122 results about "Double star" patented technology

The invention provides a method and a device for double-star time difference/frequency difference combined positioning. By using the method, the calculation efficiency and the measurement accuracy of the time difference and the frequency difference can be improved. According to the scheme, the method comprises the following steps of: (1) carrying out time difference-frequency difference combined coarse estimate, calculating A(tau, f)=FFT[r(n; tau)], directly measuring the carrier frequency of a composite signal FORMULA for the search of the time difference each time, labeling a frequency spectrum amplitude value and a time difference value and finding out a maximum position, wherein tau is equal to tau1, tau2, FORMULA and tauM; (2) extracting and filtering the composite signal FORMULA, then measuring the carrier frequency, and coarsely estimating the frequency difference; (3) accurately calculating the frequency difference in the adjacent domain FORMULA of an estimated value in the coarsely measured frequency difference and accurately estimating the frequency difference; (4) accurately calculating the time difference in the adjacent domain FORMULA of an estimated value in the coarsely measured time difference and accurately estimating the time difference; and (5) accurately estimating the time difference, estimating the time resolution 1/Ts of the time difference by using a relevant method and improving the time difference estimate accuracy by using interpolation, wherein Ts is the sampling interval of signals. In the invention, the time difference is calculated by using the signals with a high sampling rate, the frequency difference is calculated by using the signals with a low sampling rate, and the problems of the calculation efficiency and the measurement accuracy of the time difference and the frequency difference are solved by combining the time domain processing with the frequency domain processing.

The invention relates to a method for precisely measuring an earth gravitational field, in particular to a satellite gravity inversion method based on a double-satellite spatial three-dimensional interpolation principle. An earth disturbing potential (obtained by computing an inter-satellite speed of a GRACE satellite K wave band measuring instrument, a satellite orbit position and a satellite orbit speed of a global positioning system (GPS) receiver, a satellite nonconservative force of an accelerometer and a satellite three-dimensional attitude data of a fixed star sensitive device) which is positioned on a gravity double-satellite orbit with a relatively irregular spatial position is interpolated three-dimensionally onto a reference spherical surface with a relatively regular spatial position and uniform grid division, so that the earth gravitational field is precisely and quickly inversed. By the method, satellite gravity inversion precision is high, physical meaning in the resolving process is clear, the computing speed is high, requirements on performance of a computer are low, and the method is sensitive to high-frequency signals in the gravitational field, so that the double-satellite spatial three-dimensional interpolation method is an effective method for resolving the earth gravitational field with high precision and high spatial resolution.

The star choosing method for the dual constellation satellite positioning system mainly includes receiving ephemeris to get visible satellite locations to eliminate failure satellite if it can automatically perfect the analysis result, computing the direction cosine for each of the rest of visible satellite, computing the tilt of the rest of the visible satellite, choosing the biggest one, eliminating the satellite with tilt less than 5 degree, selecting several sets of four satellite groups using ergodic method, reselecting several satellite based on GDOP, the least GDOP value group will the final chosen satellite, repeating A-G at the next epoch, getting new satellite choosing result, which is sent to positioning resolve subsystem, repeating A-G to get new time satellite choosing result at the next epoch time.

The invention relates to a method for correcting in-orbit real-time interaction of double star sensors. The method comprises the steps of obtaining quaternion information of a satellite body coordinate system based on a first star sensor and a second star sensor relative to an earth core inertial coordinate system according to satellite attitude quaternion information output by the first star sensor and the second star sensor and an installation relationship between a satellite body and the first star sensor and the second star sensor, and performing synchronous calculation with current time calculated by an on-star track; calculating corrected deviations of real-time interaction between the first star sensor and the second star sensor according to the quaternion information of the satellite body coordinate system based on the two star sensors having undergone time synchronization relative to the earth core inertial coordinate system, and finally performing real-time interaction correction on the first star sensor or the second star sensor. According to the method, attitude deviations resulting from slow variation and shape change between the star sensors and a satellite reference can be reduced, and high-precision triaxial attitude determination precision of the satellite is guaranteed.

