35 results about "FDOA" patented technology

Systems and methods that may be implemented to determine the location of an emitter of electromagnetic radiation having an unknown location, using a cooperative TDOA-based location methodology. The cooperative TDOA-based location methodology (e.g., such as TDOA/TDOA, TDOA/FDOA, etc.) may be implemented using at least one cooperative transmitter that transmits a cooperative electromagnetic (EM) signal from a known location that is received at multiple different EM sensing platforms that are also each of known location. The known geolocation of the cooperative transmitter may be used to resolve the signal arrival timing relationships between the different sensing platforms that is utilized to determine the location of another EM transmitter of unknown location.

The invention relates to a rapid positioning method of a binary TDOA/FDOA satellite-to-earth integration positioning system. According to the invention, problems that exist during accurate estimation of a TDOA/FDOA and rapid positioning in a binary positioning system can be solved. The method comprises the following steps that: a binary TDOA/FDOA positioning model is constructed; and a real-time combination estimation is carried out on a TDOA and an FDOA through a fourth order cumulant two dimensional separation parameter estimation method; object location is carried out through an IMM-UKF filtering method; and then, a relationship between a positioning precision and a signal to noise ratio of a receiving signal is analyzed; at last, a situation of an influence of all factors on a positioning error is analyzed. According to the invention, a complete and trusted assessment can be carried out on a positioning system; there is no requirement on a type of a signal that is emitted by a ground radiation source and thus the rapid positioning method has a strong adaptability and a wide application range; moreover, the method has good anti-noise and anti-interference capabilities; and a positioning convergence rate is high and a high positioning precision can be reached. Therefore, the invention has a high practical application value.

Systems and methods that may be implemented to determine the location of an emitter of electromagnetic radiation, such as an RF signal emitter having an unknown location, using at least two electromagnetic radiation sensor antennas that are co-located on a single sensing platform in combination with at least one other electromagnetic radiation sensor antenna located on another sensing platform.

Systems (100) and methods (400) for space-based geolocation. The methods involve receiving by at least two first satellites a maritime signal transmitted from a vessel on or near Earth. The first satellites are deployed in space so as to have overlapping coverage areas. The maritime signal (received at the at least two first satellites) is then used to determine a geographic location of the vessel on Earth using at least one of a Time Difference of Arrival (“TDOA”) and a Frequency Difference of Arrival (“FDOA”).

The invention discloses a direct positioning method based on time difference and frequency difference. In view of a passive dual-satellite time difference and frequency difference positioning problem, the invention discloses a positioning method of firstly determining a target position range based on TDOA (Time Difference Of Arrival) and then based on a FDOA (Frequency Difference Of Arrival) model, the FDOA does not need to be measured, the difficulty of solving the time difference and the frequency difference is avoided, and the positioning precision is higher than that in a method of firstly measuring the FDOA and then performing positioning. Compared with the method of firstly measuring the time difference and the frequency difference and then performing positioning, the method of the invention has the advantages of simple processing and high positioning precision, and particularly in a condition of a low signal to noise ratio, the positioning precision has large advantages. The method does not need to change hardware design of the positioning system only needs to adopt a new positioning algorithm and is applied to engineering application and promotion. The dual-satellite time difference and frequency difference positioning precision can be improved, and a certain reference value is provided for positioning of other platforms and other positioning mechanisms.

A system and method for determining the geolocation of a signal emitter moving at an unknown velocity by combining signal data of a target detection platform (e.g., a radar system) and signal data collected by two or more moving signal collection platforms (e.g., RF signal receivers). In one embodiment, the target detection platform determines tentative location and velocity of the signal emitter, and the signal collection platforms are configured to perform TDOA and/or FDOA analysis of the collected signal data corresponding to a signal of the signal emitter. In one embodiment, solutions provided from the TDOA and/or FDOA analysis are unbiased by using the tentative velocity of the signal emitter, and the geolocation of the signal emitter is determined by matching the TDOA/FDOA solutions and the detected tentative location.

The invention discloses an external radiation source TDOA/FDOA error correction based positioning method. For the problem of external radiation source positioning under a system deviation in measurement, according to obtained TDOA and FDOA measurement information, an auxiliary variable is introduced to convert a nonlinear equation into a pseudo linear equation; an estimation model for a target position, a speed and the system deviation is built; and estimation is performed by adopting an iterative weighted least square method. A correlation least square estimation model is built by utilizing the correlation between the auxiliary variable, and the target position and the speed; and an estimation result is improved by means of correlation weighted least squares. The target position, the speed and the system deviation are jointly estimated to improve the target positioning precision. The auxiliary variable is introduced to reasonably convert a nonlinear measurement model into a pseudo linear estimation model, so that the complexity of the external radiation source positioning is reduced on the premise that the estimation performance is ensured.

