43 results about "ECEF" patented technology

The invention provides a three-dimensional positioning method and system for a satellite-borne multi-base radar system based on weighted linear iteration, and the method comprises the steps: obtaining radar echo data of a plurality of receivers, carrying out the effective detection of a target, and carrying out the searching of a pitch angle and a space taper angle of a target signal through a two-dimensional adaptive filtering technology, obtaining two-dimensional angle estimation information of the target at different bases and different visual angles; constructing a nonlinear equation set according to two-dimensional angle information and slope distance information of the target under different visual angles, and performing first-order Taylor expansion on the nonlinear equation set to obtain a corresponding linear overdetermined equation set; and forming a precision matrix according to the known measurement precision of the radar system, and carrying out normalization operation and iterative solution on the linear overdetermined equation to obtain the three-dimensional coordinate of the target in the earth-centered earth-fixed coordinate system, thereby obtaining the latitude, longitude and height information of the target, and realizing the high-precision three-dimensional positioning of the multi-static radar system.

The invention provides a bistatic ISAR imaging arc section selection method for an air moving target, and relates to the technical field of bistatic radar imaging, and the method comprises the steps: obtaining the position information of a transmitting station, a receiving station and the air moving target, and converting the position information of the transmitting station, the receiving station and the air moving target into the coordinates of an earth-centered earth-fixed coordinate system; establishing a translation simulation model, a rotation simulation model and an echo model of the air moving target; the method comprises the following steps: determining a first constraint condition and a second constraint condition of a double-base-angle change rate of an air moving target according to a translation simulation model, a rotation simulation model and an echo model of the air moving target; selecting a target imaging arc section according to the earth-centered earth-fixed coordinate system coordinates of the transmitting station, the receiving station and the air moving target; therefore, the high-resolution imaging of the air moving target can be quickly and accurately obtained according to the target imaging arc segment, and the processing efficiency and the image quality can be effectively improved.

The invention discloses a multi-view image Gaussian reconstruction method and system guided by LiDAR point cloud. The method comprises the following steps: step S1, realizing accurate registration of LiDAR point cloud and a multi-view image in the same earth-centered earth-fixed coordinate system through GNSS constrained aerial triangulation, and uniformly carrying out center-of-gravity normalization to ensure space consistency and numerical stability; s2, estimating surface normal and scale parameters based on the local geometric features of the LiDAR point cloud, constructing a Gaussian ellipsoid consistent with the local geometry, and realizing Gaussian ellipsoid initialization of geometric perception; and S3, generating a sub Gaussian ellipsoid according to the Gaussian gradient and the tangent plane direction, and improving the modeling density and geometric continuity of the detail region through local encryption and parameter inheritance. According to the method, the fusion of LiDAR point cloud high-precision geometry and multi-view image texture information is realized, the geometric precision, the structural integrity and the detail expression capability of three-dimensional reconstruction are effectively improved, and the method is particularly suitable for high-precision live-action three-dimensional modeling of unmanned aerial vehicle multi-view images.

The invention discloses an optical satellite drift angle accurate calculation and attitude correction method and system, and relates to the technical field of satellite attitude control, and the method comprises the steps: calculating a prime unitary circle curvature radius according to a WGS84 ellipsoid parameter, and converting the geodetic coordinate of a ground target point into an ECEF rectangular coordinate; calculating Julian days based on UTC time, determining an age difference angle and a nutation angle, and converting an ECEF coordinate into a J2000 coordinate; calculating the projection of the earth rotation angular velocity in a J2000 coordinate system, and determining a relative velocity vector; determining an orthogonalized body coordinate system in combination with a unit vector from the target satellite to the ground target point; and projecting the relative velocity vector to a body coordinate system, calculating a drift angle and a double-rotation-sequence Euler angle, and correcting a real-time execution attitude by rotating a matrix around a Z axis. According to the method, high-precision image motion compensation can be realized, the imaging quality of a high-resolution optical satellite in a complex task scene is improved, and a technical foundation is laid for wide application of sub-meter remote sensing images.

