A three channel common carrier radio mobile system to serve industry

To show the Communication Engineer's role in American Industry, an example is made of the engineering, installation and maintenance of a three-frequency mobile system covering the oil basin of Indiana, Illinois and Kentucky. In this instance, the so-called "Tri-State" Mobile Telephone System, it was first necessary to determine the Industry's communication needs; analyze these data, manufacture specific equipment, establish transmitter sites and control points and set up traffic handling procedures. The need for the system was two-fold. An area adjacent to an existing general highway mobile cell needed to be covered and the existing cell was overloaded. Another cell on the same frequency would only aggravate conditions in the overloaded portion. The new "Tri-State" system was devised so that each of nine base stations operated on one of three frequencies. Since, at the time the System was being engineered there were no three-frequency mobile units available, a special set had to be designed and manufactured to meet the requirements of the system. Co-channel overlap was alleviated in this system by making no adjacent cells operate on the same frequency. The customer was required to select the right channel as he moved across the area. Studies made of actual results indicate that more traffic is being handled per station in this system than in the usual area coverage (highway) system. Only through cooperation of user, manufacturer and supplier together with their engineers could an adequate system have been provided.