60 results about "Over-the-horizon radar" patented technology

A method and apparatus are disclosed that enable an over-the-horizon-radar (OTHR) system to detect and track multiple target classes simultaneously, where target classes are defined by the speed and acceleration of the tracked objects. The OTHR is tasked in a staring mode, with a bandwidth and waveform repetition frequency that enable detection of Doppler shifts from all target types, with sufficient clutter reduction and range resolution. The backscattered echoes are buffered for each target class and processed independently. The output of an automatic tracking algorithm then preferentially plots target progress on a single digital map for all target classes.

The invention discloses a microwave over-the-horizon radar echo chart calculating method, which comprises the following steps: 1) determination of relevant parameters, target parameters and environment parameters of a microwave over-the-horizon radar; 2) prediction of characteristic parameters of an evaporation waveguide and measurement of characteristic parameters of a surface waveguide; 3) calculation of an atmosphere waveguide or atmosphere refraction propagation sea surface glancing angle; 4) calculation of an atmosphere waveguide or atmosphere refraction propagation factor; 5) calculation of a sea clutter and target echo power diagram; and 6) simulation of a dynamic radar echo chart. The disclosed microwave over-the-horizon radar echo chart calculating method takes influence, formed under ocean hydrological conditions, of atmospheric duct propagation on sea surface echoes and target echoes into full consideration under the actual microwave over-the-horizon radar working environment, provides an actual radar beam sea surface grazing angle calculating method under the atmospheric refraction or atmospheric duct condition on the basis of radar system parameters and marine hydrometeorological parameters, and with relevant sea clutter models being combined, can effectively predicate and estimate the sea surface echo power.

The invention discloses a radar cross-section (RCS) layered calculation method of a ship target within an atmospheric duct range. According to the invention, after partition of a three-dimensional geometric model of a ship target, most similar basic geometrical shapes of the all partitioned parts of the three-dimensional geometric model are selected and are approximated as basic scatterers; geometric information of all basic scatterers are extracted and RCSs of the all basic scatterers are calculated; Change relations of RCS values of all parts of the ship target at different heights are calculated by combining heights of all parts of the ship target; and scattering power intensity of the ship target is calculated according to a transmission factor of an electromagnetic wave of an atmospheric duct. According to the RCS calculation method of the ship target within the atmospheric duct range provided in the invention, computational complexity and requirements for computing equipment canbe substantially reduced and real-time calculation is allowed. Besides, an influence of up-and-down sea surface on transmission of an electromagnetic wave is fully considered, and a calculation result is more reasonable and effective. The method provided in the invention has important military significances for technological development, equipment update, and operational application of microwave beyond-the-horizon radar.

The invention discloses a sky-wave beyond visual range radar adaptive space-time joint interference-resistant method which inhibits interference by comprehensively utilizing two methods of adaptive beamforming and interpolation and compensation after a time domain is eliminated and achieves the purpose of making up for each other deficiencies through reasonable scheduling strategies. The transient interference entering a side lobe is resisted by utilizing the adaptive beamforming of a space domain, and the transient interference entering a main lobe is inhibited through the interpolation and the compensation after the time domain is eliminated, therefore compensating errors caused by time domain elimination and beam distortion caused by main lobe interference are prevented; and a diagonal loading amount which is in proportion to interference strength is formed for the non-transient interference entering the main lobe through interference space distribution information, therefore the strong main lobe interference is prevented from causing the serious distortion of the shapes of adaptive beams. The invention is established on the basis of a dimension-reducing beam space adaptive beamforming method, thereby greatly reducing the amount of signal processing calculations; and concrete steps are seen in an attached figure. The invention is not limited to a sky-wave beyond visual range radar system, can be widely applied to large-sized phased array radars of multiple types and has popularization and application value.

