432 results about "Impedance variation" patented technology

A near field RF communicator (100) has an inductive coupler (102) and a first signal provider (109, 110, 111) to cause the inductive coupler to provide a first signal that when inductively coupled to the inductive coupler of another near field RF communicator in near field range is insufficient to cause initiation of communication with that other near field RF communicator. A sensor (116) senses a change in an impedance of the inductive coupler (102) due to inductive coupling of the first signal between the inductive couplers of the said near field RF communicator and a said other near field RF communicator in near field range. A controller (107) determines whether or not another near field RF communicator is in near field range on the basis of any change in impedance sensed by the sensor and, if another near field RF communicator is determined to be in near field range, causes a second signal to be inductively coupled to the other near field RF communicator to initiate communication between the two near field RF communicators. The sensor may use a phase detector (118) to enable a change in impedance to be sensed by detecting a change in a current-voltage phase relationship resulting from a change in impedance.

The invention relates to a device that can be used to monitor the penetration of a penetration member into anatomical structures and, in particular, bone structures of a living body, the structures having at least two different electrical impedance areas. The device is characterized in that it comprises: at least one impedance meter which can be connected to at least two electrodes, at least one of the electrodes being located at a distal end of the penetration member; and at least one alert device which can produce an alert signal if the impedance meter detects an impedance variation. The invention also relates to a penetration member for the device and to an electronic board for the device.

A network tap monitors network information flow over a particular connection. By duplicating the signal and diverting a copy, the information flow can be analyzed, both in real time and without interference through the monitoring process. When the power to the tap is either turned on or off, however, the change in impedance in the tap's circuit can create an interference spike in the connection that interrupts the information flow. By reducing or eliminating the impedance change in the tap circuitry, such disruptive interruptions can be eliminated.

An improved electrical connector is provided by compensating for skew in signal conductors of a differential pair while ensuring a uniform impedance along the differential pair. Skew is equalized by regions of lower dielectric constant preferentially positioned adjacent the longer conductor of each pair. Impedance along the length of the signal conductor is equalized by a compensation portion in the first conductor that offsets for a change in impedance associated with the change in dielectric constant adjacent the longer conductor. The compensation portion may be a widening in the first conductive element relative to a nominal width of the conductive element. The skew compensation portion may be along a longer edge of the longer conductor and the impedance compensation portion may be along the shorter edge of the longer conductor.

A radio frequency (RF) power amplifier, including an external control loop and a protection circuit, which functions to maintain a constant output power during variations in impedance on the RF load. In the external control loop a collector current from an output transistor is detected and then regulated with respect to a reference current. The regulated signal is utilised to generate a bias control signal which is input to the base electrode of both a driver transistor and the output transistor. The protection circuit detects a voltage envelope at the collector electrode of the output transistor and utilises this signal to form a bias reduction signal which is input to the base electrode of the driver transistor.

A focused ultrasound system includes a transducer array, a controller for providing drive signals to the transducer array, and a switch. The transducer array includes a plurality of “n” transducer elements, and the controller includes a plurality of “m” output channels providing sets of drive signals having respective phase shift values, “m” being less than “n.” The switch is coupled to the output channels of the controller and to the transducer elements, and is configured for connecting the output channels to respective transducer elements. The controller may assign the transducer elements to respective output channels based upon a size and / or shape of a desired focal zone within the target region, to steer or otherwise move a location of the focal zone, and / or to compensate for tissue aberrations caused by tissue between the transducer array and the focal zone, geometric tolerances and / or impedance variations of the transducer elements.

To maintain consistency in different environments with different impedances, a high voltage current driver may be used as a signal generator to output a tactile signal with a constant current. The constant current ensures that the voltage between the user's finger and the object's surface or electrode remains the same even if impedances in the electrical path change. Specifically, the current driver includes a current sensing circuit that determines the average current being generated. Using a feedback loop, the measured current is compared to a reference current to determine if the correct tactile sensation is perceived by the user. As the impedance changes, the current driver detects the resulting change in the signal's current and adjusts the voltage amplitude of the generated tactile signal in order to match the measured current to the reference current.

A modular electrical connector with separately shielded signal conductor pairs. The connector may be assembled from modules, each containing a pair of signal conductors with surrounding partially or fully conductive material. The modules may have projecting portions, of conductive and / or dielectric material, that are shaped and positioned to reduce changes in impedance along the signal paths as a function of separation of conductive elements, when the connectors are separated by less than the functional mating range.

