Abstract: An airborne geophysical surveying system comprising a receiver coil assembly for towing by an aircraft, the receiver assembly including a receiver coil for sensing changes in a magnetic field component of a magnetic field, and a receiver coil orientation sensing system for sensing orientation changes of the receiver coil. A controller receives signals representing the sensed changes in the magnetic field component from the receiver coil and the sensed orientation changes from the receiver coil orientation sensing system and corrects the sensed changes in the magnetic field component to provide a signal that is corrected for noise caused by changing orientation of the receiver coil in a static geomagnetic field.

Abstract: According to one example embodiment is a time domain electromagnetic (TDEM) geophysical survey system for producing a B-field measurement, comprising: a transmitter coil; a bucking coil positioned in a substantially concentric and coplanar orientation relative to the transmitter coil; a receiver coil positioned in a substantially concentric and coplanar orientation relative to the bucking coil; an electrical current source connected to the transmitter coil and bucking coil for applying a periodic current thereto; and a data collection system configured to receive a magnetic field time-derivative signal dB/dt from the receiver coil and integrate the magnetic field time-derivative signal dB/dt to generate, a magnetic B-field measurement, the transmitter coil, bucking coil and receiver coil being positioned relative to each other such that, at the location of the receiver coil, a magnetic field generated by the bucking coil has a cancelling effect on a primary magnetic field generated by the transmitter coil.

Abstract: A tow assembly for an airborne electromagnetic surveying system, including: a transmitter coil frame supporting a transmitter coil, the transmitter coil frame being formed from a plurality of serially connected frame sections forming a loop, the transmitter coil frame having rotating joints at a plurality of locations about a circumference thereof enabling the transmitter coil frame to at least partially bend at the rotating joints; and a suspension assembly for towing the transmitter coil frame behind an aircraft, the suspension assembly being attached to the circumference of the transmitter coil frame at spaced apart locations.

Abstract: A tow assembly for an airborne electromagnetic surveying system including a semi-rigid transmitter coil frame supporting a transmitter coil, the transmitter coil frame being formed from a plurality of serially connected frame sections forming a loop, the transmitter coil frame having articulating joints at a plurality of locations about a circumference thereof enabling the transmitter coil frame to at least partially bend at the articulating joints; and a suspension assembly for towing the transmitter coil frame behind an aircraft, the suspension assembly comprising a plurality of ropes and attached to the circumference of the transmitter coil frame at spaced apart locations.

Abstract: The present invention relates to a HTEM system that includes a semi-rigid bucking coil and an algorithm to determine the magnetic field B from the measured signal dB/dt. The bucking coil may be positioned in a concentric coplanar manner relative to a transmitter coil and receiver coil, in order to minimize spurious signals at the receiver coil during data acquisition time. Signals gathered by the system may be further processed by a signal processing means. Moreover, measurements performed upon data generated by the system may be performed upon the entire period of a current waveform applied to the transmitter and bucking coils.

Abstract: A receiver coil apparatus for an electromagnetic survey system, comprising: a tubular outer frame defining an internal passage; a rigid inner member; a receiver coil; a plurality of first elastic suspension members suspending the receiver coil from the rigid inner member within the internal passage; and a plurality of second elastic suspension members suspending the rigid inner member within the internal passage.

Abstract: A receiver coil tow assembly for geophysical prospecting, comprising: multiple receiver coils, each receiver coil being housed within a respective tubular outer frame section that defines a continuous passageway in which the receiver coil extends, the tubular outer frame sections being connected together to provide a skeletal frame maintaining the receiver coils in a substantially constant position relative to each other; and a tow cable connected to the skeletal frame for towing the frame to conduct a geophysical survey.

Abstract: A geophysical survey method and system that comprises: measuring along multiple axes at multiple locations within a survey area magnetic field components of a low frequency magnetic field resulting from naturally occurring electromagnetic sources using a first sensor system; measuring along multiple axes magnetic field components of a low frequency magnetic field resulting from naturally occurring electromagnetic sources using a second sensor system; and receiving information about the magnetic field components measured by the first sensor system and the second sensor system and in dependence thereon computing parameters from the received information that are independent of rotation of the first sensor system or the second sensor system about any axis thereof.

Abstract: A tow assembly for an airborne electromagnetic surveying system, including: a transmitter coil frame supporting a transmitter coil, the transmitter coil frame being formed from a plurality of serially connected frame sections forming a loop, the transmitter coil frame having rotating joints at a plurality of locations about a circumference thereof enabling the transmitter coil frame to at least partially bend at the rotating joints; and a suspension assembly for towing the transmitter coil frame behind an aircraft, the suspension assembly being attached to the circumference of the transmitter coil frame at spaced apart locations.

Abstract: The present invention is a double-suspension receiver coil apparatus and system for conducting electromagnetic surveys including, both ground-based and airborne measurements. The present invention includes at least one receiver coil suspended by way of first suspension members within an inner frame and said inner frame being suspended by second suspension members within an inner ring which is further enclosed within an outer frame. The double-suspension receiver coil apparatus functions so as to maintain the receiver coil position while minimizing vibrations in order to achieve a high signal-to-noise ratio and enable accurate measurements. The receiver coil may be in an airborne system in a near-horizontal position or in a ground system in a vertical position.

