Drill hole electromagnetic method and apparatus for geophysical exploration utillizing in-phase and out-of-phase nulling voltages

Claim 1

A METHOD OF ESTABLISHING THE PRESSENCE OF A SUBSURFACE CONDUCTING ORE BODY COMPRISING PASSING AN ALTERNATING CURRENT THROUGH A TRANSMITTING COIL THEREBY CREATING A PRIMARY ALTERNATING MAGNETIC FLUX FIELD THROUGH A REGION OF GROUND TO LINK WITH A CONDUCTING ORE BODY, OBTAINING A SIGNAL INDUCED IN A RECEIVING COIL BY REASON OF EDDY CURRENTS FLOWING IN THE CONDUCTING ORE BODY, OBTAINING IN-PHASE AND OUT-OF-PHASE NULLING VOLTAGE COMPONENTS AND IN-PHASE AND OUT-OF-PHASE DEMODULATOR SWITCHING VOLTAGE COMPONENTS RELATIVE TO THE CURRENT FLOWING IN THE TRANSMITTING COIL, APPLYING THE SAID NULLING VOLTAGE COMPONENTS TO THE RECEIVING COIL IN DEGENERATIVE SENSE RELATIVE TO THE SIGNAL VOLTAGE INDUCED IN THE RECEIVING COIL TO THEREBY DEVELOP AN ERROR SIGNAL THEREAT, AMPLIFYING THE ERROR SIGNAL, APPLYING THE ERROR SIGNAL AS AN INPUT TO A PHASE SENSITIVE DEMODULATOR, FEEDING EITHER THE INPHASE OR OUT-OF-PHASE DEMODULATOR SWITCHING VOLTAGE COMPONENT TO THE DEMODULATOR AS A DEMODULATOR SWITCHING SIGNAL, ADJUSTING THE IN-PHASE NULLING VOLTAGE COMPONENT TO CANCEL OUT THE IN-PHASE SIGNAL VOLTAGE COMPONENT AT THE RECEIVING COIL TO THEREBY REDUCE THE DEMODULATOR OUTPUT TO ZERO WITH AN IN-PHASE DEMODULATOR SWITCHING VOLTAGE APPLIED THERETO, AND ADJUSTING THE OUT-OF-PHASE NULLING VOLTAGE COMPONENT TO CANCEL OUT THE OUT-OF-PHASE SIGNAL VOLTAGE COMPONENT AT THE RECEIVING COIL TO THEREBY REDUCE THE DEMODULATOR OUTPUT TO ZERO WITH AN OUT-OF-PHASE DEMODULATOR SWITCHING VOLTAGE APPLIED THERETO.

Claim 2

A METHOD OF ESTABLISHING THE PRESSENCE OF A SUBSURFACE CONDUCTING ORE BODY COMPRISING PASSING AN ALTERNATING CURRENT THROUGH A TRANSMITTING COIL THEREBY CREATING A PRIMARY ALTERNATING MAGNETIC FLUX FIELD THROUGH A REGION OF GROUND TO LINK WITH A CONDUCTING ORE BODY, OBTAINING A SIGNAL INDUCED IN A RECEIVING COIL BY REASON OF EDDY CURRENTS FLOWING IN THE CONDUCTING ORE BODY, OBTAINING IN-PHASE AND OUT-OF-PHASE NULLING VOLTAGE COMPONENTS AND IN-PHASE AND OUT-OF-PHASE DEMODULATOR SWITCHING VOLTAGE COMPONENTS RELATIVE TO THE CURRENT FLOWING IN THE TRANSMITTING COIL, APPLYING THE SAID NULLING VOLTAGE COMPONENTS TO THE RECEIVING COIL IN DEGENERATIVE SENSE RELATIVE TO THE SIGNAL VOLTAGE INDUCED IN THE RECEIVING COIL TO THEREBY DEVELOP AN ERROR SIGNAL THEREAT, AMPLIFYING THE ERROR SIGNAL, APPLYING THE ERROR SIGNAL AS AN INPUT TO A PHASE SENSITIVE DEMODULATOR, FEEDING EITHER THE INPHASE OR OUT-OF-PHASE DEMODULATOR SWITCHING VOLTAGE COMPONENT TO THE DEMODULATOR AS A DEMODULATOR SWITCHING SIGNAL, ADJUSTING THE IN-PHASE NULLING VOLTAGE COMPONENT TO CANCEL OUT THE IN-PHASE SIGNAL VOLTAGE COMPONENT AT THE RECEIVING COIL TO THEREBY REDUCE THE DEMODULATOR OUTPUT TO ZERO WITH AN IN-PHASE DEMODULATOR SWITCHING VOLTAGE APPLIED THERETO, AND ADJUSTING THE OUT-OF-PHASE NULLING VOLTAGE COMPONENT TO CANCEL OUT THE OUT-OF-PHASE SIGNAL VOLTAGE COMPONENT AT THE RECEIVING COIL TO THEREBY REDUCE THE DEMODULATOR OUTPUT TO ZERO WITH AN OUT-OF-PHASE DEMODULATOR SWITCHING VOLTAGE APPLIED THERETO.