Disclosed is a system for updating a reference time from a decaying rotational period of a pulsar. The system can include: a database (DB) configured to store: coordinates for a pulsar; a recorded rate of rotation (RROR) for the pulsar; a rotational rate of decay (RROD) function for the pulsar; and a recorded reference time for the pulsar. A sensor can be configured to collect electromagnetic pulsar radiation from the pulsar and generate sensor data. A signal processor module can be configured to receive the sensor data, generate an observed rate of rotation (OROR) signal profile, generate a current rate of rotation (CROR) for the pulsar from the OROR signal profile, and update the RROR from the CROR. A time processor module can be configured to receive the RROD function and the CROR, and to solve the RROD function to output a reference time of the pulsar.

Disclosed is a magnetotelluric measurement system, comprising: a magnetic sensor probe for collecting an electromagnetic signal as an impulse response of an earth and transmitting the same to a signal readout circuit; the signal readout circuit configured for receiving and amplifying the electromagnetic signal collected by the magnetic sensor probe; a data acquisition and processing module configured for receiving and processing electromagnetic signal amplified by the signal readout circuit; a storage module configured for storing the electromagnetic signals amplified by the signal readout circuit and processed by the data acquisition and processing module; a first casing for enclosing the magnetic sensor probe and the signal readout circuit; and a second casing for enclosing the data acquisition and processing module and the storage module. The disclosure realizes the detection of low-noise wide-frequency band magnetic field signal, and solves problems involving deep detection of the mineral resources in complex areas.

Techniques for improved modeling of subsurface formations are disclosed that employ a combination of streaming potential and controlled source electromagnetic techniques to gain an improved understanding of subsurface conditions.

A distributed three-dimensional (3D) induced polarization (IP) data acquisition and processing device, including: a transmitter module, a computer and multiple receiver modules, where the transmitter module is configured to transmit a preset current signal to a ground where a region to be measured is located, and record the current signal in real time; the receiver modules each are configured to acquire a voltage signal and an apparent polarizability of the ground where the region to be measured is located, and record the voltage signal and the apparent polarizability in real time; and the computer is configured to acquire the current signal, the voltage signal and the apparent polarizability, respectively process the current signal and the voltage signal to obtain an apparent resistivity of the region to be measured, and analyze, according to the apparent polarizability and the apparent resistivity, a polarizability and a conductivity of the region to be measured.

A system for detecting an object in a subsurface environment includes a first recorder of a vertical electromagnetic component, including first pair of polarization orientation components, of an electromagnetic field in a region of interest, a second recorder of an orthogonal electromagnetic component, including second pair of polarization orientation components, of the electromagnetic field in the region of interest, at least one processor configured to derive a pair of transfer functions that relates the vertical electromagnetic component and the orthogonal electromagnetic component of the electromagnetic field for each of the polarization orientation components, at least one processor configured to determine a simulation of the pair of transfer functions for a given impedance distribution, and at least one processor configured to infer a subsurface impedance map using the pair of transfer functions of the recorded data and the simulation of the pair of transfer functions.

A tool, method and system for ranging between two wellbores. The target wellbore includes a conductive member disposed within a portion of the target wellbore. An investigative wellbore includes an electromagnetic gradiometer positioned within the wellbore, as well as emitter electrode and return electrode spaced apart along an investigative wellbore, preferably in the process of being drilled. The position of the emitter electrode and the return electrode are selected to optimize current transmission to the target wellbore in order to enhance the electromagnetic field emanating from the conductive member at a desired point along the conductive member. Where the electrodes and gradiometer are carried by a drill string, gap subs are positioned along the drill string to minimize conduction of current along the drill string therebetween. In some embodiments, the gradiometer is positioned between the emitter and return electrodes.

The present disclosure is adapted to the field of geological exploration, and provides to a high-frequency magnetotelluric sounding instrument-based inversion method for energy spectrum, which provides that the energy spectrum obtained by transforming the time sequence signal in the high-frequency magnetotelluric data is defined as the model objective function and the data in the inversion objective function, to obtain the underground large-scale conductivity structure by inversion, which avoids the modification of the conventional detection method and detection instrument, and does not add extra expense and is easy to operate.

A method of locating a coal-rock main fracture by an electromagnetic radiation from a precursor of a coal-rock dynamic disaster is provided. At least four groups of three-component electromagnetic sensors are arranged in the underground tunnels, and each group of sensors includes three directive antennas for receiving electromagnetic signals orthogonal to each other. The electromagnetic signals are collected by a monitoring host. The signals are ensured to be received by different sensors synchronously via an atomic clock. The direction of the magnetic field line is determined by performing a vector superposition on strengths of the three-component electromagnetic signals of each group of sensors. The planes of electromagnetic wave propagation perpendicular to the direction of the magnetic field line are determined accordingly. The location of the coal-rock fracture is determined by the intersection point of the planes of electromagnetic wave propagation determined by the multiple groups of sensors.

An electromagnetic (EM) receiver system for measuring EM signals. The EM receiver system includes a platform; a coil for measuring EM signals; and first to third suspension mechanisms located between the platform and the coil so that the coil oscillates relative to the platform, and the first to third suspension mechanisms attenuate motion induced noise introduced by towing the receiver system above ground.

A transmission device of a submarine resource exploration system includes a transmission unit which transmits a predetermined transmission artificial signal transmitted in order to perform exploration of submarine resources in water using water as a medium. A reception device includes a reception unit which receives a composite signal of a received artificial signal representing a signal propagated to the reception device using water as a medium in the transmission artificial signal, and a self-potential propagated to the reception device using water as a medium due to a potential anomaly generated due to submarine resources. A signal processing device includes a signal processing unit which separates the composite signal into the received artificial signal and the self-potential.