Bell telephone magazine (1922) (14568537268)

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:

many re-finements. Some ofthese grew out of expe-rience with the Bostonsystem. Some are prod-ucts of research whichbecame available whilethe Boston tests were inprogress. Among thelatter, a better antennaand a better vacuumtube * were especially important. Linking New York and San Fran-cisco are more than 100 relay sta-tions. At each of these are two pairsof antennas, one pair pointed towardthe next station to the east, and onetoward the next station to the west.One antenna of each pair is used toreceive incoming waves, the other tosend waves forward. Each antenna,however, is capable of receiving orsending six different broad band chan-nels simultaneously. A fully equippedroute, therefore, could accommodatethousands of conversations simultane-ously; or it could carry six televisionprograms in each direction. Only a few of these relay stationshave attendants on duty. Special caremust therefore be taken to assureservice reliability. There are starultnpower plants to take over if commer-

Text Appearing After Image:

* See Spanning the Continent by Radio Re-lay, Magazine, Winter 1950-51. An engineer adjusts microwave radio relay equipment cial power fails. There are also spe-cial circuits over which alarms aresounded at some place, such as anearby telephone office, where a main-tenance man is on duty at all times,and over which coded signals are sentto him to tell the character of thetrouble which has developed. One of the six possible channels isto be held as a standby, ready to takeover if serious trouble occurs. Atpresent, the load must be switched tothis channel manually at some relaypoint where attendants are on duty;but arrangements are now being de-veloped to make the substitution au-tomatic, even at unattended points. As a complement to this long-hauldesign, a simpler one has also beenworked out for use over short dis-tances. It serves two purposes: topick up television programs and carrythem to the nearest point on a back-bone route; or to provide short-haul 172 Bell Telephone Magazine AU

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1922

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