. The Bell System technical journal . is desirable that starting and stoppingboth the transmitter and the receiver be separately controlled from thetelephone ofifice. Local testing arrangements should also be providedif possible, to allow the test board operator to determine whether thetransmitter and receiver are operating properly. In order to obtain representative information on the feasibility ofoperating an ultra-high-frequency telephone circuit on an unattendedbasis in the telephone plant and to secure a better idea of the mechanicaland electrical requirements, equipment was constructed
. The Bell System technical journal . is desirable that starting and stoppingboth the transmitter and the receiver be separately controlled from thetelephone ofifice. Local testing arrangements should also be providedif possible, to allow the test board operator to determine whether thetransmitter and receiver are operating properly. In order to obtain representative information on the feasibility ofoperating an ultra-high-frequency telephone circuit on an unattendedbasis in the telephone plant and to secure a better idea of the mechanicaland electrical requirements, equipment was constructed by BellTelephone Laboratories for such an installation. With the cooperationof the New England Telephone and Telegraph Company this equip-ment has been used to establish an experimental ultra-short-wave 536 BELL SYSTEM TECHNICAL JOURNAL circuit between Green Harbor and Provincetown, Massachusetts, asindicated on the map. Sand dunes near Provincetown, rising about 80feet, make it possible to secure an optical path across the bay. The. Fig. 2—Ultra-short-wave transmitter mounted in metalcontainer suitable for pole mounting. radio circuit is extended by wire from Green Harbor to Boston to forma direct Boston-Provincetown toll circuit. It is used as one of a groupof terminal circuits and is operated at the normal overall net loss for ULTRA-SHORT-WAVE RADIO TELEPHONE SYSTEM 537 this type of circuit, namely, 9 decibels. Transmission from GreenHarbor to Provincetown is accomplished on a frequency of 65 mc. andin the reverse direction on 63 mc. This does not represent the minimumpossible frequency spacing for this equipment, but was a convenientone for the experiment. At Boston and at Provincetown the circuit appears at a jack in theswitchboard beside the jacks of wire toll circuits. As far as the oper-ator is concerned, switching and ringing operations are performed in thesame manner as for other similar grade toll circuits and there is nothingto designate that this toll circuit has
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Keywords: ., bookcentury1900, bookdecade1920, booksubjecttechnology, bookyear1
