301 results about "Harmonic amplitude" patented technology

Distortion modeling produces distortion models for use by a distortion synthesizer to synthesize the harmonic distortion effects of audio distortion devices. A sinusoidal waveform is distorted by an audio distortion device and analyzed using a Fourier transform to produce a distortion model comprising harmonic amplitude and phase parameters. A phase correction process compensates for phase shifts induced by the audio distortion device. The distortion synthesizer uses a distortion function that distorts a digital audio signal according to the distortion model. The distortion model can be modified to alter the distortion effect and can be stored in a data-storage device for later retrieval. A frequency bandsplitter and signal mixer allow the distortion effect to be applied only to the low frequency content of the digital audio signal, thus providing spectral headroom to suppress the production of aliasing noise. Aliasing-noise suppression is provided for a full-bandwidth signal by up-converting the sampling rate of the signal before applying the distortion function and down-converting the sampling rate afterwards. A process is provided to remove the direct-current component that may be induced into the signal by the distortion function.

The invention discloses a harmonic amplitude measurement method and system of a power signal. The method comprises the following steps: performing digital filtering on an imaginary vector sequence and a real vector sequence to generate an imaginary vector filter sequence and a real vector filter sequence; equally dividing the real vector filter sequence and the imaginary vector filter sequence into two sections of sequences to generate a real vector filter front-section sequence, a real vector filter rear-section sequence, an imaginary vector filter front-section sequence and an imaginary vector filter rear-section sequence respectively; integrating the real vector filter front-section sequence, the imaginary vector filter front-section sequence, the real vector filter rear-section sequence and the imaginary vector filter rear-section sequence in sequence to solve phase and phase difference; converting the phase difference and reference frequency into fundamental wave frequency of the power signal. The product of the fundamental wave frequency and a harmonic factor is used as the reference frequency to perform harmonic wave amplitude measurement. By implementing the method and the system, mixed frequency interference elements in the imaginary vector sequences and the real vector sequences can be inhibited to generate the harmonic wave amplitude with high precision.

A speech coding system (10) and associated method relies on a speech encoder (15) and a speech decoder (20). The speech decoder (20) includes a harmonic generator (70) which modulates the phase of each generated harmonic with a low frequency, low bandwidth signal to remove the buzzy quality of the speech and to produce natural sounding speech. The amplitude of the phase modulating signal is adjusted in accordance with the harmonic magnitude. For harmonics residing in a spectral valley the amplitude of the modulating signal is relatively large and for harmonics residing near spectral peaks, the amplitude of the modulation signal is relatively small.

The present invention provides a method, system, and apparatus to monitor cardiovascular signals such as arterial blood pressure (ABP), pulse oximetry (POX), and intracranial pressure (ICP). The system can be used to calculate and monitor useful clinical information such as heart rate, respiratory rate, pulse pressure variation (PPV), harmonic phases, pulse morphology, and for artifact removal. The method uses a statistical state-space model of cardiovascular signals and a generalized Kalman filter (EKF) to simultaneously estimate and track the cardiovascular parameters of interest such as the cardiac fundamental frequency and higher harmonics, respiratory fundamental frequency and higher harmonics, cardiac component harmonic amplitudes and phases, respiratory component harmonic amplitudes and phases, and PPV.

The invention discloses a modulation and demodulation circuit of fiber option gyroscope (FOG) open-loop signals. The circuit adopts a monolithic LVDT integrated circuit (IC) for modulating and demodulating an FOG open-loop signal, generating a sinusoidal signal, synchronously detecting and dividing one odd harmonic amplitude and one even harmonic amplitude and acquiring the tangent value of a mobile signal phase by low-pass filtration. The invention uses the monolithic LVDT IC to realize the four functions, i.e., sinusoidal signal generation of a drive phase modulator, synchronous detection, the elimination of light-source light-intensity fluctuation influence and low-pass filtration and greatly simplify a signal-processing circuit; the monolithic LVDT IC outputs the tangent value of a mobile signal phase so that when the phase increases and trends to pi/2, the tangent value bends upwards, does not trend to saturation and reduces the error of a complementary tangent operation; and a division operation is internally realized by the monolithic LVDT IC so that a digital signal processor at a high price can be replaced by a monolithic computer at a low price for non-linear corrosion.

