Distance Telephone Service Research Articles

Carrier Systems on Long Distance Telephone Lines1

Two previous papers before the American Institute of Electrical Engineers discussed the activities of the Bell System in the development of multiplex telephone and telegraph systems using carrier current methods. The present paper describes developments which have resulted in improvements in the carrier telephone art during the past few years. A new, so-called type “C” system is described in detail, together with suitable repeaters and pilot channel apparatus for insuring the stability of operation; the line problems are considered and typical installations pictured. The growth of the application of carrier telephone systems and their increasingly important part in providing long distance telephone service on open-wire lines are shown.

Applications of long distance telephony on the Pacific Coast

This paper deals with the general problem of providing long distance telephone service on the Pacific Coast. A description of the present toll plant is given and the applications which have been made of recent developments in telephone practise are illustrated. Reference is made to the extensive use which has been made of carrier telephone and telegraph systems, and the many special problems, such as the loading of long toll entrance cables, which these systems introduce, are pointed out. The service to Catalina Island is described to illustrate the changes which are taking place in the communication art. This service was first provided by means of a radio link to which a privacy system was later added. This radio system was later replaced by two submarine cables between the island and the mainland. The mechanical and electrical characteristics of these cables are given, together with a description of the work of laying, which was done principally by the government cable ship, “Dellwood.”

Telephone transmission over long cable circuits

James J. Pilliod: Metallic conductors interconnecting cities and territories must be used in ever increasing quantities to meet the requirements for long distance telephone service. For many conditions, open wires carried on pole lines provide the best method and t he one with which we are all generally familiar. The other available method and the one with which this paper specifically deals, is to bunch the wires together within the limits of a small lead sheath and this, as might well be supposed, introduces new problems and some of the most important of these are problems of transmission. The two methods mentioned are complementary and both have wide fields of application.

Applications of Long Distance Telephony on the Pacific Coast

This paper deals with the general problem of providing long distance telephone service on the Pacific Coast. A description of the present toll plant is given and the applications which have been made of recent developments in telephone practise are illustrated. Reference is made to the extensive use which has been made of carrier telephone and telegraph systems, and the many special problems, such as the loading of long toll entrance cables, which these systems introduce, are pointed out. The service to Catalina Island is described to illustrate the changes which are taking place in the communication art. This service was first provided by means of a radio link to which af privacy system was later added. This radio system was later replaced by two submarine cables between the island and the mainland. The mechanical and electrical characteristics of these cables are given, together with a description of the work of laying, which was done principally by the government cable ship, ``Dellwood.''

Telephone Transmission Over Long Cable Circuits

The application of telephone repeaters has made it possible to use small gauge cable circuits to handle long distance telephone service over distances up to and exceeding 1,000 miles. A general picture of the long toll cable system which is being projected for use in the northeastern section of the United States was presented recently by Mr. Pilliod and published in the July number of the Technical Journal. Many of the circuits in these toll cables are so long electrically that a number of effects, which are comparatively unimportant in ordinary telephone circuits, become of large and sometimes controlling importance. For example, the time required for voice energy to traverse the circuits becomes very appreciable so that reflections of the energy may produce “echo” effects very similar to echoes of sound. The behavior of the circuits under transient impulses, even when two-way operation is not involved so that “echoes” are not experienced, is very important. In order to keep within proper limits of variation of efficiency with frequency over the telephone range special corrective measures are necessary. Owing to the small sizes of the conductors, the attenuations in the longer circuits are very large. Special methods are, therefore, required to maintain the necessary stability of the transmission, including automatic means for adjustment of the repeater gains to compensate for changes in the resistance of the conductors caused by temperature changes.

Telephone Transmission Over Long Cable Circuits

The applicatton of telephone repeaters has made it possible to use small gage cable circuits to handle long distance telephone service over distances up to and exceeding 1000 miles. A general picture of the long toll cable system which is being projected for use in the northeastern section of the United States was presented recently by Mr. Pilliod before this Institute.* Many of the circuits in these toll cables are so long electrically that a number of effects, which are comparatively unimportant in ordinary telephone circuits, become of large and sometimes controlling importance. For example, the time required for voice energy to traverse the circuits becomies very appreciable so that reflection of the energy may produce ``echo'' effects very similar to echoes of sound. The behavior of the circuits under transient impulses, even when two-way operation is not involved so that ``echoes'' are not experienced, is very important. In order to keep within proper limits of variation of efficiency with frequency over the telephone range special corrective measures are necessary. Owing to the small sizes of the conductors, the attenuations in the longer circuits are very large. Special methods are, therefore, required to maintain the necessary stability of the transmission, including automatic means for adjustment of the repeater gains to compensate for changes in the resistance of the conductors caused by temperature changes.

Telephone transmission over long cable circuits

The application of telephone repeaters has made it possible to use small gage cable circuits to handle long distance telephone service over distances up to and exceeding 1000 miles. A general picture of the long toll cable system which is being projected for use in the northeastern section of the United States was presented recently by Mr. Pilliod before this Institute. <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">∗</sup> Many of the circuits in these toll cables are so long electrically that a number of effects, which are comparatively unimportant in ordinary telephone circuits, become of large and sometimes controlling importance. For example, the time required for voice energy to traverse the circuits becomes very appreciable so that reflections of the energy may produce “echo” effects very similar to echoes of sound. The behavior of the circuits under transient impulses, even when two-way operation is not involved so that “echoes” are not experienced, is very important. In order to keep within proper limits of variation of efficiency with frequency over the telephone range special corrective measures are necessary. Owing to the small sizes of the conductors, the attenuations in the longer circuits are very large. Special methods are, therefore, required to maintain the necessary stability of the transmission, including automatic means for adjustment of the repeater gains to compensate for changes in the resistance of the conductors caused by temperature changes.