1021 results about "Clutter" patented technology

A bistatic radar system having a transmitter that generates unique signals at spatially independent transmitter degrees of freedom and a receiver that filters the signal at each receiver degree of freedom into a group of signals identical in number to the number of transmitter degrees of freedom. The receiver formats the filtered signals into a 2-dimensional array of elements. The receiver rotates the array so that the new axes are aligned with the Doppler gradient. The data is then re-sampled and projected to linearize the clutter signal. The receiver may be integrated with a broad class of adaptive and non-adaptive clutter mitigation approaches such as electronic clutter tuning and projected bistatic space-time adaptive processing, or STAP.

A method for sensing occupancy status within an automotive vehicle uses a radar sensor system, the radar sensor system comprising an antenna system, at least one sensor (10) and processing circuitry (18). The method comprises illuminating, using the antenna system, at least one occupiable position within the vehicle with continuous wave (CW signals), the CW signals being frequency modulated in time. At least one sensor signal (a) reflected as a result of the CW signals, is received using at least one sensor (10) the at least one sensor (10) defining a plurality of receive channels (1 . . . i), each channel having a different frequency (f₁ . . . f_i). Processing circuitry (18) is operable for applying, for each receive channel (1 . . . i), DC offset removal to the corresponding sensor signal (a) to generate a modified signal (b); and generating, based on the modified signals (b) one or more occupancy status signals (34, 38), the occupancy status signal indicating a property related to said at least one occupiable position. A system for carrying out the method is also disclosed. The techniques provide for in-vehicle occupant detection and classification (airbag suppression), for passenger presence detection and passenger's vital sign monitoring and for seat-belt reminder functionality (SBR). The radar system may consist of one or two (or four) outputs (I/Q) per channel. The received signal may be mixed down with a single channel demodulator or an I/Q demodulator into the baseband. An advanced signal processing including an auto calibration routine and clutter removal may be used to detect occupants and their vital sign (breathing and heart beat) and to determine their distance to the radar system.

A moving target detection imaging method of a dual-channel frequency modulation continuous wave SAR system comprises the steps of recording echo data by a radar system, performing residual video phase removing processing on the echo data, performing Doppler frequency shift compensation on the data, performing phase deviation compensation on two-channel conversion data, and performing subtraction processing on the two-channel data; performing migration correction and direction dechirping processing on an image with clutter cancellation to realize the rough imaging of a target, and detecting the moving target and extracting one by one; performing inverse transformation on the extracted targets to an original data domain, estimating motion parameters to construct a precise direction dechirping function of the moving target, performing residual video phase removing processing, precise direction dechirping processing and distance migration correction, constructing a fuzzy function for compensation, and then performing Keystone transformation to finish the precise image of the moving target. The moving target detection imaging method solves the imaging problem of the fast moving target when motion parameters are unknown under the continuous wave system, so the signal-to-noise rate and the target detection probability are greatly improved.

The invention concerns a passive radar receiver for a received orthogonal frequency division multiplex-type signal consisting of symbol frames each emitted on coded orthogonal carriers. After formatting the received signals into digital symbols (S₁ S₁), a filtering circuit (2) eliminates by subtraction or using a covariance matrix, in the symbol signal at least unwanted signals with null Doppler effect so as to apply a filtered signal (X′) including essentially signals backscattered by mobile targets to a Doppler-distance correlator (4).

The invention relates to a radar imaging method of an electrically large size target in the ocean clutter environment. The radar imaging method is that the radar imaging of the electrically large size target in the ocean clutter environment is achieved by establishing a surface-box complex target scattering model in a multi-interference environment and adopting electromagnetic simulating calculation through a numerical and analytical hybrid algorithm and a rapid back projection imaging mode. The electrically large size in the radar imaging method means that the ratio of the physical dimension to the wavelength of the target is larger than ten. The working frequency range of a radar is generally in a high frequency area, for example, the L waveband frequency ranges from 1GHz to 2 GHz, and the S waveband frequency ranges from 2GHz to 4 GHz. Some military targets, such as fighters, invisible planes and aircraft carriers in the L waveband and the S waveband belong to the electrically large size. According to the radar imaging method, the radar imaging of the electrically large size target in the ocean clutter environment can be achieved by means of geometric modeling of complex targets, the electromagnetic simulating calculation, the rapid back projection imaging algorithm and Kaiser window edge filtering.

The invention belongs to the field of radar technologies, relates to designs for transmission waveforms of centralized MIMO (multiple input multiple output) radar, and discloses a method for hierarchically designing transmission waveforms of MIMO radar for detecting targets in clutter. The method includes steps of 1, building an MIMO radar signal model and acquiring the intensity of the clutter in a space domain and mainlobe response priori knowledge in a time domain; 2, designing autocorrelation matrixes Rx of transmission signals on the basis of intensity priori knowledge of the clutter in the space domain; 3, combining each optimal mainlobe synthesized signal (MSS) with a mismatched filter to suppress mainlob clutter signals; 4, designing transmission waveform matrixes under constant-modulus conditional constraints. The method has the advantages that the clutter suppression performance can be improved, and accordingly the radar can be used for detecting the targets in the heavy clutter.

