35 results about "Phase perturbation" patented technology

A system and method is provided that employs a frequency domain interpolative CODEC system for low bit rate coding of speech which comprises a linear prediction (LP) front end adapted to process an input signal that provides LP parameters which are quantized and encoded over predetermined intervals and used to compute a LP residual signal. An open loop pitch estimator adapted to process the LP residual signal, a pitch quantizer, and a pitch interpolator and provide a pitch contour within the predetermined intervals is also provided. Also provided is a signal processor responsive to the LP residual signal and the pitch contour and adapted to perform the following: provide a voicing measure, where the voicing measure characterizes a degree of voicing of the input speech signal and is derived from several input parameters that are correlated to degrees of periodicity of the signal over the predetermined intervals; extract a prototype waveform (PW) from the LP residual and the open loop pitch contour for a number of equal sub-intervals within the predetermined intervals; normalize the PW by a gain value of the PW; encode a magnitude of the PW; and separate stationary and nonstationary components of the PW using a low complexity alignment process and a filtering process that introduce no delay. The ratio of the energy of the nonstationary component of the PW to that of the stationary component of the PW is averaged across 5 subbands to compute the nonstationarity measure as a frequency dependent vector entity. A measure of the degree of voicing of the residual is also computed using openloop pitchgain, pitch variance, relative signal power, PW correlation and PW nonstationarity in low frequency subbands. The nonstationarity measure and voicing measure are encoded using a 6-bit spectrally weighted vector quantization scheme using a codebook partitioned based on a voiced/unvoiced decision. At the decoder, a stationary component of PW is reconstructed as a weighted combination of the previous PW phase vector, a random phase perturbation and a fixed phase vector obtained from a voiced pitch pulse.

A method for reducing the interference between a source transmitting pulses and equipments having nominal bandwidths which are outside the nominal bandwidth of the transmitted pulses, but which respond to sideband energy of the pulses. Phase perturbations are applied to the edges of the pulses produced by the source, to thereby tend to null the sideband energy lying in the nominal bandwidth of the equipments occupying the adjacent nominal bandwidths.

The invention discloses an island detection method adopting low-frequency sinusoidal phase perturbation. The island detection method comprises the following specific steps: 1, determining a grid-connected inverter output current instruction; 2, determining the island detection judging rule according to the grid-connected inverter output current instruction in the step 1 and the value of the quality factor Q of a local load; 3, computing the voltage frequency f at the common connection point between a photovoltaic grid-connected system and a power network in a real-time manner; 4, carrying out island effect determination according to the frequency f obtained in the step 3 and the island detection judging rule obtained in the step 2. The island detection method has the characteristics that no detection blind zone exists; the distortion of grid-connected current is low.

The invention discloses an estimation method for the magnitudes and phases of a radar uniform linear array, and relates to the field of array signal processing. The method comprises the steps that (1) the radar antenna array is set to be provided with M array elements, wherein errors do not exist in the magnitudes and phases of the first g array elements; (2) pre-estimated values of the magnitudes and phases are used as disturbance initial values of the magnitudes and phases of the uniform linear array, and an array flow pattern of the uniform linear array is built through the disturbance initial values of the magnitudes and phases; (3) a subspace of a measurement matrix is constructed; (4) a target sparse matrix is solved through the array flow pattern and the subspace of the measurement matrix; (5) the array flow pattern is optimized through the array flow pattern, the subspace of the measurement matrix and the target sparse matrix; (6) the estimated magnitude value and the estimated phase value of the uniform linear array are obtained through matrix diagonal elements of the optimized array flow pattern. According to the estimation method for the magnitudes and phases of the radar uniform linear array, the magnitudes and phases of the uniform linear array are effectively estimated under the situation of a low signal-to-noise ratio and a small number of snapshots.

A digital IF demodulator includes an analog-to-digital (A/D) converter that receives an analog IF signal and converts it to a digital IF signal. A parallel multiplier then down-converts the digital IF signal to a baseband signal having a video component and an audio component. The frequency down-conversion uses a parallel multiplier driven by an outer feedback loop that corrects gross frequency errors in said digital IF signal. The digital IF demodulator also includes a video recovery circuit that selects the video component from the baseband signal and further down-converts the baseband signal to a video baseband using a video complex mixer driven by an inner feedback loop that corrects fast phase perturbations in the video recovery circuit. Finally, the digital IF demodulator includes an audio recovery circuit that (i) receives said baseband signal from the parallel multiplier, and (ii) down-converts the audio component to an audio baseband signal using an audio complex mixer.

Methods and apparatus are presented for unintentional islanding detection for grid tie converters in which the phase angle disturbance is introduced by modification of grid side converter switching control signals and a mismatch of reactive power between generation and the grid load is formed upon the occurrence of unintentional islanding, where the applied phase disturbance is determined according to two pre-defined curves to form an equivalent positive feedback at different frequencies to prevent the converter from forming an island at a new stable frequency after the grid is disconnected.

