24 results about "Phase error compensation" patented technology

A calibration system and related methods for optical phased array chips. The calibration system includes an adjustable mount module, an infrared microscopic observation module, an arrayed driver module, a two-dimensional laser beam scanning module, a photoelectric conversion module and an upper computer, and utilizes computer-vision-enabled positioning and phase error compensation algorithms as software components. Collimated laser is emitted from the target beamforming angle and aimed at the emission aperture of the chip, and is subsequently sampled by the array elements in a reversed injection manner. Based on the reciprocity of light propagation, by maximizing the power reversely output from the bus waveguide of the optical phased array chip, beamforming at the target angle is achieved supported by software implementations of optimization algorithms. The system and related methods are readily achievable, highly automated, and offers fast and batch calibration with relatively low expenses, good flexibility and long-term compatibility.

The invention discloses a unified beam control mode back projection SAR imaging post-processing method, and relates to the technical field of radar signal processing, and the method comprises the steps: carrying out the range pulse compression and side lobe suppression of original echo data; then establishing a minimum error imaging grid and performing coordinate system conversion; constructing a uniform spectrum compression function, and designing an azimuth time domain windowing function according to the relative position of the beam pointing and the grid point; integrating a unified frequency spectrum compression function and an azimuth time domain windowing function in a back projection imaging process to realize focusing reconstruction of a preprocessed signal; and finally, a high-quality post-processing image is obtained through phase error compensation. The method effectively improves the imaging precision and efficiency, and is suitable for various beam control modes.

The invention discloses a method and a device for analyzing and correcting influence of phase errors between sub-bands of step-frequency ultra-wideband SAR (Synthetic Aperture Radar) data, and belongs to the technical field of synthetic aperture radar signal processing. The method comprises the following steps: carrying out amplitude error estimation and compensation on each sub-band echo signal; preliminarily estimating a phase error by using the partial overlapping characteristic of the sub-band spectrum; performing distance compression on each sub-band signal; establishing an optimization model based on a maximum norm, and solving an accurate phase error by taking the preliminarily estimated phase error as an iteration initial value; carrying out sub-band splicing and distance resolution compression on the sub-band signals after phase error compensation; and finally, a corrected SAR image is obtained through a CS imaging algorithm. According to the method, extra calibration signals are not needed, high-precision phase error correction can be achieved only based on echo data, the calculation efficiency is high, and the method is suitable for a high-resolution SF-SAR system.

The invention relates to an SAR photoelectric processor phase error compensation method based on a Zernike polynomial, and the method comprises the steps: obtaining an SAR photoelectric processor to be subjected to phase error compensation, and employing the Zernike polynomial to express the modulation phase of a spatial light modulator in the SAR photoelectric processor; respectively calculating two-dimensional frequency domain phases of an ideal SAR echo signal and a non-ideal SAR echo signal of the SAR photoelectric processor, determining a focusing phase error, fitting the focusing phase error by adopting a Zernike polynomial, and evaluating focusing phase error (parameter) estimation performance; a plurality of Zernike coefficients are randomly generated for a Zernike polynomial, optimization of the Zernike coefficients is carried out by adopting a genetic algorithm, and the quality of the SAR image is used as a fitness value of the genetic algorithm until the Zernike coefficients meeting optimization conditions of the genetic algorithm are obtained and used for prediction of a modulation phase. Compared with the prior art, the two-dimensional frequency domain phase error can be effectively corrected, and a theoretical foundation is laid for an automatic focusing algorithm special for SAR optical processing.

The application relates to a kind of multi-resident observation 2D super-resolution ISAR imaging methods based on fast IWF, comprising S1 modeling 2D super-resolution ISAR imaging of multi-resident observation signal;S2 initialize the accuracy of signal in fast IWF method, and set the maximum iteration number of fast IWF method;S3 calculate the LC decomposition factor of the inverse matrix G ‑1 of auxiliary observation covariance matrix;S4 estimate target rotation speed, for compensating distance space variable phase error, and obtain error compensation after observation signal;S5 based on the LC decomposition factor of G ‑1 And distance space variable phase error compensation after observation signal, signal estimation value is calculated using 2D-FFT, and the accuracy of signal is updated;S6 repeat steps S3-S5 to carry out cyclic iteration, stop after reaching convergence, obtain super-resolution ISAR image based on signal estimation value and realize transverse calibration based on target rotation speed estimation value.The application has low computational complexity, strong robustness, high reconstruction accuracy and fast convergence, and can efficiently obtain super-resolution ISAR image with good focusing effect and accurate target size estimation value.