The invention discloses a frequency-domain super-resolution micro-multipath height finding method of a sky-wave beyond visual range radar, wherein the frequency-domain super-resolution micro-multipath height finding method is suitable for a signal processing system of the sky-wave beyond visual range radar. The frequency-domain super-resolution micro-multipath height finding method comprises the following specific steps of: filtering an interested target and multipath signals thereof by using band-pass FIR (Finite Impulse Response) filtering; estimating a mean distance value of the interested target by using a super-resolution method, and designing a distance rectangular projection matrix to filter and remove partial redundant micro-multipath signals; forming a Doppler domain weighted signal sub-space, estimating a mean Doppler value of the Doppler domain weighted signal sub-space; and calculating a Doppler parameter by using a micro-multipath model, correcting by using the mean Doppler value to form a Doppler projection matrix, matching the weighted signal sub-space with the Doppler projection matrix, searching to obtain the estimated height value of the target, wherein the specific steps are shown in figure 1. The method has the advantage of reducing the probability of matching failure caused by noise and parameter errors of an ionization layer. The technology disclosed by the invention is not limited to a sky-wave beyond visual range radar system and can be widely applied to a target height finding occasion with a ground multipath effect, and has popularization and application values.

The invention provides a sea surface wind direction extraction method based on a ship-borne high-frequency ground wave beyond visual range radar, belongs to the field of ocean remote sensing, and solves the problems that an existing sea surface wind direction extraction method is small in detection range and has no continuity, and the system is complicated. The sea surface wind direction extraction method comprises the following specific steps: obtaining a first-order sea clutter widening spectrum in a distance door by using a single receiving array element; determining corresponding positive and negative Bragg peak values and a spatial resolution of a sea clutter incidence direction according to a first-order sea clutter space-hour distribute property; obtaining a sea surface wind direction according to the relative strength of the positive and negative Bragg peak values; applying the sea surface wind direction to a resolution unit of each sea area in the distance door and extracting the wind directions of all the sea areas in the distance door; comparing the sea surface wind directions of the resolution units of the adjacent sea areas and eliminating wind direction blurs to obtain the sea surface wind direction of the distance door; and repeating the steps until the sea surface wind directions of all the distance doors are obtained. The sea surface wind direction extraction method based on the ship-borne high-frequency ground wave beyond visual range radar is used for monitoring the sea environment.

The invention provides a motion compensation method for a float-type high-frequency over-the-horizon radar. The motion compensation method comprises the following steps: step 1, obtaining motion state parameters of a buoy platform, converting the coordinates of the motion state parameters, mapping the motion state parameters in a buoy coordinate system into a geodetic coordinate system, and obtaining motion state parameters of the buoy platform in the geodetic coordinate system; step 2, calculating array variations generated by the motion of the buoy platform, performing amplitude correction and phase compensation to a buoy radar array according to the array variations, and obtaining sweep frequency sequences after amplitude correction and phase compensation; and step 3, performing digital beam forming to the sweep frequency sequences obtained in step 2 so as to obtain sweep frequency sequences for all beam directions after phase compensation, and performing Doppler frequency compensation to radar received signals according to the motion state parameters of the buoy platform in the geodetic coordinate system obtained in step 1, and compensating the radar received signals from radar echo signals to obtain the sweep frequency sequences for all beam directions after Doppler frequency compensation. Therefore, the influence of the motion of the buoy platform to radar signals is reduced.

The invention discloses a method for simultaneously receiving sky wave and ground wave BVR radar signals. A distance offset method is used for transmitted signals on a sky wave transmitting station and a ground wave transmitting station so that a ground wave radar station on a shore base can simultaneously receive echo signals obtained by signals transmitted by a sky wave radar and a ground wave radar and scattered by a sea surface or a ship or a low altitude flight object. The method is simple and convenient to achieve, distance offset only needs to be conducted on sky wave transmitting signals and ground wave transmitting signals, it is guaranteed that the ocean of the sky wave radar and the ground wave radar or an object echo wave spectrum is within the bandwidth of a receiver filter, and aliasing of the distances and spectrum can not happen. An existing ground wave radar receiving system is used so that the purpose that the two BVR methods of sky wave transmitting and ground wave transmitting can be simultaneously used for detecting the ocean or target can be achieved. The combined detection mode can improve the detection accuracy of ocean surface dynamic parameters such as wind, waves and currents, the detection distance of a high-frequency BVR radar system is increased, and close distance fine detection and long distance ocean surface dynamic element detection are achieved.

