Dedicated wire performs better

Proposes that mine operators can improve trolley carrier phone communications by using dedicated wire instead of the trolley wire/rail as the transmission path. Explains that when the mine dispatcher's carrier phone is connected to the dedicated wire, the natural electromagnetic coupling between the dedicated-wire/rail line and the trolley-wire/rail line provides enough signal coupling to achieve strong communications throughout the mine's rail haulage network. Presents a simplified schematic mine map of a rail haulage network showing the dedicated wire layout with its terminations and signal splitters. Points out that the dedicated wire should be suspended from the roof or rib on the wide side of the haulageway tunnel like a pager phone line. Concludes that the simple and stable configuration of the dedicated wire/rail transmission line is the key to its predictable and reliable performance.