The invention relates to a three-phase photovoltaic inverter anti-islanding method based on phase angle deviation positive feedback, which comprises the steps as follows: carrying out disturbance to a power grid phase with T being used as a cycle, a disturbance phase angle for each time is delta theta under a grid synchronization condition of the inverter; and beginning to accumulate when a power grid voltage phase angle is 0 degree and assuming total accumulating n times within T, namely a current phase leading voltage is n*delta theta degrees, and calculating an error value delta f of the current frequency and the last periodic frequency of the power grid voltage, so that the error value is adopted as phase angle deviation positive feedback quantity. When islanding happens, the frequency of the current voltage is more than that of the last period, the delta f is positive, a control loop leads the plosive value into the positive feedback, the disturbance quantity is changed into n*delta theta+delta f at the moment, and equivalently, the forward disturbance is increased, so that the more the phase disturbance is, the more the voltage frequency deviation is, so as to form a forward deviation positive feedback system; and the system reports an overfrequency error until the frequency exceeds standard, so as to achieve the islanding protection purpose.

Disclosed is a photovoltaic grid-connected island detection algorithm based on abrupt phase change and active phase shifting. The photovoltaic grid-connected island detection algorithm comprises the steps of (1) collecting a grid-connected current frequency value, a common point voltage phase and a grid-connected current phase through a phase-locked loop apparatus; (2) setting upper and lower threshold values of a frequency, a common point voltage and a phase deviation threshold value of a grid-connected current; according to national island detection standard, setting the frequency threshold valve |f-f0| to be less than or equal to 0.5Hz; and setting the phase difference |delta <phi>| to be less than or equal to 2 degrees; and (3) when the grid-connected current frequency, or the common point voltage and the phase deviation of the grid-connected current exceed the corresponding threshold values, starting island protection; and when the current frequency of the grid-connected point and the |delta <phi>| are not greater than the corresponding threshold values, applying phase perturbation, wherein theta<SMS> is equal to 5 degrees sin(pi/2*delta f/3), on an inverted output current until the current frequency of the grid-connected point or the |delta <phi>| is greater than the corresponding threshold value, starting island protection. By adoption of the photovoltaic grid-connected island detection algorithm, seamless switching of different algorithms can be realized; detection blind regions can be reduced while the detection speed can be accelerated when a passive method is adopted singly; and in addition, the power grid current THD can be lowered when an active phase shifting method is adopted singly.

The invention provides a BLDC motor phase detection method based on back electromotive force wave crests and wave troughs. The method is a peak detection method using motor electromotive force, an accurate phase-change position is acquired, the comparison with neutral point voltage is avoided, and filtering detection is carried out on the back electromotive force phase voltage of a BLDC motor. Due to the fact that the back electromotive force phase voltage is closely related with the relative positions of a rotor and a stator of the BLDC motor, the phase-change angle of the BLDC motor can be calculated in a compensating manner through the phase detection of the back electromotive force wave crests and wave troughs. The BLDC motor phase detection method based on the back electromotive force wave crests and wave troughs provided by the invention has the advantage of high disturbance rejection ability, the defect of phase-change angle miscalculation caused by neutral point phase-position disturbance does not exist, excessive zero crossing point detection error caused by neutral point shaking in a certain specific environment is avoided, and accurate basis is provided for phase-change operation of the BLDC motor.

The invention discloses an island detection method for sine low-frequency phase disturbance of a three-phase grid-connected photovoltaic inverter. The island detection method comprises the following steps that low-frequency phase disturbance deltatheta which changes according to a sine principle is applied between an inverter output current vector I with phase disturbance and a power grid voltage vector E; during normal grid connection, detected voltage of a public connection point is power grid voltage; after the power grid is switched off, the voltage of the public connection point is determined by inverter output current and a local load commonly; a voltage frequency is changed along with the change of the frequency of the inverter output current so that the frequency exceeds a regulated frequency range and an island phenomenon is detected. According to the island detection method for the sine low-frequency phase disturbance of the three-phase grid-connected photovoltaic inverter, hardware does not need to be additionally arranged; compared with a traditional active type detection method, the island detection method has the advantage of no detection blind region; the applied disturbance is periodically changed, so that the island detection method has the advantage of small grid-connected current distortion when being compared with a traditional fixed disturbance frequency detection method.

The invention discloses a device and method for measuring an atmospheric absorption coefficient based on phase perturbation. The device comprises a mechanical compensation zoom system, a sample storage pipe, an optical fiber interferometer and an extinction tube, wherein the sample storage pipe also comprises a sample inlet and a sample outlet. In the invention, a relation between the phase perturbation and the atmospheric absorption coefficient is established, the effects of dispersion and absorption to the atmosphere are effectively separated, the atmospheric absorption coefficients corresponding to parallel laser beams with different wavelengths can be measured in a non-contact way while the original properties of the atmosphere are maintained, the evolution law of the atmospheric absorption coefficient along with time can be detected, and the method has the characteristics of high detection speed, high sensitivity and simple operation.

