747 results about "Common-mode signal" patented technology

The invention discloses a balance feed differential slot antenna for restraining common-mode noise. Based on a planar substrate integrated waveguide structure, the slot antenna is adopted as a radiating unit; due to different electric field distributions in the substrate integrated waveguide under different stimulation modes, energy can be effectively radiated under the different-mode signal stimulation, and most of energy is reflected under the common-mode signal stimulation. Due to the adoption of the antenna of the structure, different-mode signals can be effectively transmitted and received, meanwhile, common-mode signals are restrained from being transmitted and received, and therefore the function of restraining common-mode noise is achieved.

An apparatus for monitoring bioelectric signals of a patient which includes a processing system and an interface for receiving external electrical signals representative of a condition of the patient. The interface is configured to convey a representation of the received external signals to the processing system, and includes a common mode cancellation amplifier circuit which is adapted to reduce common mode signal noise present in the external signals.

In order to overcome problems when using an adaptive filter for cancellation of common-mode noise in digital subscriber loops, caused by a portion of the differential signal being converted to common mode, which degrades the performance of the filter, a noise cancellation technique is proposed which compensates for this cross-coupled signal energy. In particular, a digital noise detector is used to detect one or more noisy frequency bands of the common mode signal and pass only the digitized common mode signal in those detected frequency bands through the adaptive filter to produce a digital common mode noise estimate signal. A control unit adjusts coefficients of the adaptive filter to reduce correlation between the differential signal and common mode signal. It is also proposed to compensate for the effects of stray capacitive coupling across the usual hybrid device by including an equivalent capacitive component in a common mode noise estimation circuit.

A system and device for mitigating interference in patient physiological monitoring is provided, particularly in surgical environments. One or more sets of electrodes are placed on a patient's body and connected to corresponding terminals of an input extender. The terminals of the input extender are connected to a set of signal wires encased by a ferrous shielded cable. The ferrous shielded cable connects to a signal processing unit, which includes a differential amplifier and an active drive topology to drive the shield with a common mode signal. The signal processing unit connects to physiological monitoring equipment.

The invention is directed to a method and system for supporting multiple time division duplexed (TDD) based wireless services or frequency division duplexed (FDD) wireless services on a Distributed Antenna System (DAS). A DAS can support a many wireless services, including voice and data services using the same physical equipment. TDD based services use a common clock signal to synchronize the components of the DAS for transmission and reception of TDD signals. In accordance with the invention, the DAS can include a GPS receiver which can extract a timing signal (such as a 1 pps signal) from a GPS signal and distribute the timing signal to any and all components of the DAS to enable synchronization of the components for transmitting and receiving TDD signals. The GPS receiver can be part of the interface that connects a TDD based service to the DAS or separate component of the DAS. In accordance with the invention, the DAS can distribute a reference clock signal to all of the components of the DAS in order to maintain zero frequency shift while manipulating with the carrier frequencies of the various wireless services carried by the DAS. In addition, and in accordance with the invention, two analog architectures for better integration between the services sources (BTS) and the DAS are disclosed.

A system for providing voltage isolation includes the first and second chips, each containing functional circuitry. The chips are interconnected via at least one RF isolation link that provides voltage isolation between the first chip and the second chip and limits common mode signals therebetween.

An electroimpedance tomograph with a plurality of electrodes (1) is provided, which can be placed on the body of a patient and are connected via a selector switch (60) with a control and evaluating unit (20). The control and evaluating unit (20) cooperates with the selector switch (60) such that two electrodes each are supplied with an alternating current from an AC power source (22) and the detected analog voltage signals of the other electrodes are processed in order to reconstruct therefrom the impedance distribution of the body in the plane of the electrodes, wherein a symmetrical AC power source is used to reduce common-mode signals. To further suppress interferences due to common-mode signals, provisions are made for the control and evaluating unit (20) to be set up, furthermore, for detuning the common-mode signal of the alternating current on the body against the ground by means of a common-mode signal measuring electrode (4) and, based on this, the symmetry of the symmetrical AC power source such that the common-mode signal on the body is minimized, and the corresponding detuning parameters are stored for each electrode pair.

In an adaptive filter for cancelling common-mode noise in digital subscriber loops, a narrowband noise estimator is used to detect one or more noisy frequency bands of the common mode signal and derive therefrom a first noise estimation signal. A wideband noise estimator derives from the remainder of the common mode signal a second noise estimation signal. The first and second noise estimation signals are subtracted from the differential signal, The wideband noise estimator comprises a bandstop filter for removing the frequencies detected by the narrowband noise estimator, an analog-to-digital converter for digitizing the bandstopped signal, and an adaptive filter for deriving the second noise estimation signal from the digitized bandstopped signal and, in the process, compensating for phase and gain differences, especially attributable to the interference being injected at different points along the length of the channel.

It is possible to realize an ultrasonic imaging apparatus capable of eliminating deterioration of the S/N of the ultrasonic image while suppressing enlargement of the circuit size. The ultrasonic imaging apparatus includes: an ultrasonic probe having a plurality of transducers arranged for transmitting and receiving ultrasonic waves to/from an object to be examined; transmission means for supplying a drive signal to each of the transducers; reception means for phasing/adding and receiving a reflected echo signal received by each transducer; and an image processing unit for reconfiguring an ultrasonic image based on the reflected echo signal received. The transmission means divides the plurality of transducers into a plurality of groups, supplies a common drive signal to the transducers belonging to the same group, and performs focus control by group units.