A high-precision imaging attitude pointing control method based on the agile satellite is provided. The method comprises that: an attitude maneuvering process is planned according to the specified ground imaging target and time; in the maneuvering process, the attitude prediction information and the corresponding time are calculated and transmitted to a star sensor according to a fixed frequency;the star sensor predicts the sky window according to the time and attitude data, and keeps trying to extract the attitude in a window tracking mode; the satellite moves to the vicinity of the target and gradually decelerates, the star sensor captures the satellite attitude information quickly in a high-precision manner, and the system uses double star-sensitive optical axis vectors to compete attitude reset; and finally, closed-loop correction is performed by using the difference between the reset attitude and the target attitude to complete the high-precision attitude pointing control. According to the method provided by the present invention, the star-sensitive high-precision attitude information available only at small angular velocities is fully used to compensate for the influence ofgyro measurement information with nonlinear and drift variation characteristics on imaging pointing precision.

The invention discloses a method for building a global gravitational field model by utilizing an inter-satellite distance interpolation. The method disclosed by the invention is as follows: an inter-satellite distance interpolation satellite observation equation is built through introducing the precise inter-satellite distance of a satellite-borne K waveband gauge into a star attachment componentof a double-star opposite rail position vector so as to build a global gravitational field model with high precision and high spatial resolution. The method has high satellite gravity inversion precision, explicit observation equation physical meaning and low computer performance requirement, is easy to sense medium and high frequency gravity field signals, and is favorable for the error analysisof the gravity satellite system.

The invention relates to the field of interleaving techniques such as satellite geodesy, geophysics, space science and the like, and provides a satellite gravity inversion method based on a two-star energy interpolation principle. In the method, the global gravity field is accurately and rapidly inverted by introducing high-accuracy inter-satellite distance interpolation of a satellite-loaded K waveband measuring instrument into two-star relative orbits kinetic energy and further establishing a two-star energy interpolation observation equation. The method has the advantages of high satellitegravity inversion accuracy, definite physical meanings of the observation equation, contribution to error analysis of a gravity satellite system, easiness for sensing high-frequency gravity field signals and low requirement on the computer performance. The sensing accuracy of a 120-step GRACE earth gravity field can be increased substantively, so that the two-star energy interpolation principle method provided by the invention is an effective method for establishing a new generation high-accuracy and high-space-resolution global gravity field model.

The invention relates to a combined defining method for the carrier attitude of a double-star sensor, and belongs to the field of celestial navigation. The method comprises the following steps: firstly, in an astronomical refraction correction method based on the star reference vectors for a star sensor, realizing the correction of astronomical refraction by amending the star reference vectors; secondly, in a ship body attitude determination method based on the star observation vectors of a combined double-star sensor, combining the observation vectors of each recognizable star of the double-star sensor in two fields into an observation vector matrix, and finally completing ship body attitude resolving with a corresponding star reference vector matrix. On the basis of simplifying the astronomical refraction correcting algorithm of the star sensor, the capability of obtaining the ship body attitude of the double-star sensor is improved at the same time. The main contents refer to the two aspects of the astronomical refraction correction method based on the star reference vectors and the ship body attitude determination method based on the star observation vectors of the combined double-star sensor.

The invention relates to a double-satellite formation SAR satellite joint test system and method in a satellite ground test system. The double-satellite formation SAR satellite joint test system comprises a double-star dynamics simulator, a double-user GNSS simulator, a double-user radar target echo simulator and a microwave switch system. The double-star dynamics simulator provides time, orbit and attitude information of double-star on-orbit simulation flight. The double-user GNSS simulator receives time starting point, position and speed information provided by the double-satellite dynamicssimulator and then generates a navigation radio frequency signal in real time and provides the signal for an on-satellite GNSS receiver. The double-user radar target echo simulator receives the time-frequency information of the GNSS simulator then sends echoes to an on-board radar; and the echoes are received by the on-board SAR system. The microwave switch system establishes an inter-satellite communication link and a load phase synchronization link between two satellites and has a link switching function. According to the invention, the on-orbit joint work mode of the double-satellite formation SAR satellite can be simulated truly; and the double-satellite formation SAR satellite joint test system and method can be used for implementing the ground double-satellite function and performance joint testing of the double-satellite formation SAR satellite.

