20 results about "Azimuth compression" patented technology

The invention discloses a multi-scattering SAR (Synthetic Aperture Radar) imaging simulation method, system and device based on physical consistency modeling and a medium. The method comprises the following steps: constructing a three-dimensional electromagnetic model of a target; constructing a geometric model under the working mode of the ray tracing auxiliary transmitting-receiving co-located SAR; a high-frequency electromagnetic scattering algorithm based on ray tracing is adopted, multiple scattering paths of a first order, a second order and a higher order are considered, superposition and amplitude modulation are carried out on scattering contributions of all orders, scattering field distribution of a target under the far field condition is calculated, and a far-field scattering field is obtained; performing spatial propagation mapping on the total far-field scattering field, and mapping a far-field scattering result into a radar platform near-field echo signal; correcting the amplitude of the echo signal to obtain a two-dimensional SAR near-field echo matrix; sAR imaging processing is carried out, wherein the SAR imaging processing comprises distance compression, range migration correction (RCMC) and azimuth compression. According to the invention, the authenticity and precision of SAR imaging simulation in a complex target scene are improved.

The invention discloses an SAR image self-focusing distortion correction method and device, and belongs to the technical field of synthetic aperture radars. The method comprises the following steps: carrying out distance blocking and orientation sub-aperture division on a defocused SAR image, selecting a sample, and carrying out orientation decompression to a phase historical domain; performing azimuth dechirp processing on the sub-aperture data in each distance sub-block, and estimating a phase error through a standard PGA algorithm; after splicing sub-aperture phase errors and removing an overall linear phase, performing phase compensation and azimuth compression to obtain a focused image; and for azimuth distortion caused by residual linear phase of the compensated image, extracting a phase error linear term coefficient through a sliding window, deducing an azimuth shift distance in combination with Fourier transform time shift characteristics, and finally performing shift correction by adopting sinc interpolation. According to the method, the image focusing quality is improved, and meanwhile, the ground feature continuity and the image resolution are kept.

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.

This invention relates to the field of radar imaging technology, and proposes a system and method for detecting local surface defects in field equipment based on a robotic arm. The system includes: a robotic arm unit with a SAR transceiver antenna mounted at its end, which transmits electromagnetic signals to the surface of the field equipment to be inspected and receives echo signals; a motion controller connected to the robotic arm unit, which controls the movement trajectory of the robotic arm; and an industrial control computer, which has a built-in SAR imaging data processing module and a path optimization module. The industrial control computer is electrically connected to the motion controller and the SAR transceiver antenna, respectively, driving the robotic arm unit to move according to the planned sampling trajectory, and simultaneously controlling the signal transmission and reception timing of the SAR transceiver antenna; the SAR imaging data processing module performs range compression, azimuth compression, and two-dimensional inverse Fourier transform processing on the received echo signals to generate SAR images characterizing the surface and internal defects of the equipment. This invention achieves full automation of the field equipment defect detection process.

The application provides a terahertz SAR high-efficiency self-focusing imaging method and system based on RB-PCA, comprising: obtaining original echo signal data and performing pretreatment; performing distance block in the distance direction on the pretreated echo signal data to obtain a plurality of distance blocks, performing sub-aperture segmentation in the distance block for each distance block to obtain a plurality of sub-aperture signal data; performing desquamation processing on each sub-aperture signal data to obtain desquamation signal data; performing PCA processing on the desquamation signal data and selecting a characteristic vector with the largest characteristic value as a target characteristic vector; obtaining each sub-aperture phase error gradient estimation value through adaptive PGA estimation on the target characteristic vector; obtaining two-dimensional space-varying phase errors of each distance block through global splicing and fusion on each sub-aperture phase error gradient estimation value; and performing phase compensation and azimuth compression on the pretreated echo signal data based on the two-dimensional space-varying phase errors to obtain focused imaging results.

The application discloses a kind of vehicle-mounted video SAR imaging methods based on sub-aperture spectrum fusion, comprising: establishing vehicle-mounted SAR sub-aperture imaging model, and determining the instantaneous slant range of arbitrary point P under "walk-stop" assumption;After the difference frequency processing of each sub-aperture signal and transmission signal, difference frequency signal is obtained, and signal after range compression is obtained;The range compressed signal is subjected to azimuth Fourier transform, and two-dimensional frequency domain signal is obtained;Two-dimensional frequency domain signal is subjected to inverse distance Fourier transform and distance curvature compensation, and signal after range migration correction is obtained;The range migration corrected signal is subjected to distance Fourier transform and azimuth compression, and two-dimensional focused first signal is obtained;First frame image is generated using the first M first signals and azimuth compensation function, and the first signal of the i frame and the i-1 frame image overlap, the latest first signal and the time sequence offset function are used to generate the i (i>1) Frame image.The application solves the imaging distortion problem caused by space variation.