Abstract: An airborne geophysical surveying system comprising a receiver coil assembly for towing by an aircraft, the receiver assembly including a receiver coil for sensing changes in a magnetic field component of a magnetic field, and a receiver coil orientation sensing system for sensing orientation changes of the receiver coil. A controller receives signals representing the sensed changes in the magnetic field component from the receiver coil and the sensed orientation changes from the receiver coil orientation sensing system and corrects the sensed changes in the magnetic field component to provide a signal that is corrected for noise caused by changing orientation of the receiver coil in a static geomagnetic field.

Abstract: According to one example embodiment is a time domain electromagnetic (TDEM) geophysical survey system for producing a B-field measurement, comprising: a transmitter coil; a bucking coil positioned in a substantially concentric and coplanar orientation relative to the transmitter coil; a receiver coil positioned in a substantially concentric and coplanar orientation relative to the bucking coil; an electrical current source connected to the transmitter coil and bucking coil for applying a periodic current thereto; and a data collection system configured to receive a magnetic field time-derivative signal dB/dt from the receiver coil and integrate the magnetic field time-derivative signal dB/dt to generate, a magnetic B-field measurement, the transmitter coil, bucking coil and receiver coil being positioned relative to each other such that, at the location of the receiver coil, a magnetic field generated by the bucking coil has a cancelling effect on a primary magnetic field generated by the transmitter coil.

Abstract: An airborne time domain electromagnetic survey system is provided. The system and apparatus of the present invention are able to address the interest in exploring base metals and uranium deposits at depths approaching 1 kilometer. It encompasses a transmitter coil having a large magnetic dipole moment, flight stability, which is light weight, compatible with small helicopters, and can be transported, setup and repaired in the field. It is of a semi-rigid modular structure that can decrease the incidence of damage or breakage during take-off or landing in rough terrain.

Abstract: A receiver coil apparatus for an electromagnetic survey system, comprising: a tubular outer frame defining an internal passage; a rigid inner member; a receiver coil; a plurality of first elastic suspension members suspending the receiver coil from the rigid inner member within the internal passage; and a plurality of second elastic suspension members suspending the rigid inner member within the internal passage.

Abstract: A tow assembly for an airborne electromagnetic surveying system, comprising: a semi-rigid transmitter coil frame supporting a transmitter coil, the transmitter coil frame being formed from a plurality of serially connected frame sections forming a loop, the transmitter coil frame having articulating joints at a plurality of locations about a circumference thereof enabling the transmitter coil frame to at least partially bend at the articulating joints; and a suspension assembly for towing the transmitter coil frame behind an aircraft, the suspension assembly comprising a plurality of ropes and attached to the circumference of the transmitter coil frame at spaced apart locations.

Abstract: A geophysical survey method and system that comprises: measuring along multiple axes at multiple locations within a survey area magnetic field components of a low frequency magnetic field resulting from naturally occurring electromagnetic sources using a first sensor system; measuring along multiple axes magnetic field components of a low frequency magnetic field resulting from naturally occurring electromagnetic sources using a second sensor system; and receiving information about the magnetic field components measured by the first sensor system and the second sensor system and in dependence thereon computing parameters from the received information that are independent of rotation of the first sensor system or the second sensor system about any axis thereof.

Abstract: A receiver coil tow assembly for geophysical prospecting, comprising: multiple receiver coils, each receiver coil being housed within a respective tubular outer frame section that defines a continuous passageway in which the receiver coil extends, the tubular outer frame sections being connected together to provide a skeletal frame maintaining the receiver coils in a substantially constant position relative to each other; and a tow cable connected to the skeletal frame for towing the frame to conduct a geophysical survey.

Abstract: A suspension net is provided for distributing tension forces from a tow rope to an electromagnetic bird used for geophysical surveying. The suspension net allows large transmitter loop sizes, and the net structure generally avoids rope confusions that can occur during lift-up.

Abstract: The present invention relates to a HTEM system that includes a semi-rigid bucking coil and an algorithm to determine the magnetic field B from the measured signal dB/dt. The bucking coil may be positioned in a concentric coplanar manner relative to a transmitter coil and receiver coil, in order to minimize spurious signals at the receiver coil during data acquisition time. Signals gathered by the system may be further processed by a signal processing means. Moreover, measurements performed upon data generated by the system may be performed upon the entire period of a current waveform applied to the transmitter and bucking coils.

Abstract: An airborne time domain electromagnetic surveying system is provided. The system includes a tow assembly with a flexible support frame. The flexible support frame spaced apart from the aircraft includes a transmitter section with a transmitter loop and a receiver section with a sensor aligned with the central axis of the transmitter section. The flexible support frame has a lightweight modular structure that enables the surface area of the transmitter section to be increased and decreased to suit particular survey applications. The transmitter loop sends a pulse in an “ON” interval, and in an “OFF” interval the sensor measures the earth response to the pulse. The tow assembly also includes a sensor for generating selected survey data in the “ON” interval. A transmitter driver enables the creation of earthbound pulse. The system components are linked to a computer and control computer program linked thereto for controlling the functions thereof.