1334 results about "Signal response" patented technology

A prefilter (5) for an audio system comprising a loudspeaker (1) in a room (2), which corrects both amplitude and phase errors due to the loudspeaker (1) by a linear phase correction filter response and corrects the amplitude response of the room (2) whilst introducing the minimum possible amount of extra phase distortion by employing a minimum phase correction filter stage. A test signal generator (8) generates a signal comprising a periodic frequency sweep with a greater phase repetition period than the frequency repetition period. A microphone (7) positioned at various points in the room (2) measures the audio signal processed by the room (2) and loudspeaker (1), and a coefficient calculator (6) (e.g. a digital signal processor device) derives the signal response of the room and thereby a requisite minimum phase correction to be cascaded with the linear phase correction already calculated for the loudspeaker (1). Filter (5) may comprise the same digital signal processor as the coefficient calculator (6). Applications in high fidelity audio reproduction, and in car stereo reproduction.

A method for communication over a wireless local area network (WLAN) includes receiving uplink signals from a plurality of stations in the WLAN. Responsively to the uplink signals, a set of the stations is selected for inclusion in a spatial multiplexing group. Downlink signals are transmitted simultaneously to the stations in the set using spatial division multiplexing (SDM).

A power supply including a regulation circuit that maintains an approximately constant load current with line voltage. An example circuit includes a switch including first, second and third terminals. The first terminal is coupled or decoupled to the second terminal in response to a control signal received at the third terminal. Voltage sense circuitry is included and is coupled to sense a voltage drop across the switch. The voltage drop is representative of a current in the switch during an on time of the switch. The voltage sense circuitry has a variable current limit threshold that increases between a first level and a second level during the on time of the switch. The control signal is responsive to the variable current limit threshold to regulate a power supply with an output characteristic having an approximately constant output voltage below an output current threshold and an approximately constant output current below an output voltage threshold.

A wireless transceiver (5008) includes a low power radio frequency (LPRF) component (5010) that powers down to conserve energy and powers up in response to a signal; and a second receiver (5014) that provides the signal via line (5018) in response to receipt of a radio frequency broadcast. The broadcast is targeted to activate particular transceivers by including in the broadcast identifications such as class designations, in which case the transceivers power up and form networks. A transceiver may include one or more identifications and may include a unique identification of the transceiver itself. The LPRF component may be a Bluetooth radio, but the overall transceiver itself only draws about 10 to 15 μA while actively awaiting and screening for a targeted broadcast.

A multimode wireless receiver circuit (10) includes multi-receiver control and interference detection logic (50) and least two separate receivers: a first receiver (20) associated with a first radio access technology and a second receiver (30) associated with a second radio access technology. The multi-receiver control and interference detection logic (50) simultaneously controls the second receiver (30) to detect an interference blocker signal (100), while the first receiver (20) receives at least a portion of the wireless signal (80) and the interference product signal (90). In response to the second receiver (30) detecting the interference blocker signal (100), the multi-receiver control and interference detection logic (50) adjusts at least one operating condition of the first receiver (20) such that the interference product signal (90) received by the first receiver (20) is reduced.

A method for communication includes arranging a first plurality of access points, including at least first and second access points, to communicate on a common frequency channel in a wireless local area network (WLAN) with a second plurality of mobile stations, comprising at least first and second mobile stations. The access points are linked to communicate with one another over a communication medium. A message is sent over the communication medium to at least one of the first and second access points so as to cause the first and second access points to simultaneously transmit downlink signals to the first and second mobile stations, respectively. The downlink signals are transmitted simultaneously from the first and second access points responsively to the message.

A wireless location and identification system includes a controller and a tag. The controller has a projector configured to generate a unique temporal sequence of light intensities for each pixel in an output image of the projector and a wireless transceiver configured to emit an output signal and receive an input signal. The tag includes a photo-sensor configured to sense the unique temporal sequence of light intensities of a particular pixel, a transducer configured to receive the output signal from the transceiver, and a means for modulating, according to the unique temporal sequence of light intensities, the input signal for the transceiver in response to receiving the output signal and sensing the unique temporal sequence of light intensities of the particular pixel to indicate a location of the tag to the controller.

Systems and methods utilized a wireless transceiver (5008) having a low power radio frequency (LPRF) component (5010) that powers down to conserve energy and powers up in response to a signal; and a second receiver (5014) that provides the signal via line (5018) in response to receipt of a radio frequency broadcast. The broadcast is targeted to activate particular transceivers by including in the broadcast identifications such as class designations, in which case the transceivers power up and form networks. A transceiver may include one or more identifications and may include a unique identification of the transceiver itself. The LPRF component may be a Bluetooth radio, but in such case the overall transceiver itself only draws about 10 to 15 μA while actively awaiting and screening for a targeted broadcast.