The invention relates to a double star Ka FMCW SAR inner scaling system, method and imaging system. The inner scaling system comprises an emission inner scaling subsystem and a reception inner scaling subsystem, wherein the emission inner scaling subsystem and the reception inner scaling subsystem are mounted at two satellite platforms, the emission inner scaling subsystem comprises an emission frequency synthesizer, a T scaling network, a T scaler, a first high frequency reception assembly, a first intermediate frequency receiver, an emission Ka frequency band auxiliary antenna, a T feed network and a T assembly, the reception inner scaling subsystem comprises a reception frequency synthesizer, an R scaler, a power splitter, a second high frequency reception assembly, a second intermediate frequency receiver and a reception Ka frequency band auxiliary antenna, and each reception channel of the reception inner scaling subsystem is internally provided with an R scaling network, an R feed network and an R assembly. The double star Ka FMCW SAR inner scaling system, method and imaging system is advantaged in that the inner scaling function of the double star Ka FMCW SAR imaging system is realized.

The invention relates to a time difference of arrival/frequency difference of arrival estimation method of high and low-orbit double-star high-time-varying received signals. The invention aims to solve the problem of large error and large calculation quantity of TDOA (time difference of arrival)/FDOA (frequency difference of arrival) estimation of a high and low-orbit double-star passive positioning system. According to the method of the invention, two segments of data of which the time lengths are equal are adopted to estimate the change rage of frequency difference of arrival, and the estimated values of the TDOA (time difference of arrival) and FDOA (frequency difference of arrival) at the start time point of data acquisition can be calculated accurately. The implementation process of the invention includes the following steps that: (1) two segments of data of which the time lengths are equal are acquired; (2) TDOA and FDOA are jointly estimated; and (3) the estimated values of the TDOA (time difference of arrival) and FDOA (frequency difference of arrival) at the start time point of data acquisition are calculated. With the method of the invention adopted, the fast and accurate estimation of the TDOA and FDOA of high-time-varying received signals in the high and low-orbit double-star passive system can be realized. The method has a high practical value.

The invention discloses a method for detecting fault satellites of a satellite navigation system, which comprises the steps: all visible satellites are divided into a first satellite subgroup and a second satellite subgroup according to a satellite top view direction angle in a navigating constellation, and fault detection is carried out on the first satellite subgroup and the second satellite subgroup respectively to obtain the fault satellites. The method adopts the technical scheme that all the visible satellites are grouped according to the satellite top view direction angle in the navigating constellation; the satellites with close or approximately reverse satellite top view direction angles are divided into a group according to the geometric distribution characteristic of the satellites; and LSR detection and MLE recognition are carried out on the grouped satellite subgroups respectively . The invention effectively increases the detection speed and the recognition rate of the fault satellites, is suitable for double-star detection and single-star detection and can be applied to a multiple-constellation satellite navigation system.

The invention provides a test device which simulates a satellite in-orbit state and separates two independent stars A and B through unlocking and separating devices on the ground and a detecting method. According to the scheme, a simulated star A is suspended by a structure mainly, and is unloaded gravitationally so as to simulate a test environment during separation of the star A and the star B;an unlocking bolt is unlocked by gas separation equipment, and the simulated star A acquires an upward thrust through a separating spring; by a pulley block and a balance weight mode, the gravity of the simulated star A is balanced; and by T-Prob of a laser tracker, position postures (x, y, z, alpha, beta, gamma) of the simulated star A in a whole upward movement process are acquired in real time.The test principle is simple, and the test device is easy to operate; an in-orbit state can be simulated, and gravitational balanced unloading to a spacecraft is realized effectively; a separation route is not lower than 80 mm; a balance force in the route is stable, and deviation is not greater than 0.1%; and a separation route is finished, the gradient of a system is smaller than 1 degree, andthe stability of the system is good.