The invention relates to a quality improvement method for a high-resolution image. The method comprises the following steps: obtaining an equal-target two-way slope distance; calculating a distance error; calculating a two-dimensional frequency spectrum; calculating a truncation phase error; obtaining data of each receiving array element after micro-Doppler phase error compensation; obtaining all receiving array element data after micro-range migration error correction; obtaining data of the class receiving and transmitting combined synthetic aperture sonar; obtaining N data blocks after truncation phase error compensation; obtaining multi-receiving array element synthetic aperture sonar data; filtering to obtain filtered data; obtaining the data after the nonlinear frequency modulation processing; calculating an accurate phase; obtaining a system frequency modulation rate after second-order Taylor series approximation; calculating a coefficient of the expression of the delay time and the distance direction frequency; solving an undetermined coefficient; performing high-order phase error compensation; and a high-resolution synthetic aperture sonar image is obtained. According to the method, the reconstruction performance can be effectively improved under the conditions of larger transmission signal bandwidth and larger accumulated beam angle.

This application relates to the field of space imaging technology and provides a method for decoupling translational and rotational motion in space-based microwave imaging of space targets based on parameter estimation. The method first uses adjacent cross-correlation and self-focusing methods to perform preliminary compensation for the translational motion components of the microwave imaging echo data. Then, using the first-order translational motion parameters fitted by the former as initial values ​​and minimizing the image entropy of the echo data as the cost function, it combines Keystone transform to optimize and compensate for the translational linear phase components. Next, it uses Keystone transform to compensate for the spatially varied range cell migration caused by the rotational motion components. Finally, it performs a second compensation for the residual translational motion components, obtaining echo data after almost complete compensation of the translational and rotational MTRC. By performing spatially varied phase error compensation and azimuth compression on this data, the imaging result of the space target can be obtained. This method achieves a balance between the efficiency and accuracy of parameter estimation, effectively improving imaging quality.

The application provides a RAA residual error compensation method suitable for a curve trajectory SAR, comprising: using a radius angle interpolation algorithm to perform imaging processing on obtained SAR echo data, using a new residual error modeling method to perform error modeling, and designing a residual error compensation method to perform phase error compensation to obtain a final SAR image. The radius angle interpolation algorithm is introduced into airborne curve trajectory large forward-looking SAR imaging, and under the condition of large forward-looking, there is a large approximation in the derivation process of the algorithm, there is a large residual phase error for scene edge point targets, and the imaging quality of image edge points is poor. The application compensates the residual phase error of the initial imaging result by constructing a residual phase error space model, improves the focusing depth of the algorithm under the condition of the curve trajectory large forward-looking, expands the effective imaging scene, and greatly improves the limitation of the residual error on the large forward-looking and large scene imaging.

The airborne SAR real-time self-focusing imaging method comprises the following steps: estimating Doppler center frequency based on an amplitude equalization method; iterative calculation: utilizing the estimated Doppler center frequency, introducing a migration parameter correction term delta D (eta) and a frequency modulation correction term delta Km (eta), and recalculating a distance Doppler domain signal of the current iteration round; based on the improved CSA processing chain, performing phase error compensation on each range gate by using a space-variant phase error compensation function to obtain a compensated range Doppler domain signal; carrying out distance direction and azimuth direction compression in parallel to generate a focusing image, and evaluating image quality indexes; if not, extracting strong scattering points, estimating the residual two-dimensional phase error of each range gate, fitting and updating delta D (eta) and delta Km (eta), and carrying out the next round of iterative calculation; and if so, ending iteration, and outputting the focused image of the current round. According to the method, the pixel-by-pixel suppression of motion error correction and space-variant error independent of external sensing and embedded real-time imaging processing are realized.