The invention discloses a high-precision harmonic parameter estimation method based on a composite iterative algorithm. The method comprises the steps as follows: firstly, a harmonic amplitude value is directly calculated by utilizing a three-peak interpolation algorithm, and meanwhile, a harmonic phase is calculated to serve as an initial phase value for composite iteration, then the initial phase value is transmitted to a phase difference correction algorithm to obtain a frequency deviation value by utilizing the phase difference correction algorithm, and the phase difference correction algorithm is combined with a spectral leakage cancellation algorithm so as to obtain a phase value for the first-time iterative computation; circulating iteration is performed between the phase difference correction algorithm and the spectral leakage cancellation algorithm repeatedly until a phase iteration result meeting the error limit requirement is obtained. According to the invention, with the adoption of the three-peak interpolation algorithm, the estimation precision of the harmonic amplitude value is improved, and the phase obtained by utilizing the three-peak interpolation algorithm serves as an initial value, and the phase difference correction algorithm and the spectral leakage cancellation algorithm are combined to construct the composite iterative algorithm, so that the estimation precision of a harmonic phase and frequency is greatly improved.

The invention provides a permanent magnet synchronous motor inter-turn shorted-circuit fault diagnosis method. The method uses a Hall current sensor to collect a current signal at a stator end. The current signal is subjected to FFT analysis using a Nicolet data acquisition instrument, then the harmonic amplitude is processed, a fault coefficient of the collected current signal is compared with a preset fault coefficient, and that whether the permanent magnet synchronous motor has an inter-turn shorted-circuit fault or not is determined.

The invention discloses a distribution method based on waveform matching for harmonic voltage responsibility. The distribution method comprises the steps of: step 10) acquiring harmonic test data, and forming a harmonic data sequence; step 20) setting basic matching parameters; step 30) calculating an Euclidean distance, wherein normalization processing is performed on the harmonic data sequence which is formed in the step 10) according to a sequence of subsequences based on the basic matching parameters set in the step 20) to obtain harmonic sample data, and the Euclidean distance between a harmonic voltage and a harmonic current in the harmonic sample data is calculated; step 40) screening the subsequences, wherein similarity of each subsequence is calculated, and the subsequence with the similarity not less than a set value is screened out; step 50) and distributing harmonic responsibility, wherein system-side equivalent harmonic impedances of the screened subsequences is estimated by adopting a least square method, and a mean value of the equivalent harmonic impedances is utilized for calculating the harmonic voltage responsibility. The distribution method can quantify harmonic pollution liability of a feeder by utilizing harmonic amplitude data, and is suitable for engineering practice.

The invention relates to a blood pressure prediction method and in particular relates to a human body blood pressure prediction method based on pulse wave. The human body blood pressure prediction method comprises performing filtering and accumulation and superposition processing and effectiveness judgment on a pulse wave signal and constructing a regression prediction model of blood pressure values by use of the least square method with the harmonic amplitude of the effective pulse wave signal as a characteristic parameter; the prediction process is simple and the prediction error is low; the blood pressure prediction method can be widely applied to family life.

The invention relates to a chaotic signal source with adjustable dynamic amplitude linearity and a system with identical dynamic characteristics, comprising an inverse proportion circuit, a first integrating circuit, a second integrating circuit and a third integrating circuit, wherein the output ends of a third operational amplifier, a second operational amplifier and a first operational amplifier sequentially output three state variables (x, y, z) of the chaotic signal source; when the chaotic signal source works, the dynamic amplitudes of the three state variables (x, y, z) are linearly adjusted by adjusting the output voltage of a DC power supply, and the three state variables (x, y, z) are enabled to have the identical dynamic characteristics. Because the chaotic signal source has adjustable amplitude and frequency spectrums of different frequency ranges and the like under the precondition without changing the dynamic characteristics of an output signal, the chaotic signal source is indicated to have extensive application prospect and important application value in the high technology fields of chaotic radars, secret communication, electronic countermeasure, and the like.