The invention discloses a satellite attitude determination method based on a Samsung sensor. The method comprises the steps of obtaining a matrix of optical axis vectors of three star sensors under a satellite ontology coordinate system; obtaining the matrix of the optical axis vectors of the three star sensors under inertial system coordinates; and based on a transformation matrix of the inertial system coordinates and the satellite ontology coordinate system and a transformation matrix of an orbit coordinate system to the inertial coordinate system, obtaining an attitude matrix of the orbit coordinate system to the satellite ontology coordinate system. The method of the invention is applicable to the installation of the satellites with three or more star sensors, can make full use of on-board resources, can compensate the shortcoming of poor precision of the single-star sensor optical axis, avoids the introduction of a cross-product vector in a double star sensor attitude determination algorithm, reduces attitude determination errors, and is high in reliability, simple in algorithm, and easy in on-board software implementation.

A double stars orientation navigation method bases on the GPS. Divide up the movement track of vehicle into order coterminous beeline segments and confirm the channel of aim vehicle from the beeline segments. Set up positional restriction equation of vehicle on the channel, get the needed information form the signal of the two stars by GPS in vehicle to found the secondary planet observation equation. Orient the two stars and work out the vehicle position and proportion gene from the vehicle position restriction equation and secondary planet observation equation. Set up the directional restriction equation of vehicle speed on the current channel and form the Doppler observation equation of the two GPS secondary planet using the incepted information from the GPS in vehicle. The double stars test speed is working out the vehicle movement speed by directional restriction equation of vehicle speed and the Doppler observation equation to confirm the state of current vehicle through the proportion gene. It solves the disabled problem of GPS for lock of the observation amount to secondary planet to keep the precision of the GPS orientation.

The invention discloses a designing method for installation orientation of a three-field star sensor on a sun-synchronous orbital satellite. According to the method, vector relation between stray light and a coordinate system of a satellite body is analyzed on the basis of a vector model for stray light and the coordinate system of a satellite body during in-orbit operation of the satellite, and areas free of influence by stray light are resolved by establishing a stray light boundary curve mathematical equation; on the basis of included angle relation of boundary curves, the method determines workable conditions of three star sensors and the scope and equation of installation orientation and calculates relation between a maximum sunlight shielding angle and a maximum earth-atmosphere radiation shielding angle of the light shields of the star sensor for suppressing stray light; and the method brings forward optimal schemes for installation orientation of star sensors to allow at least two star sensors to be in operation under a single condition when installation conditions for double star sensors are not met in areas free of influence by stray light under a variety of working conditions. The method has the advantage that a design scheme of practical application value is provided for installation orientation and designing of star sensors to prevent influence of stray light.

In order to solve the problem that the existing track measurement system is of low reliability and precision and cannot be used normally in harsh environments, the invention provides a global high-precision track measurement system. The global high-precision track measurement system is a set of double-star multi-frequency high-precision measurement system which supports a Starfire star-station differential function and integrates a GPS and a GLONASS. The system comprehensively employs the star-station differential technology, the RTK technology, the GIS technology and the wireless communication technology, measures and records the trajectory, speed, attitude and other real-time information of a mobile carrier, can remotely monitor and analyze the mobile carrier in real time, and is used for evaluating the motion process of the carrier and testing the actual working condition of the carrier. The system has the technical characteristics of high reliability and high precision, satisfies the using demand in harsh environments, and can be widely applied to all kinds of test measurement and control fields. The test accuracy can reach 1cm within 50km and 10cm within the global range, so that the test demands of different flight carriers can be satisfied.

The invention discloses a GNSS-R-based double-star positioning method for sea-surface targets. The method comprises the following six steps: step one, extracting and storing time delay Doppler maximum correlation values PMax 1 and PMax 2 of two satellites Sat 1 and Sat 2 corresponding to a receiver platform; step two, extracting time layer values and Doppler frequency values of the delay Doppler maximum correlation values, and respectively recording the time layer values and Doppler frequency values as tMa*1, tMa*2 and fMa*2; step three, calculating longitudes and latitudes of mirror spot positions of the two corresponding satellites according to a mirror spot position calculating method; step four, estimating distances between the correlation power maximum value points to the mirror spots according to the time delay Doppler distribution of detection areas, and recording the distances as d1 and d2; step five, calculating longitude and latitude (TLon, TLat) of the corresponding correlation value maximum spot which is a target occurring position spot according to parameters obtained by the steps 1-4; step six, building a multi-satellite optimization model, calculating all the navigational satellites at the moment according to the method of the step five, then fitting results to obtain an optimum value.