The invention discloses a method for simulating distributed type MIMO sky wave beyond visual range radar sea clutter, and belongs to the field of radar radio wave propagation. An existing simulating method is mainly suitable for a sky wave beyond visual range radar of a traditional (standard) single base or a double-base ground-wave radar but not suitable for the situation of a distributed type MIMO sky wave beyond visual range radar, and not all physical factors are taken into consideration. The method is suitable for the situation of the distributed type MIMO sky wave beyond visual range radar, the geometrical relationship between the incidence direction and returning scattering direction of receiving and sending channels relative to the sea surface of the observing area is calculated based on digital ray tracing, and the scattering sectional area expression of normalization of double-base one-order and two-order sea clutter of all the receiving and dispatching channels is inferred; after the scattering sectional area expression and the Doppler transfer function of a receiving and dispatching propagation path are convoluted, the sea clutter power spectral density of the receiving end is obtained based on the radar equation; lastly, the random time sequence of sea clutter and noise at the receiving end is obtained according to the power spectral density. According to the simulation method, the factors affecting the distributed type MIMO sky wave beyond visual range radar sea clutter are fully taken into consideration, precision is high, universality is good, and the method has popularization and application value.

The invention provides a signal processing method for an MIMO (Multiple-Input Multiple-Output) sky-wave OTHR (Over-the-horizon Radar). By utilizing the advantages that an MIMO-OTHR distinguishes multi-path echoes of a target, the multi-path echoes of a target are separated at the signal processing end of the MIMO-OTHR, so that an association relationship between the multi-path measurement of the target and propagation paths is obtained, and the processing complexity of OTHR data is greatly reduced by virtue of the multi-path measurement and the propagation paths. Compared with a conventional OTHR data processing mode, a data processing mode of the separated multi-path echoes through the MIMO-OTHR has the advantages that the calculated amount is greatly decreased, and the two modes are not obviously different in accuracy.

The invention provides a method for removing non-linear phase pollution from a sky wave OTHR (over-the-horizon) radar echo signal, which relates to the field of the method for removing the non-linear phase pollution from the sky wave OTHR (over-the-horizon radar) echo signal and aims at solving the problems that the existing non-linear phase pollution has an effect on the sky wave OTHR echo signal and further reduces detecting performance under all kinds of conditions, especially under the lower signal-to-noise ratio. The method provided by the invention comprises the following steps that a data acquisition module collects to-be-processed sky wave OTHR time domain data; a data selecting module converts the to-be-processed sky wave OTHR time domain data; a pollution function computing module obtains a non-linear phase pollution function; and a signal correcting module obtains the sky wave OTHR echo signal after being subjected to removing the non-linear phase pollution. The method provided by the invention solves the problem of influence caused by the non-linear phase pollution in the sky wave OTHR radar echo signal, obviously reduces errors and has better effect under the lower signal-to-noise ratio. The method provided by the invention is used for processing the sky wave OTHR radar echo signal.