The application belongs to the field of GPS positioning, and relates to a dynamic GPS signal interference influence evaluation method and system, which comprises the following steps: calculating the instantaneous position vectors and velocity vectors of visible satellites, a receiver and an interference source in the Earth-Centered Earth-Fixed coordinate system; obtaining the directional gain of a receiving antenna to multiple visible satellite signals and multiple interference signals respectively; calculating the noise power spectral density, the power of multiple visible satellite signals and the power of multiple interference signals arriving at the radio frequency front end of the receiver; modeling the equivalent carrier-to-noise ratio to obtain the equivalent carrier-to-noise ratio of multiple visible satellites; simulating the influence of the visible satellites on the code tracking loop of the receiver to obtain the pseudorange measurement error of multiple visible satellites; and performing positioning solution through a weighted matrix least square method to obtain the positioning accuracy, so that the interference effect can be accurately, real-timely and quantitatively evaluated.

This invention provides a method and apparatus for three-dimensional display of space situation coverage beams, relating to the field of three-dimensional situation display technology, including: establishing a beam body coordinate system with the satellite's beam origin P as the origin; and in the beam body coordinate system X... b O b Y b Z b Establish a spatial cone model; uniformly select n points P on the base circle of the spatial cone model. i Establish a global coordinate system ECEF with the Earth's center as the origin; map point P... i Transform the coordinates to the Earth coordinate system ECEF to obtain the coordinates P in the Earth coordinate system ECEF. i '; Calculate the intersection of the generatrix and the Earth as the boundary region drawing point, and generate a vertex drawing queue; in the beam body coordinate system X b O b Y b Z b The beam geometry is drawn, and a queue is drawn based on the beam boundary vertices to draw the beam boundary; the beam is then displayed in the Earth coordinate system ECEF. This application draws the beam boundary, which can clearly represent the beam coverage range, thereby adapting to the ground coverage performance requirements under various operating conditions.

The invention relates to the field of satellite orbit calculation, in particular to a low-orbit satellite ephemeris analysis method based on a satellite orbit plane coordinate system, which comprises the following steps: acquiring TLE two-line orbit data of a target satellite, geodetic coordinates of a terminal, UTC time and earth rotation average angular velocity; calculating the state of the satellite in the orbital plane; calculating a transformation matrix from a geocentric inertial coordinate system ECI to a satellite orbit plane coordinate system; the LBH coordinates of the terminal are converted into ECEF rectangular coordinates; a rotation matrix from the ECEF to the ECI is constructed, and the ECI system speed of the terminal is calculated; according to the transformation matrix, transforming the ECI coordinate of the terminal into a final satellite orbit plane coordinate system; performing simplified calculation based on a unified calculation framework of a satellite orbit plane coordinate system; and outputting the distance, the relative speed, the Doppler frequency offset and the propagation time delay result which are calculated under the satellite orbit plane coordinate system. And the calculation complexity and the realization difficulty of high-precision orbit forecasting are obviously reduced.

The application discloses a single-epoch GNSS arbitrary direction positioning precision factor one-step prediction map method, comprising the following steps: obtaining a double-difference observation cofactor matrix and a double-difference coefficient matrix according to GNSS observations, and obtaining a weighted coefficient matrix in a geocentric geodetic coordinate system by using a least square method; establishing a station-centered rectangular coordinate system with a mobile station as an origin, and converting the double-difference coefficient matrix and the weighted coefficient matrix in the geocentric geodetic coordinate system to the station-centered rectangular coordinate system; calculating the plane coordinates of the station-centered rectangular coordinates of a grid point; calculating a double-difference coefficient vector and a double-difference cofactor in a station-centered polar coordinate system; reconstructing and adding the weighted coefficient matrix in the station-centered rectangular coordinate system after any grid point, and calculating the arbitrary direction positioning precision factor value at the grid point; and constructing the arbitrary direction positioning precision factor one-step prediction map by using a bilinear interpolation method; and the application provides important method support for quickly and efficiently selecting GNSS observation satellites with the minimum positioning precision factor value and analyzing the GNSS positioning precision influence mechanism.