The invention discloses a switch self-phase-shifting passive phase shifter, which comprises a switch self-phase-shifting unit, a transmission line segment network and a phase error compensation network, and is characterized in that the switch self-phase-shifting unit comprises a single-pole double-throw switch, and the single-pole double-throw switch comprises a common end, a first throw end and a second throw end; the transmission line segment network is electrically connected with the single-pole double-throw switch and is used for providing different path lengths or equivalent phase responses for signals when the single-pole double-throw switch is in different switching states, so that a predetermined phase difference is generated; the phase error compensation network comprises an inductance element which is connected in parallel between a preset node of the single-pole double-throw switch and a reference potential; the inductance element and an inherent parasitic capacitor of the single-pole double-throw switch jointly form an LC network presenting a negative group delay characteristic in a target working frequency band, and the LC network is used for compensating a frequency-related error of a predetermined phase difference; according to the invention, the layout compactness and the array expandability are improved at the same time.

The application provides a synthetic aperture radar range-aperture space-variant motion compensation method based on linear scaling, which adopts the first step of consistent compensation in two-step motion compensation to compensate for main distance non-space-variant motion error components of panoramic echo, obtains distance pulse pressure target migration curve image data, calculates sub-aperture bandwidth parameters by using image minimum defocus principle, and first-order Taylor expansion of residual range-aperture space-variant error, further introduces linear scaling in two-dimensional time domain to compensate for constant components and linear components, synchronously completes residual azimuth phase error compensation, finally splices sub-aperture data time domain to form ideal echo data without motion error, and outputs final panoramic image through traditional imaging processing. The application realizes high-precision residual range-aperture space-variant motion error compensation, has simple principle, is suitable for airborne and missile-borne platforms with complex trajectories, has high accuracy and strong robustness, and has high practicability.

The invention discloses a moving object imaging method, device and system. The method comprises the following steps: receiving an echo signal from a moving object, and determining a mathematical representation of the echo signal after zero-frequency filtering; in the mathematical representation, a motion phase error is determined, and the motion phase error is used for representing an additional phase introduced by the motion of the moving object in the echo signal; according to the motion phase error, a phase error compensation item is determined, and the phase error compensation item is used for counteracting phase distortion caused by the motion phase error to the echo signal; and performing compensation processing on the echo signal based on the phase error compensation item to obtain a compensation processing result, and generating an imaging result of the moving object according to the compensation processing result. According to the invention, the technical problem of poor imaging result quality caused by the increase of the motion phase error in the echo signal due to the non-linear motion of the moving object is solved.

The application discloses a nonlinear phase error compensation method of an optical fiber demodulator, and relates to the technical field of phase error compensation.The method comprises the following steps: synchronously collecting interference signals output by a photoelectric detector by an analog-to-digital converter, performing low-pass filtering and amplitude extraction on the digitized interference sequence by using a carrier wave and a twice-frequency orthogonal reference signal, calculating a current amplitude ratio according to a fundamental wave amplitude and a second harmonic amplitude, estimating a current actual phase modulation depth by using a Bessel function relationship, and generating an error signal by a digital PID.The application adjusts a driving voltage amplitude in real time by using an analog voltage control programmable high-voltage driving source, thereby guaranteeing the safety monitoring of a high-pressure gas pipeline and solving the problem of system failure caused by phase modulation depth drift in long-distance oil and gas pipeline network distributed optical fiber sensing in the prior art.

The application discloses an IQ imbalance mirror suppression method of a zero intermediate frequency receiving array, and comprises the following steps: calculating a radio frequency signal received by each array element; obtaining M radio frequency signals after phase shifting; obtaining M intermediate frequency signals output by mixing and filtering; obtaining M baseband analog in-phase signals and M baseband analog quadrature signals; the M baseband analog in-phase signals and the M baseband analog quadrature signals are respectively subjected to A / D sampling to obtain M baseband digital complex signals; before beam synthesis of a digital array, amplitude and phase consistency of M receiving channels is calibrated to obtain M receiving channel amplitude and phase error compensation values; the M baseband digital complex signals of the digital array are subjected to channel error compensation and beam weighting compensation, and summation is performed to obtain a final beam forming output complex signal; the application has the advantages that the IQ imbalance mirror suppression capability of a multi-channel zero intermediate frequency receiving digital array is improved.

