Abstract: An electromagnetic (EM) receiver system for measuring EM signals. The EM receiver system includes a survey EM transmitter for generating survey EM signals within a first frequency range; a calibration EM transmitter for generating a calibration signal; a receiver section, including a receiver housing and a receiver, that measures both the survey EM signals and the calibration signal; and a calibration device connected to the calibration EM transmitter and to the receiver, the calibration device configured to control a frequency and waveform of the calibration signal. The calibration device is further configured to calculate a response function of the receiver, based on the calibration signal.

Abstract: An electromagnetic geophysical exploration system includes transmitter-receiver pairs configured to transmit waveforms and sense signals in different frequency bands. A controller directs the transmitters of the transmitter-receiver pairs to transmit the waveforms at different moments while the electromagnetic geophysical exploration system is flown over a subsurface formation. The signals sensed by the receivers enable geophysical exploration of the subsurface formation.

Abstract: An electromagnetic (EM) receiver system for measuring EM signals. The EM receiver system includes a survey EM transmitter for generating survey EM signals within a first frequency range; a calibration EM transmitter for generating a calibration signal; a receiver section, including a receiver housing and a receiver, that measures both the survey EM signals and the calibration signal; and a calibration device connected to the calibration EM transmitter and to the receiver, the calibration device configured to control a frequency and waveform of the calibration signal. The calibration device is further configured to calculate a response function of the receiver, based on the calibration signal.

Abstract: An electromagnetic (EM) receiver system for measuring EM signals. The EM receiver system includes a survey EM transmitter for generating survey EM signals within a first frequency range; a tracking EM transmitter for generating tracking signals within a second frequency range; and a receiver section including a receiver that measures both the survey EM signals and the tracking signals.

Abstract: An electromagnetic geophysical exploration system includes a first transmitter-receiver pair that includes a first transmitter configured to transmit a first waveform in a first spectrum and a first receiver configured to sense signals in the first spectrum; and a second transmitter-receiver pair that includes a second transmitter configured to transmit a second waveform in a second spectrum, the second spectrum having a frequency higher than a frequency of the first spectrum, and a second receiver configured to sense signals in the second spectrum; and a control portion. The control portion controls the first transmitter to transmit the first waveform with a first given strength or shape in the first spectrum, and controls the second transmitter to transmit the second waveform with a second given strength or shape in the second spectrum, after a specified time delay.

Abstract: An electromagnetic geophysical exploration system includes a first transmitter configured to transmit a first waveform in a first spectrum, a first receiver configured to sense signals in the first spectrum, a second transmitter configured to transmit a second waveform in a second spectrum, the second spectrum having a frequency higher than a frequency of the first spectrum, a second receiver configured to sense signals in the second spectrum, the second receiver configured to be minimum-coupled to the second transmitter, wherein a transmitter coil of the second transmitter is disposed between an inner receiver coil and an outer receiver coil of the second receiver, and the inner receiver coil and the outer receiver coil of the second receiver surround the transmitter coil of the second transmitter, and a control portion configured to control the first transmitter and the second transmitter.

Abstract: An electromagnetic (EM) receiver system for measuring EM signals. The EM receiver system includes a survey EM transmitter for generating survey EM signals within a first frequency range; a tracking EM transmitter for generating tracking signals within a second frequency range; and a receiver section including a receiver that measures both the survey EM signals and the tracking signals.

Abstract: A method and system for active cancellation of transient signals and dynamic loop configuration for geophysical exploration is disclosed. The method includes controlling a transmitter to transmit a waveform in a frequency spectrum during an on-time. The transmitter includes a plurality of turns of wire. The method also includes controlling a plurality of switches to direct an electrical signal through the plurality of turns of wire. The plurality of switches electrically coupled to the plurality of turns of wire. The method further includes controlling a switch of the plurality of switches to direct a first portion of a transient current in an opposite direction from a direction of a second portion of the transient current during an off-time.

Abstract: An electromagnetic (EM) receiver system for measuring EM signals. The EM receiver system includes a frame; a first EM receiver attached to the frame and configured to measure the EM signals within a first frequency range; and a second EM receiver attached to the frame and configured to measure the EM signals within a second frequency range. Corresponding axes of the first and second EM receivers are substantially parallel to each other.

Abstract: An electromagnetic (EM) receiver system for measuring EM signals. The EM receiver system includes a survey EM transmitter for generating survey EM signals within a first frequency range; a tracking EM transmitter for generating tracking signals within a second frequency range; and a receiver section including a receiver that measures both the survey EM signals and the tracking signals.

