196results about How to "Avoid estimation error" patented technology

The invention discloses a sparse recovery STAP method based on knowledge assistance. The method comprises the following steps: constructing a sample data set; constructing a space-time steering vectormatrix of a distance unit sample; performing sparse recovery on the sample data; constructing a steering vector matrix containing prior information; judging whether the steering vector of sparse recovery corresponds to clutter or not based on the steering vector matrix containing prior information, and updating the sparse recovery vector and the dictionary based on a judgment result; performing secondary sparse recovery on the sample data based on the updated sparse recovery vector and dictionary; and performing clutter covariance matrix estimation by using the estimation sample of secondarysparse recovery. According to the method, the sparse recovery dictionary is corrected by means of sample sparse recovery and prior information of clutter distribution, clutter covariance matrix estimation errors caused by off-grid are solved. Meanwhile, the influence of dense interference in samples is removed, the moving target cancellation phenomenon is overcome, and the moving target detectionperformance is improved.

The invention provides a method for compensating for an unknown network time delay in a forward path of a network cascade control system and belongs to the technical field of network control systems. A real network data transmission process between forward path nodes is adopted to substitute for a network time delay compensation model between the nodes; the measurement, the observation, the estimation or the identification of a network data transmission unknown time delay between the forward path nodes are eliminated; and the requirement on the synchronization of a node clock signal is eliminated. By the method, the influence of the unknown network time delay on the stability of the system can be reduced and the control performance quality of the system is improved. The method is applied to the dynamic compensation and control of the unknown network time delay only existing in the forward path of the network cascade control system, in which the main and secondary controlled target mathematical models are known or unknown, the network has a certain amount of packets, and the network time delay can be more than several even over ten sampling periods.

The invention provides an InSAR atmospheric delay correction method assisted by a GNSS chromatography technology. The InSAR atmospheric delay correction method comprises the following steps of S10, reconstructing a three-dimensional total refractive index field of atmospheric water vapor in a research area, S20, taking the radiosonde data of the research area as a reference value, carrying out the precision evaluation of the chromatography result, and carrying out the step S30 if the precision meets the requirements, S30, obtaining a refined three-dimensional total refractive index field by using a spatial interpolation algorithm, S40, estimating the oblique path total delay amount of the SAR signals in the main image and the auxiliary image by using a Ray-tracing algorithm, S50, generating an atmospheric delay phase diagram of the interferometric SAR image, S60, generating an SAR unwrapping interferometric phase diagram, and S70, obtaining an InSAR phase diagram of atmospheric correction. According to the InSAR atmospheric delay correction method assisted by a GNSS chromatography technology, the GNSS chromatography technology and the spatial interpolation algorithm are utilized to acquire the refined three-dimensional total refractive index field, and the Ray-tracing algorithm is combined to accurately estimate the oblique path atmospheric delay amount of the three-dimensional SAR signal, so that the inversion precision of the atmospheric delay phase of the SAR image is improved, and high-precision correction of InSAR atmospheric delay is realized.

The invention provides a delay compensation method for a network control system, belonging to the technical field of network control systems. True network data transmission processes from a transmitter node to a controller node and from the controller node to an actuator node are adopted in the method to replace network delay compensation models between the transmitter node and the controller node and between the controller node and the actuator node, thereby omitting measurement, estimation or identification on network data transmission delay between nodes and also avoiding the requirement on the node clock signal synchronicity. When an offset exists between an estimated model of a controlled object and a true model, a model offset correction controller can enhance the robustness and theantijamming capability of a system. By adopting the method, the influence of delay on the stability of the system can be lowered and the quality of the control performance of the system can be improved. The method is suitable for sectional, real-time, on-line and dynamic compensation and control on the delay of a network control system of which the network exists between the transmitter node and the controller node and between the controller node and the actuator node and of which the mathematical model of the controlled object is known or incompletely known.

The invention discloses a two dimensional direction of arrival angle estimation method of an electromagnetic signal, the two dimensional direction of arrival angle estimation method mainly solves the problems of slow reaction rate and large estimation error of the target reconnaissance and passive location caused by huge computation task of the two dimensional direction of arrival angle estimation in the prior art. The two dimensional direction of arrival angle estimation method comprises the following steps that even planar arrays are formed by the adoption of antenna receivers, echo signals of all antenna receivers are calculated, noise subspaces of the echo signals of the antenna receivers are calculated, a direction vector of the included angle of a y axis is obtained by plugging the included angle of an x-axis, which is made to be a fixed value, into an angle solving function, multiple sets of values are obtained through multiple times of computations, an amplitude spectra is generated by the adoption of multiple sets of values, the included angle of the x axis is obtained by seeking peak points of the amplitude spectra, and the included angle of the y axis is obtained through the least square method. By means of the two dimensional direction of arrival angle estimation method, the two dimensional direction of arrival angle estimation process is simplified into a one dimensional direction of arrival angle estimation process, the computation tasks are greatly reduced, the reaction rates of the target reconnaissance and passive location are improved, the parameter estimation error caused by delayed information can be avoided, and the method can be used for the quick target reconnaissance and passive location.