The application discloses a space target large-angle high-resolution radar imaging space-varying phase compensation method and system, a storage medium and an electronic device, and comprises the following steps: acquiring an ISAR original echo, completing a translation compensation and a distance beyond a cell correction; and converting residual two-dimensional space-varying phase error compensation into a high-dimensional parameter estimation problem based on image entropy minimization. A mean value, a step length and a covariance matrix of a CMA-ES algorithm are initialized, a candidate solution population is iteratively generated, and image entropy is calculated after compensation is performed on each group of space-varying phase coefficients to serve as fitness. An optimal individual is screened, a cumulative evolution path and a conjugate path are fused, and population parameters are adaptively updated. After a convergence condition is met, optimal coefficients are output, and a high-focusing ISAR image is reconstructed. The application overcomes the defects of a traditional gradient algorithm, such as being prone to local optimization and relying on initial values, utilizes global step length dynamic adjustment and a covariance adaptive mechanism of CMA-ES, has strong global optimization capability and noise robustness, and can still converge stably in a low signal-to-noise ratio environment.

This invention relates to a low signal-to-clutter ratio ISAR imaging method for ship targets based on multi-aperture rotation alignment. Specifically, it relates to ISAR signal processing and imaging, and more specifically to a ship target ISAR imaging method. The purpose of this invention is to address the problem that existing methods cannot simultaneously solve non-stationary Doppler blurring, sub-aperture rotation errors, and strong clutter interference during the imaging process, leading to low accuracy in ship target ISAR imaging. This invention establishes an echo signal model of the three-dimensional motion of ship targets in a marine environment and introduces sea clutter interference. It utilizes Keystone transform combined with a minimum entropy phase autofocus algorithm to compensate for range migration and phase error in the pulse-compressed signal. The full-aperture observation data is divided into multiple sub-aperture data blocks to generate sub-image sequences. A screening threshold is introduced to select high-quality sub-frames. The rotation error of each preferred sub-image relative to the reference frame is estimated and resampled for correction. Finally, a geometric mean fusion algorithm is used to preserve the strong scattering point features of the target.

The application discloses a kind of video synthetic aperture radar interframe image motion error compensation method and device, the method includes: obtaining the expression of two sub-aperture images corresponding to the original echo data of video synthetic aperture radar (SAR) acquisition;Analyze the correlation between the expression of two sub-aperture images;With correlation as objective function, analyze the gradient expression of objective function;Based on a plurality of initial points and the gradient expression, the global optimal value of quadratic term coefficient is obtained by optimizing and estimating objective function;The global optimal value of quadratic term coefficient is substituted into the approximate expression of azimuth direction motion error compensation, the approximate expression of azimuth direction motion error compensation is intercepted according to different frame pulse starting position and end position, and the approximate expression of azimuth direction motion compensation corresponding to each frame is obtained, to carry out phase error compensation to the corresponding frame of two sub-aperture images.The application can realize phase error compensation to full-aperture video SAR interframe image.

A kind of nonparametric framework-based terahertz rotating target imaging method and device, including detecting rotating target according to the difference of rotating target and stationary target echo time-frequency characteristics;Visual saliency feature map is obtained by using spectrum residual visual saliency detection, and background image and rotating target image in visual saliency feature map are separated;Two rotating target azimuth signals in rotating target image are taken as signal of interest, two signals of interest are phase-unravelled and additional Doppler center is estimated, then compensation function is constructed to compensate phase error of rotating target image, and after refocusing, the rotating target image is obtained, and finally complete high-resolution image is output.The present application avoids time-consuming parameter estimation of traditional parameterized method, and can adaptively consider background clutter, providing technical support for high-resolution rotating target imaging.

The invention discloses a quantum communication multichannel phase synchronization control system based on a six-level double binary system, which remarkably improves the synchronization precision and anti-interference capability of quantum communication through six groups of independent emission, reflection cross receiving, a time sequence deviation-phase error conversion model and acousto-optic modulation optimization. The system comprises six groups of orthogonal transmitting modules, a reflection receiving module, a six-level modulation module, a time sequence comparison module, a phase control module and an acousto-optic modulation module, a central control unit coordinates closed-loop control of the whole system, and phase error dynamic compensation (response time is less than or equal to 50ns) and anti-interference performance optimization (signal-to-noise ratio improvement is greater than or equal to 15dB) are realized.