The invention provides a GNSS (Global Navigation Satellite System) and INS (Inertial Navigation System) semi-tight integrated navigation method and device and electronic equipment, and the GNSS and INS semi-tight integrated navigation method comprises the following steps: carrying out system initialization on a navigation system; the navigation system is a GNSS and INS semi-tight integrated navigation system; predicting the discrete state of the navigation system to obtain the discrete state; constructing an observation model, carrying out iterative updating on the discrete state of the navigation system, and determining the optimal state of the navigation system at the current moment; and converting the current station center coordinate into an earth-centered earth-fixed coordinate system according to the iteratively updated and converged anchor point coordinate. According to the invention, high precision, low computing power and strong robustness are considered, and the problem that navigation precision and computing power are difficult to effectively balance in the prior art is solved.

The invention provides a satellite screening method and device in DVB communication, equipment and a storage medium. The method comprises the steps of determining coordinates of a satellite terminal and first satellites in an earth-centered earth-fixed coordinate system at the current moment; determining an elevation angle between the satellite terminal and each first satellite at the current moment according to the coordinates of the satellite terminal and each first satellite at the current moment; determining the first satellite of which the elevation angle at the current moment is greater than an angle threshold as a second satellite; and performing satellite screening according to the broadcast signals and the frequency offsets of the second satellites. According to the method provided by the invention, the satellites are screened according to the coordinates of the satellite terminal and the satellites in the earth-centered earth-fixed coordinate system, the broadcast signals of the satellites and the frequency offset, and the optimal satellite can be selected, so that the satellite accessed by the satellite terminal is the optimal satellite, the communication requirement is met, and the user experience is improved. And the problem that the use experience of a user is greatly influenced due to the fact that the satellite accessed by the satellite terminal is not the optimal satellite at the same moment due to single-basis satellite selection and cannot meet the communication requirement is solved.

The invention relates to the technical field of synthetic aperture radars, and discloses a bistatic SAR image space-variant ambiguity calculation method based on a positioning equation, and the method comprises the steps: setting the parameters of an SAR image, carrying out the traversal calculation in a range ambiguity period range and a Doppler ambiguity period range, and obtaining an image ambiguity distance and an image Doppler ambiguity frequency; constructing an earth-centered earth-fixed coordinate system, calculating to obtain an instantaneous slope distance and an instantaneous Doppler frequency of an image target point, and constructing an ellipsoid function about an image fuzzy point; calculating through a bistatic positioning equation set to obtain image blurring point coordinates; calculating azimuth angles and pitch angles from the radar transmitting point and the radar receiving point to the image blurring point based on the coordinates of the image blurring point; obtaining a radar transmitting point gain coordinate and a radar receiving point gain coordinate; and obtaining the ambiguity of the image target point through an ambiguity calculation formula. According to the invention, the technical problems of low ambiguity point positioning precision, unreasonable ambiguity period traversal and rough antenna gain acquisition in the prior art are solved.

The application discloses a two-way ground positioning method based on three-dimensional coordinate rotation compensation and dynamic filtering, relates to the technical field of navigation positioning and space measurement and control, and comprises the following steps: collecting phase differences obtained by all ground stations during one two-way ground positioning; obtaining a spacecraft state space equation according to dynamic modeling, further obtaining a discrete form of a state updating equation according to the spacecraft state space equation, and predicting a current spacecraft predicted state according to historical information by using the state updating equation; obtaining observation values of the spacecraft, correcting the current spacecraft predicted state by using the observation values, and obtaining a current spacecraft estimated state, wherein the current spacecraft estimated state comprises a spacecraft position estimated value and a spacecraft speed estimated value; obtaining a transmission delay according to the spacecraft position estimated value, correcting a spacecraft coordinate into a geocentric geodetic coordinate system at a positioning time, and obtaining a three-dimensional position and speed of the spacecraft in the geodetic coordinate system at the positioning time after the coordinate system is corrected.

This invention discloses a method for detecting the azimuth and elevation angles of a low-Earth orbit (LEO) satellite transit, belonging to the field of satellite communication technology. The method includes the following steps: obtaining the satellite coordinates and communication time differences for three consecutive two-way communications between a ground terminal and a LEO satellite; calculating the distance between the ground terminal and the satellite at the three communication times based on the communication time differences; calculating the ground terminal coordinates in the geocentric coordinate system based on the satellite coordinates and the calculated three distances at the three communication times; and calculating the elevation and azimuth angles of the satellite relative to the ground terminal using a vector method based on the satellite coordinates and ground terminal coordinates at the time of the last communication.

