55 results about "Slant range" patented technology

The invention discloses a squint synthetic aperture sonar imaging method based on a dynamic slant-range space-variant model, and relates to the technical field of synthetic aperture sonar imaging, and the method comprises the steps: constructing a dynamic slant-range model; inputting the converted data into the dynamic oblique variation model to obtain a residual space-variant distance bending amount, and compensating the space-variant distance bending amount by using a first filter; according to the dynamic slope distance model, expanding the azimuth time offset into an azimuth frequency modulation factor; based on the azimuth frequency modulation factor and the azimuth time offset, designing a second filter by using an improved extended nonlinear frequency modulation scaling algorithm, and filtering the corrected data by using the second filter; and carrying out Fourier transform on the filtered data, compressing the transformed data by using a third filter, and then carrying out inverse Fourier transform to obtain a focused synthetic aperture sonar image. According to the invention, the imaging performance and stability of the imaging algorithm in a low signal-to-noise ratio and strong multipath interference environment can be improved.

This invention discloses a method for characterizing the imaging resolution of arbitrary trajectory cooperative detection synthetic aperture radar (SAR) based on fuzzy functions. The method includes: constructing an arbitrary trajectory cooperative detection SAR synthetic aperture radar imaging geometric model and a target plane geometric model; acquiring the slant range history of the arbitrary trajectory cooperative detection SAR and the echo signal after range-direction matched filtering in the two-dimensional time domain; constructing a SAR generalized fuzzy function based on the slant range history and the echo signal after range-direction matched filtering in the two-dimensional time domain; acquiring a normalized SAR generalized fuzzy function; acquiring the range resolution based on range resolution information; acquiring the azimuth resolution based on azimuth resolution information; and constructing a complete arbitrary trajectory cooperative detection SAR imaging resolution model based on the range resolution and azimuth resolution. This invention can effectively characterize the resolution performance in any direction.

The application discloses an aircraft landing interval five-edge slant distance automatic calculation method and system, relates to the field of aviation, and comprises the following steps: acquiring a data set of incoming flights, and sorting the flights in the data set of incoming flights to obtain an ordered flight sequence; for each flight in the ordered flight sequence, determining whether the flight can be used as a preceding aircraft; if yes, acquiring an original track point set of the flight; screening track points meeting preset requirements from the original track point set of the flight, and taking the track points as an effective track point set of the flight; obtaining a runway and an actual landing site of the flight according to the effective track point set of the flight; according to the actual landing site of the flight, finding out a following aircraft of the flight, and determining a spatial distance between the flight and the following aircraft and an interval type between the flight and the following aircraft. The application can accurately calculate the spatial distance between the preceding aircraft and the following aircraft, automatically determine the interval type, and does not need manual intervention.

The application provides a kind of InSAR deformation monitoring point high-precision geometric positioning method combined with three-dimensional model data, belongs to synthetic aperture radar technical field, comprising: converting three-dimensional model data into space rectangular coordinates, combined with satellite orbit parameter iteration to solve row and column coordinates in SAR image, calculate the slant range projection distance of satellite-observation vector, screen and eliminate invalid data in shadow area;With the screening result as a mask, obtain a subset of three-dimensional model data, calculate the row and column coordinates of the InSAR deformation monitoring point of the subset of three-dimensional model data, and search for candidate points based on plane geometric constraints, match the accurate elevation of the monitoring point by height system deviation;Based on the determined accurate elevation, construct the RD positioning model of distance constraint, Doppler frequency constraint and ellipsoid constraint, and solve the high-precision geometric position of InSAR deformation monitoring point. It can realize the high-precision geometric positioning of infrastructure InSAR deformation monitoring point, and improve the applicability in infrastructure fine deformation monitoring.