The invention discloses a compressor high-frequency harmonic torque compensation method, a compressor controller and an air conditioner. The method comprises the steps of acquiring a vibration amplitude of the compressor in operation; when the vibration amplitude of the compressor is higher than a first preset vibration value, acquiring a load torque harmonic wave and an output electromagnetic torque harmonic wave of the compressor in the current operation working condition, determining a harmonic compensation order according to the load torque harmonic wave and the output electromagnetic torque harmonic wave; determining a harmonic frequency which corresponds with the harmonic compensation order, stacking a sine electromagnetic torque with a corresponding frequency into an output electromagnetic torque according to the harmonic frequency, adjusting a harmonic phase which corresponds with the sine electromagnetic torque according to a multiple-iteration method; and when a fact that the harmonic amplitude which corresponds with the output electromagnetic torque with the stacked sine electromagnetic torque reaches a highest value, recording the harmonic wave which corresponds with the current sine electromagnetic torque as an optimal compensation phase, and performing compensation on the high-frequency harmonic torque of the compressor according to an optimal compensation phase. The compressor high-frequency harmonic torque compensation method, the compressor controller and the air conditioner realize high-frequency harmonic torque compensation of the compressor.

A system and method for measuring and analyzing power flow parameters in RF-based excitation systems for semi-conductor plasma generators. A measuring probe (8) is connected to an RF transmission line for receiving and measuring voltage (10) and current signals (12) from the transmission line (4). A high-speed sampling process converts the measured RF voltage and current signals into digital signals. The digital signals are then processed so as to reveal fundamental and harmonic amplitude and phase information corresponding to the original RF signals. Multiple measuring probes may be inserted in the power transmission path to measure two-port parameters, and the networked probes may be interrogated to determine input impedance, output impedance, insertion loss, internal dissipation, power flow efficiency, scattering, and the effect of plasma non-linearity on the RF signal.

The invention discloses a cascade inverter H-bridge unit short circuit fault detecting method based on harmonic analysis of switching frequency, which is suitable for a carrier phase-shifting PWM (pulse width modulation) manner based on the harmonic analysis to output phase voltage and comprises three parts, namely output alternating voltage sampling, extracting and processing of harmonic wave close to the switching frequency, and fault judging and fault locating. Three-phase output voltage of a cascade inverter is respectively subjected to low-pass filtering and A/D (analog-to-digital conversion) sampling, and is subjected to discrete Fourier transformation to obtain characteristic harmonic; a comparison result of the characteristic harmonic amplitude and a fault threshold is utilized as the evidence of fault judging, wherein the fault threshold is obtained by carrying out a series of calculation on command voltage. The fault locating is determined through a phase angle range of the harmonic of the switching frequency. According to the cascade inverter H-bridge unit short circuit fault detecting method based on the harmonic analysis of the switching frequency, which is disclosed by the invention, the three-phase output voltage of the inverter is collected, and no other hardware circuit is additionally arranged, so that the cost is reduced, and the efficiency is improved; the application capability is strong, and the application value in the study on the real time fault detection of the cascade inverter exists.

According to one exemplary embodiment, a low harmonic switching device includes a first switching block including a first multi-gate FET, where the first switching block is coupled to a first input and a shared output of the low harmonic switching device. A first capacitor is coupled between a first gate and a source of the first multi-gate FET and a second capacitor is coupled between a second gate and a drain of the first multi-gate FET so as to cause a reduction in a harmonic amplitude in the shared output. A resistor can couple the source to the drain of the first multi-gate FET. The first switching block can further include a second multi-gate FET, where a source of the second multi-gate FET is coupled to the drain of the first multi-gate FET and a drain of the second multi-gate FET is coupled to the shared output.