Inductive position sensors and circuit configurations are disclosed for the measurement of linear, rotary, or curved position along a motion axis. The simplified sensor structures combine one or two parts of a movable core element with a simple planar substrate having first and second inductances connected in series. Movement of the core element in parallel to the planar substrate causing the impedance of at least one of the inductances to change. Simple circuit configurations are taught by which the impedance change is converted into a useful output signal that indicates position along the motion axis.

A system and method of detecting changes in the impedance of a segment of medium voltage power line is provided. In one embodiment, the method comprises receiving voltage data comprising data of the voltage of the power lines at locations at a plurality of different points in time, receiving current data that comprises data of the current flowing between adjacent locations at the plurality of points in time, intermittently determining an impedance of the power lines between adjacent locations based on the voltage data and current data, monitoring the impedance of the power lines between adjacent locations over time, and providing a notification of a change in the impedance of a power line between adjacent locations upon detection of a change in the impedance beyond a threshold change.

A system for non-destructively evaluating components fabricated by additive manufacturing, comprising a sensor array that includes a plurality of individual elements arranged in a predetermined pattern for allowing uniform coverage of an area of an electrically conductive component to be evaluated, wherein each element in the plurality of elements further includes at least one coil that acts as an exciter coil for generating an alternating electromagnetic field when activated or a receiver coil for measuring a change in impedance of the at least one coil or both an exciter coil and receiver coil, wherein the alternating electromagnetic field generates eddy currents in the component to be evaluated, and wherein the individual elements in the sensor array are excited in a predetermined sequence during a single pass of the array over the area to be evaluated; and an XY-scanner arm adapted to receive the sensor array, wherein the XY-scanner arm is operative to generate a C-scan of the area being evaluated during the single pass.

According to the general concept disclosed herein, a circuit for adaptive matching of a load impedance to a predetermined load-line impedance of a load-line connected to a power amplifier output includes a fixed matching network between the power transistor and an adaptive matching network, whereby the fixed matching network acts as an impedance inverter which results in a relatively low insertion loss at high power. Results indicate that the impedance-inverting network can be used over more than a factor of 10 in impedance variation. Further, the usage of the fixed matching network, close to the power transistor, allows for the implementation of transmission zeros and / or for a well defined load impedance at a predetermined harmonic frequency, independent of the (variable) load impedance at the fundamental frequency.

An RF driver circuit and an orthogonal antenna assembly / configuration, are disclosed as part of a method and system for generating high density plasma. The antenna assembly is an orthogonal antenna system that may be driven by any RF generator / circuitry with suitable impedance matching to present a low impedance. The disclosed RF driver circuit uses switching type amplifier elements and presents a low output impedance. The disclosed low-output impedance RF driver circuits eliminate the need for a matching circuit for interfacing with the inherent impedance variations associated with plasmas. Also disclosed is the choice for capacitance or an inductance value to provide tuning for the RF plasma source. There is also provided a method for rapidly switching the plasma between two or more power levels at a frequencies of about tens of Hz to as high as hundreds of KHz.

The invention provides a foreign body detection method and system based on an impedance characteristic. The method comprises the steps that a detection coil is laid in an area to be detected, wherein the detection coil is connected with a capacitor element to form a resonant circuit, and a high frequency carrier signal is loaded on the resonant circuit; a resonant current signal on the resonant circuit is collected; other induction signals outside the frequency band of the high frequency carrier signal are filtered out; and finally, amplitude and phase analysis is carried out on the filtered resonant current signal to determine whether a foreign body is in the area to be detected. The method has the advantages that the impedance change of the detection coil is correspondingly acquired by detecting the change of the phase and amplitude of the resonant current signal, so as to judge whether a foreign matter exists. The method has the advantages of low cost and good effect. The original system is changed less. Especially for a wireless power transmission system, without affecting the efficiency of the original system, the method and system can be well adapted to foreign body detection in a variety of magnetic fields to improve the safety of the wireless power transmission system.