The invention relates to the field of vector geomagnetic field survey, in particular to a method and system for measuring a vector geomagnetic field by using an unmanned aerial vehicle. The system comprises a tetrahedral rigid supporting structure made of a non-magnetic material, four GNSS antennas are installed at the top point and three bottom points of the tetrahedral rigid supporting structure respectively, and an RTK-GNSS multi-antenna system is formed and used for obtaining low-frequency attitude data under an earth-centered earth-fixed coordinate system; the sensor unit integrates a vector magnetic sensor and an inertial measurement unit and is used for acquiring three-axis data and high-frequency angular velocity data of a geomagnetic field; the GNSS receiver is used for receiving multi-antenna observation data; the calibration system is used for constructing a reference coordinate system in a ground calibration stage and determining a first rotation matrix between a magnetometer coordinate system and the reference coordinate system; and the attitude and magnetic field data processing unit fuses the low-frequency attitude and high-frequency angular velocity information, calculates a second rotation matrix between the REF reference coordinate system and the earth-centered earth-fixed coordinate system, and realizes three-axis earth magnetic field data output under the earth-centered earth-fixed coordinate system through multi-stage rotation matrix conversion.

The invention provides an earth observation SAR satellite point target observation time window calculation method and system. The method comprises the steps that the incident angle range of an SAR load is set to be alpha1-alpha2, and the azimuth angle range is set to be beta1-beta2; calculating an orbital instantaneous element and an orbital mean element of the satellite under the instantaneous inertial coordinate system; performing orbit recursion on the satellite every other period T, and solving the position of the satellite in the earth-centered earth-fixed coordinate system; calculating the distance d between the satellite and the target; the method comprises the following steps of: converting an incident angle alpha1-alpha2 into a side swing angle phi1-phi2, solving a distance d1-d2 between a ground point corresponding to the side swing angle phi1-phi2 and a satellite, if d is between d1-d2, calculating an azimuth angle beta of a target, if beta is between beta1-beta2, determining that the target is in an observable area of the SAR satellite, otherwise, solving the position of the satellite in an earth-centered earth-fixed coordinate system again. According to the method, orbit recursion is performed under the instantaneous inertial coordinate system, so that the conversion error between the inertial coordinate system and the earth-centered earth-fixed coordinate system is eliminated, and the calculation result of the point target observation time window by the SAR satellite is more accurate and reliable.

The present invention discloses an integrated optical, electromagnetic, and tropospheric lightning detection system, comprising a detector, a flight platform, and a ground center. The detector is equipped with a three-dimensional electric field detector, a three-dimensional magnetic field detector, an image acquisition device, a spectrophotometer, a GNSS navigation system, and a six-axis sensor. The GNSS receiver uses real-time phase kinematics (RTK) to measure the phase difference between the antennas to obtain the azimuth of the two GNSS receivers relative to true north. The six-axis sensor performs attitude and inclination correction to obtain the detector's ECEF coordinates, which are then converted to an ENU coordinate system with the ground center as the origin. The image acquisition device captures lightning images, the spectrophotometer identifies lightning discharge types, the three-dimensional electric field detector measures vector electric field intensity, and the three-dimensional magnetic field detector measures vector magnetic field intensity. The detection system utilizes multi-dimensional technology to integrate optical, electrical, and magnetic sensors, overcoming the limitations of single sensors to form an integrated optical, electromagnetic, and tropospheric lightning detection system.

The application provides a kind of based on weighted linear iteration's spaceborne multi-base radar system three-dimensional positioning method and system, comprising: obtaining the radar echo data of multiple receivers and effectively detecting target, search the elevation angle and spatial cone angle of target signal by two-dimensional adaptive filtering technology, obtain the two-dimensional angle estimation information of target under different base different visual angle;According to the two-dimensional angle information and slant range information of target under different visual angle, construct nonlinear equation group, and carry out first-order Taylor expansion to it, obtain corresponding linear overdetermined equation group;According to the measurement accuracy known to radar system, form accuracy matrix to the linear overdetermined equation and carry out normalization operation and iterative calculation, and calculate the three-dimensional coordinates of target in the earth-centered earth-fixed coordinate system, and then obtain the longitude and latitude and height information of target, realize the high-precision three-dimensional positioning of multi-base radar system.

