237 results about "Azimuth direction" patented technology

The invention relates to a single-channel moving target refocusing method and device based on a bunching mode, and the method comprises the steps: detecting a ground moving scene through a terahertz video radar, obtaining a single-channel echo signal, generating a two-dimensional image of the ground moving scene, and extracting a target image of a moving target from the two-dimensional image; the method comprises the following steps of: performing azimuth inverse Fourier transform on a target image to obtain a one-dimensional range image, performing secondary phase compensation by using an image displacement algorithm, and performing range envelope alignment on a compensated signal by using an adjacent cross-correlation algorithm of linear interpolation to correct a nonlinear error term so as to obtain a moving target refocusing image after the nonlinear error term is corrected. And the two-dimensional image is filled with the image to obtain a complete image. By adopting the method, the problem of image defocusing caused by micro-distance migration can be effectively solved.

The invention discloses an unattended turntable servo control system. The method is applied to a two-dimensional rotary table, the rotary table comprises an azimuth rotating shaft and a pitching rotating shaft, and each rotating shaft is driven and controlled by a motor. The system comprises a control unit and a driving unit, the control unit is used for receiving the position information of the rotary table, the current information of each motor and a control instruction sent by external communication equipment, calculating a control signal required for driving each motor to a target position based on the received information, and sending the calculated control signal to the driving unit; and the driving unit generates a driving current based on the received control signal to drive the motors to rotate, so that each motor moves to a corresponding target position. According to the invention, free control of the rotary table under two degrees of freedom in the azimuth direction and the pitching direction can be autonomously realized.

The invention relates to a shadow-based ground moving target parameter estimation method, device and equipment, and the method comprises the steps: constructing a geometric model of terahertz video SAR (Synthetic Aperture Radar) moving target imaging in a bunching mode, and obtaining an echo mathematical model of a moving target based on the geometric model; after an echo signal obtained by detecting a ground motion scene by a terahertz video radar is expressed based on the echo mathematical model, the distance direction speed of a moving target is estimated through the relative offset of a moving target image and a shadow in the azimuth direction, and the distance direction speed of the moving target is calculated through the frequency broadening of the target image and the shadow in the azimuth direction. And estimating the azimuth direction speed of the moving target, and estimating the distance direction acceleration of the moving target according to the frequency modulation rate of the secondary phase through the compensation of the secondary phase. By adopting the method, accurate target parameter estimation can be obtained.

The invention provides a satellite-borne bistatic FMCW-SAR imaging method based on a non-stop-walk model, and relates to the technical field of signal processing, and the method comprises the steps: reading full-aperture echo data and imaging parameters which have been subjected to line frequency resolution processing, and carrying out the average segmentation of the full-aperture echo data in the azimuth direction, and obtaining a plurality of sub-aperture echo data; performing backward projection processing on all the sub-aperture echo data for realizing residual video phase term removal and range interpolation in a preset imaging grid to obtain a sub-aperture image corresponding to each piece of sub-aperture echo data; and carrying out compression, azimuth upsampling and decompression calculation on all the sub-aperture images, and carrying out coherence superposition calculation on the decompressed sub-aperture images to obtain a final imaging result. According to the scheme, high-precision focusing of echo data under a spaceborne bistatic FMCW-SAR system can be realized.

A bottom hole assembly includes a downhole conveyance that is extendable from a terranean surface, through a wellbore, and to a subterranean formation; and a perforating tool configured to couple to the downhole conveyance and create a perforation cluster in the subterranean formation. The perforation cluster includes perforations arranged along a longitudinal direction of the wellbore. The perforations includes one or more first perforations extending along a first azimuthal direction, one or more second perforations extending along a second azimuthal direction at a first offset angle with respective to the first azimuthal direction, and one or more third perforations extending along a third azimuthal direction at a second offset angle with respective to the first azimuthal direction. The one or more second perforations and the one or more third perforations are alternative with each other along the longitudinal direction of the wellbore.