The invention discloses a method for eliminating a parallel dilution effect of multiple inverters and an island detecting method in the field of electrical equipment and electrical engineering. A timeof outputting a phase angle zero-crossing point of a phase-locked loop is used as a starting position of disturbance of multiple parallel inverters within each period to realize synchronous disturbance of multiple parallel inverters; after synchronous disturbance, directions of voltage frequency deviations of common points become consistent; voltages obtained by the parallel inverters are from common points at one same bus and after convergence of the phase-locked loop, the obtained disturbance phases are same. According to the invention, the island detecting method with phase disturbance isimproved to find out a phase-locked-loop-based island detecting method capable of realizing synchronous disturbance of multiple inverters and being easy to extract the disturbance amount, so that theisland detecting method is perfected.

The method includes phase perturbation of information element and phase perturbation of suppression element. In orthogonal FDM system of using phase perturbation method for suppressing peak average power ratio, modulation vector is composed of component of information element and component of suppression element. Characters are that the method includes following steps: (1) when peak average power ratio is larger than threshold value setup in time domain, pseudo-random phase is added to information element phase; (2) perturbation phase of suppression element is obtained through searching by using gradient algorithm; (3) after sampling and demodulating, receiver deletes information in frequency domain on relevant sub carrier wave directly so as to obtain useful information.

A clock generator includes an oscillator configured to generate an oscillating signal and a signal path configured to provide an output clock signal based on the oscillating signal. In response to a control signal, the clock generator is configured to neutralize periodic phase perturbations in the oscillating signal using opposing periodic phase perturbations. The neutralization may occur in the signal path. The signal path may be responsive to the control signal to adjust at least one of a duty cycle, a rise time, and a fall time of the output clock signal to cause alternating phase perturbations of the periodic phase perturbations to apply as the opposing periodic phase perturbations in the output clock signal. The neutralization may occur in the oscillator. The clock generator may include an auxiliary path configured to provide an auxiliary signal to the oscillator.

The invention discloses a mixing island detection method based on the combination of a wavelet neural network and an SMS. According to the technical scheme, in the first state, by detecting a voltagesignal on a public coupling point in a cycle, wavelet transformation is conducted to obtain an average value of a wavelet coefficient absolute value in a voltage cycle, the average value is used as aninput signal of a BP neural network, and finally, the BP neural network is used for mode recognition; in the second stage, phase perturbation in an SMS algorithm is introduced, so that whether the frequency of public coupling point voltage exceeds a threshold value or not is detected, through the frequency detection, whether an island phenomenon really occurs or not is determined, and thus when agrid-connection power generation system is in an island state, a corresponding island protection measure is taken. The reliability of island detection is greatly improved, and on the premise of guaranteeing the island recognition rate, the influence of the detection method on the system electric energy quality is greatly lowered.

A method for modifying a signal transmitted from a mobile communication device comprising perturbing a transmit diversity parameter from its nominal value by modulating the parameter with respect to the nominal value in alternating directions, receiving a feedback signal including feedback information relating to the modified signal as received at a feedback device, and based at least on the feedback information, adjusting the nominal value of the transmit diversity parameter by increasing, decreasing, or preserving the nominal value. The perturbations are selected to minimize phase discontinuities.

A tester for determining phase discontinuity is described for a transmitter having multiple antennas sending signals to a receiver. Typically the transmitter is provided in a mobile telephone and the receiver is in a base station. The transmitter sends out the RF signals in a shaped beam using transmission diversity. The RF signals define multiplexing slots. The tester receives the RF signals as they are fed to a respective antenna port, analyses phases of these signals on a slot-by-slot basis comparing phase differences between adjacent slots to a threshold derived from legacy devices.

The invention discloses a perturbed phase modulation DDS sine wave signal generation method. The method is different from ordinary DDS of using a single-frequency control word and a single accumulatorand starts from the time-domain sampling process of the sine waveform, by means of the mutual effect of two control words and two accumulators, integral sampling time moments and perturbed fractionalsampling time moments are generated, precise moment sampling of each sine cycle is achieved, and sine waves are synthesized by means of phase perturbation and quadrature phase modulation; and due tothe fact that the independent accumulators are adopted in perturbation components, trigonometric function values of a perturbed phases can be approximately calculated, the table look-up capacity of the trigonometric functions is reduced, the frequency resolution is increased, the high-resolution Doppler frequency offset subcarrier digital signal generation problem is solved, and a new method is provided for generation of a wireless receiving synchronization system or low-phase noise sine wave signals.

The invention relates to a multi-light-beam phase perturbation apparatus and method. The multi-light-beam phase perturbation apparatus is characterized in that each winding shaft is a cylindrical winding shaft; a groove is formed in the side surface, in a direction perpendicular to a shaft, of each winding shaft; multiple-core optical fibers are wound in the groove around the winding shaft; a pressing sheet adopts an arch bridge shape; the multiple-core optical fibers are fixed on a perturbator by the pressing sheet; the perturbator is arranged between two winding shafts; and the perturbator adopts a vibration source to drive the multiple-core optical fibers fixed by the pressing sheet to shake left and right regularly. The multi-light-beam phase perturbation apparatus is simple in structure, capable of performing multi-wavelength and multi-light-beam optimization synchronously, high in optical energy utilization rate, without changing linewidth of a laser source and the output divergence angle of optical fibers, flexible in use, and low in manufacturing cost and manufacturing difficulty, and batch production can be realized.