The present invention relates to a system for measuring the impedance of a skin / electrode interface and selectively modifying the system gain of the monitoring circuit to compensate for errors introduced by variations in the skin / electrode impedance. More particularly, a simplified, low-cost method for measuring and compensating for skin / electrode impedance variations is provided. The skin / electrode impedance measuring circuit and determines a system gain correction factor which may be applied to the measured signal using a software algorithm, thereby eliminating the need to change the circuit topology with a programmable gain amplifier or programmable resistor network.

The present invention relates to a microchip using polyelectrolyte salt bridge for cytometry, velocimetry, and cell sorting. The microchip comprises; a) an inlet for solution to be analyzed, b) a microchannel which provides a moving passage for solution to be analyzed, c) at least one outlet for solution to be analyzed which has passed through the moving passage, d) at least one electrode system comprising a first and a second salt bridges connected to the microchannel (the two salt bridges face each other), and a first and a second reservoirs connected to said each salt bridge (the reservoir comprises electrode and standard electrolyte solution). The microchip detects analytes in the solution to be analyzed (for example, a cell) by detecting change of impedance. In detail, anion in the standard electrolyte solution, which is comprised in the first reservoir, moves from the first salt bridge to the second salt bridge across the microchannel. Impedance change occurs by interference of anion moving across the microchannel and the change can be detected by impedance analyzer connected to electrodes in the first and the second reservoirs.

A portable electronic device is provided for sending and receiving a communication signal to and from a target, respectively. Among other components, the portable electronic device includes an antenna, a transceiver, a signal processing system and control circuitry. The signal processing system determines a distance between the target and the portable electronic device. There are various ways to determine the relative distance between the target and the device. One such methodology is to use a change in a signal that is transmitted from the transceiver and reflected from the target back to the transceiver. The change can be a frequency shift, a phase shift, a capacitive coupling change, an impedance change, or any other change which notes the presence of a target relative to the transceiver. The control circuitry may be used to change the amount of power applied to the antenna and / or to change at least one security measure of the device depending on the distance detected between the target and the device.

A method and apparatus for monitoring an AC line for impedance change. In one embodiment, the method, comprises superimposing a tone on an AC current coupled to the AC line, wherein the tone is a higher frequency than an AC voltage waveform on the AC line; applying a correlation over a sampled AC voltage waveform, obtained by sampling the AC voltage waveform, to generate a correlated signal; and determining whether at least one change in characteristic of the correlated signal occurs.

A calibration circuit block includes a first resistor network, a second resistor network, and a feedback loop. The first resistor network includes a set of transistors and receives a constant current from a constant current source. The second resistor network receives a tracking current from a tracking current source. The impedance of the second resistor network changes with temperature and process variations on the integrated circuit. The tracking current source compensates for variations in the impedance of the second resistor network that are caused by process and temperature variations to maintain a constant reference voltage at the second resistor network. The feedback loop generates calibration control signals for controlling the conductive states of the transistors in the first resistor network. The feedback loop adjusts the calibration control signals to maintain a constant impedance in the first resistor network.

The invention discloses a distributed generator islanding detection method based on impedance measurement, the principle utilizes the feature that a great change of system equivalent impedance occurs in DG synchronization and isolated network states, high-frequency voltage signals are injected at a synchronization contact point, and impedance change can be reflected by measuring voltage change, thus judging whether the system is connected with a large grid at present. In theory, the method is not influenced by load, has nothing to do with characteristics of a DG synchronization inverter, the DG number in the island in an islanding state and the topological state of a power grid, has easy realization of self-adaption setting and does not need coordination relationships. Experiment results show that the principle has excellent sensitivity, selectivity and rapidity.

The invention discloses a power grid impedance self-adaption based LC type grid-connected inverter dual-mode control method. According to the invention, a power grid impedance boundary value of mutual switching between a current source grid-connected mode and a voltage source grid-connected mode of an inverter is determined at first, the inverter adopts a current source grid-connected mode control method when the power grid impedance boundary value is less than a switching boundary value, and the inverter adopts a voltage source grid-connected mode control method when the power grid impedance boundary value is greater than the switching boundary value; and an impedance hysteresis loop based switching mode is adopted in order to improve the stability in switching. The method disclosed by the invention solves a defect that the inverter can only operate stably within a small power grid impedance variation range when adopting a single current source or voltage source grid-connected mode under different power grid impedance conditions, and stable operations of the inverter within a large power grid impedance variation range are realized through mutual switching between the current source power-grid mode and the voltage source grid-connected mode.