| 摘要 |
An electromagnetic warning system 10 for miners working in underground mines 100 comprises: a transmitter unit 11, for transmitting an ultra-low frequency signal 54 through the strata 101 that define the mine openings 102; an ultra-low frequency micro-circuit receiver unit 12 equipped with antenna 50 which is tuned to the frequency of the transmitter unit 11 for producing a warning signal to the miners within an underground mine 100. The receiver may be powered from the battery of a miners cap lamp or a vehicle or a powered piece of equipment. The antenna 50 may comprise a high permeability ferrite core and tuned by capacitors in series with the antenna. The warning may be provided via a flicker in the lamp, audibly via a speaker or vehicle horn. An LCD screen may also be associated with the receiver. <IMAGE> |