The invention discloses a phase delay extraction and compensation method for PGC phase demodulation. A sinusoidal phase modulation interferometric signal is converted into a digital interferometric signal through an analog-to-digital converter after amplifying and filtering, first-order, second-order and fourth-order harmonics of the digital interferometric signal are subjected to orthogonal downmixing simultaneously, and three pairs of orthogonal harmonic amplitude signals are obtained. Phase delays are extracted from the three pairs of orthogonal harmonic amplitude signals, and corresponding phase delay correction coefficients are calculated out by using the phase delays. The phase delay correction coefficients are multiplied by the absolute harmonic amplitude signal equal to the sum ofthe absolute values of the orthogonal harmonic amplitude signals to obtain new harmonic amplitude signals which are not affected by the phase delays, and then a to-be-measured phase is obtained through antitangent operation. The problems are solved that in the PGC phase demodulation technology, phase delay is difficult to measure and non-linear errors caused by the phase delay are difficult to compensate for in real time, the phase measurement accuracy is improved, and the method is widely applied to the technical field of sinusoidal modulation interference.

The invention discloses a method for detecting a power frequency series arch failure, and belongs to the field of circuit operation protection. By collecting current data in a circuit and conducting fast Fourier transformation, a spectrogram is obtained; then, amplitude values of a fundamental wave and all sub-harmonics are counted, and a specific value of all the sub-harmonic amplitude values andthe fundamental wave amplitude value is calculated; finally, the specific value of all the sub-harmonic amplitude values and the fundamental wave amplitude value is added into an internal matrix, then principal component analysis is conducted, and in other words, PCA calculation is conducted; an obtained principle component matrix is derived and compared with a given threshold value to determinethe type of a load and the operating state to which the load belongs; meanwhile, the length of a null zone of obtained original current data is calculated and compared with the threshold value, and when the two conditions are met at the same time, it can be determined that the electric arc failure occurs. The method can recognize different loads, is high in accuracy, can effectively protect the circuit, and ensures that a user can use electricity safely.

Provided is a low-current ground fault line selection device. Active domains of various line selection methods are determined through the rough set theory, the line selection methods comprise the group amplitude comparison and phase comparison method, the harmonic amplitude comparison and phase comparison method, the wavelet method, the first half-wave method, the active component method, the energy method and the like, reliability quantitative evaluation is conducted on the fault line selection result obtained in each line selection method according to fault signal characteristics, all the line selection methods are integrated by applying the evidence theory, and advantage complementation among all the line selection methods is guaranteed to the maximum. In order to prevent fault signals from being interfered to cause mistaken selection, the device utilizes the continuous line selection method, data are recollected to be analyzed at intervals of a certain time, and line selection calculation of the device will not stop as long as faults do not disappear.

The invention discloses a method and a device for digitally and automatically controlling bias voltage of an electro-optic light modulator. The method comprises the following steps: after inputting scanning bias voltage to a light modulator, calculating to obtain half-wave voltage of the light modulator; calculating error feedback coefficients and the dithering amplitude of a dithering signal according to the half-wave voltage; after inputting working bias voltage and the dithering signal to the light modulator, calculating to obtain harmonic amplitude and an offset phase; according to the offset phase, combining the error feedback coefficients, the harmonic amplitude and the working bias voltage to calculate to obtain new bias voltage; after taking the new bias voltage as the working bias voltage, returning the step for inputting the working bias voltage to the light modulator. According to the method for digitally automatically controlling the bias voltage of the electro-optic light modulator, in a light modulator working procedure, the working bias voltage can be continuously corrected, so that the working performance of the light modulator is more stable; furthermore, when the new bias voltage exceeds a voltage threshold range, the new bias voltage is modulated back, so that the working bias voltage is prevented from being too high or too low.