The invention discloses a high-frequency sky-ground wave MIMO radar realization method, and provides an effective solution for the problems of multipath and multi-mode effect and clutter Doppler expansion and the like for a sky-ground wave over-the-horizon radar. A radar system is formed by a plurality of sky wave transmitting stations and a plurality of ground wave receiving stations. Each transmitting station and each receiving station are formed by a plurality of antenna units, so that coexistence of distributed and intensive MIMO radars is realized, and spatial resolution is improved, and multi-angle observation can be realized. By allocating different frequency bands or phases to transmitting subunits, a multiplexed orthogonal effect of transmitting signals is realized. The receiving stations realize pulse compression through frequency mixing and filtering, so that separation of multipath orthogonal signals is realized. The multi-angle observation enlarges detection range and improves detection precision; and MIMO virtual array elements enable the sky-ground wave MIMO radar system to have flexible wave beam formation capability, and influence from different-spatial-orientation multipath and multi-mode effect and clutter expansion due to ionosphere contamination in the sky-ground wave radar can be eliminated properly.

The present invention provides a ground wave over-the-horizon radar power range assessment method based on an equivalent noise coefficient, and the present invention relates to a ground wave over-the-horizon radar power range assessment method. The problem is solved that a current technology is complex in calculation and cannot directly assess the power range through the noise and clutter background intensity. Through derivation and fitting, in an over-the-horizon detection area, a detection distance variation [Delta]R and a noise coefficient variation [Delta]F are approximate to a linear relation to obtain slopes kRF of the two so as to obtain the variation of a radar system detection distance according to the variation of the equivalent noise coefficient relative to an expected value andsolve the problem that a traditional method is complex in calculation. The ground wave over-the-horizon radar power range assessment method only needs a simple linear operation to assess the power range so as to avoid repetitive computation, effectively improve the practicability, reduce the calculated amount and to be simple and convenient in actual application. The ground wave over-the-horizonradar power range assessment method is used in the ground wave over-the-horizon radar detection field.

The invention provides a multi-source detection semi-physical simulation and time window analysis system. The system comprises an upper computer, an Ethernet router, a comprehensive control system, a dynamics/kinematics simulation machine, a ground-based beyond visual range radar simulation machine, a space-based satellite detection simulation machine, a simulation radiation source, a quantity of passive radar, a GPS tame rubidium clock, a multi-station collaborative signal processor, a real-time reflective memory network, a direct-current voltage-stabilized power supply and a UPS power supply. The system is based on the real-time reflective memory network and an Ethernet network, a mathematical simulation and radio frequency simulation combination real-time system architecture is adopted, combination properties of the multi-source detection system can be effectively verified, simulated analysis can be carried out on a target indication time window, and thus technological support can be provided for target guidance system argument of an aircraft.

The invention discloses a method for evaluating the influence of an offshore wind plant on the detection efficiency of ground wave beyond visual range radar. The method comprises the following steps:according to ground wave over-the-horizon radar parameters and a pre-selected area of a wind power plant, carrying out scene analysis, and screening out objects needing key analysis; establishing a fan electromagnetic model according to the provided parameters of a wind turbine generator, and realizing establishment of a single fan electromagnetic model; according to longitude and latitude coordinates of a fan of a pre-built wind power plant and radar relative position information, building an array in FEKO electromagnetic calculation software, building a scene model, and analyzing shielding influences; calculating RCS changes of a single fan device in different states; analyzing the influence of Doppler frequency; deriving a multipath effect theoretical formula; enabling scene actual measurement to be equivalent to electromagnetic environment noise data, and evaluating the influence range of the wind power plant. By means of electromagnetic simulation calculation, theoretical derivation, actual measurement scene equivalence and the like, a quantitative evaluation result is given.

The invention relates to a Riemann distance-based generalized sidelobe cancellation algorithm, and relates to a sea clutter suppression method for high-frequency beyond visual range radar in a hybridpropagation mode. In order to solve the problem of suppression of a non-stable sea clutter received by the high-frequency beyond visual range radar under the hybrid propagation mode, the invention provides the Riemann distance-based generalized sidelobe cancellation algorithm. On the basis of a traditional generalized sidelobe cancellation processing method, an effective training sample is selected according to Riemann distance between training sample covariance matrixes, and non-stable cluster suppression is performed. The Riemann distance-based generalized sidelobe cancellation algorithm isused for suppressing sea cluster and other non-stable cluster by the high-frequency beyond visual range radar under the hybrid propagation mode, so that the signal-to-noise ratio is improved, and thetarget detection probability is improved.

