115 results about "Satellite motion" patented technology

A method of determining the location of an unknown source 10 transmitting a signal to satellite relays 14 and 16 comprises receiving replicas of the signal from the relays at receivers 18. The receivers 18 also transmit and receive reference signals via respective relays 14 and 16. All signals are downconverted, digitized and correlated with one another in pairs using a correlation function including a term which compensates for time varying differential frequency offset (DFO). Compensation for time varying differential time offset or time dilation is achieved by replicating or adding to signal samples and applying phase corrections. This procedure enables a correlation maximum and associated measurement results to be obtained despite the effects of relay satellite motion which mitigate against this. Results are used in a prior art geometrical technique to locate the unknown transmitter.

The invention discloses a non-cooperative spacecraft attitude estimation method based on virtual sliding mode control, and belongs to the technical field of non-cooperative spacecraft navigation. The non-cooperative spacecraft attitude estimation method comprises the following steps: utilizing a virtual control sliding mode controller based on the Lyapunov principle; using target satellite absolute attitude obtained by a stereoscopic vision system as a control objective; according to motion characteristics of the target satellite, establishing a virtual satellite motion model of the target satellite; using a kinetic model of the virtual satellite as a controlled member to obtain attitude parameters of the virtual satellite; using attitude parameters estimated by the virtual satellite and the target satellite absolute attitude obtained by the stereoscopic vision system as controlled input, and calculating the virtual revolving moment on the motion model of the virtual satellite through the virtual sliding mode controller, so as to realize the estimation of the target satellite attitude parameters by the virtual control sliding mode controller. The non-cooperative spacecraft attitude estimation method disclosed by the invention is low in calculated amount, and can still achieve higher convergence rate and higher precision when the initial error of the state variables is high or the system error emerges, so as to meet the requirements of the high performance navigation system.

The invention provides an electromagnetic formation satellite attitude and track relative control method. The method comprises the following steps: 1, attitude dynamics equations are built; 2, according to the attitude dynamics equation in a linear form with quaternion representation built in the first step, an attitude dynamics equation in a body coordinate system and a rigid satellite dynamics equation, a satellite attitude control system feedback control law is designed and obtained; and 3, according to the feedback control law obtained in the second step, relative control is carried out on the electromagnetic formation satellite attitude and the track. The method of the invention has the advantages that the attitude dynamics equations, a relative motion dynamics equation and electromagnetic force and electromagnetic torque models are built, the designed satellite attitude control system feedback control law, a flywheel angular momentum magnetic unloading algorithm, a large angle attitude maneuver method, an electromagnetic formation flying satellite motion controller and a magnetic dipole control distribution method can have good working performance, and high-efficiency relative control on the electromagnetic formation satellite attitude and the track can be realized.

The invention discloses an autonomous synthetic aperture radar (SAR) satellite orbit determination method based on an extended kalman filter and belongs to the technical field of autonomous satellite orbit determination. Due to the adoption of a global positioning system (GPS) which adopts a half-autonomous orbit determination mode, the conventional autonomous satellite orbit determination technology has the problems of low autonomy and low instantaneity. By the orbit determination method, the problems can be solved. The method comprises the following steps of: 1, establishing a satellite motion equation based on orbit dynamics so as to obtain a state equation; 2, establishing an observation equation by taking a distance between an SAR and a ground identification point and a Doppler shiftfrom the SAR to the ground identification point as observation values; 3, establishing a recurrence equation of the extended kalman filter; and 4, thus obtaining state information of a satellite to obtain a position and a speed vector of the satellite. By the method, the orbit determination precision of the satellite is improved; the method has the characteristics of autonomy and instantaneity; and high-precision real-time autonomous orbit determination for low-orbit satellites can be realized.

An apparatus for regulating or controlling a satellite includes: at least one sensor for detecting reference targets such as stars, which is connected to arrangements for selecting and determining the position of reference targets, and to an arrangement for estimating model parameters of the satellite and of external interferences; a memory for storing a reference target catalog and a reference trajectory; a regulating unit for regulating the position of the satellite; and a filter that is connected to the arrangement for position determination of the reference targets, the arrangements for estimating the model parameters, the memory and the regulating unit. A method for regulating a satellite's position includes the following steps: detecting, determining the position of, and selecting reference targets; estimating model parameters of the satellite and external interferences; calculating the present position and/or attitude and motion conditions of the satellite on the basis of the estimated model parameters with the aid of dynamic models of the satellite motion; comparing the determined positions of selected reference targets with stored reference target data; and correcting the calculated position and/or attitude and motion conditions dependent on the result of the comparison. Such an apparatus and method achieve a high accuracy by successively updating and improving the accuracy of the reference target data.

