330 results about "Minimum phase" 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 noise suppression device receives data representative of a noise-corrupted signal which contains a speech signal and a noise signal, divides the received data into data frames, and then passes the data frames through a pre-filter to remove a dc-component and the minimum phase aspect of the noise-corrupted signal. The noise suppression device appends adjacent data frames to eliminate boundary discontinuities, and applies fast Fourier transform to the appended data frames. A voice activity detector of the noise suppression device determines if the noise-corrupted signal contains the speech signal based on components in the time domain and the frequency domain. A smoothed Wiener filter of the noise suppression device filters the data frames in the frequency domain using different sizes of a window based on the existence of the speech signal. Filter coefficients used for Wiener filter are smoothed before filtering. The noise suppression device modifies magnitude of the time domain data based on the voicing information outputted from the voice activity detector.

A novel and useful whitening matched filter (WMF) for use in a communications receiver. The WMF is constructed by cascading a matched filter and a noise-whitening filter. The response of the matched filter is derived from the time reversed complex conjugate of the channel impulse response. The whitening filter is derived by extracting the minimum phase portion of the mixed phase channel impulse response using homomorphic deconvolution. The whitening filter is implemented using either an FIR or IIR filter adapted to process the data received before and after the training sequence using a minimum phase system in a direction in time opposite to that of the direction of corresponding data sample processing performed by the equalizer.

A method for tuning phase relationships for a multi-port amplifier. The method includes providing a plurality of amplifiers arranged in a multi-port configuration, which has more than two amplifiers. The method includes selecting one of a plurality of test patterns to be input into one or more of the plurality of amplifiers to detect phase information of one or more of the amplifiers and detecting an output signal at a designated output coupled to the plurality of amplifiers. The method also includes adjusting a phase relation of the one or more amplifiers based upon the output signal.

A method and system which provides wireless, noninvasive electrical stimulation to different muscle groups to allow the user to conduct physical activities, such as walking, by stimulating various muscle groups in the body at the correct times of activation or by stimulating muscle groups in a simulation mode when standing, sitting or lying down, whereby walking is not required to stimulate the various muscle groups. The system provides a small portable wearable system which utilizes available software, including Bluetooth technology, to provide electrical nerve stimulating pulses with low current, minimal phase charge which is controlled remotely and induce desired muscle contraction with increased comfort for the user. The present method and system applies electrical stimulation with accurate timing, based on a three-dimensional motion sensor, as a trigger to initiate stimulation and which is adapted to turn itself on and off when not walking.

Cardiac catheterization is carried out by memorizing a designation of a contact state between an electrode of the probe and the heart wall as one of an in-contact state and an out-of-contact state, and making a series of determinations of an impedance phase angle of an electrical current passing through the electrode and another electrode, identifying maximum and minimum phase angles in the series, and defining a binary classifier adaptively as midway between the extremes. A test value is compared to the classifier as adjusted by a hysteresis factor, and a change in the contact state is reported when the test value exceeds or falls below the adjusted classifier.

This invention discloses one method and device to improve time zone signals frequency stability measurement, which comprises the following steps: reference time signals are processed through DDS technique to get stable and accurate circle signals; expending measurement frequency signals range to get better reference signals and signals to be tested at fine time measurement; using DDS unit to process measurement frequency signals; when circle sample time singles come, according to fine time measurement module minimum resolution rate to test signals to be tested with reference time signals minimum phase difference to make the meter work to fulfill frequency signal measurement.

A three-phase DC motor output stage including a predriver that supplies drive voltages to power MOSFETs supplies output voltages to three-phase coils, monitors whether each of gate-to-source voltages of the power MOSFETs is greater than or equal to a predetermined voltage and thereby detects a current zero cross, and employs the output of such current zero cross detection in PLL control for controlling energization switching timing and thereby forms drive voltages of 180-degree energization. Lower hooks with a voltage minimum phase as GND and upper hooks with a voltage maximum phase as a source are set as patterns alternately repeated for every electrical angle of 60 degrees. The patterns are expressed in linear approximation to generate sine wave-like drive voltages, thereby causing sine wave-like currents to flow into the three-phase coils.