The invention belongs to the technical field of image processing, and discloses a three-dimensional radar sub-aperture imaging deformation monitoring device and method, and the device comprises a radar which is used for collecting echo signals passing through a preset position, processing the echo signals according to frequency mixing and analog-to-digital conversion, obtaining a three-dimensional echo matrix, and outputting the three-dimensional echo matrix; the three-dimensional echo matrix and a sampling ending signal are sent to a motion compensation module; the motion compensation module is used for resampling the azimuth direction of the three-dimensional echo matrix by adopting an interpolation algorithm; the distance matching filtering module is used for performing pulse compression on the distance direction of the three-dimensional echo matrix; the migration correction module is used for carrying out migration correction on the distance direction of the three-dimensional echo matrix after pulse compression; the sub-aperture imaging module is used for calculating a three-dimensional echo matrix after migration correction according to a sub-aperture imaging algorithm; and the deformation monitoring module is used for performing interference difference processing on the three-dimensional complex image to obtain deformation data. The imaging quality and the deformation monitoring precision can be improved.

The invention discloses a receiving and transmitting combined synthetic aperture sonar distance stack imaging method, system and device, and relates to the technical field of image processing, and the distance stack imaging method comprises the steps: calculating a two-way slant range course for a reference point target in an imaging region; calculating a reference echo signal of a reference point target based on the two-way slant range course and the parameters of the transmitted signal, and performing two-dimensional frequency domain transformation to obtain a reference frequency spectrum; two-dimensional frequency domain transformation is carried out on an original actually-measured echo signal of the receiving and transmitting combined synthetic aperture sonar to obtain an echo frequency spectrum, and conjugate multiplication is carried out on the echo frequency spectrum and a reference frequency spectrum in a two-dimensional frequency domain; coherent accumulation is carried out in a range direction frequency domain according to a conjugate multiplication result, and inverse Fourier transform is carried out in an azimuth direction; and processing the pixels at other distances in the imaging area according to the steps to obtain processing results of all the pixels in the whole imaging area, and carrying out carrier frequency removal on the basis to obtain an imaging result of the whole imaging area.

A satellite constellation (100) includes a plurality of artificial satellites (111 to 116) that number a multiple of 6. Each of the plurality of artificial satellites orbits in an inclined circular orbit a plurality of times a day. Normals to a plurality of orbital planes corresponding to the plurality of artificial satellites are shifted by an equal angle from each other in an azimuth direction. The plurality of orbital planes make up one or more orbital plane sets each consisting of six orbital planes. Timings at which the six artificial satellites orbit on the six orbital planes of each orbital plane set are synchronized with each other.

The invention relates to the technical field of image data processing, and discloses a long-time-sequence glacier flow velocity monitoring method, which comprises the following steps of: acquiring a glacier SAR (Synthetic Aperture Radar) image sequence and preprocessing to generate a plurality of multi-view SAR images; setting a time baseline threshold value, performing image pair combination on all the multi-view SAR images, performing offset estimation, and respectively generating a plurality of offset sequences in azimuth and distance directions; constructing a nonlinear glacier flow velocity model based on seasonal components, optimizing all offset sequences, generating an optimized offset sequence, calculating a glacier surface average flow velocity field, and generating a glacier flow velocity direction matrix in combination with second glacier cataloguing data; taking the optimized offset sequence as an observed quantity, setting a glacier flow direction as a constraint condition, and carrying out iterative solution on displacement distribution corresponding to the imaging moment of each multi-view SAR image by adopting a least square method to obtain optimal displacement distribution corresponding to the imaging moment of each multi-view SAR image; according to the method, the reliability and precision of glacier flow velocity calculation are improved.

The invention discloses a high-resolution SAR deception jamming signal rapid generation method and device, and belongs to the technical field of radar countermeasure. The method comprises the following steps: intercepting an SAR signal and measuring parameters of the SAR signal; obtaining a deception jamming template image, and carrying out edge optimization processing; performing two-dimensional partitioning on the template in the distance direction and the azimuth direction to obtain a plurality of sub-templates; calculating a phase compensation function for the central point of each sub-template, and carrying out phase optimization; the optimized sub-templates are superposed, and a high-quality product modulation matrix is generated; and multiplying the matrix by an intercepted SAR signal, and transmitting after digital-to-analog conversion and up-conversion to form a deception jamming signal. According to the method, through block phase compensation and template edge optimization, the imaging quality and concealment of the deception jamming image under the high-resolution SAR are remarkably improved, meanwhile, low calculation complexity is kept, and the method is suitable for satellite-borne and airborne SAR systems.

