20 results about "Modulation spectrum" patented technology

The invention provides a stimulated Brillouin scattering suppression device and method of an optical fiber amplification system, and the device comprises a seed source, a signal generator, a radio frequency amplifier, a signal modulator and a spectrum filter. And performing power amplification on the LFM radio-frequency signal output by the signal generator by using a radio-frequency amplifier so as to drive the signal modulator to modulate the seed laser and generate a modulation spectrum containing a carrier and a plurality of sidebands, and finally screening out a single target sideband through a spectrum filter to obtain a sweep-frequency light source. Effective suppression of stimulated Brillouin scattering is realized in an optical fiber amplification system. According to the invention, high modulation voltage can be prevented from being applied, and the voltage-withstanding range of an existing commercial signal modulator is adapted; meanwhile, the modulation period range is large and controllable, the short modulation period can meet the short optical fiber scene requirement of the optical fiber amplification system, and the SBS suppression effect of the optical fiber amplification system is effectively improved.

This invention relates to the field of passive underwater target identification technology, and in particular to a propeller noise cyclic coherent demodulation method based on an improved real-number genetic algorithm. Based on cyclic stationarity analysis theory, an optimal coherent weighted quadratic envelope spectrum is constructed by replacing the fixed integration frequency band with a weighting function, and an adaptive detection threshold is constructed based on the false alarm probability. The observed spectrum is modeled as the sum of harmonics and noise, and a sparse non-negative optimization problem is solved to extract the harmonics. Using the total harmonic intensity of the envelope spectrum as the cost function, an improved real-number genetic algorithm is used to optimize and search for the optimal weighting coefficient vector. The demodulated spectrum is obtained by coherently weighting and integrating the normalized cyclic modulation spectrum. This invention achieves autonomous allocation of weighting coefficients and adaptive selection of demodulation frequency bands, effectively improving the signal-to-noise ratio gain of cyclic demodulation, and is applicable to passive target identification in data backtracking and review systems.

The application discloses a synchronous measurement and analysis method and system for torsional vibration of a steam turbine shaft system and blade vibration, and belongs to the technical field of monitoring of steam turbine generator units. The method comprises noise suppression processing on multi-mode synchronous signals and correlation analysis, so as to obtain coupling modal characteristics representing the comprehensive state of the steam turbine shaft system-blade, and to evaluate and analyze the coupling modal characteristics based on a pre-constructed coupling analysis model. In the application, an adaptive filter is used to filter the blade vibration signal, and cross modulation spectrum of the torsional vibration demodulation timing information and the vibration modal characteristic component is determined based on a mutual information function, so as to accurately determine the cross phase relationship at the sampling point, obtain the coupling modal characteristics representing the comprehensive state of the steam turbine shaft system-blade, and more comprehensively and accurately reflect the overall operation state of the steam turbine.

The application provides a modulation spectrum circuit and a power amplifier, wherein the modulation spectrum circuit comprises an operational amplifier, a field effect transistor, a first resistor, a first control circuit, a second control circuit, a second resistor, a third control circuit, a third resistor and a comparison circuit; a first end of the first resistor and a drain of the field effect transistor are connected and serve as an output end of the modulation spectrum circuit, and are used for outputting a modulation signal with a preset modulation spectrum to a final stage amplifier in the power amplifier; an input end of the second control circuit is used for connecting a feedback signal formed by an output current of the final stage amplifier; and the comparison circuit is used for controlling the conduction or the turn-off of the first control circuit, the second control circuit and the third control circuit. The modulation spectrum circuit of the application can not only meet the modulation spectrum under the condition of large power output, but also optimize the modulation spectrum under the condition of small power output.

The modulation spectrum adaptive feature purification method based on feature energy entropy reconstruction belongs to the field of underwater acoustic target recognition. The method is used for solving the problem that the existing modulation spectrum feature extraction method cannot solve the influence of harmonic interference on the final estimation result. The method comprises the following processes: in step one, the cavitation noise in the ship radiated noise is demodulated through a plurality of preset demodulation frequency bands, a plurality of demoded signals are obtained, and the optimal demodulation frequency band is selected from the demodulation frequency bands corresponding to the demoded signals by adopting the minimum entropy criterion; in step two, the demoded signal obtained under the optimal demodulation frequency band is decomposed through the VMD algorithm, and the signals of the intrinsic mode functions of all orders are obtained; in step three, the feature energy entropy of the signals of the intrinsic mode functions of all orders is calculated, the feature energy entropy is reconstructed by using the FEER algorithm, and the reconstructed signal is obtained; in step four, the power spectrum analysis is carried out on the reconstructed signal, and the purified modulation spectrum is obtained. The method is mainly used for purifying the modulation spectrum.

