An apparatus comprises a first substrate and two coils supported by the first substrate and arranged next to each other, the coils configured to each generate a magnetic field which produces eddy currents in and a reflected magnetic field from a conductive target, the two coils arranged so their respectively generated magnetic fields substantially cancel each other in an area between the coils. One or more magnetic field sensing elements are positioned in the area between the coils and configured to detect the reflected magnetic field.

An apparatus comprises a first substrate and two coils supported by the first substrate and arranged next to each other, the coils configured to each generate a magnetic field which produces eddy currents in and a reflected magnetic field from a conductive target, the two coils arranged so their respectively generated magnetic fields substantially cancel each other in an area between the coils. One or more magnetic field sensing elements are positioned in the area between the coils and configured to detect the reflected magnetic field.

The present invention describes an electromagnetically positioning system, which can measure a position and orientation of a remote object in an isolated targeted examination area with time. Specifically, the remote object is a remote miniaturized examination device. During the location process, both the electromagnetically positioning system and the remote miniaturized examination device can have expected or unexpected, controlled and can-not-be-controlled movement. By implementing the electromagnetically positioning system, disclosed herein, position and orientation information of the remote miniaturized examination device can be linked with time, any information collected by the remote miniaturized examination device, for example, the photo images collected, can be associated kinetically with time and positioning information of the examination device, when the remote miniaturized examination device travels inside an isolated target examination area.

One embodiment is a magnetic field measurement system that includes at least one magnetometer having a vapor cell, a light source to direct light through the vapor cell, and a detector to receive light directed through the vapor cell; at least one magnetic field generator disposed adjacent the vapor cell; and a feedback circuit coupled to the at least one magnetic field generator and the detector of the at least one magnetometer. The feedback circuit includes at least one feedback loop that includes a first low pass filter with a first cutoff frequency. The feedback circuit is configured to compensate for magnetic field variations having a frequency lower than the first cutoff frequency. The first low pass filter rejects magnetic field variations having a frequency higher than the first cutoff frequency and provides the rejected magnetic field variations for measurement as an output of the feedback circuit.

One embodiment is a magnetic field measurement system that includes at least one magnetometer having a vapor cell, a light source to direct light through the vapor cell, and a detector to receive light directed through the vapor cell; at least one magnetic field generator disposed adjacent the vapor cell; and a feedback circuit coupled to the at least one magnetic field generator and the detector of the at least one magnetometer. The feedback circuit includes at least one feedback loop that includes a first low pass filter with a first cutoff frequency. The feedback circuit is configured to compensate for magnetic field variations having a frequency lower than the first cutoff frequency. The first low pass filter rejects magnetic field variations having a frequency higher than the first cutoff frequency and provides the rejected magnetic field variations for measurement as an output of the feedback circuit.

An electronic device is provided. The electronic device includes an inertial-measurement unit, an environmental-parameter database, and a computation unit. The inertial-measurement unit is configured to detect inertial information of the electronic device to generate sensor data. The computation unit is configured to perform pose estimation according to the sensor data to obtain a first pose. In response to the electronic device being in a non-moving state, the computation unit performs pose calibration on the first pose according to an environmental parameter in the environmental-parameter database corresponding to a current location at which the electronic device is located.

A non-metallic layer stranded optical cable with a reversal point capable of being positioned and a detection method thereof, which solves the problems of determining a reversal point of a cable core and performing an operation of drawing out an optical fiber from the optical cable. The present invention relates to a non-metallic layer stranded optical cable, and the key points of the technical solution thereof includes a cable core and a metal film provided at each reversal point of the cable core, and an outer sheath is provided on the cable core.

An active shield magnetometry system comprises at least one magnetic field actuator configured for generating an actuated magnetic field that at least partially cancels an outside magnetic field, thereby yielding a total residual magnetic field. The active shield magnetometry system further comprises a plurality of magnetometers respectively configured for measuring the total residual magnetic field and outputting a plurality of total residual magnetic field measurements. The active shield magnetometry system further comprises at least one feedback control loop comprising at least one optimal linear controller configured for controlling the actuated magnetic field at least partially based on at least one of the plurality of total residual magnetic field measurements respectively output by at least one of the plurality of magnetometers.

An exemplary magnetic field measurement system includes a wearable sensor unit and a single controller. The wearable sensor unit includes a plurality of magnetometers and a magnetic field generator configured to generate a compensation magnetic field configured to actively shield the magnetometers from ambient background magnetic fields. The single controller is configured to interface with the magnetometers and the magnetic field generator.

An exemplary magnetic field measurement system includes a wearable sensor unit and a controller. The wearable sensor unit includes 1) a magnetometer comprising a photodetector and 2) a magnetic field generator configured to generate a compensation magnetic field configured to actively shield the magnetometer from ambient background magnetic fields. The controller is configured to interface with the magnetometer and the magnetic field generator and includes a differential signal measurement circuit configured to measure current output by the photodetector.