The invention discloses a method for realizing elliptic cone scanning by a communication-in-moving antenna. The method comprises the following steps: determining the value of a scanning position point number parameter N; determining the value of the maximum scanning offset angle delta A in the azimuth angle direction and the value of the maximum scanning offset angle delta E in the pitch angle direction; determining values of an expected azimuth angle alpha 0 and an expected pitch angle beta 0 of the current antenna; setting a scanning counter i; when i is less than 4N, calculating a parameter theta i, calculating a scanning offset angle delta i, calculating a scanning track beta i of a pitch angle, and calculating a scanning track alpha i of an azimuth angle; the pitch angle of the antenna is controlled to rotate to a new position beta i, and the azimuth angle of the antenna is controlled to rotate to a new position alpha i; and updating the scanning counter i, i = mod (i + 1, 4N), and returning to execute. The method not only can realize elliptic cone scanning, but also can realize cone scanning, and can effectively solve the problem that the average receiving level is reduced when the communication-in-moving antenna of which the cross section of the beam main lobe is elliptic performs cone scanning.

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.

The invention relates to a satellite-borne SAR antenna pointing deviation in-orbit identification and satellite attitude compensation method, which comprises the following steps: determining a satellite attitude angle imaged according to a nominal beam according to a nominal installation matrix and an imaging lower visual angle, and controlling a satellite to complete SAR load positive side view strip imaging according to the satellite attitude angle to obtain image data; determining a distance deviation distance between a sheet center and an expected sheet center, a center Doppler frequency deviation value of the sheet center, and center Doppler frequency deviation values of a sheet far end and a sheet near end according to the image data; calculating a distance direction deviation angle, an azimuth direction deviation angle and a torsion deviation angle of the actual wave beam relative to the nominal wave beam; and calculating an antenna deviation matrix, updating the nominal installation matrix, and determining the satellite attitude according to a new installation matrix during next imaging. According to the method, the satellite-borne SAR antenna pointing deviation can be effectively eliminated, the SAR image quality is improved, and the on-orbit application efficiency of an SAR satellite is improved.

The invention provides a method for obtaining a three-dimensional body through two-dimensional seismic reflection data gridding, and belongs to the field of seismic data processing. Through a technical means of constructing a virtual grid through rotation, a two-dimensional measuring line is converted into a three-dimensional data body which is uniformly distributed in space, and subsequent data processing is not limited to one direction any more. Specifically, latitude and longitude coordinates of each discrete reflection data are obtained and converted into UTM projection rectangular coordinate values, and coordinate values of a longitude minimum point are determined; calculating the optimal azimuth angle of the grid according to the plane distribution characteristics of the discrete points, and determining the grid spacing along the azimuth angle direction and the vertical azimuth angle direction; the grid is rotated to the three-dimensional grid direction, the coordinates of the point with the minimum longitude value after rotation are extended outwards by a half grid interval, and the coordinates of the point serve as base points of the grid; all the coordinate points are rotated in the same way, data falling into the same grid are superposed, then the coordinate number of each point in the grid is calculated, and a three-dimensional data volume is obtained accordingly.

The invention discloses a block self-focusing ISAR (inverse synthetic aperture radar) imaging method and system based on an FPGA (field programmable gate array), and the method comprises the steps: obtaining ISAR echo data, and sequentially carrying out the preprocessing and global self-focusing processing, thereby obtaining a global self-focusing correction matrix; dividing the global self-focusing correction matrix into a plurality of sub-matrix blocks in a sliding window partitioning manner; performing minimum entropy self-focusing processing on each sub-matrix block to generate an optimized sub-matrix block; performing fast Fourier transform on the optimized sub-matrix blocks in the azimuth direction to generate two-dimensional image data; determining an offset according to an overlapping region of the adjacent sub-matrix blocks, performing cyclic shift processing on the two-dimensional image data corresponding to the current optimized sub-matrix block in the azimuth direction based on the offset, and aligning the two-dimensional image data corresponding to the previous adjacent optimized sub-matrix block; and outputting the aligned corrected two-dimensional image data as an ISAR imaging result. According to the invention, the azimuth focusing performance is improved, and the overall imaging quality is obviously improved.