An ultrasound imaging system with pixel oriented processing is provided in which an acoustic signal is generated, echoes from the acoustic signal are received at a plurality of receiving elements to obtain echo signals that are then stored, a given pixel is mapped into a region of the stored signals, the mapped region of the stored echo signals is organized into array for the given pixel after which the array is processed to generate a signal response for the given pixel to obtain acoustic information for the given pixel. The system can be implemented entirely on plug-in cards for a commercial PC motherboard. The system and method can be implemented for pixel-oriented or voxel-oriented image processing and display, eliminating intermediate data computations and enabling extensive use of software processing methods. Advantages include improved acquisition of signal dynamic range, flexible acquisition modes for high frame rate 2D, 3D, and Doppler blood flow imaging.

System and method for canceling crosstalk in high-speed communications systems. An embodiment comprises precomputing channel pulse responses for a set of communications channels in a communications backplane, precomputing channel signal responses for the set of communications channels in the backplane with a training sequence, estimating noise coefficients using receiver training and the training sequence, storing noise coefficients for each communications channel in the set of communications channels, and canceling noise in a received transmission of a data sequence using the stored noise coefficients. The regularity of the communications backplane enables the precomputing of various values, which reduces computational requirements. Furthermore, it is often the case that a victim receiver has access to the digital data that is being transmitted by its dominant crosstalking transmitters, thereby simplifying noise cancellation.

Systems and methods for an RF nulling scheme are provided. An RF nulling scheme can minimize the level of unwanted RF signal reflections entering the receiver without attenuating the desired signal response from an RFID tag. In one aspect of the RF nulling scheme a synthesizer signal can be split between a main path and a nulling path. In the nulling path the signal from the splitter can be routed through an electronically variable phase shifter and variable gain amplifier to create a nulling signal. The nulling signal can cancel the unwanted reflected signal. The phase or amplitude of the nulling signal can then be adjusted to improve cancellation as necessary.

A device to regulate current produced by a permanent magnet machine responsive to a plurality of phase current signals. The motor produces torque for application on a shaft. A processing and drive circuit responsive to a direct current command signal and a quadrature current command signal produces phase current signals for input to the motor. A command circuit responsive to the phase current signals, an angular position of said shaft, and a voltage input command signal to produce a direct current error signal and a quadrature current error signal. A control circuit responsive to the direct and quadrature current error signals produces the direct voltage signal command and the quadrature voltage signal command. The control circuit has a direct and quadrature proportional gain, integrator and clamp circuits. An algorithm produces limited or clamped voltage modulation index signals to obtain maximum efficiency and maximum torque per ampere in the speed range. The algorithm ensures that the current regulator does not run out of voltage by limiting the voltage vector to the achievable voltage vector range that provides maximum torque per ampere and maximum efficiency.

A lamp control circuit is described, containing a power factor corrector, coupled to it a digitally controlled ballast, having power devices. The digitally controlled ballast is capable of powering a lamp. The ballast is controlled by a current feedback loop, coupled between the power devices and the digitally controlled ballast, and a voltage feedback loop, coupled between the lamp and the digitally controlled ballast. Further, a method of operating a lamp-control circuit is presented, the circuit containing a digital controller, an output stage, a current feedback loop, and a voltage feedback loop. In operation the digital controller receives a current feedback signal or a voltage feedback signal from the output stage and the lamp. In response to the received signal the digital controller generates a digital control signal and powers a lamp through the output stage according to the generated digital control signal.

The present invention is directed to improved speech intelligibility in telephones with multiple microphones. Such a telephone includes a first microphone, a second microphone, a voice activity detector (VAD), a receiver module, and a signal processor. The first microphone outputs a first audio signal, which comprises a voice component when a near-end user talks and a background noise component. The second microphone outputs a second audio signal. The VAD generates a voice activity signal responsive to a ratio between the first audio signal and the second audio signal. The voice activity signal identifies time intervals in which the voice component of the near-end user is present in the first audio signal. The receiver module receives a third audio signal, which comprises a voice component of a far-end user. The signal processor modifies the third audio signal responsive to the voice activity signal.

