A magnetic field monitor includes a magnetic field sensor that generates an electronic signal at a time period representing a magnetic field of the environment and includes a sensor transducer having a sensor bobbin, a primary coil, a secondary, over-winding coil, a sensor circuit, a controller connected to the primary coil, and a digitally controlled potentiometer connected to the secondary coil and controller. A non-linear output is converted to a quantitative linear output.

A magnetic field sensor includes a substrate, a first channel comprising a first magnetic field sensing element supported by the substrate and configured to generate a first magnetic field signal indicative of a first magnetic field experienced by the first magnetic field sensing element, a second channel comprising a second magnetic field sensing element supported by the substrate and configured to generate a second magnetic field signal indicative of a second magnetic field experienced by the second magnetic field sensing element, and at least one shield configured to reduce a bandwidth of the first magnetic field by a first amount and to reduce a bandwidth of the second magnetic field by a second amount. The shield is able to act as a magnetic anti-aliasing filter for the magnetic field sensing elements, which can then be chopped or sampled.

Methods, apparatuses, and systems for detecting a stray magnetic field are provided. An example apparatus may include a first magnetic sensor element at a first position relative to a magnetic field source to detect a target magnetic field emitted by the magnetic field source, a second magnetic sensor element at a second position relative to the magnetic field source to detect the target magnetic field emitted by the magnetic field source, and a processor element electronically coupled to the first magnetic sensor element and the second magnetic sensor element. In some examples, the processor element may be configured to: receive a first output from the first magnetic sensor element, receive a second output from the second magnetic sensor element, and detect the stray magnetic field interfering with the target magnetic field based at least in part on the first output and the second output.

A magnetic field monitor includes a magnetic field sensor that generates an electronic signal at a time period representing a magnetic field of the environment and includes a sensor transducer having a sensor bobbin, a primary coil, a secondary, over-winding coil, a sensor circuit, a controller connected to the primary coil, and a digitally controlled potentiometer connected to the secondary coil and controller. A non-linear output is converted to a quantitative linear output.

An exemplary wearable sensor unit includes 1) a magnetometer comprising a vapor cell comprising an input window and containing an alkali metal, and a light source configured to output light that passes through the input window and into the vapor cell along a transit path, and 2) a temperature control circuit external to the vapor cell and configured to create a temperature gradient within the vapor cell, the temperature gradient configured to concentrate the alkali metal within the vapor cell away from the transit path of the light.

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.

A magnetic field measurement system includes a wearable device having a plurality of wearable sensor units. Each 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 plurality magnetometers from ambient background magnetic fields. A strength of a fringe magnetic field generated by the magnetic field generator of each of the wearable sensor units is less than a predetermined value at the plurality of magnetometers of each wearable sensor unit included in the plurality of wearable sensor units.

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 that includes a magnetometer, a magnetic field generator configured to generate a compensation magnetic field configured to actively shield the magnetometer from ambient background magnetic fields, a twisted pair cable interface assembly electrically connected to the magnetometer, and a coaxial cable interface assembly electrically connected to the magnetic field generator.

A magnetic field generator includes a plurality of conductive windings comprising a first conductive winding arranged in a first plane and a second conductive winding arranged in a second plane that is substantially parallel to the first plane. The plurality of conductive windings are configured to generate, when supplied with a drive current, a first component of a compensation magnetic field. The first component of the compensation magnetic field is configured to actively shield a magnetic field sensing region located between the first conductive winding and the second conductive winding from ambient background magnetic fields along a first axis that is substantially orthogonal to the first plane and the second plane.