The present invention provides a high-speed ultra-short-range SAR local BP fast imaging method, which includes constructing a geometric model of a two-dimensional imaging scene and deriving the target scattering point echo signal received by the radar based on the model. The method also includes the following steps: pixel segmentation of the ultra-short-range SAR application scene based on a polar coordinate system; performing frequency modulation processing on the echo signal to obtain the distance R of all targets to the radar when the slow time is zero in the frequency domain. n ; The distance is R n , n∈{1…N}, azimuth direction from θ0 to θ m For a certain pixel in the range, the echo signal amplitude is coherently accumulated in the slow time domain; all azimuth pixels are traversed to obtain the range R n The imaging result is obtained by looping through all target distances using the method in step 3, and obtaining a frame image of the entire scene. The present invention proposes a local BP imaging method based on polar coordinates, which uses the target distance obtained by Fourier transform to narrow the imaging range.

The invention discloses a side lobe suppression method for an SAR image, and the method comprises the steps: obtaining an imaging result containing a high side lobe through a CS algorithm; secondly, re-arranging a scene only containing one point target with the intensity of 1, performing echo simulation on the newly arranged scene and imaging based on the CS algorithm, and obtaining an imaging result of the point target under the CS algorithm as a convolution kernel; and finally, a real scene image is obtained through Lucy-Richardson-based time domain filtering deconvolution. According to the invention, the sidelobe interference in the orientation in the imaging process can be inhibited, the robustness and universality of the imaging method are improved, and the imaging quality is further improved.

The application discloses a kind of real synthetic aperture imaging methods for multichannel radar forward-looking imaging, first, the echo data of the region to be imaged is obtained, second, the data obtained is compressed in range direction pulse, then the data after pulse compression is respectively processed in synthetic aperture and real aperture, for synthetic aperture dimension, using BP algorithm is focused in azimuth direction, and the results of each channel are incoherently accumulated, to obtain left-right ambiguous image, for real aperture dimension, the imaging scene is divided into grid, constructs guide matrix, reconstructs target scattering coefficient to realize super-resolution imaging, finally, the results of two dimensions are multiplied, to obtain non-ambiguous and super-resolution result.The method of the application fully utilizes the advantages of high resolution obtained by platform motion synthetic aperture in squint region and high resolution obtained by azimuth real aperture super-resolution in forward-looking region, overcomes the problem of single-base radar forward-looking imaging ambiguity and low resolution, and realizes multichannel radar non-ambiguous forward-looking high-resolution imaging.

The application provides a master-slave type star cluster cooperative SAR-GMTI system and method, which comprises: an azimuth multi-channel master star M1, a small satellite cluster M2 along a heading direction, and an on-board joint processing module M3; the azimuth multi-channel master star M1 is used for transmitting radar signals in a full array and receiving radar signals in an azimuth direction; the small satellite cluster M2 along the heading direction is composed of at least two small satellites in a receiving mode only, and the small satellite cluster is linearly distributed along the heading direction; and the on-board joint processing module M3 is used for fusing SAR image data of the azimuth multi-channel master star M1 and the small satellite cluster M2 along the heading direction, and completing target detection and relocation through space-time adaptive processing. The application effectively solves problems such as a large minimum detectable speed of a single platform system and speed ambiguity of a distributed system, and provides important technical support for subsequent spaceborne SAR earth imaging observation.

