63 results about "Frequency domain algorithm" patented technology

The invention discloses a brain electrical signal independent component extraction method based on convolution blind source separation. The brain electrical signal independent component extraction method based on the convolution blind source separation includes concrete steps: building a brain electrical signal independent component extraction system based on the convolution blind source separation, which comprises an AD (analog to digital) sampling module, a short time Fourier transformation module, a frequency domain instantaneous blind source separation module, a sequence adjustment module and a short time inverse Fourier transformation module; using the AD sampling module to sample brain electrical signals; using the short time Fourier transformation module to transform the brain electrical signals from a time domain to a frequency domain; using the frequency domain instant blind source separation module to separate instantaneous mixing signals in the frequency domain; using the sequence adjustment module to perform sequence adjustment on independent components in a vector on each frequency domain segment; using the short time inverse Fourier transformation module to transform a frequency domain separation result into an independent component on the time domain. The brain electrical signal independent component extraction method based on the convolution blind source separation extracts the independent components of brain electrical signals based on a true convolution mixing model, uses a convolution blind source separation frequency domain algorithm, and is simple to achieve, good in separation effect, and low in calculation complexity.

The invention belongs to the field of optical communication, and is applied to the polarization demultiplexing of a polarization diversity multiplexing coherent optical communication system. According to the invention, for the problem of the polarization demultiplexing in the polarization diversity multiplexing coherent optical communication system, a special training sequence and related algorithms are designed. Through the method, a coherent receiver can fast, automatically and accurately perform the polarization demultiplexing. As the track of the training sequence, viewed from a planisphere, rotates along a unit circle after sign power is normalized, the training sequence provided by the invention is called a constant rotation sign training sequence. The invention discloses two processing algorithms for the constant rotation sign training sequence, which are a frequency-domain algorithm and a time-domain algorithm respectively, wherein the frequency-domain algorithm can be combined with frequency-domain dispersion compensation without adding a frequency spectrum calculation module. Through the method, the receiver does not need synchronizing with an initial position of the training sequence.

The invention discloses a time-frequency domain hybrid adaptive active noise control algorithm. According to the algorithm, an entire control filter is divided into two blocks according to time delay characteristic of noise propagation; one of the two blocks is used for finishing filtering in time domain to guarantee no time delay, and frequency-domain filtering is adopted by the other one of the two blocks; the updating of both the filters of data of the two blocks is finished in the frequency domain; and thus, the algorithm guarantees that zero time delay control of a noise signal is firstly achieved and the amount of calculation of the entire system is reduced by utilizing a multi-time delay frequency domain algorithm, thereby integrally improving the applicability and the performance of the multi-time delay frequency domain algorithm. The time-frequency domain hybrid adaptive active noise control algorithm has the obvious advantage of breaking through the time delay limit of the multi-time delay frequency domain adaptive algorithm and can be used at places without time delay requirements.

The invention relates to a large frequency deviation estimation and correction method for quadrature frequency division multichannel signal carriers, comprising the following steps: time domain frequency deviation estimation of frequency deviation, and time domain frequency deviation correction according to estimation results. The invention also comprises the following steps: smooth processing of the time domain frequency deviation estimation is performed, namely a low pass filter is adopted to smooth down peak values and valley values of time domain frequency deviation estimation values; after the time domain frequency deviation correction, Fourier transformation is performed; frequency domain frequency deviation estimation is performed on transformation results; frequency domain frequency deviation estimation results or time domain frequency deviation estimation results after smooth processing participate in time domain frequency deviation correction once again. The method of the invention overcomes limitation of the prior frequency domain algorithm on frequency deviation estimation and has the advantages of capability of processing large frequency deviation, capability of guaranteeing smooth signal processing, capability of quickly tracking frequency deviation caused by movement, and capacity of being conveniently realized in an integrated circuit design.

The invention discloses a vehicle-induced bridge transverse vibration reaction calculation method based on a frequency domain method, provides a novel railway bridge transverse vibration response determination method. Compared with a traditional time domain analysis method, the novel railway bridge transverse vibration response determination method has the advantages that a train load spectrum issubdivided into a load sequence spectrum and a bridge harmonic modal spectrum, the influence relation of transverse simple harmonic frequency, train speed, a load sequence and different load amplitudes on the spectrums is researched, and calculation is simplified theoretically; transverse vibration of an axle is directly decoupled, bogie force is simplified for wheel set transverse force, and random vibration analysis is facilitated by adopting a frequency domain algorithm according to the power spectral density of the wheel set transverse force; therefore, the method provided by the inventionis small in calculation amount and high in calculation efficiency; and based on the determined modal number, the calculation precision is relatively good.

