112 results about "Harmonic spectrum" patented technology

A system and method is disclosed for reconstructing high frequency components of a digital audio signal using a harmonic enhancer in a baseband integrated circuit of a receiver handset. The original spectrum of the digital audio signal is upsampled in a times two (2) upsample unit to double the size of the bandwidth. A low pass filter then removes a high frequency alias of the original spectrum. The spectrum is then modulated with a first carrier frequency and sent to a first filter bank where a low pass filter and a high pass filter shape the modulated harmonic spectrum. After gain adjustment, the modulated harmonic spectrum is added to a delayed version of the original spectrum. Additional harmonic spectra are similarly created at other carrier frequencies and added to the audio output spectra to reconstruct high frequency components of the audio signal.

The invention discloses a method for detecting harmonic waves of an electric system based on window and interpolated FFT. The method comprises the following steps of obtaining sampling data of detected signals by an analog to digital converter, carrying out an operation of adding Hanning window FFT on the sampling data, searching a peak and an adjacent secondary peak of a spectral line to obtain an interpolation coefficient of a fundamental wave, obtaining the interpolation coefficient of each level of harmonic wave by the interpolation coefficient of the fundamental wave, eliminating the interference of the fundamental wave frequency spectrum to the adjacent harmonic wave frequency spectrum to modify the spectral line of the harmonic wave, and finally obtaining the frequency, the amplitude value and the phase of the fundamental wave and each level of harmonic wave by an interpolation operation. The invention firstly puts forwards that a real spectral line of the harmonic wave can be obtained by eliminating the interference of the fundamental wave frequency spectrum to the adjacent harmonic wave frequency spectrum in the Hanning window FFT spectral line. The scheme of the invention has the advantages of providing the method for detecting the window interpolated FFT harmonic wave with a small calculation amount and high analyzing precision.

The invention belongs to the technical field of digital signal processing, in particular relates to a harmonic spectrum interpolation correction analysis method of a power network. The method provides the method for using the interpolation correction method to eliminate the phase change to further correct the spectrum through the analysis of the reasons of the spectrum leakage. The method utilizes the windowed interpolation spectrum analysis method to estimate the changing phase and utilizes the estimated result to construct a corresponding anti-phase function, the constructed anti-phase function is multiplied by a discrete sequence which is generated by Fourier inverse transformation in a time domain, and the multiplied discrete new sequence is carried out the Fourier transformation again, thereby achieving the spectrum correction effect. The analysis, the simulation and the experiment results can show that the method effectively improves the precision of the harmonic spectrum analysis of the power network during the non-synchronous sampling simultaneously when verifying the effectiveness of the method of the invention.

A signal portion is extracted per frame having a specific duration from an input signal, thus generating a per-frame input signal. The per-frame input signal in the time domain is converted into a per-frame input signal in the frequency domain, thereby generating a spectral pattern of spectra. Peak spectra having peaks are detected in the spectral pattern. A harmonic spectrum is determined, in the peak spectra, having a harmonic structure showing a relationship between a fundamental pitch and a harmonic overtone.

The invention discloses a three-phase inverter topology structure with adjustable DC bus voltage and a method of adopting the structure to realize dynamic DC bus voltage adjustment, which belong to the field of high-speed motor spindle driving control, and solve the problem that the existing inverter topology structure results in huge torque ripple in a controlled high-speed motor, applied square wave voltage during the control process generates current harmonics rich in a harmonic spectrum, and thus, loss in the motor is increased abruptly. The topology structure comprises a three-phase rectifier bridge, a DC bus supporting capacitor, a DC bus input voltage detection module, a Buck-Boost voltage adjusting circuit, a DC bus output voltage stabilizing capacitor, a DC bus output voltage detection module, a three-phase half-bridge inverter circuit, a three-phase current detection module and a driving control circuit. The dynamic bus voltage adjustment method is realized by adopting a DC bus voltage online dynamic adjustment strategy and a sensorless control strategy. The structure and the method are mainly used to dynamically adjust the DC bus voltage according to a motor operation state.