The invention discloses an autonomous control method for inclined orbit satellite yaw maneuvering. The method comprises the steps of measuring and calculating the solar altitude and the satellite yaw axis attitude at the current moment; obtaining the moving direction of the sun relative to a satellite according to the solar altitudes at two different moments; determining the expected attitude of the satellite yaw axis according to the solar altitude at the current moment; determining a yaw maneuvering target value and a yaw maneuvering mode according to the solar altitude at the current moment, the satellite yaw axis attitude at the current moment and the moving direction of the sun relative to the satellite; starting control through a satellite actuator, and controlling the satellite to change to the expected attitude of the satellite yaw axis from the satellite yaw axis attitude at the current moment to carry out yaw axis attitude maneuvering. According to the autonomous control method for the inclined orbit satellite yaw maneuvering, the satellite forms an approximately fixed nightside through the yaw axis attitude maneuvering of the satellite, layout and design of star sensors can allow the star sensors to avoid sun shine, the star sensors are protected, and continuous output of measured data of the star sensors is guaranteed.

The present invention provides a staring imaging simulation and quality evaluation method and device taking regard of satellite comprehensive motion, the method is as follows: according to the application requirements, load physical parameter indexes are designed; according to the satellite platform design specifications, a satellite motion trail under ideal state is simulated, and perturbation factors are corrected; according to the satellite motion trail and imaging target location, an attitude maneuver angle at the moment of satellite staring imaging can be automatically calculated, and drift angle is corrected; according to the satellite motion trail, attitude data and camera design parameters and the like, an ideal staring imaging simulation image is generated; by discretization of the exposure time, transient simulation image sequences with satellite motion errors within the exposure time can be generated, a first exposed simulation image is synthesized, an edge method is used for statistics of image MTF value, target staring imaging quality under satellite comprehensive motion can be evaluated, the staring imaging simulation and quality evaluation method achieves the target staring imaging image simulation under satellite comprehensive motion, and staring imaging image quality evaluation taking regard of satellite comprehensive motion.

The invention provides a satellite-borne multi-band one-dimensional synthetic aperture one-dimensional real aperture microwave radiation detection method. According to the method, a microwave radiation detection technology is adopted; by means of a parabolic cylindrical antenna reflecting surface, real aperture radiation detection in an along-orbit direction is realized, and synthetic aperture detection is realized in a cross-orbit direction; cross-orbit electrical scanning is realized by means of array beam synthesis, and along-orbit scanning is realized through satellite motion; the mechanical scanning of a large-diameter antenna is realized on the basis of the cross-orbit electrical scanning and the along-orbit scanning; and therefore, the problem of difficulty in compensating dynamic unbalance amount can be solved, and the service lives of instruments are prolonged. The method can avoid the mechanical scanning of the large-diameter antenna compared with a traditional two-dimensional real-aperture radiation detection technology and can assist in greatly reducing the number of array elements compared with a traditional two-dimensional synthetic aperture radiation detection technology, thereby realizing the optimal compromise of the radiation detection technology of the large-diameter antenna.

The invention relates to a test system for impact analysis of imaging quality of TDICCD (Time Delayed Integration Charge Coupled Device) by multi-source interference, which can be divided into an error source interference and an equivalent sub system thereof, a TDICCD imaging sub system, an optical target, gesture error and an interference measuring sub system thereof, a signal collecting and processing sub system, and a wireless communication and ground comprehensive processing sub system. The error source interference and the equivalent sub system thereof is used to simulate interference generated by a solar sailboard/a control torque gyro system (CMGs) and a satellite platform in a spatial environment for the satellite. The measuring sub system is used to measure the gesture angle of the satellite platform and the vibrating linear velocity. The signal collecting and processing sub system collects sensor information and processes and analyzes and calculates the information correspondingly. According to the invention, main interference by motion errors of the satellite to the imaging quality of the TDICCD is simulated in the spatial environment on the ground, and the impact analysis of the imaging quality of the TDICCD by the multi-source interference is realized by combining a floating turntable for dynamical test and analysis of satellite gesture.