A method and system of the present inventions reduces both near-end crosstalk (NEXT) and far-end crosstalk (FEXT) interferences due to handshake tones into upstream and downstream neighboring services, both at the customer premises equipment (CPE) and at the central office (CO), when handshake is experienced. An embodiment of the present inventions is directed to significantly reduce the NEXT and / or FEXT interferences due to handshake tones. For example, NEXT and / or FEXT interferences due to G.994.1 handshake tones, identified as, bins 7 and 9 for the Upstream channel and bins 12, 14 and 64 for the Downstream channel may be reduced. An embodiment of the present inventions provides an algorithm that may be used for both NEXT and FEXT Handshake Interferences reduction at the CO and at the CPE. In addition, the algorithm may operate in the time domain and in the frequency domain. Frequency domain algorithm offers two options, both versions taking advantage of the high correlation time of the Handshake tone signals.

The invention belongs to the field of signal and information processing, particularly relates to a signal processing method, system and device based on a phased array incoherent scattering radar, andaims to solve the problems of low real-time performance and accuracy of signal processing of the existing incoherent scattering radar. The method comprises the following steps: acquiring an echo signal scattered by an ionized layer to aquire an IQ digital signal as a first signal through down-conversion, AD sampling and digital orthogonal down-conversion; performing complex weighting and summationoperation on the first signal to obtain a second signal; removing clutters of the second signal through a preset clutter removing method, and obtaining autocorrelation data through a frequency domainFFT algorithm; circularly acquiring autocorrelation data, accumulating the autocorrelation data, removing background noise after accumulation, and performing calibration correction through a preset data calibration method and a spectrum ambiguity function; and fitting the calibrated and corrected data with theoretical autocorrelation data to obtain ionospheric parameters. According to the invention, the real-time performance and the accuracy of signal processing of the incoherent scattering radar are improved.

The invention discloses a Staggered-SAR echo signal reconstruction method, and the method employs fonformal Fourier transform to process a radar signal after distance compression. The method gives full consideration to the characteristics of Staggered-SAR echoes, and can obtain a uniform azimuth frequency spectrum suitable for the high-quality imaging of a radar. The frequency spectrum obtained through the method can accurately reflect the frequency spectrum characteristics of azimuth echoes under the conditions of data loss and non-uniform sampling, and finally can be used by a Staggered-SAR system for high-quality imaging. Compared with a conventional method, the method can obtain the uniform azimuth frequency spectrum, is suitable for a classical frequency domain algorithm, and can obtain a high-quality imaging result.

The invention relates to an echo cancellation method and system based on an all-phase multi-delay partitioning frequency domain. The method comprises the following steps: receiving remote audio signals, performing sample processing to obtain continuous remote audio sampling signals, and separately storing the continuous remote audio sampling signals; receiving near-end audio signals, performing sample processing to obtain continuous near-end audio sampling signals, and separately storing the continuous near-end audio sampling signals; respectively integrating the remote audio sampling signals and the near-end audio sampling signals, and respectively performing all-phase processing to obtain remote signals and near-end signals; performing Fourier transform processing on the remote signals and the near-end signals, and performing adaptive echo cancellation processing on the remote signals and the near-end signals converted into the frequency domain by using a multi-delay partitioning frequency domain algorithm to obtain audio signals; and encoding the audio signals, and sending the audio signals to a remote receiving end. Therefore, the spectrum leakage problem resulting from that the multi-delay partitioning frequency domain algorithm needs to be converted from the time domain into the frequency domain is solved, the echo estimation is better, and a better echo cancellation effect is achieved.

The invention discloses a low-frequency oscillation online control strategy based on mode matching, and relates to the technical field of power system stabilization and control. The low-frequency oscillation online control strategy comprises the step of applying a dynamic stability control strategy generated by small interference calculation and sensitivity analysis to low-frequency oscillation online based on mode matching. According to improved Prony, QR and IRA algorithms and a characteristic value sensitivity principle, a criterion of mode matching and an online modal calculation method are provided, advantages of the time domain improved Prony algorithm, the frequency domain QR algorithm and the IRA algorithm are combined to match a small interference calculation result with mode information obtained in real time by the on-line improved Prony algorithm, when a vibration mode calculated by small interference real-time scanning is mismatched, a power system stabilizer PSS based on aparticle swarm optimization technology is adopted for restraining low-frequency oscillation, the low-frequency oscillation recognition speed of a large power grid is improved on the whole, meanwhile,the real-time performance and the accuracy of discovery and solution are met, parameter optimization is conducted on the PSS through the particle swarm optimization technology, and the robustness ofthe system is improved.