The application relates to the technical field of eddy current encoders, and discloses an eddy current encoder-based measurement method, device, circuit and encoder. The eddy current encoder-based measurement method comprises the following steps: in a starting stage of the eddy current encoder, a main frequency, an amplitude corresponding to the main frequency and an initial phase value are determined from a first quadrature signal group output by the eddy current encoder, and a second quadrature signal group is generated according to the main frequency, the amplitude corresponding to the main frequency and the initial phase value; in the case of a running stage of the eddy current encoder, the second quadrature signal group is taken as reference signals of a third quadrature signal group output by the eddy current encoder, and digital signal processing is performed to obtain a physical quantity measurement value. At least, the method is beneficial to realizing more accurate measurement by constructing reference signals with better phase error compensation effects.

A phase error compensation circuit and a method for compensating a phase error between a reference clock and a feedback clock are provided. The phase error compensation circuit includes a first programmable delay circuit, a second programmable delay circuit and at least one swapping circuit. The first programmable delay circuit provides a first delay. The second programmable delay circuit provides a second delay. At a present cycle, the first delay is unchanged, wherein the swapping circuit applies the first delay to the feedback clock for generating a compensated feedback clock and applies the second delay to the reference clock for generating a compensated reference clock. At a next cycle, the second delay is unchanged, where the swapping circuit applies the second delay to the feedback clock for generating the compensated feedback clock and applies the first delay to the reference clock for generating the compensated reference clock.

This invention provides a joint tracking and phase compensation method for a dynamic bistatic synthetic aperture sonar system. The method is characterized by constructing a unified state-space model, where the state vector includes at least the target's position and velocity, the positions and velocities of the transmitting and receiving platforms, and the time-varying phase error caused by platform dynamics and oscillator frequency deviations. Joint observation information from both platforms is acquired, including the target's angle of arrival (AOA) and time difference of arrival (TDOA), as well as the platform's navigation and positioning data, to establish a nonlinear observation equation. An extended Kalman filter (EKF) is used to recursively estimate the state-space model, including state prediction and observation updates based on the observation information, achieving joint estimation of the target state and phase error. The jointly estimated phase error is used to perform phase compensation on the raw echo signal of the synthetic aperture sonar. The phase-compensated echo signal is then used for synthetic aperture sonar image reconstruction.

The invention discloses a three-dimensional moving target fine focusing method based on block gradient descent sparse representation, and the method comprises the steps: carrying out the block processing of a whole image, carrying out the phase error estimation through a phase self-focusing algorithm PGA, and carrying out the delinearity processing, and obtaining a phase error compensation result of each block; taking a certain block as the center, comparing the difference values of the phase compensation results of the eight blocks around the block and the central block, and carrying out merging processing; for each block, constructing a phase error compensation parameter matrix, taking the optimal sparse characteristic of the image as a target, taking image entropy gradient descent as an iteration direction, and utilizing a sparse optimization algorithm to obtain a fine focusing image of the moving target; and re-combining the fine focusing images of the moving target subjected to block processing into a target image according to an original sequence to obtain a fine focusing result of the target image. According to the invention, the self-focusing processing of the moving target is completed, and the sparse processing result is lower in background clutter energy and clearer in target details compared with the background clutter energy of the traditional method.

This invention discloses a two-dimensional spatially varied high-precision phase error compensation method for bistatic SAR. This method is based on two-dimensional sparse autofocusing bistatic SAR moving target imaging processing. Its main steps include: constructing a bistatic SAR data acquisition geometric model, acquiring echo data, processing it using PFA, and deriving the two-dimensional frequency phase error; analyzing the spatially varied characteristics of the two-dimensional phase error expression; performing coarse compensation on the image based on the derived two-dimensional phase error expression; after coarse compensation, performing range spatially varied compensation in the range direction, azimuth spatially varied compensation, and image segmentation and stitching. Experimental simulations verify the effectiveness of this invention's two-dimensional compensation method under arbitrary tracks and arbitrary motions.