Underground Communication Research Articles

Line sources above lossy media for low-frequency underground communication

In this communication the equations for the radiation of a line source above a lossy medium (earth) are presented. Numerous data on the variation of the field as a function of distance and direction from the source, operating frequency, and conductivity are included. Changes as a function of source position are also investigated. The results can be used in the design of mine rescue communication systems.

坑内通信用誘導線の安全性に関する研究

坑内通信用誘導線の安全性に関する研究

Underground communications

DURING THE PAST few years interest in underground communications has been growing since such systems, particularly if they are installed far below the surface, are inherently invulnerable.

Investigation on the design of underground communication systems

Summary form only. An abstract of the above-titled article, taken from the 1963 IEEE International Convention (held March 25-28, New York, NY, USA), is presented.

Methods and Experience in Underground Cathodic Protection

Abstract An account is given of various methods used by a telephone company to minimize the corrosion of lead sheathed underground communication cables. Controlled drainage connections were established into all d-c railway substations, forced drainage systems set up to overcome end effects and use made of rectifiers, magnesium anodes and magnesium ribbon to overcome anodic conditions. Utility structures were consistently isolated from each other. Insulation joints were used at building entrances, resistance bonds were avoided at pipe line crossings and insulators used in anchor guys. But the advantages of isolation will soon need re-consideration in view of the growing tendency to interconnect telephone cable sheaths and power company multi-grounded neutral system. 5.2.1, 7.7, 8.2.1

A Monte Carlo Problem in Underground Communications

A Monte Carlo Problem in Underground Communications

A Monte Carlo Problem in Underground Communications

THE problem presented in this paper was a part of a larger survey into the study of the adequacy of underground communications in British collieries. The results of this were summarized in a paper to the International Conference on Operational Research in September 1957. The particular aspect considered here is a method by which the times to warn each man and clear the colliery may be calculated taking into account the various probabilities of obtaining an answer from some of the telephone points. When the Field Investigation Group of the National Coal Board were studying the problem, they devised a method of carrying out repeated warning trials by pencil and paper methods which proved to be laborious. They therefore approached the Mathematics Division of the National Physical Laboratory for advice on how this could be speeded up by the use of machines. It was found that the best method was to use punched card machines in the initial stages, to perform the mathematical calculations in the middle on the ACE pilot model, and to use punched card machines at the end. It is felt that a description of the method of using these machines to solve a particular problem may be of interest to a wider audience and this paper has therefore been prepared. In this paper, the method of approaching the problem is given first. We then derive the mathematical formulation of the problem, illustrating it with a numerical example for a particular simple telephone layout. The method of obtaining the results for repeated trials using the punched card and ACE pilot model equipment is then given. Since the need for the mathematical formulation adopted may not be apparent and since a more detailed worked example may be of interest, the Appendix gives a full statement of the solution for one colliery. The final section of the body of the report quotes the results obtained in this instance and in two others where the method was used.

Underground Communications

Underground Communications

Underground Communications

Underground Communications

Carrier current transmission for underground communication

Carrier current transmission for underground communication