The embodiment of the invention provides a gravity abnormal boundary enhancement method and device. The method comprises the steps of: obtaining gravity abnormal data of a target work area, and meshing the gravity abnormal data; adopting a space domain operator to extract the gravity abnormal boundary extremum information of a first grid mesh point in a preset direction one by one; and based on the abnormal boundary extremum information of the first mesh point, calculating a coherent enhancement value of a second mesh point. According to the invention, space domain processing is carried out on the gravity abnormal data, the amplification effect of a conventional frequency domain algorithm on data noise is avoided, and the clear and continuous gravity abnormal boundary information can be obtained.

The invention belongs to the field of rail traffic rail detection and provides a rail traffic rail detection system based on acoustic waves. The rail traffic rail detection system based on acoustic waves comprises an impact hammer, a sound pick-up, a signal amplifier and a microprocessor; the impact hammer is a metal hammer; by using the impact hammer to strike a rail, the rail produces a sound; the sound pickup receives the sound produced by the rail; after amplifying a sound signal received by the sound pickup, the signal amplifier outputs the sound signal to the microprocessor; the microprocessor calculates the received signal by using a time domain-to-frequency domain algorithm to obtain frequency spectrum data of the received signal; the calculated frequency spectrum data are comparedwith hub frequency spectrum saved in the system; and therefore, rail cracks and screw loosening are detected.

The invention discloses a modified geosynchronous orbit SAR (synthetic aperture radar) frequency-domain imaging method. A part with zero Doppler frequency rate can be effectively imaged by the method, with good focusing effect; meanwhile, for the part with non-zero Doppler frequency rate, the method allows better focusing performance than the traditional frequency-domain algorithm does. According to the method, the Doppler frequency rate caused by an acceleration component along a slant range direction is compensated, nonlinear azimuth time-frequency relation of raw echo is converted into linear time-frequency relation, and thus, in following operations, the SAR frequency-domain imaging algorithm can be used to correct a range migration in range Doppler. Meanwhile, an acceleration value subjected to compensational optimization is selected by numerical retrieval, variance of azimuth is greatly reduced, and focusing of a larger scene can be achieved during azimuth focusing. Verifications show that the method is suitable for imaging different parts of a GEO (geosynchronous orbit) SAR rail.

The invention discloses a high-sampling-rate vibration analysis device based on a Zynq Ultra Scale + MPSoC platform. The high-sampling-rate vibration analysis device comprises a front-section analog circuit, the Zynq Ultra Scale + MPSoC platform and peripheral equipment, the front-section analog circuit is used for conditioning signals of the acceleration sensor and the rotating speed sensor; theZynq Ultra Scale + MPSoC platform is used for processing a signal; and the peripheral equipment comprises an LCD display screen and is used for displaying processing results of the frequency domain algorithm and the time domain algorithm. The problems that in the prior art, the real-time performance is low, and real-time analysis and positioning of working states of all parts of the rotating machine by technicians are not facilitated can be solved.

The invention discloses a non-visual-field single-input multiple-output three-dimensional reconstruction method for non-uniform fast Fourier transform. A single-input multiple-output technology is introduced in the field of non-vision-field imaging for the first time, and an existing system is utilized to perform rapid imaging on a non-vision-field scene through non-uniform fast Fourier transform.The method comprises the following steps of non-uniformly scanning a reflection medium surface by adopting a laser, receiving a time-photon histogram of an echo by using a detector, preprocessing received data, and converting the received time-photon data into time-amplitude data, utilizing an optimization algorithm to solve the optimal time wave number spectrum for the preprocessed data througha two-dimensional non-uniform fast Fourier transform relation of the spatial dimension, and then performing one-dimensional fast Fourier transform on the time wave number spectrum in the time dimension, performing interpolation processing on the transformed frequency spectrum by using a single-input multi-output frequency domain algorithm, and performing inverse fast Fourier transform on the frequency spectrum after interpolation processing to obtain a non-vision-field scene three-dimensional reconstruction result.

The invention discloses a modified geosynchronous orbit SAR (synthetic aperture radar) frequency-domain imaging method. A part with zero Doppler frequency rate can be effectively imaged by the method, with good focusing effect; meanwhile, for the part with non-zero Doppler frequency rate, the method allows better focusing performance than the traditional frequency-domain algorithm does. According to the method, the Doppler frequency rate caused by an acceleration component along a slant range direction is compensated, nonlinear azimuth time-frequency relation of raw echo is converted into linear time-frequency relation, and thus, in following operations, the SAR frequency-domain imaging algorithm can be used to correct a range migration in range Doppler. Meanwhile, an acceleration value subjected to compensational optimization is selected by numerical retrieval, variance of azimuth is greatly reduced, and focusing of a larger scene can be achieved during azimuth focusing. Verifications show that the method is suitable for imaging different parts of a GEO (geosynchronous orbit) SAR rail.