The invention discloses a field programmable gate array (FPGA)-based KeyStone transformation range migration correction method, which comprises the following steps of: transposing data in a double data rate 3 (DDR3) to a range direction, performing inverse Fourier transformation in the range direction, transposing the data to an azimuth direction and storing the data back to the DDR3; zero padding is carried out on the head and the tail of data in the DDR3 by controlling the dual-port RAM; the data size and the signal parameters are transmitted into a chirp generation module to generate phase compensation so as to calculate a stepping factor; multiplying the zero-filled data by a stepping factor, and performing inverse Fourier transform along the azimuth to obtain a first transform result; carrying out conjugate processing on the stepping factor and carrying out inverse Fourier transform along the azimuth direction to obtain a second transformation result; multiplying the first transformation result and the second transformation result, and performing Fourier transformation along the azimuth to obtain a third transformation result; multiplying the third transformation result by a stepping factor, and performing inverse Fourier transform along the azimuth to obtain a fourth transformation result; and sampling the fourth transformation result in the azimuth direction and carrying out Fourier transformation along the distance direction to obtain a correction result. The method is high in correction efficiency.

An acoustic window including a convex surface that extends in an azimuth direction and contacts an examination target, and a first wall portion and a second wall portion that extend divergently from each other. At least a portion of the first wall portion is provided along an inner surface of the probe case, and the second wall portion has an outer surface that is contiguous with the convex surface.

The application discloses a vortex electromagnetic wave radar forward-looking imaging method and system based on a concentric circular array design, a storage medium and an electronic device, and specifically comprises the following steps: establishing a new system radar imaging model according to a radar working mode; designing a concentric circular array and a vortex mode transmitting function; deriving a return model; obtaining distance direction high-resolution information of a target; performing distance correction, phase decoupling and Bessel amplitude compensation on the azimuth direction of the return, and coherently superimposing the compensated return to reestablish a dual relationship between a mode and an azimuth angle; and finally, realizing vortex electromagnetic wave radar forward-looking two-dimensional imaging through fast Fourier transform on the azimuth direction. The forward-looking imaging can increase the observation time of a region of interest, keep the region of interest in a main lobe range, enhance the strength of a return, increase return information, and effectively improve the azimuth direction resolution.

The invention relates to a method for calibrating the normal azimuth of an antenna array surface of an interference system, which comprises the following steps of: arranging high-precision control points near an interference antenna of a certain type by introducing methods such as national geodetic point positioning and single-point positioning, and measuring coordinate information of required point positions by measuring equipment; spatial data fitting is carried out on an interference antenna surface of a certain type and a geometric center normal of the interference antenna surface by using SMN precision industrial measurement software, and center normal spatial pointing and azimuth information of an antenna array surface is solved. And enabling a geometric center normal of a horn antenna opening surface to reversely coincide with a center normal of an antenna array surface through a total station lofting method, and modulating the center phase direction of each frequency point main lobe beam of a certain type of interference antenna by using phase modulation software to be consistent with the azimuth direction of the geometric center normal of the antenna array surface. By means of the method, the normal orientation alignment precision of the geometric center of an antenna array surface of a certain type of interference system can be improved from 1 degree to 10 seconds, and therefore the precision of main lobe beam center phase pointing of the interference antenna array surface is indirectly improved.

A surveying prism can include a housing, optical features, and a bumper. The optical features can be located on a radial surface of the housing azimuthally offset from one another by equal arcs. The bumper can cover the optical features. The bumper can include flat edges and position indicators. The flat edges can correspond to the optical features. Each flat edge can have a different first center point of first center points that is approximately at the same azimuthal angle with respect to the surveying prism as a corresponding second center point of a corresponding optical feature of the optical features. The position indicators can correspond to the optical features, and each position indicator can be positioned at a central point of a different flat edge of the flat edges.

The invention relates to the technical field of satellite communication, and particularly discloses a Ka frequency band measurement and control antenna and a Ka frequency band measurement and control communication device and method.The Ka frequency band measurement and control antenna comprises a hollow quadrangular frustum pyramid, pyramidal horn antennas are arranged on the four side faces of the quadrangular frustum pyramid, and each pyramidal horn antenna comprises a hollow rectangular feed waveguide and a hollow horn; the rectangular feed waveguide penetrates through the side face of the quadrangular frustum pyramid from the interior of the cavity of the quadrangular frustum pyramid, extends out of the cavity of the quadrangular frustum pyramid and is expanded to form the horn, the beam width of the pyramid horn antenna in the azimuth direction is larger than 90 degrees, and the beam width of the pyramid horn antenna in the pitching direction is larger than 50 degrees. According to the Ka frequency band measurement and control antenna, after the wave beams generated by the pyramid horn antennas arranged on the four side surfaces of the quadrangular frustum pyramid are combined, the space of 0-360 degrees in azimuth and 0-50 degrees in pitch can be covered, and communication between the Ka frequency band measurement and control antenna and high-orbit relay satellites in the earth can be achieved conveniently.

