Preliminary Performance Predictions For Electromagnetic Through-The-Earth Mine Communications

This report comprises three working memoranda that present preliminary performance estimates for baseband voice and narrowband through-the-earth electromagnetic communications systems of principal interest to the Bureau of Mines for operational/emergency mine communications. The calculations were prepared to obtain early indications of the feasibility and governing parameters of such communications systems. They are based on limited but pertinent coal mine electromagnetic noise data acquired to date by Bureau contractors and on theoretical signal-attenuation characteristics for two transmitter antenna types of interest to the Bureau.