Abstract: An apparatus for inductive charging a battery. The apparatus includes a housing with a lower surface and a charging surface. A rechargeable device with a rechargeable battery may be placed on the charging surface. The apparatus further includes a controller for driving an oscillator, wherein the controller receives power from a power source. A first charger coil and second charger coil are disposed within the housing and are coupled to the oscillator. The first charger coil and second charger coil create a substantially horizontal magnetic field in the volume of space above the charging surface.

Abstract: A wireless communication system automatically aligns a magnetic induction field to establish a two-way communication link between a stationary base unit located, for example, at a user's work station, and a remote unit worn by the user, for example, as a headset or body pack. At any point in time, the base unit and the remote unit have an arbitrary relative orientation to each other. The base unit senses this orientation, then aligns the magnetic induction field to maintain the communication link with the remote unit. In one embodiment, the base unit preferably includes an aerial array having a number of mutually orthogonal windings. Each winding produces a signal when a magnetic induction field generated by the remote unit passes through the base unit. A selector module selects the longitudinal axis of the winding with the strongest signal as an approximation of a direction vector defining the orientation of the magnetic induction field relative to the base unit.

Abstract: Communication systems requiring a user to wear a headset or body pack preferably include small aerials that use ferrite cores to achieve transmission efficiency. Driving such aerials typically requires the use of a transformer to obtain the strongest possible magnetic field where only a limited supply voltage is available. The limited supply voltage is addressed by combining a step-up transformer and an aerial array on a single permeable core. The transformer includes a primary winding and a secondary winding that are wound along the circumference of the circular cross-section of a toroidal core. The aerial array includes a transmit winding and a receive winding. The transmit winding is wound along the diameter of the toroidal core and the receive winding is wound along the circumference of the toroidal core. In one embodiment, the receive winding is divided into two matching halves.

Abstract: A communication link includes a base unit and a remote unit that each include a transmit aerial and a receive aerial. These units communicate via magnetic inductive fields. The transmit aerial may be an array that shapes the field to transmit in front of the base unit to minimize interference between adjacent base units. Transmission from the base unit to the remote unit preferably uses magnetic inductive fields that are orthogonal to the magnetic inductive fields that transmit from the remote unit to the base unit. Accordingly, the aerials include aerials for receiving and transmitting in such orientations. A tri-axial array includes three aerials that are orthogonal to each other to allow the aerials to be driven by currents that are phase shifted and amplitude modulated so that the plane of the field is selectively tilted to maximize coupling between the base unit and remote unit. Such tilting allows the user of the remote unit to move relative to the base unit and maintain maximum coupling.

Abstract: A system for tracing routes of conductors is disclosed. An alternating signal is applied to the object to be traced (12), and the field produced by this signal is detected remotely from the object. In order to distinguish between signals produced by the object being traced and those produced by nearby conductors (14) due to capacitive coupling, the alternating signal has first and second components, related in frequency and phase, and the field is detected at a plurality of positions. The phase relationship of the detected signals is investigated to determine unambiguously the position of the object concerned. In one embodiment, the second frequency component is a harmonic of the other. In another embodiment the frequency of the second component is the frequency of the first, plus or minus a sub-harmonic of the first.

Abstract: A temporarily inaccessible object such as a locator in a buried pipe has a first transmitter (1) which produces an electromagnetic field rotating about a horizontal axis (A--A) and a second transmitter (7) which produces a solenoidal field centered on that axis. The rotating field is remotely detected at a receiver using a vertical axis coil (6) which locates the object and a reference signal is obtained by a horizontal coil (9) at the receiver. The roll .alpha. of the object may be determined by detecting the phase difference between the detected signal and the reference signal. The yaw or angle .beta. of departure from a desired horizontal direction is obtained from a maximum output of the horizontal receiver coil (9). With a third transmitter (15) producing another phase related field rotating about a horizontal axis transverse to the first one (A--A) a similar technique at the receiver gives the pitch angle .gamma..

Abstract: An apparatus and method for determining the position and orientation of a remote object in relation to an observation point comprises a transmitter for sending a magnetic field signal and a receiver for receiving and analyzing the magnetic field signal. The transmitter or the receiver is positioned at the observation point and the other is secured on the remote object. The transmitter has three coils positioned on a ferromagnetic core with their axes mutually orthogonal to each other and connected to a polyphase power to produce a magnetic field around the coils. The coils are connected and energized in pairs to produce a magnetic field rotating about the axis of the third coil. The receiver has three coils positioned on a ferromagnetic core with their axes mutually orthogonal to each other and responsive to the magnetic field produced by the tranmsitter. The receiving coils are connected in pairs to detect the phase relationship and magnitude of the signal to indicate the orientation of the remote body.