Bell telephone magazine (1922) (14752984651)

Identifier: belltvol20elephonemag00amerrich (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:

vided betweentwo cables, one for transmission inone direction and the other for trans-mission in the reverse direction. Ofcourse, 1800 circuits would hardlyever be required on a single route, andfor this reason most of the cables be-ing installed at the present time con-sist of a pair of much smaller cables,perhaps 40 or 50 pairs each. Two 50pair cables are large enough, however,to have an ultimate circuit capacitymore than twice as great as one of the300 pair cables of an earlier day. Repeaters and Other Equipment In connection with the difference inthe size of the cable, it is to be bornein mind that the multiplication of thenumber of circuits per pair of wiresin the cable is attained by the additionof new and complicated types of car-rier equipment. Under the oldertechnique, the cost of equipment andterminations was already an impor-tant part of the total cost of the cir-cuits. With the carrier technique, theequipment and terminations are a stilllarger proportion of the total cost.

Text Appearing After Image:

Fig. 3. Exterior of an AuxiliaryRepeater Station Buildings such as these, normally un- aliended, are located along the routes of cable carrier-system toll lines Under the carrier technique, sev-eral channels are amplified by eachrepeater, but the repeaters are neededat more frequent intervals along theline. Under the old voice technique,telephone repeaters were placed at 50to 100 mile spacing, while under thenew technique the higher frequenciesused require new energy about every17 miles. Figure 3 shows an outside view ofa typical auxiliary repeater station ofthe new art. These small buildingsare generally about 20 feet squareand house as many as 100 repeaters,amplifying 1200 voice channels. Thecompact manner in which apparatusis fitted into one of these small re-peater stations is very interesting andcan be readily seen in Figure 4. Nospace is provided for permanent op-erating forces, and the building isdesigned wholly for telephone repeat-ers, power supply, and control equip-ment. Th

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1922

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