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 moving target positioning method based on a TDOA (Time Difference of Arrival) and an FDOA (Frequency Difference of Arrival). The moving target positioning method comprises the steps of: setting that one moving target for transmitting a signal, one mobile sensor used for receiving the signal and used as a reference sensor and a plurality of mobile sensors only used for receiving the signal exist; then calculating a distance difference between a transmission distance from the moving target to each mobile sensor only used for receiving the signal and a transmission distance from the moving target to the reference sensor and a distance difference change rate; next, calculating initial values of a position and a speed of the moving target; then determining a positioning problem of the moving target so as to solve to obtain an accurate estimated value of the position of the moving target; and finally, optimizing an estimated value of the speed of the moving target by utilizing the accurate estimated value of the position so as to obtain an accurate estimated value of the speed. The moving target positioning method has the advantages that the position and the speed of the moving target can be accurately estimated; calculation complexity is low; and running time is short.

The invention discloses a moving radiation source TDOA and FDOA positioning method based on a weighted multidimensional scale and the Lagrange multiplier technology. The method comprises the followingsteps: simultaneously obtaining a TDOA observed quantity and an FDOA observed quantity of a motion radiation source signal by utilizing a plurality of motion sensors, and constructing two scalar product matrixes by utilizing a distance difference observed quantity and a distance difference change rate observed quantity so as to form a multi-dimensional scale pseudo-linear equation; quantitativelyanalyzing the influence of TDOA/FDOA observation errors on the pseudo-linear equation so as to determine an optimal weighting matrix; constructing two quadratic equation constraints by utilizing algebraic characteristics of an augmented unknown vector, and constructing a biquadratic equation constraint weighted least square optimization model in combination with a pseudo-linear equation; and finally, performing numerical optimization on the model by utilizing the Lagrange multiplier technology, obtaining an optimal solution of a Lagrange multiplier by utilizing Newton iteration, and further obtaining estimated values of a radiation source position vector and a radiation source speed vector. According to the invention, the positioning precision of the moving radiation source can be furtherimproved.

A method and system for locating an emitter E transmitting a signal toward a receiver A comprising N radio frequency channels (N≧1), the characteristics of said signal being unknown to the receiver and said signal being reflected off P reflectors B_i (P≧1) of known positions, includes a step of multi-channel joint estimation/detection of the time differences of arrival or TDOA τ_i and of the frequency differences of arrival or FDOA f_i for each reflected path, a step of angular estimation of the direction θ₁ of the direct path of the signal emitted by a goniometry procedure, and a step of location in the plane of the position (x,y) of the emitter E on the basis, at least, of the pairs (τ_i, f_i).

The invention discloses an unmanned aerial vehicle high-precision positioning method based on TDOA and FDOA, wherein the method comprises the following steps: receiving a TDOA measurement value and anFDOA measurement value through a receiving station in space, and enabling the TDOA measurement value and the FDOA measurement value to be equivalent to a distance difference measurement value and a distance difference change rate measurement value; performing joint estimation on the position coordinates of the receiving station to construct a to-be-estimated vector; constructing expressions between the corresponding distance difference measurement value, the distance difference change rate measurement value and the receiving station position measurement value and the to-be-estimated vector; solving a nonlinear weighted least square optimization model of a cost error function; solving an optimal closed-form solution of the to-be-estimated vector through Taylor series joint iteration; and obtaining the position and speed of the target when an iteration termination condition is satisfied. According to the method, the position coordinates of the receiving station are subjected to joint iterative estimation, so that the influence of the position error of the receiving station on the positioning precision is reduced; and a more accurate iterative initial value is provided by utilizing positioning error correction, and the target positioning precision is improved while the convergence is ensured and the convergence speed is improved.

The invention relates to a multi-moving-target positioning method based on an improved TDOA/FDOA algorithm, and mainly solves the problems that the adaptive capacity of noise errors is poor and the positioning precision is limited when a traditional algorithm is used for positioning a plurality of dynamic targets. The method comprises the following steps: firstly, setting K moving targets which do not coincide with one another in a three-dimensional space, deploying M sensors, and acquiring a measurement vector of target information; then constructing a TDOA/FDOA positioning equation set about the position information of the target and the sensor so as to estimate the speed and the position of the target; constructing a global constraint condition according to a relationship between the targets and additional variables, introducing a Lagrange multiplier technology, and adopting a quasi-Newton BFGS iterative formula to solve a positioning equation. According to the method, constraint conditions are comprehensively and systematically considered, and the Lagrange multiplier technology and the quasi-Newton BFGS iterative formula are introduced, so that calculation of a Hessian matrix is avoided, the calculation amount is greatly reduced, and the positioning precision is improved.

The invention provides a TDOA/FDOA estimation precision improving method based on singular value decomposition, and the method comprises the steps: step 1, constructing a global expansion matrix gammacomposed of a TDOA/FDOA measurement value and a second order of the TDOA/FDOA measurement value, assuming that M targets exist, the positions and speeds of the M targets being xm, and d representingthe dimension; step 2, performing singular value decomposition on the global expansion matrix gamma, and reconstructing the global expansion matrix gamma by using the maximum 2M+2d singular values; and step 3, constructing a local expansion matrix and carrying out singular value decomposition on the local expansion matrix, reconstructing the local expansion matrix by using the maximum 6d+4 singular values of the local expansion matrix, and repeating the process for n times until the change of the TDOA/FDOA measurement values of the previous and later two times is smaller than a preset range, nbeing a natural number. Simulation experiments prove that the method can improve the estimation precision of the TDOA/FDOA measurement value.