86 results about "Bistatic synthetic aperture radar" patented technology

A detection method of double-threshold constant false alarm movement object on double-base synthetic aperture radar includes finalizing distance compression of various pulse-sampling, dividing orientation time to be multiple CPI, carrying out FFT in each CPI to enter orientation frequency domain, comparing data amplitude of frequency channel at external of clutter region with the first threshold and outputting point trace, making coagulation on point trace, making Hough transform in point trace domain and making decision of the second threshold.

The invention provides a satellite-machine combined frequency domain imaging method of Bistatic Synthetic Aperture Radar (Bistatic SAR), which utilizes characteristics of the SA-BSAR system to obtain the analytical expression of two-dimensional spectrum of the system, and then utilizes Omega-k algorithm thought to obtain SA-BSAR two-dimensional Stolt mapping relation according to the expression of the two-dimensional spectrum; finally, two-dimensional Stolt interpolation can be approximately achieved by using inverse scale Fourier transform and phase multiplication in frequency domain through studying the two-dimensional Stolt mapping relation, so as to complete the compensation for the two-dimensional space variance of the system; the method can avoid the problem of huge calculation and high complexity caused by two-dimensional Stolt interpolation, thereby effectively achieving SA-BSAR imaging with high resolution.

The invention relates to a bistatic synthetic aperture radar phase synchronization method and belongs to the field of radar technologies. The bistatic synthetic aperture radar phase synchronization method includes the following steps that: echo signals generated by radar signals transmitted by a first SAR are simultaneously received by the first SAR and a second SAR, so that first echo receiving signals and second echo receiving signals are obtained; the first SAR receives phase synchronization signals transmitted by the second SAR, so that first synchronous receiving signals are obtained; thesecond SAR receives phase synchronization signals transmitted by the first SAR, so that second synchronization receiving signals are obtained; peak phase difference between the first synchronous receiving signals and the second synchronous receiving signals is determined, and a compensation phase is determined through a first preset rule according to the peak phase difference; and phase compensation is performed on the second echo receiving signals according to the compensation phase. The invention also discloses a bistatic synthetic aperture radar phase synchronization device based on encoded signals. With the device adopted, a condition that the normal operation of a radar is interrupted can be avoided, and therefore, the working efficiency of the radar can be improved.

The invention discloses a spatial synchronization method of bistatic synthetic aperture radar (SAR). The method comprises steps of initializing parameters and converting a World Geodetic System (WGS)-84 coordinate system to a spatial rectangular coordinate system; converting the spatial rectangular coordinate system to an aerial carrier geographic coordinate system; converting the aerial carrier geographic coordinate system to an aerial carrier coordinate system; converting the aerial carrier coordinate system to a radar reference coordinate system; and aligning antenna beams. Global positioning system (GPS) special coordinate information and attitude information of an aerial carrier platform are used, the coordinate conversion is conducted in accordance with the sequence of the WGS-84 coordinate system, the spatial rectangular coordinate system, the aerial carrier geographic coordinate system, the aerial carrier coordinate system and the radar reference coordinate system, the accuracy of antenna pointing control parameters which are obtained finally can be guaranteed, the GPS special coordinate information and the attitude information of the aerial carrier platform are used, airborne bistatic SAR antenna pointing control parameters can be exported through the conversion of multi-coordinate systems, and the antenna beam pointing for receiving and transmitting the aerial carrier can be aligned through antenna pointing control parameters.

The invention discloses a simulation method of a bistatic synthetic aperture radar sea wave direction spectrum, which comprises the following steps of calculating a JONSWAP sea wave spectrum and a sea wave vertical displacement according to sea wave parameters; obtaining BiSAR echo signals comprising sea wave orbital velocity and accelerated velocity according to a radar wave modulation principle and BiSAR system parameters; carrying the matched filtering on the echo signals according to a BiSAR distance and Doppler imaging algorithm to obtain an analysis formula of a BiSAR sea wave image; working out the BiSAR sea wave image by adopting a numerical integration method; and at last, carrying out two-dimensional FFT operation on the BiSAR sea wave image to obtain the BiSAR sea wave direction spectrum. The BiSAR sea wave image can be worked out by adopting the numerical integration method without producing the echo signals and processing the image in a time domain, therefore, the invention has higher operation efficiency.