The invention relates to the technical field of radar signal processing and provides a self-adaptive target detection method and device. The method includes performing area division on each frame of radar echo wave data of the same geographic location and obtaining amplitude data in radar echo wave data corresponding to different data frames of different areas; acquiring the mean value of the amplitude values in the radar echo wave data corresponding to a plurality of continuous data frames of each area and obtaining current threshold values of the radar echo wave data of different areas; fitting the current threshold values of the radar echo wave data of the different areas and taking the fitting result as background noise of the current radar echo wave data, and detecting a target signal from the current radar echo wave data. According to the invention, the current threshold values of the radar echo wave data are obtained through actual echo wave statistics and the threshold values are adjusted in a self-adaptive manner along with actual sea conditions. Therefore, accurate description of sea clutter features is realized and marine target detection is further realized accurately.

The invention discloses a distance blur clutter suppression method based on pitch frequency diversity STAP. The method comprises the steps that down-conversion and matched filtering are sequentially carried out on a detected received signal to sequentially acquire the pitch-azimuth-time three-dimensional clutter snapshot model of each range gate, the pitch frequency expression of each range gate and the corresponding clutter compensation item; an appropriate clutter compensation item is used to separate distance blur clutters of different distance rings; due to the fact that pitch frequencies of different distance blur clutters are separated from each other, the distance blur clutter of each distance ring needs a filter with corresponding coefficients for filtering, and then all distance blur clutters are inhibited to solve the problem of distance blur; and finally, after the pitch distance blur clutters are separated, pitch frequency spectrum distribution and digital frequency periodicity are used to acquire the selection criteria of frequency increment. According to the invention, the freedom of a system and the operation complexity are not increased.

The invention relates to an infrared target detection method based on a space-time cooperation framework. The method comprises the following steps: 1. acquiring a background frame Bg and a current frame Ft of a video, combining the background frame Bg and the current frame Ft to carry out background clutter suppression and acquiring a background suppression graph Gt after the background clutter suppression is performed; 2. for the background suppression graph Gt obtained in the step 1, firstly establishing a space-time background model, and then carrying out target positioning aiming at space-time background model information after the model is established; 3. according to an imaging mechanism of the infrared target, analyzing a space difference of the infrared target and the surrounding background, using a fuzzy adaptive resonance nerve network to carry out local classification aiming at the target which is positioned in the step 2 and then extracting the infrared target. The method has the following advantages that: the method does not depend on any target shapes and motion information priori knowledge; the method is suitable for a complex outdoor scene; a signal to noise ratio can be increased; a target detection rate can be increased and a calculated amount can be reduced; false targets can be effectively removed and a false alarm rate can be reduced; the method is beneficial to follow-up target identification.

The invention relates to a real-time detection and separation method of multiple moving objects by a through-the-wall radar. The method comprises: a complex background signal is rejected by using a clutter suppression algorithm based on an exponential smoothing filter and information of moving human objects can be kept rapidly and accurately; with an envelope detection algorithm based on Hilbert transform, all moving objects are arranged at different envelope peaks; and all moving objects can be separated at different areas rapidly according to an algorithm based on combination of a fixed threshold value and an adaptive threshold value. According to the invention, the method which is simple has the high execution efficiency and is suitable for detection on multiple moving human objects by a portable through-the-wall radar; a powerful guarantee can be provided for accurate positioning of all moving objects by the through-the-wall radar; and the working efficiency of the through-the-wall radar can be improved effectively.

The invention proposes a multi-target tracking method based on random finite set filter coupling, and the method comprises the contents: an RMB (robust multi-Bernoulli) filter, a GLMB (generalized label multi-Bernoulli) filter, an enhanced GLMB filter, and a multi-target tracker. The process comprises the steps: employing the GLMB filter as a main tracker under the condition of an unknown clutter rate so as to generate a track parameter; enabling the one-step RMB filer to modify the unknown clutter rate based on the provided track parameter and track existing probability; inputting the clutter rate estimated by the RMB filter into the GLMB filter, thereby achieving the robust online visual multi-target tracking. The method breaks the limit that different targets cannot be tracked and recognized during the filtering of the unknown clutter rate, and one multi-target tracker is designed for generating independent tracks. Moreover, the unknown clutter rate is estimated in operation, and the method can effectively adapt to a real scene, and achieves a robust multi-target tracking performance.

The invention belongs to the technical field of radar. The invention relates to a flight path optimization method, in particular to a target track optimization method based on dual-fusion maximum entropy fuzzy clustering JPDA. The method comprises the following steps: (1) performing state prediction and updating by adopting a Kalman filter on the basis of a maximum entropy fuzzy clustering method,and performing preliminary screening on a target trace point set obtained at a moment k + 1according to an elliptical wave gate rule during scanning and tracking; (2) multiplying the measurement membership degree taking the wave gate center as the clustering center by the corresponding position of the wave gate membership degree taking the effective measurement data as the clustering center to obtain the bidirectional membership degree between each effective measurement and all the wave gate centers; and (3) analyzing clutter distribution and combining the bidirectional membership degree to obtain a final association probability, obtaining state estimation and estimation error covariance of the target according to a standard JPDA algorithm filtering program, and finally iterating trackingtrack information of the target. The method is high in tracking precision, and avoids complex correlation matrix splitting.