A method of utilizing beamforming to selectively locate one or more ambient electromagnetic power harvesting (AEPH) chips, implemented by a reader apparatus comprising multiple antennas, the method comprises transmitting, to the AEPH chips, an interrogation signal from multiple transmit antennas by a reader application executing on a processor of the reader apparatus in a first frequency band to activate the AEPH chips; receiving, from at least one AEPH chip by multiple receive antennas of the reader apparatus, one or more signals in response to the interrogation signal; processing the one or more signals to determine a direction of the at least one AEPH chip; and adjusting, using a beamformer, a beam direction of the multiple transmit antennas of the reader apparatus in the direction of the at least one AEPH chip to deliver the maximum power to the at least one AEPH chip.

The invention relates to the technical field of power system equipment protection, in particular to a phase modifier protection method based on fusion of vibration characteristics and non-electrical parameters. Comprising the following steps: synchronously acquiring vibration signals, thermal parameters and operation condition parameters; extracting a vibration feature vector through a wavelet packet energy entropy modulation spectrum, and establishing a thermal parameter health reference model to calculate a residual feature to form a thermal feature vector; generating a dynamic adjacency matrix according to the current working condition by adopting a dynamic weight generation network, and outputting node update features through graph convolution; when the node update feature exceeds the limit, calculating the abnormal confidence coefficient according to the over-limit state of the cross-domain strong association node; diagnosing the fault through cross-domain attention fusion; and establishing an equipment risk, power grid risk and economic cost multi-objective function, and performing Pareto optimization on the candidate protection action set to select an optimal protection action. According to the invention, working condition self-adaptive multi-physics field depth coupling analysis and intelligent protection decision are realized.

This invention relates to a magnetic sensing deep learning-driven intelligent metamaterial on-demand design system and method. By setting up a terminal device, a unit cell structure device, a prediction device, and a simulation device, the unit cell structure device can generate a magnetic field modulation spectrum with the same dimension as the target band structure matrix using user-defined target parameters. Furthermore, it uses a magnetic conditional generative adversarial network model algorithm to transform the magnetic field modulation spectrum into multiple candidate unit cell structures. The prediction device can screen out all candidate unit cell structures whose bandgap attribute characteristics deviate from the target bandgap by less than a first threshold. The simulation device can perform finite element simulation on each candidate unit cell structure screened by the prediction device, selecting all candidate unit cell structures that simultaneously meet the bandgap performance threshold and engineering constraints. Ultimately, this achieves rapid and accurate prediction of the band structure of intelligent metamaterials under given excitation field conditions and on-demand design of unit cell structures.

This invention provides a modulation spectrum circuit and a power amplifier. The modulation spectrum circuit includes an operational amplifier, a field-effect transistor (FET), a first resistor, a first control circuit, a second control circuit, a second resistor, a third control circuit, a third resistor, and a comparator circuit. The first terminal of the first resistor is connected to the drain of the FET and together serve as the output terminal of the modulation spectrum circuit, used to output a modulation signal with a preset modulation spectrum to the final stage amplifier in the power amplifier. The input terminal of the second control circuit is used to receive a feedback signal formed by the output current of the final stage amplifier in the power amplifier. The comparator circuit is used to control the on / off state of the first, second, and third control circuits. The modulation spectrum circuit of this invention can not only meet the modulation spectrum requirements under high power output conditions but also optimize the modulation spectrum under low power output conditions.

The application discloses a warning sign processing method and device, a storage medium and an electronic device. The method is applied to the metal detection field, and comprises the following steps: sampling a target area by using an eddy current detector to obtain original waveform data; performing interpolation processing on the original waveform data to obtain first waveform data; performing processing on the first waveform data by using a complex modulation frequency spectrum refinement algorithm to obtain first frequency spectrum data; determining metal information in the target area according to the first frequency spectrum data, and controlling installation of a warning sign according to the metal information. Through the application, the problem that the installation efficiency of the warning sign is low due to the fact that the traditional eddy current metal detector is easily affected by noise and interference in a complex environment because of the limited number of coils, and the detection accuracy is reduced is solved.