The application relates to a space target joint imaging and attitude inversion method based on a spaceborne platform, and relates to the field of inverse synthetic aperture radar imaging, in particular to a space target joint imaging and attitude inversion method based on a spaceborne platform. The application aims to solve the problems that in the existing space target imaging process of a spaceborne platform, three-dimensional high-order space-variable range migration and phase errors caused by complex relative motion between the target and the platform are difficult to realize high-precision imaging, and the existing attitude estimation algorithm needs to be completely compensated for the rectangular component segmentation and orbit error before the attitude inversion can be realized. The process is as follows: one, a narrowband tracking system of a radar obtains target slant range and a radar line-of-sight unit vector; two, a wedge-shaped transformed signal is obtained; three, spatial Doppler parameter distribution of a special point is obtained; four, an imaging result is obtained; and five, accurate estimation of target attitude parameters is completed through plane coefficient fitting.

The application discloses a time-domain point-by-point imaging method, system and device of a transceiver combined synthetic aperture sonar, and the time-domain point-by-point imaging method comprises the following steps: for any pixel in an imaging area, calculating a synthetic aperture length and a synthetic aperture time; calculating a distance between a sonar at a signal transmitting time and the pixel, and calculating a distance between a sonar at a signal receiving time and the pixel to obtain an accurate two-way slant range history; according to the two-way slant range history and relevant parameters of the signal, calculating a reference echo signal corresponding to the pixel; performing distance domain transformation on a measured echo signal and a reference echo signal, and performing conjugate multiplication processing on the transformed results; coherently accumulating all the conjugate multiplication results as an imaging result of the pixel; and repeating the above steps for other pixels in the imaging area to obtain imaging results of all the pixels in the entire imaging area.

The application discloses a BP imaging Sinc interpolation optimization method and device based on FPGA and belongs to the technical field of radar signal processing. The method realizes seamless connection of data through double-BRAM ping-pong buffering. Fixed-point and floating-point mixed operation is adopted to optimize the slant range and index calculation module and the Sinc coefficient array calculation module, wherein fixed-point is used for general calculation, floating-point is used for square root and division, resource consumption is significantly reduced, and precision is improved. Efficient interpolation calculation pipeline processing is realized through a parallel fixed-point multiplication and addition array. While guaranteeing high-precision interpolation, the application greatly reduces LUT, register and DSP resource occupation of the FPGA, and significantly improves the calculation speed and imaging quality of BP real-time imaging.

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 invention discloses a method and system for de-flattening preprocessing, belonging to the field of radar imaging. The method includes: acquiring a main radar image and a secondary radar image, each containing several main image scattering points and several secondary image scattering points; calculating the secondary image scattering points corresponding to the main image scattering points to form several scattering point pairs; performing a flat-ground phase acquisition action to obtain an ideal flat-ground phase, thereby forming an ideal flat-ground phase map and completing the de-flattening preprocessing process. The flat-ground phase acquisition action includes: calculating the main image Doppler history and the secondary image Doppler history of the scattering point pairs; determining the main image focusing time that meets a preset time threshold to calculate the main image slant range, thereby determining the secondary image focusing time that meets the preset time threshold, and calculating the secondary image slant range based on the secondary image focusing time; and obtaining the ideal flat-ground phase of the scattering point pairs based on the main image slant range and the secondary image slant range. The de-flattening preprocessing method disclosed in this invention can effectively reduce the processing error of de-flattening preprocessing methods.

The invention discloses a multi-mode fusion positioning method and system for diving bell emergency communication, and relates to the field of signal localization, and the method comprises the steps: collecting underwater mixed sound signals, and carrying out the spectrum analysis of the underwater mixed sound signals, and obtaining environment background noise characteristic parameters; inputting the underwater mixed sound signal into a preset bistable stochastic resonance system model, and adjusting a barrier height parameter of the bistable stochastic resonance system model according to the environmental background noise characteristic parameter to obtain an effective signal waveform after signal-to-noise ratio enhancement; performing signal separation on the effective signal waveform to obtain a continuous sound wave carrier signal and a positioning pulse signal; doppler frequency shift analysis is carried out on the continuous sound wave carrier signal to obtain a radial speed, and time arrival difference calculation is carried out on the positioning pulse signal to obtain a slant distance; and carrying out data fusion on the radial speed and the slope distance to obtain fused data, and obtaining a motion track and a current three-dimensional coordinate of the diving bell according to the fused data.