This invention discloses a MIMO-SAR echo separation method based on image post-processing in complex detection scenarios, belonging to the field of signal processing. The method includes: designing the MIMO-SAR transmit waveform and collecting echo signals using a multi-channel elevation system; performing range and azimuth compression sequentially on the received data from the multi-channel elevation system using a classic imaging algorithm to complete imaging processing; constructing an elevation-dimensional spatial snapshot signal based on the processed multi-channel data and estimating the sample covariance matrix using range samples; performing eigenvalue decomposition on the covariance matrix to estimate the number of sources in the spatial domain; estimating the angle of arrival (AHA) of the sources using the MUSIC algorithm, given a fixed number of sources; calculating the optimal weight vector based on the least squares criterion and processing the spatial snapshot to suppress interference signals in the echo, thus solving the echo separation problem in MIMO-SAR. This method can effectively mitigate the impact of AHA mismatch caused by terrain undulations on echo separation performance and improve the imaging performance of the MIMO-SAR system in complex detection scenarios.

The application relates to an improved Omega-K imaging method suitable for curve trajectory squinted SAR and belongs to the field of radar signal processing. Two-dimensional Fourier transformation is carried out on two-dimensional time domain echo data acquired by the curve trajectory squinted SAR, and the two-dimensional time domain echo data are transformed into a two-dimensional frequency domain; after the two-dimensional frequency domain signals are multiplied by a reference function and specially Stolt mapping, the signals are transformed into a range Doppler domain by using inverse Fourier transformation in the range direction; range migration correction, azimuth compression and azimuth offset correction are carried out in the range Doppler domain; inverse Fourier transformation is carried out in the azimuth direction, the signals are transformed into two-dimensional time domain, and finally, imaging results are obtained. The application utilizes a specially designed Stolt mapping to avoid complex additional range migration caused by a traditional Stolt mapping, and then range migration correction and azimuth compression are sequentially carried out in the range Doppler domain to solve the problem that equivalent radar speed and other parameters cannot change with distance.

A method for automatically selecting time points for multi-target ISAR imaging includes the following steps: S1: performing pulse compression on a broadband echo sequence for multi-target imaging; S2: performing range image averaging and calculating the waveform entropy of the average range image; S3: taking the time corresponding to the range image with the maximum waveform entropy as the time reference and performing a Keystone transform; S4: performing azimuth compression on the range image sequence to obtain a multi-target range-Doppler two-dimensional image; S5: after target separation on the range-Doppler plane, performing motion compensation and R-D imaging processing on each target to obtain an ISAR image of each target. By calculating the waveform entropy of the average range image, the present invention can automatically select the time point at which the multi-target overlap is minimized, thereby improving computational efficiency. The automatically selected time point exhibits the best separability of target echoes, thereby improving imaging efficiency.

The invention discloses a vehicle-mounted SAR (Synthetic Aperture Radar) real-time imaging method based on an improved distance Doppler algorithm, and relates to a close-range and large-squint-angle imaging algorithm in a vehicle-mounted scene. The method comprises the following steps: dividing a full aperture into sub-apertures; compensating a residual video phase term; doppler frequency shift items caused by fast time are eliminated; carrying out high-order Taylor expansion on the distance and azimuth coupling terms of the signal, constructing a distance migration filter based on the second term of Taylor expansion to carry out distance migration correction, and constructing a secondary distance compression filter based on the third term and higher-order terms of Taylor expansion to carry out secondary distance compression; azimuth compression processing is carried out after distance dimension focusing, and two-dimensional focusing is completed; and after all the sub-apertures are focused, splicing the sub-aperture images to obtain a full-aperture image. According to the invention, high-order Taylor expansion is carried out on the distance and azimuth coupling term, so that the coupling term is accurately compensated, and high-precision near-field imaging can be completed while the advantage of the classical RDA imaging speed is kept.

The application discloses a kind of small SAR data processing method and system based on PCIe RDMA, it is related to radar signal and information processing technical field, comprising the following steps: S1, data preprocessing: the original echo data received by radar is preprocessed;S2, range compression: the original echo data after preprocessing is compressed in range;S3, azimuth compression: the original echo data compressed in range is compressed in azimuth, and the SAR image of target area is obtained;S4, image post-processing: SAR image is post-processed, and post-processing includes geometric correction, radiation correction and image enhancement.The application adopts the above-mentioned small SAR data processing method and system based on PCIe RDMA, eliminates the data copy overhead of CPU participation in traditional communication model, realizes the direct access of cross-node memory after the interconnection of multiple hosts through PCIe, significantly reduces data transmission delay, and improves system bandwidth.