The invention discloses a bistatic synthetic aperture radar (BSAR) frequency domain imaging method which specifically comprises the following steps of: initializing parameters of an imaging system; calculating a point target echo two-dimensional spectrum; performing rough matching focusing on a TV-BSAR by utilizing a reference point two-dimensional spectrum; performing Taylor expansion on the slope distance of a transmitting station, and combining residual phase terms; performing azimuth-to-frequency Stolt transform; performing distance-to-frequency Stolt transform; and performing two-dimensional inverse Fourier transform. The method disclosed by the invention adopts the two-dimensional Stolt frequency transform which enables the echo phase after rough focusing of the BSAR in a shift variant mode to finish the linearization of the airspace and frequency domain, thereby finishing residual distance migration correction, residual secondary distance compression and residual azimuth compression. The method effectively solves the two-dimensional space-variant problem in a shift variant bistatic mode, thereby realizing the precise focusing imaging of the BSAR in a shift variant mode.

The invention discloses a bistatic forward-looking SAR (Synthetic Aperture Radar) motion compensation method. Azimuth-slow time decoupling operation is adopted, and different azimuth point targets in the same distance unit are separated and processed. The method mainly comprises steps of: (1) space-invariant motion error compensation; (2) distance focus processing; (3) distance space-variant motion error compensation; (4) azimuth space-variant motion error compensation; and (5) azimuth compression. The problem that the traditional SAR motion compensation method and the existing bistatic SAR motion compensation method are hard to correct motion error azimuth space variance can be overcome. The motion error azimuth space variance can be effectively removed, and precise compensation and focusing of the bistatic forward-looking SAR can be realized.

The invention discloses a frequency domain expansion based spaceborne/airborne hybrid bistatic synthetic aperture radar imaging method. Firstly a spaceborne/airborne hybrid bistatic synthetic aperture radar oblique distance type model is built in any mode; then a two-dimensional frequency domain model is obtained by deduction; and then the phase item of the frequency spectrum is subject to Taylor expansion in fast time frequency and slow time frequency, and phase compensation is carried out, thus obtaining good focusing effect; and finally distortion is corrected, thus obtaining correct position of a target. The invention has the advantages that flow is simple, computation is less, and good focusing effect of target can be obtained in spaceborne and airborne platform high-angle diagonal flying mode and airplane squint mode; the invention can be used for imaging of large scene spaceborne/airborne hybrid bistatic synthetic aperture radar and is applicable to the fields of synthetic aperture radar imaging and earth remote sensing.

The invention discloses a moving-target parameter estimation method of common-rail bistatic synthetic aperture radar (SAR). The method mainly aims at resolving the problem that moving-target parameter estimation under the Doppler ambiguity condition cannot be achieved in the prior art. The method includes the following steps: (1) carrying out distance compression on radar echo signals of bistatic SAR of different channels; (2) carrying out clutter cancellation on the distance-compressed signals with the data processing control area (DPCA) method, and obtaining sparse moving-target signals; (3) carrying out radon transformation on the sparse moving-target signals, and obtaining a moving-target vertical heading speed and distance position coordinates; (4) carrying out range cell migration correction by means of the moving-target vertical heading speed, meanwhile compensating for the linear phase caused by the range cell migration correction, and eliminating Doppler center frequency ambiguity; and (5) utilizing the optimization method based on the compressed sensing theory to acquire the moving-target heading speed and the position. According to the moving-target parameter estimation method, moving-target parameter estimation of a bistatic SAR system under the low pulse repetition frequency (PRF) condition can be achieved. The method can be used for moving-target imaging and target tracking.

The invention belongs to the technical field of bistatic synthetic aperture radar (BiSAR) transmitting and receiving, and discloses a space synchronizing method of a BiSAR with unknown target position coordinates. The method comprises the steps that initialization processing is conducted; according to a transmitter, the unit direction vector of antenna orientation is determined, the vector of a carrier coordinate system and the vector of a geographic coordinate system are converted, the vector of the transmitter to the center of a target area is determined, the geographic coordinate system and an earth coordinate system are converted, the vector of the transmitter under the earth coordinate system is determined, and the position vector of the center of the target area is determined; according to a receiver, the position vector of the receiver on the earth coordinate system is determined, the pointing vector of the receiver which points to the center of the target area is determined, the pointing vector under the geographic coordinate system is determined, the pointing vector under the carrier coordinate system is determined, and thus antenna orientation space synchronization of the receiver and the transmitter is achieved. The space synchronizing method of the BiSAR with the unknown target position coordinates has the advantages that the space synchronizing efficiency of the BiSAR can be effectively improved, the accuracy is high, the airplane mode is flexible, and the method is beneficial to being widely used.