An x-ray diagnostic apparatus and methods performs Real-Time Digital Radiography with particular application in dental x-ray imaging modalities, such as Orthopantomography, Scannography, Linear Tomography and Cephalography, by using a versatile and modular electronic unit, featuring ultra fast computation capability to serve diversified image sensor typology and scanning modality.

In Digital Orthopantomography and Scannography, a plurality of tomographic images at different depths of the jaw can be generated, based on the pre-selection made by the user interface.

The image processing unit utilizes for the tomo-synthesis of the diagnostic image an accurate and economic digital simulator of the radiographic film speed, including a digital frequency synthesizer fed with film cassette speed digital input and high resolution clock signal, ensuring accurate and reproducible phase continuity of the output frequency signal.

It also introduces an automatic adaptation of the frame acquisition rate in frame transfer mode, based on the actual speed of the cassette unit. By this method the dynamic of the exposure signal is reduced, and a better optimization of the signal response of the x-ray detector is achieved.

A method for concurrently communicating over each phase of an electrical power distribution network (N). A first outbound signal (SO1) is transmitted over one phase (AN-A) of a bus (S) by an outbound modulation unit. The unit is released as soon as the first outbound signal (SO1) is transmitted so the unit can transmit a second outbound signal (SO2) over a second phase (BN-B or CN-C) of the bus. The second outbound signal is transmitted concurrently with an inbound signal (IB1) sent in response to the first outbound signal (SO1). The unit is again released, as soon as the second outbound signal (SO2) is transmitted, so the unit can transmit a third outbound signal (SO3) over the third phase (BN-B or CN-C) of the bus. This third outbound signal is transmitted concurrently with a second inbound signal (IB2) sent in response to the second outbound signal (SO2). The method allows concurrent communications over all three phases of the network (N).

The invention discloses a structure and a design method of an improved active-disturbance-rejection position controller for a direct current (DC) motor; the DC motor is taken as a controlled object, and an output position signal is taken as a controlled variable; the controller mainly consists of four parts, i.e., a tracking differentiator, a nonlinear state error feedback part, an extended state observer and a disturbance compensation part. The improved active-disturbance-rejection position controller is mainly used to improve a fal function in a nonlinear function in the extended state observer, and the fal function is used to determine the tracking performance of the extended state observer and the controller; the concrete improvement measure is adding a linear feedback area into non-linear feedback; therefore, the problem that in the traditional method, timely control cannot be realized when the system error is too large and the gain is too low can be solved on the basis of guaranteeing system stability. By comparing simulation lines obtained before and after the improvement for the controller, the structure and the design method which are provided by the invention are proved to accelerate the output signal response speed under the condition that the position error of the DC motor is larger, thus improving the integral control performance of a system.

A communications system having an ATM transmission line and an IP transmission line is disclosed that includes a base station capable of communicating with a mobile terminal through a radio link; and a radio network controller capable of communicating with the base station through the ATM or IP transmission line. The radio network controller includes a division part dividing transmission data into signals of a predetermined data size; a transmission part transmitting the divided signals to the base station at predetermined time intervals; a retransmission part retransmitting the signals transmitted to the base station when a response signal from the mobile terminal is not received within a predetermined period; a measuring part measuring a signal response period in a communications channel between the radio network controller and the mobile terminal through the base station; and a determination part determining the predetermined data size based on the measured response period.

Methods and systems for estimating values of parameters of interest of actual device structures based on optical measurements of nearby metrology targets are presented herein. High throughput, inline metrology techniques are employed to measure metrology targets located near actual device structures. Measurement data collected from the metrology targets is provided to a trained signal response metrology (SRM) model. The trained SRM model estimates the value of one or more parameters of interest of the actual device structure based on the measurements of the metrology target. The SRM model is trained to establish a functional relationship between actual device parameters measured by a reference metrology system and corresponding optical measurements of at least one nearby metrology target. In a further aspect, the trained SRM is employed to determine corrections of process parameters to bring measured device parameter values within specification.

A switching regulator includes a switching device to switch a transformer from a primary-side to secondary side. A control circuit generates a switching signal for regulating output of the switching regulator. The control circuit includes a first circuit to generate a first signal and a timing signal by measuring a reflected signal of the transformer. A second circuit produces a second signal by integrating a current signal with the timing signal. The current signal represents a primary-side switching current of the transformer. A first feedback circuit produces a first feedback signal in response to the first signal and the reference signal, in which the reference signal is varied in response to the change of the second signal. Furthermore, a second feedback circuit generates a second feedback signal in response to the second signal. A switching control circuit generates the switching signal in response to the feedback signals.