File:Bell telephone magazine (1922) (14570360377).jpg

Identifier: belltelephonemag26amerrich (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

View Book Page: Book Viewer
About This Book: Catalog Entry
View All Images: All Images From Book
Click here to view book online to see this illustration in context in a browseable online version of this book.

Text Appearing Before Image:
Hillat Waltham, Mass. On the roof of each radio relay stationare four antennas, two facing along theroute toward New York, two facing alongthe route toward Boston. This allows fortwo-way operation—with one antenna ofeach pair for transmitting, the other forreceiving. The antennas are ten feet square and incorporate a metal lens capa-ble of focussing the micro-wave signalsinto a beam sharper than that provided byan anti-aircraft searchlight. At each station there are repeaters, oramplifiers, to keep the signals up to theproper strength as they are relayed alongto the next station. Signals are carriedfrom the receiving antenna to the repeatersand out again to the transmitting antennathrough hollow metal pipes called waveguides. There are four such pipes at eachstation: one associated with each of thefour antennas. The first floor of each radio relay towercontains heating and ventilating equipment,as well as an emergency battery and power 1947-4^ New York-Boston Radio Relay System 107
Text Appearing After Image:
Cut-away view of a typical radio relay station betweenNew York and Boston, showing the arrangement ofequipment in the building. Emergency power equip-ment and storage batteries are on the first floor, radioequipment on the second floor, and the special microwaveantennas which receive and beam the communicationsignals are on the roof generator to give double protection againstfailure of the power supply. The initial equipment comprises a regu-lar and a spare circuit in each direction.For operation of these two circuits, fre-quencies in the range 3700 to 4200 mega-cycles have been assigned by the FederalCommunications Commission. Each cir-cuit carries a signal band width of aboutfive megacycles. Such a band can handlehundreds of telephone conversations, or atelevision program. Terminal equipment capable of carrying240 simultaneous telephone conversationswill be installed for experiment next spring,and it is expected that more channels willbe added later. Plans are well under way for a r

Note About Images