Radio communication in subways and mines through repeater amplifiers and leaky transmission lines
Isberg, R.A.
Vehicular Technology Conference, 1978. 28th IEEE
Volume 28, Issue , 22-24 March 1978 Page(s): 248 - 254
Digital Object Identifier
Summary: This paper is a report of the Author's visits to London Transport, the National Coal Board's Mining Research Establishment and the Cadley Hill Coal Mine where a "daisy chain" radio repeater and leaky feeder system is used for underground communication. A considerable amount of research and development of "daisy chain" radio repeater systems using leaky transmission lines has been accomplished in the United Kingdom by Dr. D. J. R. Martin of the National Coal Board's Mining and Research Establishment and Mr. Q. V. Davis of the University of Surrey. The basic "daisy chain" repeater system is similar in concept to coaxial cable telephone repeater and submarine communications cable systems which use amplifiers spaced at intervals to compensate for the attenuation of the cable. London Transport also has developed a prototype "daisy chain" radio repeater system which was commissioned into regular operation on a three mile section of the Bakerloo Underground railway in August, 1977. This system uses twenty-two 400 milliwatt repeater amplifiers spaced approximately 500 meters apart along leaky coaxial transmission lines which are supported from the walls of the subway tunnels and under the platforms of passenger stations. The other half of the Bakerloo Underground is equipped with three conventional twenty-five watt base stations feeding tee sections of leaky coaxial transmission line. While both systems perform satisfactorily, the section that is equipped with "daisy chain" amplifiers does not have transition zones between the tee sections of leaky cable, requires fewer telephone control lines and uses a simpler control system. By combining the techniques of the on-channel signal booster and the "daisy chain" repeater system using selective filters and wide band linear amplifiers it should be possible to extend signals received from base stations above ground into subways. This would satisfy the requirements for providing, at a much reduced cost, multi-channel radio communications for not only the transit system but also police, fire, para-medical and paging services.
View citation and abstract |
Cart