A method and system of the present inventions reduces both NEXT and FEXT interferences due to handshake tones into upstream and downstream neighboring services, both at the CPE and at the CO, when handshake is experienced. An embodiment of the present inventions is directed to significantly reduce the NEXT and / or FEXT interferences due to handshake tones. For example, NEXT and / or FEXT interferences due to G.994.1 handshake tones, identified as, bins 7 and 9 for the Upstream channel and bins 12, 14 and 64 for the Downstream channel may be reduced. An embodiment of the present inventions provides an algorithm that may be used for both NEXT and FEXT Handshake Interferences reduction at the CO and at the CPE. In addition, the algorithm may operate in the time domain and in the frequency domain. Frequency domain algorithm offers two options, both versions taking advantage of the high correlation time of the Handshake tone signals.

The invention discloses an Alzheimer's disease diagnosis method based on a self-adaptive fine-grained causal brain network, and relates to the field of bioinformatics. The method mainly comprises four parts of adaptive fine-grained division, causal brain network construction, causal network fusion based on intervention and disease diagnosis based on the causal brain network. The method comprises the following specific steps: firstly, finely dividing a brain network according to tense period difference of a brain region by adopting a self-adaptive fine-grained division method, and capturing spatiotemporal characteristics of different scales; then, spatial-temporal features are extracted from the fine-grained partitions, feature learning is performed by using deep learning and a frequency domain algorithm, and multi-granularity feature representation of the brain network is obtained; and then, constructing a causal brain network by using a causal inference technology, identifying a causal relationship between brain regions, and analyzing correlation between different brain regions. Furthermore, in combination with a causal intervention strategy, information of the brain-level causal network is integrated into the fine-grained causal network. And finally, by constructing a diagnosis model based on a fine-grained causal brain network, brain network features are classified by using a graph neural network, and early diagnosis of the Alzheimer's disease is realized. The process allows a causal brain network to be constructed based on brain region division, causal changes between brain regions are revealed, and the Alzheimer's disease diagnosis result is improved.

The invention discloses a time domain and frequency domain combined non-reciprocal medium micro-discharge threshold prediction method. The method is characterized in that a time domain method and a frequency domain method are combined, and in order to solve the problem that a non-reciprocal medium electric field and a non-reciprocal medium magnetic field cannot be accurately solved in a time domain algorithm, a finite element method is used for solving the size and distribution of the fields in a frequency domain; in order to solve the problem of low efficiency of a particle propulsion calculation method in a frequency domain algorithm, a solving frequency domain field is combined with a time domain algorithm, so that the operation efficiency is further improved. In addition, a particle motion technology, a secondary electron emission model and particle-electromagnetic boundary conditions are utilized to quickly calculate and predict the micro-discharge threshold of the non-reciprocalmedium. Particularly, when the micro-discharge threshold value is calculated, the prediction track of the equivalent macro particle motion can be obtained, so that the distribution of the equivalent macro particles and the electric quantity of the macro particles can be predicted.

The invention provides a sea clutter simulation method based on an air-based bistatic radar system, and the method comprises the steps: irradiating a to-be-monitored sea surface through a radar carried on a satellite launching platform, and dividing a radar irradiation sea area in each radar coherent processing interval CPI into a plurality of sub-regions; determining a single-beam monopulse sea clutter signal corresponding to each sub-region based on the frequency domain characteristics of each sea surface scattering point in each sub-region through a sea clutter frequency domain algorithm; and according to the corresponding single-beam monopulse sea clutter signal in each sub-region, determining an echo signal corresponding to a beam in each radar coherent processing interval CPI, so that a sea clutter frequency domain algorithm can be utilized to convert relatively complex Fourier transform into frequency shift and linear calculation, the calculation amount of simulation is reduced, and the simulation efficiency is improved.

The invention discloses a Staggered-SAR echo signal reconstruction method, and the method employs fonformal Fourier transform to process a radar signal after distance compression. The method gives full consideration to the characteristics of Staggered-SAR echoes, and can obtain a uniform azimuth frequency spectrum suitable for the high-quality imaging of a radar. The frequency spectrum obtained through the method can accurately reflect the frequency spectrum characteristics of azimuth echoes under the conditions of data loss and non-uniform sampling, and finally can be used by a Staggered-SAR system for high-quality imaging. Compared with a conventional method, the method can obtain the uniform azimuth frequency spectrum, is suitable for a classical frequency domain algorithm, and can obtain a high-quality imaging result.