The invention discloses an orbit forecasting method for short-time sudden maneuver of a star chain satellite, and mainly solves the problems of updating lag and large forecasting error during sudden maneuver of the satellite in the prior art. According to the scheme, the method comprises the following steps: 1) performing initial orbit calculation based on TLE and SGP4 models; 2) ground observation data are received and differentiated with the predicted value to generate a residual sequence; (3) residual error abnormity is recognized through an abnormity detection algorithm, and a rapid orbit model fine adjustment mechanism is triggered when a sudden maneuvering event is detected; 4) updating antenna pointing parameters in real time through chained coordinate conversion of ECI, ECEF and ENU to realize tracking pointing; and 5) calculating transit starting and ending time by adopting Hermite interpolation based on the corrected satellite orbit and antenna position, and finishing orbit forecasting. According to the method, the orbit prediction precision in the sudden maneuvering state and the real-time response capability of a ground tracking system are remarkably improved, and the limitation that a traditional method depends on a TLE updating period is overcome.

The invention discloses a space measurement method based on an unmanned aerial vehicle real-time video, and the method comprises the steps: obtaining the parameters of an unmanned aerial vehicle in real time, including the pixel coordinates of a target point in a video image, the image size, the size of a camera sensor, the focal length, the zoom multiple, the attitude angle of an unmanned aerial vehicle camera, and the position and height of the unmanned aerial vehicle; defining a plurality of coordinate systems, including a pixel coordinate system, a camera coordinate system, an airframe north-east-earth coordinate system, an airframe north-east-sky coordinate system, an earth-centered earth-fixed coordinate system and a WGS84 geographic coordinate system; performing coordinate conversion calculation among a plurality of coordinate systems based on the unmanned aerial vehicle parameters; calculating geographic coordinates of all target points in the recognition area according to the step 3; and according to the geographic coordinates of each target point, constructing a geometric object representing the recognition region, and calculating the area of the geometric object as the area of the recognition region. The method can be suitable for real-time and rapid calculation of the target position and area in an emergency scene.

The invention discloses a method for realizing efficient image matching. The specific matching process comprises the following steps: constructing an internal reference matrix by utilizing a focal length f, 35mm focal length information f35, an image width w and an image height h; pixel coordinates (u, v) of four corners of the image are converted into camera coordinates through the internal reference matrix; the longitude lon, the latitude lat and the height alt of the image are converted into ECEF coordinates, and the ECEF coordinates, the yaw angle yaw, the pitch angle pitch and the roll angle roll are used for constructing a picture extrinsic parameter matrix; using an external parameter matrix to convert camera coordinates of four corner points of the image into ECEF coordinates, then converting the four ECEF coordinates into latitude and longitude coordinates, and connecting the obtained four latitude and longitude coordinates in sequence to form a projection of a contour area of the image; whether the two pictures need to be matched or not can be judged according to the obtained intersection relation of the picture contour areas. According to the image matching method, various information in the image acquired by the unmanned aerial vehicle can be fully utilized, and meaningless matching can be effectively reduced and the matching efficiency can be improved on the premise of reducing accumulated errors.

The invention discloses a tracking maintaining method of a moving platform warning radar under a large pitch dimension error. The tracking maintaining method comprises the following steps: carrying out attenuation compression on a pitch angle to obtain a compressed pitch angle; converting the compressed pitch angle and other measurement information to an earth-centered earth-fixed coordinate system to obtain a first offset, and obtaining a measured earth-centered earth-fixed value according to the first offset; obtaining a filtering result at the t-th moment according to the measured earth-centered earth-consolidation value at the t-th moment and the predicted position at the t-th moment; based on an inversion mode, a pitch angle of compression filtering is obtained according to a filtering result; sequentially carrying out amplification reduction and threshold judgment on the compressed and filtered pitch angle to obtain a pitch angle to be output; and obtaining a final earth-centered earth-fixed output value according to the pitch angle to be output and other filtering information. The tracking maintaining method is a compression processing method based on the pitching dimension, can keep continuous tracking of the target in the direction, and has certain pitching dimension tracking precision.

