundin the development of telephony. Lab-oratories engineers undertook investi-gations which laid the groundworkfor the standardization and improve-ment of sonar techniques. In 1941 and 1942 they establishedthe first lake calibration stations, onein New Jersey and the other in Flor-ida. These were later taken over bythe National Defense Research Com-mittee as the national standardizinglaboratories for underwater sound. Sonar locates hostile submarinesby projecting a beam of vibrationsthrough the water and observing the Bell Laboratories^ Role in Victory 117

Text Appearing After Image:

Above: the Elcovee,^^ a floatinglaboratory used in the develop-ment of sonar Right: How the sonar antennais lowered and retracted CROSSSECTfON 01= 5MIP time and direction of the echo. Theprinciple is the same as that of radarbut the vibrations are of water mole-cules, and the frequencies are meas-ured In tens of thousands Instead ofmillions. Most difficult part of thejob was to devise a transducer, a de-vice to convert electrical vibrations tomechanical and vice versa. The Lab-oratories developed a synthetic piezo-electric crystal for this, and withWestern Electric worked out a pro-cedure to make it In very large quan-tities. Another contribution was a dometo be attached to the ships hull tohouse the transducer. Its stream-lining and other features minimizednoise pick-up—a very important fac-tor. About three-score differenttransducers were designed for spe-cial uses. Equally important was the Lab-oratories contribution in the formof good design of the sonar circuits,which generated

телефонный журнал колокол 1946 книжные иллюстрации электроэнергия история техники Нью-Джерси звонок телефонной компании телефон американская телефонно-телеграфная компания телефония изображения из интернет-архива

1922

New Jersey State Library

http://commons.wikimedia.org/

public domain