The invention relates to a multi-parameter coupling variable-speed navigation body radiation noise simulation method. According to the method, a continuous spectrum component, a line spectrum component and a modulation spectrum component are respectively generated by initializing a target category and a motion state parameter, and motion parameters such as a target navigational speed and an accelerated speed are innovatively and dynamically coupled with noise characteristics: a continuous spectrum changing along with the navigational speed is generated by using an FIR filter; doppler frequency shift and random fluctuation are introduced into the line spectrum to simulate time-varying characteristics; and dynamically calculating a modulation spectrum according to the propeller rotating speed. And finally, superposing the components to generate a high-fidelity variable-speed target radiation noise signal. The method solves the problem that the traditional model has fixed parameters and cannot reflect the dynamic evolution of maneuvering target noise, and can provide vivid and reproducible data support for sonar system test and target identification research.

The invention provides a compact range-based micro-Doppler characteristic test system and method, and aims to solve the problems of difficulty in micro-Doppler characteristic extraction, remarkable dynamic attitude influence and the like of a rotorcraft in the prior art. The system comprises a microwave anechoic chamber, a compact range reflecting surface, a feed source rotary table, a feed source antenna, a multi-degree-of-freedom low-scattering rotary table, a motion synchronous controller, a broadband vector signal generator, a receiver and an upper computer, and the method comprises the following steps: installing a tested piece on the multi-degree-of-freedom low-scattering rotary table, importing a flight attitude file and simulating the attitude of an aircraft; a broadband carrier signal is transmitted and reaches a measured object through a compact range reflecting surface, an echo signal is collected and conjugate matched filtering processing is carried out, and finally micro-Doppler modulation spectrum characteristic parameters are extracted; according to the invention, environmental electromagnetic interference and machine body strong scattering can be effectively suppressed, the signal-to-noise ratio of signals is improved by more than 20dB, and high-precision micro-Doppler feature extraction is realized.

The invention relates to a ship noise signal simulation method based on a deep neural network. The method comprises the following steps: simulating a continuous spectrum, a modulation spectrum and a line spectrum of ship noise; simulating the continuous spectrum by adopting an FIR filter design based on a Welch method; an improved model based on fusion of bidirectional LSTM and a self-attention mechanism is provided, so that the time-frequency characteristic of a modulation envelope is effectively captured, and high-precision simulation of a modulation spectrum is realized; a physical information neural network (PINN) is innovatively introduced, physical constraints are embedded into a loss function, and high-fidelity simulation of line spectrum features is achieved.

The invention discloses an intelligent prediction method and system for large deformation of surrounding rock in a deep tunnel soft rock area, and the method comprises the steps: obtaining a displacement vector of each monitoring point in real time through a sensor disposed at each monitoring point in the tunnel surrounding rock area, taking the second derivative of the displacement vector as the dynamic reaction intensity of the monitoring point under construction disturbance, and calculating the dynamic response intensity of the monitoring point; performing Fourier transform on the dynamic reaction intensity to generate a modulation spectrum of surrounding rock disturbance; calculating the strain energy density of the current monitoring point according to the displacement vector of the current monitoring point, calculating the energy divergence of the current monitoring point in combination with the change speed of the displacement vector, and performing spectral analysis on the energy divergence to obtain the spectral energy density of the current monitoring point under each frequency; and carrying out spatial maximum value search on the change rate of the spectrum energy density of all the monitoring points along with time and the change rate of the modulation spectrum along with time, and taking the corresponding monitoring point as a position where unstable deformation is most likely to occur.

A modulation spectrum direction finding method based on automatic demodulation band optimization belongs to the field of underwater acoustic detection and array signal processing technology. To address the problem that existing modulation spectrum direction finding methods often use empirically selected fixed frequency bands for demodulation, which are difficult to adapt to changes in target modulation characteristics, leading to reduced signal-to-noise ratio (SNR) and insufficient direction finding accuracy, this invention first estimates the SNR of the cyclic modulation spectrum, uses a constant false alarm rate (CFAR) detection method for detection, performs spectral line tracking on the detected cyclic modulation spectrum, and optimizes the demodulation band of the modulation spectrum. Using the optimized demodulation band, the original signal is bandpass filtered, and the filtered signal is detected to obtain the corresponding envelope. Cross-spectral analysis is performed to obtain the phase information of all modulation frequencies within the band. The received signal delay difference between sensors is calculated from the phase information, the target's azimuth is calculated, and the azimuths measured from multiple modulation frequencies are weighted and fused to obtain the final target direction finding result.