The signal processing system includes a pulse width modulator (PWM) that receives a quantizer output signal from a delta sigma modulator. Each quantizer output signal represents one of N quantization levels. For at least one of the quantization levels, the PWM can generate multiple, different PWM patterns. Thus, each quantization level in at least a subset of the N quantization levels is associated with at least two PWM patterns. In at least one embodiment, the subset of quantization levels represents the quantization of low level samples of a quantizer input signal. By associating multiple PWM patterns to at least the subset of the quantization levels, the pulse edges of the PWM patterns in a frame are shifted in time with respect to subsequent PWM patterns, which spreads the spectrum of harmonic frequencies of the PWM output signal. Spreading the spectrum of harmonic frequencies of the PWM output signal can reduce electromagnetic interference (EMI).

The invention discloses a thrust ripple suppressing method of a primary permanent magnet linear motor. Positioning force of the primary permanent magnet linear motor is obtained by measuring in practice by a finite element simulation or torque testing instrument. The waveform of the positioning force undergoes harmonic spectral analysis to confirm the component of base waves and main ultraharmonics in the positioning force. The no-load counter emf wave form of a finite element simulation motor is utilized to calculate out the three-phase current component which is used for counteracting the harmonic component of the positioning force so that additional electromagnetic force is equal to the component of the base waves and the main ultraharmonics in the positioning force in terms of amplitude, but opposite in terms of phase. Three-phase harmonic currents are filled into a current hysteresis vector control system to suppress thrust ripple of the permanent magnet linear motor. The body of the motor does not need transforming and a control strategy can be used for achieving suppression. The thrust ripple of the motor can be obviously hindered, noise in operation of the motor is reduced and characteristics of the motor such as no-load magnetic potentials and thrust outputting capability are kept unchanged.

The invention relates to a laser wavelength calibration method and device and a gas concentration analyzer. The wavelength calibration method includes the steps: storing a zero-gas secondary harmonicspectrum and a standard concentration secondary harmonic spectrum acquired in calibration; acquiring the secondary harmonic spectrum of gas to be detected; determining the absorption peak center position of the gas to be detected according to the maximum value of an absorption peak when judging that the concentration of the gas to be detected is within a first range, acquiring deviation between the absorption peak center position of the gas to be detected and the absorption peak center position of the standard concentration spectrum and generating feedback signals according to the deviation exceeding a preset value to calibrate wavelengths; determining the absorption peak center position of the gas to be detected according to the similarity of the spectrum of the gas to be detected and thezero-gas spectrum when judging that the concentration of the gas to be detected is within a second range, acquiring deviation between the absorption peak center position of the gas to be detected andthe absorption peak center position of the zero-gas spectrum and generating feedback signals according to the deviation exceeding the preset value to calibrate the wavelengths. The first range is notoverlapped with the second range, and the value of the first range is larger than that of the second range.

The invention discloses an adjacent harmonic and inter-harmonic separation and measurement method under an IEC (international electrotechnical commission) framework. The method includes the following steps: firstly, performing discrete sampling on a power grid signal; secondly, performing ten-cycle Hanning window addition DFT/FFT (discrete Fourier transform/fast Fourier transform) spectral transformation on a sampling value according to IEC standards so as to obtain a spectrum; thirdly, multiplying the spectrum by rotary phase factors to obtain a new spectrum; fourthly, solving a vector sum of neighboring spectral lines of the new spectrum so as to offset sidelobe interference of rest components on the new spectrum, and solving corresponding frequency, a frequency deviation value and amplitude phase via a spectral line phase cancellation interpolation method; fifthly, rejecting spectrum leakage values of a fundamental component and the rest components at spectral line attention positions on a frequency domain; sixthly, solving a harmonic spectrum value to obtain parameters of h subharmonics, and solving parameters of inter-harmonics adjacent to the h subharmonics. By the method, the problem that the parameters of the two adjacent harmonics and inter-harmonics cannot be measured accurately during limited data asynchronous sampling is solved.