The invention discloses a bi-static synthetic aperture radar moving target location method. The method comprises the following steps: S1) establishing an airborne BiSAR space geometry structure, and finishing parameter initialization; S2) establishing a mathematical model for moving target echo in a BiSAR imaging area; S3) obtaining a moving target equivalent radial velocity expression; S4) establishing a reception dual-channel echo in track direction; S5) carrying out phase compensation on the dual-channel echo; S6) carrying out interference processing on the dual-channel echo signals; S7) obtaining a moving target location equation through a gradient analytical method; and S8) solving the target location equation through a genetic algorithm to obtain the position of a moving target. By constructing receiver double channels, equivalent radial velocity of the moving target with respect to a receiver is obtained through the echo interference processing; the moving target positioning formula is deduced through an R-D location model; and the moving target positioning formula is calculated based on the genetic algorithm, so that the moving target can be positioned, and positioning deviation is small.

The invention discloses a bistatic synthetic aperture radar imaging method based on similar single static equivalence. A double radical sign slant distance of bistatic is equivalent to a single radical sign slant distance of a similar single static, an analytical expression of a two dimensional spectrum of a system is obtained, a solving question of a double radical sign of the bistatic is simplified, mature single static imaging methods are fully used, such as an omega-K (wk) algorithm and a range-Doppler algorithm (RD algorithm), a two dimensional STOLT relation of the system is obtained according to the expression of the two dimensional spectrum, and finally, a two dimensional STOLT interpolation is approximated according to the two dimensional non-uniform Fourier transformation, and imaging of the system is achieved. Therefore, complicated degree of an imaging algorithm of the bistatic is largely reduced, and successive imaging process is facilitated.

The present invention discloses a bistatic synthetic aperture radar location error calculation method. The bistatic synthetic aperture radar configuration mechanism is employed and the gradient analytical method is employed to complete calculation of the bistatic distance and location errors caused by Doppler center frequency shift to derive a bistatic synthetic aperture radar target location error concrete formula. The problem of difficulties in the bistatic synthetic aperture radar location error analysis and the problem that the location errors in a traditional R-D location model cannot be accurately calculated are solved. According to the error calculation formula, the location precision of the bistatic synthetic aperture radar can be calculated so as to realize measurement and assessment of the bistatic synthetic aperture radar location precision.

The invention discloses an imaging processing method of a bistatic synthetic aperture radar SAR system. The method comprises the steps of: obtaining first time domain data, wherein the first time domain data is echo data received by the bistatic SAR system; carrying out range Fourier transformation and azimuth Fourier transformation on the first time domain data so as to obtain first frequency domain data; carrying out consistent range compression on the first frequency domain data to obtain second frequency domain data; carrying out range inverse Fourier transformation on the second frequencydomain data to obtain first Doppler domain data; carrying out complementary range migration correction on the first Doppler domain data to obtain second Doppler data; carrying out azimuth compressionon the second Doppler data to obtain third Doppler data; and carrying out azimuth inverse Fourier transformation on the third Doppler data to obtain an imaging processing result. The invention furthermore discloses an imaging processing device of the bistatic synthetic aperture radar SAR system.

The invention discloses a bistatic synthetic aperture radar imaging method (BiSAR) imaging method. Echo data is subjected to range direction compression, data of range direction compression is determined, and the data of range direction compression serves as first to-be-decomposed data for first decomposition; following operation is repeatedly executed starting from n being 1, 1 is added to n every time till n reaches N, n to-be-decomposed data is subjected to upsampling processing, the upsampled data is subjected to n decomposition, the slant range dependence relationship between a reference point and a synthetic front sub-aperture and a synthetic rear sub-aperture is determined, data obtained after n decomposition is subjected to n azimuth direction synthetic processing according to the slant range dependence relationship, n azimuth direction synthetic data is obtained, and the n azimuth direction synthetic data serves as (n+1) to-be-decomposed data for (n+1) decomposition, wherein N is a positive integer larger than 1; N azimuth direction synthetic data is subjected to azimuth direction focusing through a back projection (BP) algorithm, and focusing images are obtained. The invention further discloses a BiSAR imaging device.

The invention discloses an echo frequency domain simulation method of a bi-static synthetic aperture radar (SAR) of a fixed station. According to the method, the shortest slant ranges rR and y between a receiving station and target points are used for linearizing an echo two-dimensional frequency spectrum of an imaging scene, and a two-dimensional frequency transformation expression is derived and respectively introduced into space variant effects of range and azimuth, so that the echo frequency domain of the bi-static SAR of the fixed station can be simulated, and the problem the existing mono-static SAR and the shift invariant bi-static SAR echo frequency domain simulation method cannot be applied to the same mode can be solved; and compared with the echo simulation method based on the time domain accumulation, the echo frequency domain simulation method has the advantages of low computed amount, high operation speed and relatively high computational accuracy and can meet the requirements on simulation and research of the bi-static SAR system of the fixed station.