The invention discloses a filling continuous compaction acoustic wave detection system. Based on a rolling machine, detection equipment comprises a sound field pickup, an analyzing and processing module, a displayer, a GPS receiver and the like. When a filling layer is rolled, an acoustic wave field time domain signals generated near a rolling layer are received by the sound field pickup which isarranged on an eternal machine frame of a vibrating drum of a road roller and are sampled to form acoustic wave field digital signals; meanwhile, the GPS receiver provides spatial signals related to the rolled position, the sampled acoustic wave signals are filtered and spectrally analyzed to obtain secondary harmonic amplitudes of the effective acoustic signals, a continuous compaction degree index value is established according to the relevance between the secondary harmonic amplitudes and an earth-rock material compaction degree, and combined with GPS spatial position information, a time-space compaction degree distribution diagram of a rolled area is shown on the machine-mounted displayer. The filling continuous compaction acoustic wave detection system disclosed by the invention has the characteristics of non contact, continuity, real timeliness, suitable for filling engineering continuous compaction quality control and the like. A vibrating frequency and a vibrating amplitude ofthe vibrating drum of the road roller are controlled by compaction feedback, so that an intelligent continuous compaction function can be easily achieved.

A nonlinear ultrasonic detection method for evaluating the thermo-oxidative ageing of an organic material comprises the following steps: building an organic material thermo-oxidative ageing damage nonlinear ultrasonic detection system based on a nonlinear acoustic detection system; respectively setting corresponding parameters of an excitation signal and a reception signal, and finely adjusting the corresponding parameters of the excitation signal and the reception signal by a time domain waveform signal observed and received by an oscilloscope; selecting the optimum work frequency range of a probe according to the frequency characteristic of the ultrasonic probe, and determining the initial frequency and the ending frequency of the swept frequency range; adjusting integrator gate parameters, carrying out frequency sweeping to obtain the change rule of an supersonic wave fundamental wave amplitude and a secondary harmonic amplitude with the frequency, and storing the change rule in a computer; calculating corresponding nonlinear coefficients of all frequency points in the swept frequency range, and calculating the accumulated nonlinear effect in the swept frequency range; and determining a corresponding relationship between the accumulated nonlinear effect and the thermo-oxidative ageing time of the organic material, and assessing the existence or not and the degree of the thermo-oxidative ageing damage of the organic material.

The invention discloses a method for detecting early-stage mechanical property degradation of a material by utilizing nolinear rayleigh wave, belonging to the field of nondestructive testing. The invention comprises the following steps: inputting frequency, periodicity and other parameters of a selected transmission signal to a signal generator to generate a required single sound signal, and determining the incident angle theta of the transmission signal according to the wave speed of a piece to be tested; collecting a non-linear Rayleigh wave signal in equal time intervals in the stretching or fatigue loading process of the piece to be tested; and carrying out Fourier transform to obtain basic wave amplitude and secondary harmonic amplitude, computing the ultrasound non-linear coefficient beta, and knowing the early-stage mechanical property degradation of the piece to be tested according to beta. In the invention, a sensor is directly arranged at the edge of the piece to be tested to transmit and receive Rayleigh wave to improve the excitation and receiving efficiencies of the signal and decrease the non-linear influence brought by the coupling of the sensor and the piece to be tested; and both the excitation and the receiving adopt the piezoelectric sensor, thus being more applicable to engineering actual situation, and realizing continuous on-line detection on the piece to be tested.

The invention discloses a method for measuring common-frequency periodic signal phase differences. The method includes the steps of S1, carrying out synchronous sampling on W sample data of two common-frequency periodic signals to be measured in an evenly-spaced mode, S2, obtaining harmonic amplitude values A1k and A2k and harmonic phase angles of ml subharmonic and m2 subharmonic of the two common-frequency periodic signals to be measured, S3 computing initial phase angles of the two common-frequency periodic signals to be measured according to the harmonic amplitude values A1k and A2k and the harmonic phase angles, and S4, computing the phase differences according to the difference of the two initial phase angles and obtaining high-accuracy phase different measurement results. Thus, quality of instrument devices in the fields like electrical equipment condition monitoring, signal collecting and analysis, communication and automatic control can be achieved, wherein the instrument devices are based on the phase difference technology.