Abstract: A method and system for active cancellation of transient signals and dynamic loop configuration for geophysical exploration is disclosed. The method includes controlling a transmitter to transmit a waveform in a frequency spectrum during an on-time. The transmitter includes a plurality of turns of wire. The method also includes controlling a plurality of switches to direct an electrical signal through the plurality of turns of wire. The plurality of switches electrically coupled to the plurality of turns of wire. The method further includes controlling a switch of the plurality of switches to direct a first portion of a transient current in an opposite direction from a direction of a second portion of the transient current during an off-time.

Abstract: An electromagnetic (EM) receiver system for measuring EM signals. The EM receiver system includes a frame; a first EM receiver attached to the frame and configured to measure the EM signals within a first frequency range; and a second EM receiver attached to the frame and configured to measure the EM signals within a second frequency range. Corresponding axes of the first and second EM receivers are substantially parallel to each other.

Abstract: An electromagnetic (EM) receiver system for measuring EM signals. The EM receiver system includes a frame; a first EM receiver attached to the frame and configured to measure the EM signals within a first frequency range; and a second EM receiver attached to the frame and configured to measure the EM signals within a second frequency range. Corresponding axes of the first and second EM receivers are substantially parallel to each other.

Abstract: Systems and methods for a composite magnetic field sensor is disclosed. The electromagnetic survey system includes a first receiver configured to sense signals in a first spectrum based on sensing a magnetic field. The system includes a second receiver configured to sense signals in a second spectrum based on sensing a time rate of change of the magnetic field. The second spectrum has a frequency range higher than the first spectrum. The system further includes a transmitter configured to transmit a specified waveform and a control system configured to control the transmitter to transmit the specified waveform. The control system is also configured to receive signals sensed by the first receiver, receive signals sensed by the second receiver, and store the signals received from the first receiver and the signals received from the second receiver.

Abstract: A system and method for electromagnetic geophysical exploration is provided. The system includes a first transmitter (210) configured to transmit a first waveform in a first spectrum and a first receiver (212) configured to sense signals in the first spectrum. The system also includes a second transmitter (220) configured to transmit a second waveform in a second spectrum, and a second receiver (222) configured to sense signals in the second spectrum and minimum-coupled to the second transmitter. The second spectrum has a frequency higher than a frequency of the first spectrum. The system further includes a control portion configured to control the first transmitter to transmit the first waveform, and control the second transmitter to transmit the second waveform after a specified time delay. The control portion is configured to receive signals sensed by the first receiver in the first spectrum, and receive signals sensed by the second receiver in the second spectrum.

Abstract: A method and system for active cancellation of transient signals and dynamic loop configuration for geophysical exploration is disclosed. The method includes controlling a transmitter to transmit a waveform in a frequency spectrum during an on-time. The transmitter includes a plurality of turns of wire. The method also includes controlling a plurality of switches to direct an electrical signal through the plurality of turns of wire. The plurality of switches electrically coupled to the plurality of turns of wire. The method further includes controlling a switch of the plurality of switches to direct a first portion of a transient current in an opposite direction from a direction of a second portion of the transient current during an off-time.

Abstract: An electromagnetic (EM) receiver system for measuring EM signals. The EM receiver system includes a survey EM transmitter for generating survey EM signals within a first frequency range; a tracking EM transmitter for generating tracking signals within a second frequency range; and a receiver section including a receiver that measures both the survey EM signals and the tracking signals.

Abstract: An electromagnetic (EM) receiver system for measuring EM signals. The EM receiver system includes a frame; a first EM receiver attached to the frame and configured to measure the EM signals within a first frequency range; and a second EM receiver attached to the frame and configured to measure the EM signals within a second frequency range. Corresponding axes of the first and second EM receivers are substantially parallel to each other.

Abstract: An airborne electromagnetic survey system for conducting geological mapping is disclosed. A transmitter closed loop structure is used in the system and is designed for connection to a towing airborne vehicle. The transmitter loop structure comprises a plurality of interconnected loop segments, and transmitting means are fitted to at least one of the loop segments for generating and transmitting an earthbound primary electromagnetic field effective for geological surveying. Sensing means are fitted to the loop segments for receiving and sensing a vertical component of a secondary resulting electromagnetic field which arises from an interaction of the primary electromagnetic field with ground bodies that are traversed by the sensing means, while simultaneously nulling the primary electromagnetic field.

Abstract: An airborne electromagnetic survey system for conducting geological mapping is disclosed. A transmitter closed loop structure is used in the system and is designed for connection to a towing airborne vehicle. The transmitter loop structure comprises a plurality of interconnected loop segments, and transmitting means are fitted to at least one of the loop segments for generating and transmitting an earthbound primary electromagnetic field effective for geological surveying. Sensing means are fitted to the loop segments for receiving and sensing a vertical component of a secondary resulting electromagnetic field which arises from an interaction of the primary electromagnetic field with ground bodies that are traversed by the sensing means, while simultaneously nulling the primary electromagnetic field.