The technology of this application relates to a foreign object detection apparatus that includes a controller, a first resonant network, a signal coupler, and a phase difference detector. The signal coupler may obtain a resonance current signal corresponding to the first resonant network, and couple the resonance current signal to a preset carrier signal to obtain a coupled current signal. A frequency of the preset carrier signal can be the same as a frequency of an excitation signal. The phase difference detector may extract a low-frequency signal component from the coupled current signal, and determine a phase difference signal based on the low-frequency signal component. An amplitude of the phase difference signal correspondingly indicates a phase difference between the excitation signal and the resonance current signal. The controller may determine, based on the amplitude of the phase difference signal, whether a foreign object exists in a detection area corresponding to the first resonant network.

Maintaining a fixed frequency in a resonant circuit of an inductive sensor circuit is described. In one embodiment, an apparatus includes an inductance-to-digital converter (LDC). The LDC includes a digital filter to measure an inductance change of a sensor and convert the inductance change to a digital value. The LDC further includes a digital control loop to maintain a fixed frequency in the sensor. The sensor forms an oscillator in the digital control loop. An output of the digital control loop is representative of the inductance change of the sensor.

The invention relates to a device having, as a sensor for detecting an object arranged behind an article that is transparent to electromagnetic radiation, a coil assembly having a first transmitting coil (1.1) and a first receiving coil (2.1) arranged orthogonally with respect to the first transmitting. An evaluation unit evaluates the output signals from the coil assembly. The fact that the coil assembly comprises the first transmitting coil (1.1) and at least one further transmitting coil (1.2, 1.3, 1.4), and the first receiving coil (2.1) and at least one further receiving coil (2.2, 2.3, 2.4), wherein axes (1.5, 1.6) of the first and of the at least one further transmitting coil are orthogonal to each other, and the axes (1.5, 1.6) of the first and second transmitting coil intersect the axis (2.5) of the first receiving coil (2.1) that is orthogonal to the first and second transmitting coils (1.1, 1.2), means that a device is provided that reduces or even eliminates the grating effect. According to the method, for this purpose, the electromagnetic fields emitted by the transmitting coils as a result of a periodic AC signal during a first half period are each directed in the direction of the first receiving coil (2.1) and, during the second half period, are directed away from the first receiving call (2.1), wherein the first receiving coil (2.1) is wired and operated in series with at least one further receiving coil (2.2, 2.3, 2.4). An electromagnetic field which penetrates the coil assembly, generates mutually opposed voltages in the receiving coils (2.1, 2.3; 2.2, 2.4).

A foreign object detector, a foreign object detection system and a method for operating the foreign object detector are disclosed. In an embodiment, a foreign object detector includes a conducting wire with a first section and a second section, a first node, a second node and an intermediate node, wherein the first section electrically connects the first node to the intermediate node and has a plurality of three or more vertical segments, and wherein the second section electrically connects the intermediate node to the second node and has a plurality of three or more horizontal segments.

An inductive sensor insusceptible to external electromagnetic fields. The sensor coil is designed so as to have a first winding part and a second winding part connected thereto, the first winding part and the second winding part being wound in opposite directions. The first winding part is connected to a first coil terminal and the second winding part is connected to a second coil terminal.

A radio test system for testing a device under test is described, comprising a signal generation unit configured to generate a downlink signal to be transmitted to the device under test for over-the-air testing. The radio test system has at least one antenna configured to transmit the downlink signal via an over-the-air transmission channel to the device under test. Further, a receiver is provided that is configured to receive a response signal via the over-the-air transmission channel from the device under test. In addition, the radio test system has at least one over-the-air adapter that is connected to the signal generation unit wherein the over-the-air adapter is configured to adapt the downlink signal to be transmitted such that the over-the-air transmission channel is equalized. Further, a method for testing a device under test is described.

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 method is provided for a wireless, in particular inductive, energy transmission from an energy transmission device to a consumer, and in at least one method task, an interruption of the energy transmission from the energy transmission device to the consumer takes place in conjunction with a foreign object detection. The method provides that a cycle time of the method, and/or a duration and/or frequency of the foreign object detection is/are adapted in at least one method task as a function of a characteristic energy transmission variable of the wireless energy transmission.

A method for operating an inductive charging device, in which a foreign object detection is carried out in at least one method step. It is provided that in at least one method step, the foreign object detection is carried out as a function of at least one characteristic power transmission variable.

Front-end circuits that combine inductive and capacitive sensing are described. In one embodiment, an apparatus includes a plurality of inductive elements, an inductive measurement circuit, and a frequency divider circuit. The inductive measurement circuit is to output a first signal with a first frequency. The first signal is associated with an inductance change of one of the inductive elements. A feedback circuit can maintain the sinusoidal operation of the first signal. The frequency divider circuit can generate a second signal with a second frequency that is lower than the first frequency.