The application discloses an InSAR atmospheric delay phase correction method along a slant range direction, comprising the following steps: S1, acquiring two SAR image subsets covering a research area and acquiring two clean water vapor data; S2, performing differential interference processing on the two SAR image subsets covering the research area to acquire differential interference phases; S3, accurately calculating atmospheric delay phases by using an atmospheric delay phase correction model; and S4, accurately obtaining real deformation of the ground along a radar line-of-sight direction. The application gives the latest weight value of the zenith path delay difference of each ground pixel on the slant range direction of the ground by correcting the sampling mode of the water vapor product along the ground distance direction, finally proposes an accurate and efficient slant range phase total delay calculation method along the ground distance, further optimizes and improves the repeat orbit synthetic aperture radar differential interferometry method, so that the measurement result is more scientific and reasonable, and therefore the application has a wide application prospect in the field of repeat orbit InSAR atmospheric phase correction.

The application discloses a SAR polar coordinate imaging method and device based on flat flight equivalence, and the method comprises the following steps: constructing a flat flight equivalence slant range model of a large oblique SAR to obtain a baseband echo signal formed by target area scattering; performing distance direction matched filter processing on the baseband echo signal to obtain a signal after range pulse compression; sequentially performing Dechirp processing, two-dimensional resampling processing and IFFT transformation on the signal after range pulse compression to obtain a SAR polar coordinate primary imaging result; and performing geometric correction on the primary imaging result based on reverse projection to obtain an imaging result without geometric deformation and with good focusing. The SAR polar coordinate imaging method based on flat flight equivalence provided by the embodiment avoids the problem of azimuth translation invariance caused by diving through slant conversion, solves the problem that the traditional PFA is not applicable to diving SAR, and successfully extends the PFA imaging algorithm without deformation to diving SAR by correcting the geometric deformation problem caused by diving.

The invention discloses a method for imaging a space target by a space-based ISAR (inverse synthetic aperture radar), and relates to the field of inverse synthetic aperture radar imaging, in particular to the method for imaging the space target by the space-based ISAR. The invention aims to solve the problem that high-precision imaging is difficult to realize due to high-order space-variant range migration and phase error caused by complex relative motion and large-bandwidth signals between a target and a platform in a space target imaging process of a space-based ISAR (Inverse Synthetic Aperture Radar). The method comprises the following steps of: 1, acquiring a target slant distance and a radar sight observation angle according to orbit information of a satellite-borne platform, orbit information of a space target and a narrow-band tracking system of the satellite-borne platform; obtaining a radar sight line unit vector based on the radar sight line observation angle; 2, constructing a translational motion compensation item based on a target slant distance, and calculating an imaging compensation coefficient based on a radar line-of-sight unit vector; and 3, performing translational motion compensation by using the translational motion compensation item, performing rotational motion compensation by using the imaging compensation coefficient, and finally obtaining an imaging result.

The application relates to the technical field of radar imaging, in particular to an effective vehicle-mounted SAR-BP motion compensation method, which comprises the following steps: obtaining echo signals, performing pulse compression on the echo signals based on transmission signals to obtain distance domain signals of SAR; selecting a reference strong point in the distance domain signals, performing upsampling processing on the reference strong point through interpolation to obtain a distance migration curve of the reference strong point; calculating a reference envelope offset correction factor, then estimating envelope offset correction factors of each distance gate, performing envelope offset correction on the distance domain signals to obtain signals compensated for slant range error; calculating a residual phase compensation factor, performing residual phase error correction on the signals compensated for slant range error to obtain signals compensated for residual phase; and performing imaging on the signals compensated for residual phase by using a BP algorithm to obtain a SAR image. The method reduces memory occupation, shortens calculation time consumption, has stronger universality and higher precision, and improves imaging quality.

