Wireless detonating system

Abstract

A detonator system wherein communication between detonators is achieved by using a transmitter coil in one detonator to modulate a magnetic field which is measured by means of a receiver coil in another detonator.

1 . A detonator which includes a transmitter, a receiver which in operation, receives a said first signal which is transmitted at a first signal strength from another detonator which is the same as said detonator and which is displaced by a distance from said detonator, a comparator which compares the first signal strength to the strength of said received first signal, and a processor, responsive to the comparator, operable to provide a measurement of the degree of attenuation of the received first signal from the difference between the first signal strength and the strength of the received first signal, and wherein
 a) the first signal strength is given by a value contained in the first signal, or   b) the detonator contains information based on a measurement of the first signal strength of the another detonator.   
     
     
         2 . A detonator according to  claim 1  wherein the transmitter and receiver are each adapted to function at a frequency of less than 30 kHz. 
     
     
         3 . A detonator according to  claim 2  wherein said functioning frequency is 4 kHz. 
     
     
         4 . A detonator system which includes at least a first detonator which is located in a first borehole and which includes a first transmitter and a first receiver and a second detonator, which is the same as the first detonator, which is located in a second borehole and which includes a second transmitter and a second receiver, the first borehole being spaced from the second borehole, wherein the first transmitter is actuable to transmit a first signal at a first signal strength and the second receiver is configured to receive the first signal, the second detonator including a processor to measure the strength of the received first signal and to determine at least from the difference between the strength of the transmitted first signal strength and the strength of the received first signal a measurement of the attenuation of the first signal as it travels from the first borehole to the second borehole, and wherein
 a) the first signal strength is given by a value contained in the first signal, or   b) the second detonator contains information based on a measurement of the first signal strength of the first detonator.   
     
     
         5 . A blasting system which includes control equipment and a plurality of detonators, each detonator being a detonator according to  claim 1  and including a unique identifier, and being adapted to communicate in a two-directional manner with a restricted number of detonators in adjacent boreholes, whereby a signal from the control equipment is relayed in succession via the respective transmitters and receivers of at least some of the plurality of detonators along a plurality of outbound paths to all the plurality of detonators and a signal from any detonator is relayed in succession via the respective transmitters and receivers of at least some of the plurality of detonators along a respective inbound path to the control equipment. 
     
     
         6 . A blasting system according to  claim 5  wherein each outbound path is along a path in which the sum of the degrees of attenuation of the signal between successive boreholes, in which the respective detonators are located and along which the signal is relayed, has a minimal value. 
     
     
         7 . A blasting system according to  claim 5  wherein each inbound path is along a path in which the sum of the degrees of attenuation of the signal between successive boreholes, in which the respective detonators are located and along which the signal is relayed to the control equipment, has a minimal value. 
     
     
         8 . (canceled) 
     
     
         9 . In a detonator system which includes a plurality of boreholes formed in a body of rock and a plurality of detonators which are positioned in respective boreholes, a method of determining a communication path between any two detonators, the method including the steps of transmitting from each of said plurality of detonators a respective unique signal of first signal strength, receiving said unique signal at least at each detonator in each borehole which is adjacent the borehole in which the said transmitting detonator is positioned, determining the degree of attenuation of the first signal strength for each received signal, and determining said communication path between said any two detonators as a path in which the sum of the degrees of attenuation between successive boreholes in which the respective detonators are positioned and along which a signal is relayed has a minimal value, and wherein
 a) the first signal strength is given by a value contained in said unique signal, or   b) each detonator contains information based on a measurement of the first signal strength of said unique signal transmitted by each of the other said plurality of detonators.