A modulation clock supplied to a drive circuit (7) of a display panel (1) is frequency-modulated so as to spread its harmonics spectrum. The frequency deviation is so restricted that, if at least two pixels corresponding to two adjacent scanning wirings are displayed based on arbitrary same luminance data, a difference in display luminance in a specified period between one pixel and the other pixel is less than or equal to a tolerable value determined by the luminance data. Consequently, reduction in unnecessary radiation can be achieved at a lower cost while suppressing deterioration in image quality

The invention discloses a grating sensor displacement measuring system based on phase modulation. The system comprises a grating sensing optical path unit and a signal processing unit. The grafting sensing optical path unit comprises a collimation light source, an MEMS scanning mirror, a main grafting and an indicating grafting. The signal processing unit comprises a photoelectric conversion device and phase-locked loop phase. The MEMS galvanometer structure is used for carrying out phase modulation on relative displacement signals of the indicating grating relative to the main grating, and precise measurement of displacement can be achieved through a single detector. By demodulating the signals by a phase-locked loop at the position of a specific harmonic frequency spectrum, measuring signals are migrated out of low frequency bands, the influences of direct current drifting and other low-frequency changes are overcome, the influences of high-frequency-band noise can be effectively reduced during signal processing, orthogonal errors caused by traditional grating sensor two-path or four-path signals are avoided, the influences of direct current drifting and amplitude fluctuation on the measuring result are reduced, and the measuring precision of the measuring system during low-speed and high-speed displacement measurement is improved.

The invention discloses a complex power harmonic wave parameter estimation method. The method comprises the steps that complex harmonic waves are discretized; windowing truncation is conducted on a discretization signal; amplitudes of multiple spectral lines in a frequency domain are acquired, and a harmonic wave parameter estimation problem is converted into a constraint-condition-containing nonlinear programming problem according to the theoretical amplitudes and the actual amplitudes of the spectral lines; the nonlinear programming problem is solved, and harmonic wave parameters are obtained. According to the method, the precision is high, a small calculation amount is needed, and the problem brought by different harmonic wave spectrum leakage interference can be well solved.

The invention discloses a motor control system and a noise reduction control method and device for a frequency converter of the motor control system. The frequency converter outputs a space vector pulse width modulation (SVPWM) wave to a motor in the motor control system. The method comprises the following steps: acquiring a preset central carrier frequency, a preset frequency band constant and a preset random distribution function; acquiring a current frequency band constant according to the preset frequency band constant and the preset random distribution function, and acquiring a current carrier frequency according to the preset central carrier frequency and the current frequency band constant; generating an SVPWM wave of a current period according to the current carrier frequency, so as to reduce noise of the frequency converter. Therefore, random change of the carrier frequency of the SVPWM wave based on a certain rule can change a harmonic spectrum of voltage output by the frequency converter, so as to enable the harmonic spectrum to be distributed on a relatively wide frequency band; furthermore, under a condition of not changing total harmonic energy, a harmonic amplitude value can be reduced, so that the noise of the frequency converter is decreased and suppressed.

The invention discloses a device and a method for measuring the diffusion velocity of an electronic wave packet and aims at measuring a higher harmonic spectrum, screening the relationship between the elliptic polarization independence for exciting the wavelength of laser generated by the high harmonic spectrum and the wavelength of the laser and calculating the speed of the electronic wave packet and the sizes of the electric wave packets corresponding to different laser wavelengths according to the relationship between the sensitivity to the laser elliptic polarization degree and the electronic wave packet kinetic process. The measuring device and the measuring method have the characteristics of simpleness and effectiveness and important significance on understanding the evolution of the electronic wave packets in the strong-field physics and the electronic micro kinetics.

The invention discloses a dominant interharmonic spectrum distribution calculation method. The method comprises steps: a digital quantity for three-phase voltage and current signals of an M-frequencytime window is taken for discrete Fourier transform (DFT) analysis, and a rough interharmonic signal spectrum distribution diagram is acquired; according to the rough interharmonic signal spectrum distribution diagram, a harmonic singlet effective value and a harmonic cluster effective value are calculated, and the ratio of the harmonic cluster effective value to the harmonic singlet effective value is further calculated; according to the size relationship between the ratio and a threshold, whether interharmonics exist near the harmonics is judged; and if yes, the existence range of dominant interharmonics is determined, data in a certain time window are selected for DFT analysis, and the dominant interharmonic spectrum distribution is determined. Due to the method of the invention, the dominant interharmonic spectrum distribution can be simply and quickly; a help is provided for interharmonic control; influences on a power grid by the interharmonics are reduced; and safe and stable operation of power supply equipment and power consumption equipment.