The application discloses a cross-water bridge parameter inversion method and system based on generalized compact polarization SAR total power intensity peak value, and belongs to the technical field of synthetic aperture radar remote sensing, and solves the problems of low system efficiency, non-movable discriminator, non-uniform GCP mode discriminators and precision affected by pixel deviation of the prior art. The application obtains or synthesizes a received scattering vector; total power is calculated pixel by pixel based on the received scattering vector, a filter is used for multi-view processing, a smoothed total power map is obtained, the smoothed total power profile in the distance direction is obtained by averaging in the azimuth direction within the azimuth direction interval covered by the determined bridge main span, three local maximum peak values satisfying preset conditions are identified by using a peak value detection method; and the geometric parameters of the bridge are inverted based on the pixel positions of the local maximum peak values and combined with imaging geometric parameter inversion. The application is used for the safety monitoring and quantitative inversion of geometric parameters of cross-sea and cross-river bridge infrastructure.

To fix a variation direction of an electric field vector of horizontally polarized waves emitted to an observation object at a right angle with respect to a specific plane.SOLUTION: The orientation direction of an antenna 201 is adjusted so that an azimuth direction Az of the antenna 201 coincides with a normal direction of a specific plane, and a bore site direction Boa of the antenna 201 is oriented in a direction deviated according to a deviation angle from a direction oriented to an observation object 102. The specific plane is a plane obtained by rotating a plane formed by a relative direction of the antenna 201 to the observation object 102 and the normal direction of a ground surface at the position of the observation object 102, according to a surface rotation angle around the normal direction of the ground surface at the position of the observation object 102. The surface rotation angle is set as the angle around the normal direction of the ground surface. The deviation angle is an angle in an elevation direction of the antenna 201.SELECTED DRAWING: Figure 11

A satellite (140) for operation in an orbit around the Earth includes an ADCS (131, Fig. 1) configured to mechanically steer the satellite in an azimuth direction to extend a dwell time (1105) during which a target is visible from the satellite when the satellite is orbiting above the target of choice. A processor at a ground station can be configured to process raw SAR data from any of the satellites described herein. The raw SAR data can be processed in a variety of ways to provide image information, including but not limited to forming multi-view images, compiling video sequences, and color coding images.

The application discloses a kind of moving target fast imaging method based on KT conversion, this method includes: radar receives moving target echo signal;Moving target echo signal is handled, distance compression, consistent compensation, slow time inversion;Utilize KT conversion to echo signal distance azimuth decoupling, again do fast fourier transform in azimuth direction, obtain estimated first term coefficient;Utilize estimated first term coefficient to do go after compensation echo signal walk, again utilize SOKT conversion to do correction, extract after correction echo signal do mWVD conversion, obtain estimated doppler frequency modulation;Again utilize doppler frequency modulation to do azimuth focusing processing after correction echo signal, obtain focused echo signal, obtain moving target imaging result.The application significantly improves the efficiency of moving target imaging, and can guarantee good real-time effect.

The present invention provides a two-dimensional, high-precision angle measurement method and device based on a minimally sparsely spaced L-array, belonging to the field of radar measurement technology. The method specifically involves: L-array construction: using three antenna elements sparsely spaced to form an L-array with an element spacing of , where the spacing is greater than half the wavelength of the received signal; two-dimensional angle measurement: using the constructed L-array to receive echo signals with carrier frequencies of and , constructing a virtual baseline using dual-frequency phase difference, and resolving phase difference ambiguity to obtain high-precision, unambiguous angle measurement results in both pitch and azimuth directions.