Telephone Equipment for Long Cable Circuits

Some of the important developments contemplated in the a p p a r a t u s and equipment for long toll cable circuits are described. The large number of equipment units per station in the cable plant and the greater number of stations in a given length of cable than in an open-wire system have made the economic importance of the equipment design such t h a t a comprehensive program of development, affecting many types of equipment, has been undertaken. The outstanding features of some of the n:ore important of these, including the telephone repeater equipment, test board equipment and signaling equipment, are described. The necessity for compactness in the dimensions of equipment units, uniformity in assembly arrangements, and simplicity in design, together with the need of careful correlation of the electrical and mechanical requirements, are emphasized. The methods proposed for meeting these requirements generally, are described. INTRODUCTION T HE use of lead covered cables in place of bare copper wires for long distance telephone lines has been an important development and much interesting information on this subject has already been presented to the Institute. The engineering and construction features involved in a cable system of this sort were described by Mr. Pilliod 2 in his article on the Philadelphia-Pittsburgh Section of the New YorkChicago cable, while the transmission characteristics of such a system were brought out in the recent paper by Mr. Clark. 3 It is the purpose of the present paper to deal with some of the important developments in apparatus and equipment which are contemplated for the cable plant.