The invention belongs to the field of signal and information processing, and specifically relates to an ionospheric electron density inversion method, system, and device based on the CLEAN algorithm, aiming at solving the large amount of calculation of incoherent scattered plasma spectral lines and the insufficient accuracy of electron density profile inversion The problem. The method of this system includes: obtaining the IQ digital signal; extracting and deleting the signal part collected during the pulse transmission in the IQ digital signal, and constructing a two-dimensional matrix; decoding and calculating the signal power spectrum of each range gate height through the frequency domain FFT algorithm; iteratively obtaining each distance Accumulate the power spectrum data of the gate height, and denoise through the system frequency response function; deconvolute the denoised power spectrum data based on the CLEAN algorithm; obtain the plasma spectral line of the entire height profile by the spline interpolation method, and The ionospheric electron density profile was obtained by fitting the Langmuir dispersion relation. The invention improves the real-time calculation of plasma spectral lines and the precision of electronic density profile inversion.

The embodiment of the invention provides an image processing method and device, a server and a storage medium. The method comprises the steps of acquiring a watermark image and an original image; processing the original image based on a preset first frequency domain algorithm to obtain a first frequency spectrum matrix; processing the watermark image based on the first frequency domain algorithm to obtain a second frequency spectrum matrix; embedding the second frequency spectrum matrix into the first frequency spectrum matrix to generate a third frequency spectrum matrix; and processing the third frequency spectrum matrix based on a preset second frequency domain algorithm to obtain a target image. Therefore, based on the image copyright protection of the hidden watermark, the hidden watermark information is added in the frequency domain, operations such as shearing, smearing, compressing and filtering can be resisted, and the image robustness is effectively improved.

The invention discloses a frequency domain active noise control system based on coefficient smoothing, which comprises a rear-end control filter, a coefficient smoother and a front-end control filter which are connected in sequence, and is characterized in that the coefficient smoother is used for smoothing the time domain coefficient of the front-end control filter according to the obtained time domain coefficient of the rear-end control filter; and a front-end control filter is updated to limit system noise caused by overlarge coefficient change, so that the stability and the effectiveness of the active noise control system are improved. According to the invention, the problem of noise occurring in an active noise control system using a frequency domain algorithm is solved.

The invention belongs to the technical field of radio frequency power supply control, and provides a radio frequency power supply power output control method and device. The method comprises the following steps: synchronously acquiring a load end voltage signal and a current signal; based on a time domain algorithm, calculating a phase difference through zero crossing point detection, and combining peak detection to output dynamic power P1; and outputting steady-state power P2 through FFT (Fast Fourier Transform) and phase correction calculation based on a frequency domain algorithm, processing the dynamic power P1 and the steady-state power P2 based on the dynamic weight to obtain fusion power; and adjusting the fusion power based on the incremental PID, and controlling the radio frequency power supply to output the adjusted fusion power. According to the real-time power weight distribution of the operation state of the radio-frequency power supply, high dynamic response and high steady-state precision are realized at the same time, and the problem that the microsecond-level power fluctuation of the load cannot be tracked due to dynamic response lag caused by large calculation amount of the traditional single algorithm is solved; or the performance limitation of insufficient steady-state precision caused by noise interference is avoided.

The invention discloses a time-frequency domain hybrid adaptive active noise control algorithm. This algorithm divides the entire control filter into two blocks according to the delay characteristics of noise propagation, and one block completes filtering in the time domain to ensure no delay. , the other block uses frequency domain filtering, but the filter updates of the two blocks of data are completed in the frequency domain. This not only ensures the algorithm's zero-delay control of the noise signal that arrives first, but also uses the multi-delay frequency domain algorithm to reduce the overall The calculation amount of the system is reduced, thereby overall improving the applicability and performance of the multi-delay frequency domain algorithm. The significant advantage of the present invention is that it breaks through the time delay limit of the multi-delay frequency domain adaptive algorithm, making it applicable to situations without time delay requirements.

The invention discloses an information hiding method and device and a computer storage medium, relates to the technical field of information processing, and solves the technical problem of low confidentiality of hidden information. The information hiding method comprises the following steps: acquiring a first image and a second image; processing the first image through a frequency domain algorithm to obtain a grey-scale map; carrying out gray processing on the second image according to the gray-scale map, and carrying out sub-affine transformation scrambling on the image subjected to the gray processing to obtain a third image; and embedding the third image into the grey-scale map, and obtaining a fourth image hiding the second image through a frequency domain reduction algorithm.