The application discloses a spiral trajectory glider synthetic aperture radar imaging method and device, and the method comprises the following steps: sequentially performing time domain and frequency domain compensation processing on echo signals through a time domain compensation function and a frequency domain compensation function to obtain two-dimensional frequency domain signals; wherein the time domain compensation function and the frequency domain compensation function are constructed according to the relationship between high-precision instantaneous slant range of any point in an imaging scene and instantaneous slant range of a reference point, and the instantaneous slant range is determined based on a spiral trajectory geometric model with rapid acceleration and speed change; and performing non-uniform fast Fourier transform on the two-dimensional frequency domain signals to obtain transformed two-dimensional frequency domain signals. The application can improve imaging precision.

The invention relates to the technical field of laser radars, in particular to an omnidirectional slant visibility prediction method and device based on a laser radar. The method comprises the following steps: determining a laser emission path according to a measurement area, and respectively acquiring scattered echo signal data, slant visibility data and wind data under the same range gate on the laser emission path through a micro-pulse laser radar and a coherent Doppler wind measurement laser radar; storing and processing the acquired data; and inputting the processed data into a vector autoregression exogenous variable prediction model to obtain a predicted slope visibility value at a future moment. Meanwhile, the invention discloses a device for executing the method, and the method and the device for predicting the omnidirectional slant visibility based on the laser radar are adopted, so that the slant visibility on a laser emitting path can be predicted, and technical support is provided for follow-up.

The application relates to an ultra-short baseline positioning method based on statistical difference, and relates to the field of ocean engineering. The application is used to solve the problems of small effective positioning range of the existing ultra-short baseline underwater acoustic positioning system and low positioning precision when high-precision sound velocity information is lacked. The application comprises the following steps: obtaining a slant range R T of a positioning target, a coarse measurement result cos theta T and a coarse positioning result X T ; obtaining horizontal position utilization of a difference reference station in a base array coordinate system and X T ; obtaining a reference station I with the best positioning effect; obtaining a true slant range direction angle and a direct difference correction (Delta x, Delta y) T by using the geodetic coordinates of the reference station I; obtaining a positioning target relative difference correction coordinate X=(x, y) T in the base array coordinate system by using X T , R T and (Delta x, Delta y) T ; and converting X=(x, y) T into geodetic coordinates by using a conversion matrix from the base array coordinate system to the geodetic coordinate system, so as to obtain geodetic coordinates of the positioning target. The application is used for positioning a target by using an ultra-short baseline underwater acoustic positioning system.

The invention discloses a radar error calibration method based on target track comparison, relates to the technical field of electronic information, and aims to improve the precision and coverage dimension of radar system error detection and adapt to differential detection requirements and coordinate conversion characteristics of different flight conditions so as to realize efficient and accurate error evaluation and analysis and improve the accuracy of radar system error detection. By improving the analysis precision and the anomaly recognition speed of radar system error monitoring, the quality assurance efficiency and the detection accuracy level in the operation process of a radar system are remarkably improved, pairing deviation and error evaluation quality reduction caused by subjective judgment are avoided, the pertinence and the implementation effect of an optimal matching scheme are effectively improved, and the method is suitable for popularization and application. Through accurate identification and analysis of a slant distance error, an azimuth error and an elevation angle error, and in combination with a preset number of times of radar data correction circulation mechanism, deviation abnormal factors influencing a radar system error are determined, and it is ensured that a quality management and control measure is highly matched with an actual detection defect risk.

This invention discloses a near-range wide-area single-station fixed FENLCS imaging method and system based on an ellipsoidal model. The method steps are as follows: S11. Construct a geometric model for near-range wide-area single-station fixed bistatic SAR imaging and analyze its echo characteristics and spatially variable characteristics of the oblique angle; S12. Perform range-direction preprocessing on the target echo signal in the range frequency domain; S13. Based on the results of the range-direction preprocessing, construct an ellipsoidal model to obtain the azimuth spatially variable relationship between the receiver center slant range and the oblique angle of the target at any azimuth time point within the same range cell, and improve the range-direction processing accuracy using the residual higher-order RCMC method of azimuth spatial variation; S14. Remodel the azimuth spatially variable Doppler parameters based on the constructed ellipsoidal model, and use the FENLCS algorithm to achieve azimuth equalization and compression to obtain the final focused image. This invention improves the performance of SAR imaging.