The application discloses a kind of based on physical consistency modeling multiple scattering SAR imaging simulation method, system, equipment and medium, including the following steps: constructing the three-dimensional electromagnetic model of target;Geometric model under the condition of transmitting-receiving co-located SAR operating mode is constructed by light ray tracing;Using high-frequency electromagnetic scattering algorithm based on ray tracing, considering first-order, second-order and higher order multiple scattering path, the superposition and amplitude modulation of each order scattering contribution are carried out, the scattering field distribution of target under far-field condition is calculated, and the far-field scattering field is obtained;Total far-field scattering field is mapped by space propagation, and the far-field scattering result is mapped as radar platform near-field echo signal;Echo signal amplitude is corrected, and two-dimensional SAR near-field echo matrix is obtained;SAR imaging processing is carried out, and SAR imaging processing includes range compression, range migration correction RCM and azimuth compression.The application improves the fidelity and accuracy of SAR imaging simulation under complex target scene.

The application relates to the technical field of remote sensing and radar imaging, and relates to a space target ISAR imaging and scaling integrated method based on a translation-rotation parameter joint estimation.The application is used to solve the problem that the existing space target ISAR imaging is affected by motion compensation, and the scattering points of a space target are prone to moving across distance units in a long-time accumulation.The application performs distance compression on echo obtained by a ground-based radar, performs generalized Radon Fourier transformation on a one-dimensional distance image sequence, and further estimates phase coefficients of the echo signal; the effective rotation angular velocity module value of a space uniform rotation target and a compensation signal are calculated by using the estimated value; the echo signal is subjected to translation compensation by using the compensation signal, the compensated echo signal is converted from a Cartesian coordinate system to a polar coordinate system by using the effective rotation angular velocity, and interpolation is performed; the imaging result is obtained by performing distance and azimuth compression on the interpolation result, scaling is completed according to the effective rotation angular velocity, and the space target ISAR imaging and scaling integration are realized.

The present invention discloses a method for detecting indoor moving targets using an unmanned aerial vehicle (UAV) through-the-wall radar. The method comprises: proposing a moving target detection method based on a Doppler frequency modulation profile and range-gated filtering. The imaging results of moving targets are defocused and easily submerged in strong stationary clutter, which reduces the moving target detection rate. To address this problem, the present invention analyzes the Doppler frequency modulation characteristics of stationary clutter and moving targets. Then, the range migration of the target echo is corrected in the range Doppler domain through sinc interpolation. Next, a fractional-order Fourier transform is applied to estimate the Doppler frequency modulation of each range gate of the echo. The estimated frequency modulation value is compared with the theoretical frequency modulation value of the stationary target. Based on the difference in Doppler frequency modulation, a range-gated filter is designed to suppress clutter generated by walls and stationary objects. Finally, an azimuth compression filter is constructed to achieve focused imaging of moving targets. Simulation and field experiments verify the feasibility and effectiveness of the proposed method.

The invention discloses an Omega-K and FNCS combined high-speed large-squint curve track SAR imaging method. The method comprises the steps of expanding an instantaneous slant range history to five orders through Taylor series to obtain a polynomial slant range model; linear range walk correction, range pulse pressure and acceleration de-chirp preprocessing are carried out in an echo signal range wavenumber domain; blocking the two-dimensional time domain signal distance, introducing a reference function into the two-dimensional wave number domain of a sub-block, and carrying out distance unit migration correction by using improved Stolt mapping; introducing an alignment function to the signal after range unit migration correction, and realizing range focusing by using two-dimensional IFFT (Inverse Fast Fourier Transform); during azimuth processing, a five-order perturbation function is introduced into an azimuth time domain, a five-order NCS function is introduced into an azimuth frequency domain, unified azimuth compression is performed in the azimuth time domain, and finally a two-dimensional SAR image is obtained by utilizing azimuth FFT. The method can be directly applied to a high-speed large-squint SAR system under a curve track, and high-precision curve track SAR imaging can be realized under a high-speed large-squint view angle scene.