The invention belongs to the field of digital holography, and discloses a digital holographic harmonic detection and elimination method based on spectrum energy. The method includes six steps to complete the processing of an image with harmonic interference, which are Fourier transform of the image, search of a harmonic spectrum, readout of coordinates and a complex value of the harmonic spectrum, calculation of the frequency and interference intensity coefficient of harmonics in horizontal and vertical directions and the initial phase, construction of harmonic distribution using parameters, and image correction. The method of the invention only utilizes the energy relationship between the zero-order Fourier transform spectrum and the harmonic spectrum without the need to design a filter; the acquisition of the range of harmonics corresponding to the spectrum is not required; no impact will be exerted on the information of the original light; an inverse Fourier transform is not required on the spectrum; and after the harmonic parameters are obtained using the energy relationship, the harmonic intensity distribution is constructed, the harmonic is eliminated by direct subtraction and the calculation is simple.

The present invention relates to methods and devices for estimating harmonics that reduce the calculation amount and can be used very effectively in a low transmission rate voice encoder by adjusting a harmonic interval with centering on a multiple of a basic frequency or extracting a peak so that the error between an original signal spectrum and estimated harmonic spectrum is reduced.

The invention discloses a loop signal analysis method and a device for a DC control protection board, which relate to the technical field of signal processing and aim at solving the problem that spectrum leakage generated during a loop signal analysis process can not be effectively restrained. The method mainly comprises steps: according to a preset sampling frequency, board loop signals are sampled uniformly, and discrete signals are acquired; the discrete signals are intercepted according to a mixed convolution window, and filter signals are acquired; the result of carrying out FFT (Fast Fourier Transformation) on the filter signals is determined to be a harmonic spectrum; in the harmonic spectrum with the distance with a preset basic frequency point to be smaller than preset frequency offset, a peak frequency point nearest to the preset basic frequency point and with the maximum amplitude is searched; according to the amplitudes corresponding to the preset basic frequency point and the peak frequency point, the amplitude offset is calculated; and according to the offset, every-order harmonic parameters in the harmonic spectrum are calculated, wherein the harmonic parameters comprise the amplitude, the phase and the frequency. The method and the device are mainly applied to loop signal analysis for the DC control protection board.

Embodiments of the invention provide a detection method for a two-dimensional layered material heterojunction stacking sequence, and a spectral measurement system. The method comprises the steps of acquiring secondary harmonic spectrums corresponding to a single-layer-shaped material region and a heterojunction region in a to-be-detected heterojunction at different rotation angles; extracting secondary harmonic signal peaks corresponding to the single-layer-shaped material region and the heterojunction region in the secondary harmonic spectrums at different rotation angles; acquiring a first polar coordinate distribution diagram and a second polar coordinate distribution diagram according to the secondary harmonic signal peaks; comparing the secondary harmonic signal intensities in the first polar coordinate distribution diagram and the second polar coordinate distribution diagram to obtain a stacking sequence detection result of the heterojunction. According to the method, a characteristic that secondary harmonic signals are zero when layered materials are stacked to form a central symmetric structure is used, and an optical means is adopted as a probe, so that the requirements for a heterojunction sample are reduced, and the sample does not need to be transferred to a target carrier net; the detection method is simple and convenient; and rapid nondestructive testing is realized.

The embodiment of the invention relates to a harmonic analysis method and apparatus, and a method and apparatus for determining clutter in harmonic wave. The harmonic analysis method comprises: carrying out time frequency conversion on an inputted time domain signal so as to obtain a frequency spectrum of the time domain signal at a frequency domain; carrying out filtering processing on the frequency spectrum so as to determine a target frequency spectrum; carrying out elimination processing on the clutter in the harmonic wave of the target frequency spectrum so as to determine the structure of the harmonic wave of the target frequency spectrum; and on the basis of the structure of the harmonic wave of the target frequency spectrum, carrying out a harmonic analysis on the harmonic wave. According to the embodiment of the invention, the target frequency spectrum of the harmonic analysis is determined by filtering and the clutter interference can be effectively eliminated, thereby obtaining a clear and accurate harmonic frequency spectrum and thus carrying out the harmonic analysis conveniently.