A apparatus and apparatus for compensating for video insertion loss due to transmission over long twisted pair cable lines is presented. Transmission of video over twisted pair cable is advantageous because of its superior cost advantage over coaxial cable. However, twisted pair cables have significant loss characteristics at the higher frequencies (i.e., broadband) compared to coaxial cables. At a transmitter station, the video signal is amplified in the high frequency region for possible skin effect losses thereby brute forcing the high frequency components to the receiving station. At the receiver station, the video signal is further compensated for diffusion line and skin effect losses. The total skin effect compensation applied in both the transmitter and receiver stations is such that the square root of frequency characteristics of skin effect losses is compensated for. Thus, at the receiving station, the high frequency compensation added at the transmitter to brute force the high frequency components to the receiving station may be removed if found excessive. Additionally, compensation is included to adjust for skew that may occur because of irregularities between the various twisted pairs used to transmit the individual video components. Non-minimum phase type filters are used to inject delay into the faster arriving signals so that they may coincide in phase with later arriving signals resulting in a true reproduction of the video.

The invention discloses a bidirectional direct-current converter feedback linearized back-stepping sliding-mode control mode. The bidirectional direct-current converter feedback linearized back-stepping sliding-mode control method comprises steps of using a filtering capacitance voltage and inductive current as control variables to establish a mathematic model of a bidirectional direct-current converter, performing feedback linearization on an original state variable to form a new linearized state equation, tracking an error with a new state variable as an input of a controller, combining a back-stepping method with a sliding-mode variable structure and designing a feedback control rule of a converter system, wherein the feedback control rule of the inverter system is performed on pulse width modulation and controls the bidirectional direct-current converter. The bidirectional direct-current converter feedback linearized back-stepping sliding-mode control mode combines the feedback linearization with the back-stepping sliding mode control to apply to the bidirectional direct-current converter, solves a non-minimum phase characteristic and a variable structure characteristic of the converter, greatly reduces fluctuation of bus voltage, expands a stable area of a system and has a good engineering application prospect.

The device is provided with an electric power conversion circuit including switching elements for converting a DC electric power to an AC electric power, a load connected to an output side of the electric power conversion circuit, means for detecting a current flowing through a DC side in the electric power conversion circuit, a voltage command value preparing means for controlling the operation of the switching elements in the electric power conversion circuit and a wire breaking detecting means. The wire breaking detection means judges a wire breaking in the load or an abnormality of any of the switching elements in the electric power conversion circuit by making use of a DC current detection value in a period when a current of maximum voltage phase or of voltage minimum phase of the electric power conversion circuit is flowing in a DC current.

The disclosure pertains to continuous-time filtering. More particularly, it relates to filtering in a feedback control loop, for example in a sigma-delta (SigmaDelta) modulator. The making of a filter for this type of application comes up against a major problem linked to the relativity between the amplitude and phase responses. This limits the possibilities of choice in order to take steps against the instability of the loop. A continuous-time filter with minimum phase variation carries out the bandpass integration of the signal presented at its input. The making of the continuous-time filter as a bandpass integrator raises the problem of achieving a compromise between gain variations and phase variations close to the -1 critical point, This compromise must lead to the stability of the loop. This problem is resolved by using a continuous-time bandpass integrating filter comprising at least one resonance device with minimum phase variation.

A combined multirate-based Finite Impulse Response (FIR) filter equalization technique combines a low-order FIR equalization filter operating at a lower rate for equalization of a loudspeaker-room response at low frequencies, and a complementary low-order minimum-phase FIR equalization filter operating at a higher rate for equalization of the loudspeaker-room response at higher frequencies. The design of two complementary band filters for separately performing low and high frequency equalization, keeps the system delay at a minimum while maintaining excellent equalization performance. Splicing between the two equalization filters, for maintaining a flat magnitude response in the transition region of the two complementary filters, is done automatically through level adjustment of one equalization filter relative to the other. The present invention achieves excellent equalization at low filter orders and hence reduced computational complexity.