The application discloses a UAV multi-spectral image pixel-level anisotropy correction method, and belongs to the technical field of radiation correction of UAV multi-spectral images. The application aims at the problem that the existing anisotropy correction method has limitations in the processing of complex ground cover and high-resolution images, and causes poor image radiation precision. The method comprises the following steps: three-dimensional reconstruction is carried out based on a UAV multi-spectral sub-image, geographical position data and attitude data to obtain a spliced image, a digital elevation model and optimized camera parameters of the sub-image; pixel region coordinates in the spliced image are converted from a geocentric geodetic coordinate system through a camera coordinate system to an image coordinate system; multi-angle reflectivity is obtained by extracting a projection region of the pixel region in the sub-image; multi-angle data are obtained by calculating an observation imaging angle; a fitting result is obtained by using a general BRDF model to fit the multi-angle data; and the pixel-level anisotropy correction is realized by extracting a downward-looking reflectivity to replace original reflectivity of the spliced image. The application is used for anisotropy correction of UAV multi-spectral images.

The application provides an accurate calculation method, device and equipment for ISAR imaging rotation angle. The method comprises the following steps: obtaining first coordinate information of a target in a radar large earth coordinate system; converting the first coordinate information into a geocentric coordinate system to obtain third coordinate information; calculating a first included angle and a second included angle by using the third coordinate information in the geocentric coordinate system; and calculating the ISAR imaging rotation angle by using the first included angle and the second included angle. In the application, the spatial relationship among the geocenter, the ground-based radar and the target is coupled and calculated through the conversion among the coordinate systems, so that the correlation between the rotation angle value and the target orbit radius is generated, the limitations brought by the two-by-two spatial calculation model (radar-satellite, geocenter-satellite) of the traditional method are avoided, the accuracy of the imaging rotation angle calculation is improved, and finally the application efficiency of the ISAR technology in the medium-high orbit long-distance observation scene is improved.

This invention proposes a novel high-latitude navigation method based on the ECEF system, belonging to the field of high-precision navigation technology. This invention addresses the problems of low positioning accuracy and large error fluctuations in traditional grid coordinate system and transverse coordinate system navigation algorithms in high-latitude environments, as well as the navigation interference caused by meridian convergence and high-latitude dynamic effects. The steps of this invention include: establishing a transformation matrix between the geographic coordinate system and the geocentric-fixed coordinate system; establishing discrete navigation solution equations for attitude direction cosine matrix, velocity, and position in the geocentric-fixed coordinate system; establishing error equations for attitude error, velocity error, and position error in the geocentric-fixed coordinate system; performing an S-domain transformation based on the error equations and converting to the time domain to obtain an analytical expression for inertial navigation error in the geocentric-fixed coordinate system; and obtaining optimized high-latitude navigation results based on the oscillation and divergence characteristics of attitude and velocity errors presented by the analytical expression for inertial navigation error.

The invention provides an alignment method and system of a ship-borne inertial navigation system based on optical satellite assistance, electronic equipment, a storage medium and a computer program product. Comprising the following steps: determining a conversion matrix of a carrier coordinate system relative to an earth-centered earth-fixed coordinate system by observing a plurality of fixed stars; determining an optical satellite vector observation value under an earth-centered earth-fixed coordinate system by observing an optical satellite; determining a target latitude parameter and a target longitude parameter according to the optical satellite vector observation value; determining a position error model of the position matrix and the inertial navigation position error, and determining an attitude error model of the attitude matrix and the inertial navigation attitude error; and according to the joint measurement model, solving to obtain an inertial navigation position error and an inertial navigation attitude error, solving a position error model according to the inertial navigation position error to obtain target position information, and solving an attitude error model according to the inertial navigation attitude error to obtain target attitude information.