A noise suppression circuit for a communications channel (10) comprises a hybrid device (11) coupled to the channel for providing a differential output signal corresponding to a received signal. A delay unit (12) delays the differential signal by a suitable amount to allow for the generation and subtraction of a noise estimate. A summing device (13) extracts a digital common mode signal from the channel, and a noise estimation unit (16) provides a common mode noise estimate signal in dependence upon a history of the common mode signal over a predetermined period of time and over a plurality of frequency bands. The common mode noise estimate signal is combined subtractively (19) with the delayed differential signal to cancel common mode noise elements of the delayed differential signal. The noise estimation unit may comprise an analysis filter bank (20) for producing a plurality of subband signals (S1-SM), each at a different one of a plurality of different frequencies, a plurality of noise detection circuits (231-23M), each for processing a respective one of the plurality of subband signals to provide a component of the common mode noise estimate signal, and a synthesis filter bank (24) for processing the common mode noise signal components to provide the noise estimate signal.

A system and method for ultrasonic imaging utilizing multiple sets of transmit pulses differing in amplitude, frequency, phase, and/or pulse width. One embodiment has phase differences between the k transmit signal as $\frac{360}{k}$

degrees providing for constructive interference of the k^th order harmonic pulse, while an amplitude modulation of each transmit profile is constant between sets. These sets of pulses are transmitted into media of interest and received echoes from these pulses are combined to form an averaged signal. The averaged pulses represent the net common mode signal received from each of the transmit sets. This combined signal set is used to reconstruct an ultrasound image based on broad beam reconstruction methodology.

A method and apparatus are provided that corrects for differences in reception between a user-specific signal and a common signal. In one embodiment, the invention includes receiving a common pilot signal transmitted on a wide beam at a remote terminal, receiving a user-specific signal transmitted on a directed narrow beam at the remote terminal, demodulating the user-specific signal using the common pilot signal for channel estimation, estimating a phase error in the demodulated user-specific signal using known symbols in the user-specific signal, and correcting for the phase error in the demodulated user-specific signal using the phase error estimates.

An inductive component and a method for producing an inductive component are disclosed. In an embodiment, the inductive component includes a first core part having wound first and second wires and a second core part arranged on the first core part. In various embodiments the inductive component has a low mode conversion, a low inductance in differential-mode operation, a high inductance for common-mode signals, a constant characteristic impedance, a low capacitive coupling of the wires, and/or a low leakage inductance.

A method for self-testing a dual-mass linear accelerometer in which a self-test voltage is applied to urge the two masses to move in opposite directions. Self-test signals are then applied to obtain a differential mode signal to detect masses repositioned in opposing directions. During testing, common disturbances to the two masses are rejected as common mode signals.

A digital subscriber line (DSL) modem that has a canceller digital filter for cancelling crosstalk and RF interference in a received DSL signal is disclosed. The modem includes common-mode sense circuitry and also differential-mode sense circuitry. Samples of the common-mode signal are acquired during a “quiet” period of initialization of the DSL modem, and samples of the differential-mode signal are acquired during live transmission of a DSL signal. An estimate of an autocorrelation function is obtained from the common-mode samples, and a cross-correlation of the common-mode samples and differential-mode samples is also estimated. Digital filter coefficients are derived from these estimates, based on the assumption that the common-mode samples acquired during the “quiet” phase represent crosstalk and RF interference present during differential-mode communications. The digital filter coefficients can also be updated during showtime of the DSL link, using an expanded number of samples of the common-mode and differential-mode signals.

The invention relates to a magnetic positioning method in high background magnetic fields, which comprises: using a sensor group which is arranged on two spatially symmetrical position points to detect background magnetic fields and magnetic fields of a permanent magnetic block of a target object, adopting a differential amplifier circuit to take equal magnetic induction intensity of the background fields detected by the sensor group as common-mode signals for subtraction, eliminating the high background magnetic fields, and obtaining a magnetic induction intensity difference value of the permanent magnetic block of the target object on the two sensor position points in the sensor group; using N (N is more than or equal to 5) groups of sensor groups for measurement, and obtaining a magnetic induction intensity difference value vector which comprises N (N is more than or equal to 5) magnetic induction intensity difference values; adopting a differential magnetic positioning algorithm to obtain a differential magnetic positioning equation system; establishing an objective function by the differential magnetic positioning equation system and the magnetic induction intensity difference value vector which is obtained by actual measurement; and solving the objective function, and obtaining the three-dimensional position and the two-dimensional attitude of the permanent magnetic block of the target object. A device applying the positioning method comprises a sensor array (1), a signal processing module (2) and a data processing and algorithm system (3).

A method and apparatus for identifying a ground fault in a motor drive system that includes at least one three phase power conditioner that is linked to three phase supply lines and to positive and negative DC buses, the method comprising the steps of controlling the power conditioner at an operating frequency to convert power, while controlling the power conditioner to convert power, controlling the power conditioner to apply a common mode signal on each of the three phase supply lines where the common mode signal has a frequency that is different than the operating frequency, sensing the common mode signal on at least one of the three phase supply lines and when the common mode signal on the at least one of the three phase supply lines is greater than a threshold level, indicating that a ground fault has occurred.

Embodiments of methods and apparatus for reducing electromagnetic interference of a received signal are disclosed. One method includes receiving a signal over at least two conductors, extracting a common-mode signal from the at least two conductors, processing the common-mode signal, and reducing electromagnetic interference of the received signal by summing the processed common-mode signal with the received signal.

In one embodiment, a method for speaker operation comprises sensing an input common mode signal of a driver, wherein the driver drives a speaker, and adjusting the input common mode signal of the driver based on a difference between the sensed input common mode signal and a reference signal. The method also comprises sensing a current of a coil of the speaker, and control an output volume of the speaker based at least in part on the sensed current.