Interaction of Radio Transmissions on Mine Monitoring and Control Systems

This report describes the creation of an efficient method to determine if command, control, communication, and monitoring (3cm) equipment in coal, metal, and nonmetal mines is susceptible to radio frequency interference (RFI) from the medium-frequency (MF) radio communications system. A qualitative and quantitative RFI test plan was developed for in-mine and laboratory evaluation of the equipment. The laboratory testing was accomplished using the transverse electromagnetic wave (TEM) test chamber. Detailed information on the test plan and the TEM test chamber is included. During in-mine testing of the MF system, some underground equipment malfunctioned when the transmitter's radiating antenna was in close proximity. Electromagnetic compatibility (EMC) testing was done on three levels: component (circuit or box), subsystems, and system. Nine tables are included that show the results of testing various equipment for RFI.