A method for measuring an interference baseline of a satellite-borne double-antenna interference SAR (Synthetic Aperture Radar) system is suitable for a novel satellite-borne double-antenna X-band interference SAR satellite system and comprises the following steps: acquiring'high-resolution optical camera + laser 'measurement data of the satellite-borne double-antenna interference SAR system, satellite body position, speed and attitude measurement data and earth positioning and orientation parameters; according to the data acquisition frequency of the measurement data, time synchronization is carried out by taking the measurement data of the high-resolution optical camera and the laser as the standard; constructing a transformation matrix according to the installation parameters of the SAR system measurement device, the installation parameters of the SAR antenna, the measurement data after time synchronization and the earth positioning and orientation parameters; calculating the phase center position and speed of the main and auxiliary radar antennas under the earth-centered earth-fixed coordinate system by using the constructed transformation matrix; and resolving a spaceborne double-antenna interference SAR baseline according to the phase center positions and speed information of the main and auxiliary radar antennas. The method can meet the requirement of an interference baseline in the topographic surveying and mapping process of a novel satellite-borne double-antenna X-band interference SAR (Synthetic Aperture Radar) system.

The invention provides a remote sensing image pixel observation zenith angle and azimuth angle calculation method and system. The method comprises the following steps: calculating a sight vector of a pixel under a camera body coordinate system according to an imaging geometric model; calculating a conversion matrix from the camera body coordinate system to the earth-centered earth-fixed coordinate system, and converting the sight line vector to the earth-centered earth-fixed coordinate system; calculating the position and latitude and longitude of a ground point corresponding to the pixel in the earth-centered earth-fixed coordinate system; calculating an observation zenith angle of the pixel; calculating a conversion matrix from the earth-centered earth-fixed coordinate system at the ground point to the local geographic coordinate system of the east, north and sky, and converting the sight vector to the local geographic coordinate system of the east, north and sky; and calculating an observation azimuth angle of the pixel. The zenith angle and the azimuth angle of each pixel of the remote sensing image can be simply, clearly and quickly calculated, observation angle information of the remote sensing image cannot be lost, the method is reasonable, calculation is simple, implementation is easy, and the method can be widely applied to calculation of zenith angles and azimuth angles of pixels of remote sensing satellite images of various orbit types.

The invention discloses a multi-source trace point interference elimination method based on ECEF and DBSCAN, and the method comprises the steps: collecting multi-source trace point data, and carrying out the preprocessing and fusion; converting the fused data into an ECEF coordinate system to realize unified representation; performing density clustering analysis on the plot data by using a DBSCAN algorithm; and performing multi-layer interference trace point elimination on the two data sources according to a clustering result. According to the method, multi-source information is fused, ECEF coordinate system unified processing is combined with DBSCAN clustering analysis, the accuracy and efficiency of interference trace point elimination are remarkably improved, and the method is suitable for false target identification and data purification in a multi-radar system.

This invention discloses a method and system for detecting low-Earth orbit satellite orbit changes based on stellar background. The method includes: defining a coordinate system, including a geocentric coordinate system, a celestial inertial coordinate system, and a star sensor coordinate system; acquiring star point images through a star sensor, obtaining a stellar database and a satellite ephemeris database; calculating the correspondence between each star point in the star point image and the stellar and satellite ephemeris databases using a triangulation matching algorithm within the coordinate system, and identifying stellar and satellite star points; using the identified stellar star points as a reference, calculating the satellite's spatial position based on the satellite star point's trajectory in the star point image and historical ephemeris data in the satellite ephemeris database, and comparing this position with the predicted spatial position based on historical ephemeris data to determine whether a satellite orbit change has occurred. This invention offers low detection cost, convenient execution of the detection task, and strong autonomy and anti-interference capabilities.

This invention discloses a train positioning method based on the fusion of 5G and electronic track maps in a railway 5G-R scenario. The method includes: transforming the track point set in the electronic track map from a geodetic coordinate system to a geocentric coordinate system to obtain a trajectory continuity function; determining the Time of Arrival (TOA) for each base station based on downlink PRS signals transmitted by multiple 5G base stations and a pre-configured local reference PRS signal; obtaining distance difference observations based on the Time Difference of Arrival (TDOA) between TOAs; estimating the Angle of Arrival (AOA) observation based on uplink SRS signals; constructing an objective function for TDOA based on the trajectory continuity function and the distance difference observation, and pruning the feasible solution region using the AOA observation; and solving the objective function within the pruned feasible solution region using a coarse search and locally bounded optimization algorithm to obtain a train position estimate. This invention can still obtain stable and accurate positioning results even when there are insufficient available positioning base stations.