The invention discloses a CLEAN single-channel external radiation source bistatic radar direct wave suppression method based on principal component analysis, and belongs to the field of signal processing. After echo channel signals are acquired, the distance of each frame of signal is compressed, and the distance offset and Doppler broadening are compensated according to an equivalent distance model; the method comprises the following steps: firstly, carrying out azimuth compression on a distance Doppler domain, then carrying out accumulation average processing on each frame in the distance Doppler domain after azimuth compression, then carrying out PCA principal component analysis to reconstruct a complete direct wave as a reference interference signal of a single-channel echo signal, and carrying out CLEAN correlation coefficient calculation in the distance Doppler domain to complete suppression and cancellation of the direct wave in a single channel. According to the method, strong direct wave interference in a satellite-borne passive radar system under single-channel receiving is suppressed, so that a target with relatively weak energy is not easily covered by strong direct waves or other background interference, and a foundation is laid for subsequent target detection and tracking processing.

The present invention discloses a spaceborne polar ice radar three-dimensional imaging method. The method first acquires antenna echo signals and superimposes signals received by the same antenna. The superimposed image is then subjected to secondary range compression and center point range migration correction. Complementary range migration correction is further performed. Azimuth compression is performed through phase multiplication to obtain a two-dimensional under-ice image. After corresponding additional phase multiplication, the two-dimensional under-ice image is subjected to cross-track range migration correction to ensure that the range signals of all antennas are consistent with the center antenna. The corrected two-dimensional images are written into a three-dimensional array to obtain a three-dimensional image. The three-dimensional image is multiplied by a reference function in the cross-track direction, and the additional phase in the two-dimensional image is compensated in the cross-track direction. Finally, the three-dimensional image is Fourier transformed in the cross-track direction to obtain a three-dimensional focused image. The method has high computational efficiency and can obtain richer under-ice data through compressed imaging in the third dimension.

The application relates to an airborne SAR moving target imaging method based on Doppler parameter estimation, and aims to solve the problem that a traditional RD algorithm is not applicable to airborne SAR moving target imaging. The process is as follows: 1. the Doppler center frequency and the Doppler frequency modulation slope of a target are derived; 2. a distance frequency domain signal is obtained; 3. a distance compression function is constructed to obtain distance compressed echo data; 4. an azimuth compression function is constructed to obtain azimuth compressed data; 5. a particle swarm optimization algorithm is adopted to obtain the target Doppler center frequency and the Doppler frequency modulation slope corresponding to the minimum entropy value; 6. a distance migration correction function is constructed to obtain two-dimensional frequency domain data after distance migration correction; 7. a distance matching function is constructed to obtain distance compressed azimuth frequency domain data; 8. an azimuth matching function is constructed to obtain two-dimensional time domain data, and imaging is completed. The application is used in the field of airborne SAR moving target imaging.

The invention discloses an embedded edge AI acceleration radar signal processing system and method, and relates to the technical field of radar signal processing and embedded artificial intelligence. The embedded edge AI acceleration radar signal processing system comprises a power supply module, a radio frequency subsystem and a signal processing subsystem, wherein the power supply module supplies power to the radio frequency subsystem and the signal processing subsystem, and the signal processing subsystem comprises an AI chip and an FPGA chip which are interconnected through an SRIO protocol. The embedded edge AI acceleration radar signal processing method comprises the steps that a radio frequency subsystem receives a radio frequency signal and sends the radio frequency signal to a signal processing subsystem; the FPGA chip collects data and transmits the data to the AI chip; the AI chip executes a real-time imaging algorithm including complementary RCMC, consistent RCMC, phase compensation and azimuth compression, and meanwhile, the FPGA performs frequency conversion, motion compensation and FFT operation in real time; the AI chip executes a target recognition algorithm on the SAR image; and the signal processing subsystem outputs and stores a target identification result. The system power consumption can be effectively reduced, and the delay is reduced.

The application discloses an OAM forward-looking imaging method based on time-varying modes, which firstly realizes imaging of a vortex wave front-view radar in a time-varying mode, and the implementation scheme is as follows: on the basis of three-dimensional echo, distance compression is firstly realized by a matched filtering method; under the system, the radar transmits N pulse periods in one mode, and switches to the next mode after a certain pulse period; therefore, synthetic aperture echo is decomposed into multiple sub-aperture echoes, and the mode of the echo in each sub-aperture remains unchanged; then, a target image of different modes is obtained in the range-pitch dimension by using a BP algorithm. Finally, the azimuth compression is performed in the mode dimension by using an FFT method, and finally, three-dimensional imaging of the target is realized. The application can not only improve the resolution, but also solve the left-right ambiguity problem in the forward-looking radar imaging.