The invention discloses a satellite communication system uplink timing advance gateway station prediction method. And a gateway station takes the predicted beam center point as a reference point, predicts the timing advance variable quantity of each terminal in the beam and broadcasts the timing advance variable quantity to each terminal in the beam, and each terminal updates the timing advance according to the timing advance variable quantity, thereby coping with the uplink transmission time delay deviation introduced by satellite motion. The working principle is as follows: (1) the gateway station calculates the moment when the wave beam center point receives the next timing advance variable quantity; and (2) the gateway station calculates the effective time period of the next timing advance variable quantity to the beam center point; (3) the gateway station predicts the change range of the uplink transmission delay of the beam center point caused by satellite motion in the effectivetime period; and (4) the gateway station calculates the timing advance variable quantity of the beam center point according to the uplink transmission time delay change range.

The invention provides an assessment method of agile imaging simulation and positioning accuracy of a satellite. The assessment method comprises following steps: designing a load physical parameter index according to an application demand; adopting a numerical integration method to simulate the movement trajectory of the satellite in the ideal state and correcting perturbing factors according to a platform design index; calculating an attitude maneuver angle for agile imaging in the mode of constant angular velocity or constant linear velocity and performing correction of a drift angle; generating the ideal agile imaging sequence of images by simulation and corresponding coordinate files for uniform ground grid points based on the movement trajectory of the satellite, attitude data of exposure time, design parameters of a camera, DOM data and DEM data in a corresponding data range; and obtaining an imaging simulation result of synthetic movement of the satellite according to the platform design index and movement error terms so that influence of synthetic movement of the satellite upon geometric positioning accuracy is further assessed. The assessment method of agile imaging simulation and positioning accuracy of the satellite has following beneficial effects: by adoption of the method, a real motion state and an imaging process of the satellite on orbit can be simulated; and geometric positioning accuracy for agile imaging of synthetic movement of the satellite is assessed.

The application relates to global navigation satellite system (gnss) spoofing detection with carrier phase and inertial sensors. A system to detect spoofing attacks is provided. The system includes a satellite-motion-and-receiver-clock-correction module, a compute-predicted-range-and-delta-range module, a subtractor, and delta-range-difference-detection logic. The satellite-motion-and-receiver-clock-correction module outputs a corrected-delta-carrier-phase range for a current epoch to a first input of a subtractor. The compute-predicted-range-and-delta-range module outputs a predicted delta range to a second input of the subtractor. The predicted delta range is based on inertial measurements observed for the current epoch. The subtractor outputs a difference between the corrected-delta-carrier-phase range and the predicted delta range for the current epoch to delta-range-difference-detection logic. The delta-range-difference-detection logic determines that, if the difference exceeds a selected-range threshold, the GNSS receiver was spoofed in the current epoch.

The invention discloses a correcting method for intersite time synchronization errors caused by synchronous satellite motion. The correcting method is used for correcting measurement errors, caused by motion of synchronous orbit satellites in charge of information forwarding, of wireless time transmission information between double sites. According to the method, orbit information of the synchronous satellites is obtained, accurate point location coordinates of the known double ground sites are combined, and a computer is used for calculating the measurement errors of wireless time and frequency between the double sites in real time to obtain a change rule of the measurement errors caused by fine precessional motion of the synchronous satellites. A measurement error model and actual measurement values between the double sites are offset in real time to achieve the purpose of eliminating the intersite time synchronization errors caused by synchronous satellite motion. The method is suitable for correcting time and frequency transmission errors, caused by synchronous satellite motion, of the double sites and particularly suitable for a two-way satellite time and frequency transfer (TWSTFT) system of the nonsynchronous long-distance double sites.

The invention relates to the technical field of information acquisition and processing, and relates to a method for determining the orbit of a lunar satellite. The method is to fuse the motion information of the lunar satellite obtained by the earth survey station through radio measurement methods with the satellite position information obtained by precise image matching during the lunar satellite orbiting the moon, and calculate the lunar satellite based on the optimized fusion information. precise track. The specific steps are as follows: 1) Firstly, based on the matching results of the spaceborne high-resolution camera image and the high-precision lunar surface map, the precise position of the satellite in the lunar fixed coordinate system is solved; 3) Construct a joint filter to realize the fusion of satellite matching position and ground radio measurement information; 4) Based on the information fusion results, the precise orbit of the lunar satellite is calculated through the orbit dynamics model.

Aspects of the invention provide a system and method to allow inroute frame timing synchronization without the aid of hub signal loopback or satellite ephemeris data. Furthermore, it allows tracking and compensating of the satellite motion to allow multiple remotes to use TDMA on the inroute frequencies, while minimizing the aperture. Two main techniques proposed are CLT and polling based approaches, which are used in combination for an optimum solution. In CLT based approach, hub transmits remote specific timing correction feedback messages on the outroute on as needed basis. In polling based approach, the remotes derive their timing based on a per-beam average delay estimate broadcast by the hub and a measured local delay specific to each outroute stream from a remote. An aspect of the invention uses triangulation method to determine satellite position. Furthermore, an aspect of the invention uses hub burst arrival method instead of polling approach.