A signal processing device (3) is configured to comprise: an approximate curve calculation unit (11) that calculates an approximate curve of an actual slant range change, which is a curve indicating the actual distance change with the passage of time between an observation object and a platform (1) equipped with a radar (2) that radiates a radio wave toward the observation object and then receives the radio wave reflected by the observation object; and a division unit (12) that divides each of the actual slant range change and a reception signal of the radio wave by the radar (2) into a plurality of mutually different time zones, and calculates each approximate slant range change by approximating each actual slant range change after division. The signal processing device (3) is also provided with: a compensation amount calculation unit (13) that calculates, on the basis of the difference between each actual slant range change after division by the division unit (12) and each approximate slant range change calculated by the division unit (12), a compensation amount for compensating for the phase of each reception signal after division by the division unit (12); a compensation unit (14) that uses each compensation amount calculated by the compensation amount calculation unit (13) to compensate for the phase of each reception signal after division by the division unit (12); and a divided image synthesis unit (19) that synthesizes a plurality of images reproduced on the basis of each reception signal after phase compensation by the compensation unit (14).

The application provides a ground-based bistatic radar lunar imaging geometry correction method, device and equipment, and relates to the technical field of synthetic aperture radar. The geometry correction method comprises the following steps: constructing a two-way slant range model according to the geometric relationship between the ground-based bistatic radar and the lunar imaging area, determining the mapping relationship between the lunar geographic coordinate system and the delay-Doppler coordinate system based on the two-way slant range model; constructing an initial rational polynomial coefficient model based on the mapping relationship, projecting the delay-Doppler domain image result obtained by the ground-based bistatic radar to the lunar geographic coordinate system by using the initial rational polynomial coefficient model, and obtaining a preliminary geometry correction result; analyzing the system error of the ground-based bistatic radar, adding an affine transformation in the initial rational polynomial coefficient model according to the analysis result, obtaining an improved rational polynomial coefficient model, and projecting the delay-Doppler domain image result to the lunar geographic coordinate system again based on the improved rational polynomial coefficient model, and obtaining a final geometry correction result.

The invention discloses an aircraft landing interval pentagonal slant distance automatic calculation method and system, and relates to the aviation field, and the method comprises the steps: obtaining an inbound flight data set, sorting flights in the inbound flight data set, and obtaining an ordered flight sequence; for each flight in the ordered flight sequence, judging whether the flight can serve as a front flight or not; if yes, obtaining an original flight path point set of the flight; screening out flight path points meeting a preset requirement from the original flight path point set of the flight, and taking the flight path points as an effective flight path point set of the flight; according to the effective track point set of the flight, obtaining a runway and an actual landing point of the flight; and according to the actual landing point of the flight, finding out the rear aircraft of the flight, and determining the spatial distance and the interval type between the flight and the rear aircraft. The space distance between the front machine and the rear machine can be accurately calculated, the interval type is automatically judged, and manual intervention is not needed.

The invention provides a fan clearance distance monitoring method and system based on multi-beam radar correlation detection. The system comprises a three-beam laser radar acquisition module, a data preprocessing module, a consistency verification module, an environment identification and data compensation module, and a clearance value calculation and output module. The method comprises the following steps: S1, extracting echo intensity and slant range data of each beam; s2, performing time sequence filtering processing on each path of acquired beam data, and removing instantaneous jump points deviating from a mean value center; s3, executing multi-beam time correlation verification; s4, executing multi-beam numerical value association verification; s5, calculating a visibility influence factor to judge a visibility environment; and S6, fusing the verified effective data, performing complementation by using the residual effective beam data, and outputting a final fan clearance distance monitoring value. The method is applied to the technical field of wind power generation safety monitoring.

The application relates to an equatorial ionospheric irregularity automatic detection method and system, and belongs to the field of artificial intelligence. The method comprises the following steps: downloading GOLD satellite data, pre-processing and labeling, and constructing an original data set; inputting the original data set into a deep learning network model for training to obtain a trained deep learning network model; calculating the performance index of the trained deep learning network model, and outputting an equatorial ionospheric irregularity identification result. The application solves the problem of low accuracy in identifying and detecting equatorial ionospheric irregularities caused by the influence of factors such as slant range, background airglow intensity, instrument characteristics and threshold.