The invention discloses a double-star vertex subdivision radian set fuzzy matching based marine celestial navigation method and relates to a marine celestial navigation method. The invention aims to solve the problems that the conventional navigation method is low in positioning accuracy, the positioning navigation technology in the double-star vertex subdivision radian set fuzzy matching based marine celestial navigation method is influenced by weather and sea conditions, a satellite navigation signal is easily interfered and inertial navigation equipment error is insufficient in divergence along with time. The method comprises the following steps: (1) dividing a Smithsonian star catalogue and establishing a characteristic star database; (2) photographing a star map perpendicular to the right above part of a ship plane; (3) comparing the star angular distance between stars in two possible star sets, wherein the stars with the minimum star angular distance refer to the solved star pair, and realizing star map recognition; and (4) determining the true zenith right ascension and declination according to an inclination angle read by the ship during photographing, combining the exact time, namely the double-star vertex subdivision radian set fuzzy matching-based marine celestial navigation method is finished. The method belongs to the technical field of marine navigation.

The invention discloses a method for carrying out on-satellite high-precision calculation on deviations of semi-major axes of double satellites. The method comprises the following steps of: firstly carrying out navigation filter calculation to obtain a deviation between opposite orbital elements of the double satellites according to opposite position information of the current satellites; carryingout calculation to obtain a tangential diversion central offset L (k) between the double satellites at the current moments t(k); and inversely calculating a deviation of a semi-major axis by utilizing a deviation drift rate of the offset, so as to greatly improving the precision of the deviation of the semi-major axis. The method is capable of improving the semi-major axis deviation obtaining precision without increasing extra hardware resources, and is simple in calculation and easy to realize.

The invention relates to an orbit keeping method of a double-satellite system, in particular to a method for adopting a linear quadratic type regulator for tracking control and achieving double-satellite system orbit keeping, and belongs to the technical field of aerospace. The implementation method comprises the steps of using a simplified two-body kinetic model to design a nominal orbit, then obtaining an actual orbit with an initial value of the nominal orbit under a precise two-body kinetic equation, calculating the deviation of the actual orbit and the nominal orbit, designing an optimalcontrol law based on the linear quadratic type regulator to obtain optimal accelerated speed, and applying continuous control to make the actual orbit converged around the nominal orbit, so that orbittracking and keeping under the double-satellite system is achieved. The method for adopting the linear quadratic type regulator for tracking control and achieving double-satellite system orbit keeping is applicable to double-satellite system orbit keeping under the condition of the presence of initial errors and model errors, and has the advantages of being high in convergence, high in keeping precision and the like.

The invention discloses a constellation layout of a space-based deep space relay satellite for deploying an interstellar communication relay constellation on a heliocentric orbit between the earth andthe Mars. The constellation layout comprises: the distance 1M from the relay satellite to the Mars is set to be equal to the distance 1E from the relay satellite to the earth, and meanwhile is less than a communication distance limit 1: lM = lE less than or equal to l. According to the method disclosed by the invention, the communication satellite is deployed on the heliocentric orbit between theearth orbit and the Mars orbit, so that hotspot deep space detection areas such as the Venus, the Mars, the asteroid belt, the Jupiter and the like can be covered, and the method has the advantages of wide coverage. In addition, the invention further discloses a transmitting method of the space-based deep space relay satellite. According to the method, a transmission mode of one rocket and doublesatellites is adopted, a satellite S1 and a satellite S2 are simultaneously transmitted by using the Long March 3B rocket, the fuel requirements of the satellites are completely consistent by means of the one-rocket-multiple-satellite transfer orbit design, so that batch design and manufacture can be achieved, and the transmitting method has the advantages of low cost.