The invention discloses a network capacity estimation method for a satellite network system, and the method comprises the steps: building a satellite network topological structure model according to satellite constellation configuration parameters; dividing the operation period of the satellite network into a plurality of time slots according to the link connection characteristics of the satellitenetwork and the satellite motion law, so that the topological connectivity of the satellite network in one time slot is kept unchanged; in each time slot, based on a satellite network topology structure, calculating the network capacity of each time slot by solving the network maximum flow problem according to an inter-satellite link establishment mode, the link capacity of a satellite and a ground station, the link capacity of the satellite and a user and the service volume requirement of the user; and calculating the average network capacity according to the network capacity of each time slot. According to the invention, the calculation consumption and the requirement for a simulation platform during network capacity estimation can be reduced, the influence of satellite-ground connection constraints, link topology dynamic changes, link capacity constraints and ground traffic distribution can be considered, and the effectiveness and credibility of an estimation result are ensured.

The invention relates to a method for scanning hardware and recovering errors of an on-board computer, which comprises: firstly, reading data in an external memory to correct the errors by an error detection correction module, sending data which is corrected to a bus in a processor, waiting for an order of a calculating and processing unit CPU which is connected with the bus of the processor, secondly, setting the scanning area, the scanning rate and the using function of a hardware scanning error recovering module by the CPU, starting the hardware scanning error recovering module, thirdly, writing data which is located on the bus in the processor and is corrected back to the external memory through the error detection correction module by the hardware scanning error recovering module according to the scanning area and the scanning rate which are determined by the CPU, and realizing the error recovering function. The invention improves the fault tolerance and reliability of a satellite on-board computer, lowers the risk of satellite motion in an orbit, and solves the practical problem that when a satellite is in the orbit and when faults of the memory appear, the automatic recovery of a satellite in orbit memory is realized through means of hardware automatic scanning and real time error recovery.

The invention belongs to the technical field of low-earth-orbit satellite communication, and particularly discloses a position and ephemeris-based synchronization method and system for a low-earth-orbit satellite communication system. The system comprises a low-earth-orbit satellite and a terminal, a computer program is stored in the terminal, and when the computer program is executed by the terminal, the terminal realizes the method. By adopting the technical scheme, the Doppler frequency offset and the frequency offset change rate are calculated according to the ephemeris broadcasted to the user by the satellite and the terminal position, and the terminal estimates the Doppler frequency offset caused by the movement of the low-earth-orbit satellite according to the downlink frame number, the time slot number and the frequency point, so that the Doppler frequency offset and the frequency offset change rate can be effectively compensated during uplink transmission, the frequency offset caused by terminal movement and crystal oscillator is compensated, the complexity of load demodulation is reduced, and the reliability and stability of the satellite communication system are improved.

The invention discloses a generating method and a system for a satellite track. The generating method includes obtaining satellite crossing points after leading an earth model in model space and generating a Bezier curve according to the satellite crossing points; obtaining at least two Bezier curve control points according to the Bezier curve; generating a plane which passes through a sphere center point of the earth model and the Bezier curve control points according to the sphere center point of the earth model and the Bezier curve control points; taking the sphere center point of the earth model as a center and fitting the Bezier curve control points so as to generate a Bezier curve of the satellite track on the plane; and outputting the Bezier curve of the satellite track. According to the generating method and the system, the problem of effective generation of the motion track during an animation simulation process of a satellite flight is solved, therefore track parameters are convenient to adjust, a more intuitive effect is provided, satellite motion can be better associated with, and preparations can be made for satellite animation.

The invention discloses a method and a system for modeling the equivalent satellite attitude motion of vertical rods in the deployment process of a loop antenna. The method comprises the following steps: establishing a coordinate system describing each quadrilateral unit in a ring antenna main body structure and a ring antenna coordinate system; establishing the relative position equations of eachvertical bar in the main structure of the loop antenna in the loop antenna coordinate system; combining all the vertical bars with the satellite motion equations to form the coupled motion equationsof the loop antenna and the satellite; establishing the equations of motion constraint between the radius of large loop antenna and the vertical bar; establishing the governing equation between motionconstraint and control force; obtaining motion information of the satellite and the loop antenna by solving the coupled equations of motion of the loop antenna and satellite and the governing equations of motion constraint and control force by numerical integration method. The method guarantees the calculation precision of the antenna deployment process, greatly improves the calculation rapidityand reduces the modeling complexity.