The invention discloses a squint spaceborne/airborne hybrid bistatic synthetic aperture radar imaging method. Based on characteristics of a squint SA-BSAR (spaceborne/airborne hybrid bistatic synthetic aperture radar) system, a wave number mapping relationship in a two-dimensional space can be obtained through an analytical expression of a two-dimensional spectrum of the system, and an imaging processing is efficiently achieved through two-dimensional non-uniform fast Fourier transformation. By the squint spaceborne/airborne hybrid bistatic synthetic aperture radar imaging method, a decoupling problem of a two-dimensional spatial domain and a two-dimensional frequency domain is solved, and a small scene supposition is not required; therefore, the squint spaceborne/airborne hybrid bistatic synthetic aperture radar imaging method is applicable to high-performance imaging of the SA-BSAR system with a relatively large squint angle and a relatively wide imaging scene range; the squint spaceborne/airborne hybrid bistatic synthetic aperture radar imaging method has relatively high imaging performance and relatively high computing efficiency; and a blank that the existing SA-BSAR frequency domain imaging technology cannot be applied to high-resolution imaging of the squint SA-BSAR system is filled.

The invention provides a bistatic synthetic aperture radar wave number domain efficient imaging processing method, and belongs to the technical field of radar detection and imaging. The method is usedfor improving the imaging processing efficiency of a bistatic synthetic aperture radar. The method comprises the following steps: firstly, obtaining a bistatic synthetic aperture radar echo signal model according to a geometric configuration of the bistatic radar; secondly, obtaining the echo imaging processing efficiency in different rotating coordinate systems by utilizing relations between thespatial spectrum processing efficiency and the rotating coordinate systems; thirdly, calculating out a most efficient rotation angle by utilizing a relation between the rotation angle and the processing efficiency; and finally, establishing the rotating coordinate system according to the most efficient rotation angle, projecting echo data to a spatial spectral domain, and realizing efficient imaging processing of a target by utilizing two-dimensional FFT. According to the method, based on the relation between the rotation angle of the bistatic synthetic aperture radar and the spatial spectrumprocessing efficiency, the efficient echo projection rotation angle is calculated, so that the imaging processing efficiency of the bistatic synthetic aperture radar is improved.

The invention discloses a range migration imaging method of a shift invariant bi-static synthetic aperture radar (SAR). According to the method disclosed by the invention, the shortest slant range of the frequency spectrum phase along a receiving station is linearly expanded based on the two-dimensional frequency spectrum of the bi-static SAR of the generalized Loffeld transformation, a Stolt frequency transformation expression is derived, and the migration correction, the residual secondary range compression and the residual azimuth compression of a residual range unit are conducted through the transformation, so that the spatial linearization and the frequency linearization of the residual phase can be realized, and the shift invariant bi-static SAR can be accurately focused. Compared with the existing shift invariant bi-static SAR range migration algorithm, the method disclosed by the invention has the advantages of simple form, relatively high accuracy and relatively high operation efficiency.

The invention discloses bi-static synthetic aperture radar time-domain fast imaging method. The bi-static synthetic aperture radar time-domain fast imaging method comprises the specific steps of adopting low-order approximation of a green function in a back-projection integral function to finish subaperture full view imaging, performing aperture synthesis and view division through iteration, synthesizing subaperture images at an upper-layer stage into synthetic aperture images at each iteration stage, finally finishing full-aperture imaging and accordingly achieving bi-static SAR accurate focusing. The bi-static synthetic aperture radar time-domain fast imaging method is characterized in that a method for block iteration projection from a signal space to an image space is adopted to achieve time-domain imaging, the rough sub-picture focusing is finished by utilizing the low-order approximation characteristic of the green function, and the focusing accuracy is gradually improved through the iteration.

The invention discloses a bistatic synthetic aperture radar imaging method on the basis of Doppler frequency expansion. The bistatic synthetic aperture radar imaging method includes performing Taylor expansion on an accurate two-dimensional frequency spectrum expression of bistatic SAR (synthetic aperture radar) about Doppler frequencies and simplifying solving of the two-dimensional frequency spectrum expression; acquiring a two-dimensional STOLT relation of a system by the aid of an idea of an omega-k algorithm according to the two-dimensional frequency spectrum expression; performing approximation two-dimensional STOLT interpolation by means of two-dimensional non-uniform Fourier transform by the aid of the two-dimensional STOLT relation to complete imaging of the system. Compared with the traditional method, the bistatic synthetic aperture radar imaging method has the advantages that the bistatic synthetic aperture radar imaging method is based on simple and accurate two-dimensional frequency spectra, so that point targets can be focused excellently; the influence of high-order terms of the Doppler frequencies on imaging results is sufficiently considered, so that scenes can be precisely imaged by an imaging algorithm; the complexity of the bistatic imaging algorithm can be reduced to a great extent owing to the fact that only the Doppler frequencies need to be considered.