A vortex electromagnetic wave near field azimuth identification method is provided. Four kinds of vortex electromagnetic waves with different modes are set to detect a target, four groups of echo data are obtained, two-by-two interference processing is performed on the four groups of echo data, the phase generated by the target slant range is eliminated, six groups of echo phases after interference are extracted, six groups of theoretical phases are constructed, and a search algorithm is used to obtain a high-precision target azimuth angle which makes the sum of absolute values of errors between the echo phases after interference and the theoretical phases minimum. The present application can complete azimuth identification only by using four modes under the condition of ensuring measurement accuracy, is more efficient, and is more in line with the demand of rapid direction finding of near field detector.

The application provides a time-sensitive moving target multi-beam joint focusing method, a storage medium and an electronic device, and relates to the technical field of radars.A linear processing process is formed by a constructed generalized sliding window matching function and a multi-beam focusing matching function, the problem that a weak moving target is easily submerged in noise due to the fact that a non-linear method is used to compensate for energy defocusing of the moving target in the prior art method, resulting in serious energy loss, is overcome, and the performance of focusing on the weak moving target is improved.Furthermore, the initial beam time of the moving target, the target cross-beam time, the scene center slant range, the radial velocity, the radial acceleration and the radial jerk obtained by searching are used for compensating for additional azimuth window modulation due to the fact that the moving target crosses multiple beams and complex range-azimuth migration in a single beam, and precise focusing of the weak moving target is realized.

The invention relates to a long synthetic aperture time SAR imaging airborne test verification method, and belongs to the field of satellite overall design. Building a ground test system; designing a frequency band of the SAR antenna; designing a polarization mode of the ground test system; designing the flight height of a flight platform in the ground test system; designing an incident angle range of an SAR antenna beam in the ground test system; designing the flight speed of the flight platform; designing a radar slope distance in the ground test system; designing the breadth of the ground test system; designing a beam incident angle of the ground test system; the synthetic aperture time of the ground test system is designed; designing the azimuth resolution of the ground test system; designing the bandwidth of the ground test system; the flight platform flies according to the design parameters, test original echo data are obtained, a final imaging image is obtained, and verification of the imaging performance of the SAR satellite with the long synthetic aperture time is completed; according to the method, the long synthetic aperture time SAR satellite imaging performance and function are verified in the satellite ground development stage.

The adaptive distance detection method, system and medium based on the TOF sensor include obtaining an original slant range measurement value and an original attitude angle measurement value; correcting the original slant range measurement value to obtain an effective slant range value; performing attitude solving processing on the original attitude angle measurement value to obtain an attitude angle component; performing time alignment processing based on the effective slant range value and the attitude angle component to obtain a correlated data tuple; calculating a calibrated straight-line distance based on the data tuple and a preset formula; performing effectiveness verification on the calibrated straight-line distance to obtain an effective straight-line distance; calculating a time sequence statistic based on a plurality of continuous effective straight-line distances, and calculating a time sequence change based on a plurality of continuous attitude angle components; comparing the time sequence statistic with a first static threshold value, and comparing the time sequence change with a second static threshold value; and adjusting a ranging frequency of the TOF sensor according to a comparison result.

This invention discloses a mid-orbit curve SAR frequency domain imaging method based on spatially varied azimuth preprocessing. This invention relates to an imaging algorithm that, under long synthetic aperture time and slant-look observation geometry conditions, suppresses the two-dimensional spatial variation of range cell migration (RCM) through improved azimuth resampling technology, thereby achieving high-precision focusing. This invention is achieved through the following technical solution: Step 1, constructing a two-dimensional spatially varied model of the higher-order slant range history and its parameters for MEO SAR. Step 2, establishing an improved azimuth resampling model based on range gate dependence. Step 3, solving for the optimal azimuth resampling coefficients. Step 4, performing improved azimuth resampling and imaging focusing processing.