The invention discloses a high-frequency over-the-horizon radar station selection auxiliary system and a method. The auxiliary system comprises an antenna, a transmit-receive switch, an emitting module, a receiving module, a signal processing and transmitting module and a display and control module. The high-frequency over-the-horizon radar station selection auxiliary system is capable of simulating the working mode of the radar to comprehensively test the environment condition of the site selection of a radar station, and analyzing the influence of the environment factor on the radar operation through the detection of an echo, and finally choosing a proper site location according to a testing result. The high-frequency over-the-horizon radar station selection auxiliary system provided by the invention is light, portable and low in power consumption, and capable of evaluating by simulating the actual working mode of the radar and considering the site electromagnetic environment, so that the station site selection is more scientific and effective, and the success rate of the station selection can be increased.

The invention discloses an ionospheric side scatter detection method, which includes: arranging receiving stations on both sides of the line connecting the transmitting station and the known target detection area; transmitting radio signals sent by the transmitting station, reflected by the ionosphere, and detecting the target After the area is scattered, it is received by the receiving station; by analyzing the Doppler spectrum of the received signal at the receiving station, it is determined that it contains side scatter signal information. The invention provides a new ionospheric detection method and lays the foundation for the ionospheric network detection. The invention can provide technical support for the ionospheric diagnosis of the sky-wave over-the-horizon radar network detection, so that the sky-wave over-the-horizon radar network detection can exert greater advantages, and greatly shorten the development cycle of the sky-wave over-the-horizon radar network system.

The invention discloses a sky-wave over-the-horizon radar target and ionized layer parameter joint estimation method, which belongs to the field of radar technologies. According to the invention, a parameter to be estimated is set as a target and ionized layer joint parameter; an analytical model is used to transform the error of an ionized layer detection device into a target parameter estimation error; and the estimated parameter is corrected to realize ionized layer and target parameter joint estimation. The problem that joint ionized layer parameter error estimation cannot be carried out by the existing estimation method is solved. The ionized layer error information is effectively utilized. The estimation accuracy is improved.

The invention discloses a sky-wave over-the-horizon radar short-time detection method based on the extrapolation of an AR model. According to the method, a Burg method is used to carry out AR model reconstruction and extrapolation on original pulse data which is subjected to space-time domain processing, original data and reconstructed data are used comprehensively, an obtained result is closely related to a real spectrum, an improvement result of the reconstructed data is introduced, by the adoption of a large-scale model order and an extrapolation length, the extrapolation effect is improved, and the possibility of distortion is avoided while a spectrum estimation effect is improved. Specific steps are shown in attached drawings. The technology is not limited to a sky-wave over-the-horizon radar system and can be widely applied to many types of large-scale phased-array radars, and the method has the value of promotion and application.

The present invention proposes an aircraft carrier formation identification method based on confidence rule base reasoning. Taking the identification of aircraft carrier formations in the remote early warning system as the application background, firstly, the aircraft carrier formation identification confidence rule base is constructed based on the constraint relationship of sub-targets in the aircraft carrier formation. ; Then based on the confidence rule base, the evidence reasoning algorithm is used to realize the reasoning of the multi-layer confidence rule base, and the method of using historical data to learn the parameters of the confidence rule base is studied. Finally, the confidence of different evaluation results output by the reasoning system is identified, so that To achieve the purpose of accurate identification and early warning of aircraft carrier formations under various uncertain information. The scheme of the present invention can use the output information of the sky-wave over-the-horizon radar to realize the identification and early warning of the aircraft carrier formation, which is of great significance for the practical engineering application of the sky-wave over-the-horizon radar and the improvement of the function and performance of the remote early warning system.