A method is disclosed for calculating the quality factor Q from a seismic data trace. The method includes calculating a first and a second minimum phase inverse wavelet at a first and a second time interval along the seismic data trace, synthetically dividing the first wavelet by the second wavelet, Fourier transforming the result of the synthetic division, calculating the logarithm of this quotient of Fourier transforms and detennining the slope of a best fit line to the logarithm of the quotient.

An adaptive control system is disclosed. The control system can control uncertain dynamic systems. The control system can employ one or more derivative-free adaptive control architectures. The control system can further employ one or more derivative-free weight update laws. The derivative-free weight update laws can comprise a time-varying estimate of an ideal vector of weights. The control system of the present invention can therefore quickly stabilize systems that undergo sudden changes in dynamics, caused by, for example, sudden changes in weight. Embodiments of the present invention can also provide a less complex control system than existing adaptive control systems. The control system can control aircraft and other dynamic systems, such as, for example, those with non-minimum phase dynamics.

The invention comprises apparatuses and methods for providing the capability to stabilize and control a non-minimum phase, nonlinear plant with unmodeled dynamics and/or parametric uncertainty through the use of adaptive output feedback. A disclosed apparatus can comprise a reference model unit for generating a reference model output signal y_m. The apparatus can comprise a combining unit that combines and differences a plant output signal y of a non-minimum phase plant for which not all of the states can be sensed, and a plant output signal y, to generate an output error signal {tilde over (y)}. The apparatus can further comprise an adaptive control unit for generating an adaptive control signal u_ad used to control the plant.

Adaptively processing an input signal, such as an input signal of a hearing aid. The input signal is passed through an adaptive time domain filter to produce an output signal. At least one of the input signal and the output signal is used as an analysis signal. The analysis signal is transformed into a transform domain to produce a transformed analysis signal, which is analysed to produce a desired gain for each respective transform domain sub-band. A minimum phase time domain filter characteristic is synthesised which approaches the desired gains. The adaptive filter is updated with the synthesised filter characteristic.

A system and method for controlling a plant having a minimum phase transfer function P(s) and given an input signal u, the plant having an output y and a plant frequency range comprising a transfer function J(s) comprising the product of a high gain filter J₁(s) having a gain k₁ sufficient that

when |ω|≦ω₁ and |1+J(ω)|>1/M for all ω wherein ω₁ is selected to obtain a desired time response, and a low pass filter J₂(s) selected such that |1+J(ω)|>1/M for all ω and J(s) is strictly proper, wherein ε<1 and M>1 and ε and M are selected to meet a desired sensitivity requirement. An error signal e is calculated comprising the difference between the system input signal u and the plant output signal y, and the error signal modified according to the transfer function C(s)=P⁻¹(s)J₁(s)J₂(s) and inputting the error signal into the plant. The system and method can be extended to unstable invertible plants. A global sensitivity bound M≧1 could also be achieved for plants including right half planes zeros. The system and method are shown applied to a read-write head positioning actuator of a hard disk drive, but can be applied equally to other systems such as electrical systems, mechanical systems, industrial processes, military applications, flight control, power generation, computer servo systems, phase lock loops and the like.

This invention discloses a channel quality estimation method for continuous phase modulation self adapting frequency hopping system through referencing the extent of CPM modulation signal interfered by other signal in communication, which contains first accounting the received signal phase in one code element time and phase of standard reference signal, then accounting the phase distance between received signal and standard reference signal, finding out minimal phase distance in all signal phase possible being transmitted, taking the average value, comparing the average value with set threshold value to judge the frequency point quality. Said invention can self adaptively select optimized channel to make frequency hopping communication for keeping the communication system in fine communication state.