This invention discloses a method for estimating the envelope spectrum of ship radiated noise based on spectral whitening, belonging to the field of underwater acoustic signal processing. The method first determines the main frequency band containing the modulation characteristics of the target signal through cyclic modulation spectrum analysis; then, it processes the background noise spectrum within the main frequency band using smoothing, and calculates a spectral shaping factor based on the median of the smoothed spectrum to construct a conjugate symmetric whitening filter; finally, it performs weighted shaping of the target signal spectrum in the frequency domain, and restores the whitened spectrum to the time domain for amplitude demodulation and power spectrum analysis. This invention effectively improves the signal-to-noise ratio (SNR) of broadband envelope spectrum estimation by introducing a spectral whitening mechanism, providing a reliable guarantee for accurately extracting physical characteristics such as the number and rotational speed of ship propellers. Experiments show that this method can improve the average SNR of the envelope spectrum by approximately 7 dB, demonstrating strong engineering practical value.

This invention discloses a method for simulating underwater acoustic radiation noise of AUV thrusters based on CVAE (Continuous Array Electron Microscopy). The method comprises the following steps: S1: radiated noise component modeling and parameterization; S2: line spectrum signal simulation; S3: modulation spectrum envelope simulation; S4: continuous spectrum generation based on the CVAE model; S5: conditional continuous spectrum generation and conversion; and S6: analog signal synthesis. This method can simulate the radiated noise signal of an autonomous underwater vehicle (AUV) thruster with high fidelity based on the thruster's real-time operating parameters. This method is particularly suitable for providing high-quality simulation data for scenarios such as sonar system development, underwater target recognition algorithm training, and AUV acoustic stealth performance evaluation.

The invention provides a ship radiation noise data augmentation method based on spectrum reconstruction, a medium and a system, and belongs to the technical field of ship radiation noise processing. After a continuous spectrum and a line spectrum are separated through smooth filtering, a continuous spectrum segmentation parameter, a line spectrum frequency amplitude parameter and a modulation spectrum fundamental frequency parameter are extracted; constructing a continuous spectrum reconstruction game model and a line spectrum detection game model to respectively optimize a filter coefficient and a detection threshold, solving the filter coefficient based on the continuous spectrum reconstruction game model by adopting a variable step size normalized adaptive iterative algorithm, and generating a continuous spectrum reconstruction time domain signal; a line spectrum effective frequency set is determined by adopting a constant false alarm rate adaptive detection algorithm based on a line spectrum detection game model, then a line spectrum reconstruction time domain signal is generated, a modulation pulse sequence is constructed according to the main shaft frequency and the blade number to generate a modulation spectrum reconstruction time domain signal, and the technical problem that the number of ship radiation noise samples is insufficient is solved.

The application relates to the technical field of automatic control, and particularly discloses a heat dissipation fan rotating speed smooth control method based on noise feedback, which comprises the following steps: based on the transient temperature response of a thermocouple array, extracting a thermal wave dispersion relationship and predicting the spatiotemporal evolution of vortex structure, outputting a heat flux density field and a vortex structure time sequence marker; in response to the time sequence marker, collecting a pulsating vortex field and aerodynamic noise, establishing a sound-vortex coupling transfer function, identifying a matching window, and generating a modulation spectrum instruction; acquiring motor multi-physical field data, inputting the heat flux density field, a steady-state reference value and matching window parameters into an electromagnetic-thermal-mechanical multi-frequency response model, solving an optimal broadband rotating speed track and driving a fan; constructing a reward signal according to actual operation deviation, optimizing a strategy through deep reinforcement learning, and reversely injecting each model to realize self-evolution. Through four-order progression of thermodynamic reconstruction-sound-vortex modulation-multi-field optimization-self-evolution, the application realizes predictive smooth control of the heat dissipation fan.

A method of utilizing beamforming to selectively locate one or more ambient electromagnetic power harvesting (AEPH) chips, implemented by a reader apparatus comprising multiple antennas, the method comprises transmitting, to the AEPH chips, an interrogation signal from multiple transmit antennas by a reader application executing on a processor of the reader apparatus in a first frequency band to activate the AEPH chips; receiving, from at least one AEPH chip by multiple receive antennas of the reader apparatus, one or more signals in response to the interrogation signal; processing the one or more signals to determine a direction of the at least one AEPH chip; and adjusting, using a beamformer, a beam direction of the multiple transmit antennas of the reader apparatus in the direction of the at least one AEPH chip to deliver the maximum power to the at least one AEPH chip.