The invention discloses a sea clutter Doppler spectrum characteristic analysis and comparison method. The method comprises the following steps: step 1, sea clutter average Doppler spectrum estimationand frequency shift spectrum width calculation; step 2, sea clutter frequency shift and spectral width correction of the shipborne platform; and step 3, marine environment parameter matching and testparameter influence analysis and comparison. Aiming at the phenomena of platform difference influence and complex and diverse test parameter conditions existing in sea clutter Doppler spectrum characteristic analysis and comparison of the same radar in multi-platform test, the invention provides the sea clutter Doppler spectrum characteristic analysis and comparison method. The influence caused bythe movement of the shipborne platform is corrected, and a certain analysis sequence and steps are designed according to the size difference of the influence of radar parameters and marine environment parameters, so that the Doppler spectrum characteristic difference of the same radar under various marine environment conditions tested by different platforms can be conveniently and quickly obtained.

The invention discloses a method and system for identifying a marine oil spill object by a marine radar. The method of the invention comprises the following steps: A, converting output image signals from radar projection into Descartes projection; B, correcting images and compensating motion; C, processing the radar images corrected in the step B by a Gamma filtering method, reserving marginal information and simultaneously filtering high-frequency noise of the radar images; D, detecting a strong signal area in the images, according to the distribution of signal strength in the images, determining the saturated state strength as the strength threshold of the signal area, and directly deleting the signal data exceeding the strength threshold; and E, carrying out image segmentation by a gray level co-occurrence matrix method to abstract the marine oil spill object. The system comprises a radar main controller, a marine radar controller, a junction box, an acquisition device, a processing device and a display device. The invention utilizes the noise wave information such as ocean wave and the like to obtain a small object, identifies the oil spill object by a texture algorithm, and can better abstract the marine oil spill object.

The invention discloses a space-time adaptive processing method for radar clutters based on prior knowledge. An airborne radar is determined, the airborne radar includes N array elements, each array element includes L distance units, each distance unit includes K coherent pulses, Doppler domain data vectors in the first distance units of the N array elements of the airborne radar are calculated, and the weighted coefficient alphanlk of the first distance unit in the nth array element and the kth Doppler unit, the Doppler domain data vectors znlk of the first distance unit in the nth array element in the (k-1)th, kth and (k+1)th Doppler channels, and a covariance matrix Rnlk of the first distance unit of the weighted nth array element in the kth Doppler channel are calculated successively; a space-time filter coefficient wnlk of the first distance unit in the nth array element and the kth Doppler channel is calculated, and output data ynlk of the first distance unit in the nth array element and the kth Doppler channel after clutter inhibition is calculated; and further, final Doppler-spectrum output data of the airborne radar after clutter inhibition is calculated.

The invention discloses a sky wave and ground wave hybrid radar echo spectrum simulating method. The method comprises the following steps of calculation on positioning of an object of a sky wave and ground wave radar, calculation on transmission attenuation, simulation on a radar echo spectrum under the background of noise and simulation on a radar echo spectrum under the background of sea clutter. A complete process of a sky wave and ground wave hybrid radar is completely shown from an objective positioning model; in the complete process, a sky wave radar transmits high-frequency electromagnetic waves, a ground wave receiving station receives sea echo and also receives noise, attenuation and clutter in the process, and the final echo spectrum shows that the radar with the novel system can detect a given object on a certain sea surface really; and the detection performance of the radar in the type is analyzed, and a certain reference is provided for later research on a novel processing algorithm and construction of a guiding position.

The invention relates to an unmanned ship sea surface correlation filter target tracking method suitable for a blocking scene. In the event of target blocked or high background similarity in the target tracking process of the surface unmanned ship, the tracker is interfered along with further blocking of the target or background clutter, resulting in the model being polluted by occlusion, becomingmore and more impossible to discriminate and finally causing drifting of the tracking model. Aiming at the problem, based on the correlation filter KCF algorithm, the tracking state is discriminatedby defining the oscillation index and the peak value of a correlation filter response graph to realize self-adaption update of the correlation filter model. The method in the invention has obvious advantages in sea surface target tracking aspect, particularly, the sea surface target tracking in the case that the target is blocked; and the real-time requirement of tracking of the unmanned ship is achieved.

The invention discloses field programmable gate array (FPGA) implementation equipment and an FPGA implementation method for self-adaptive clutter suppression of external radiation source radar. The method comprises the following steps of inputting four paths of channelized data to be processed into a finite impulse response (FIR) filter module through a first in first out (FIFO) memory inside a self-adaptive clutter suppression module of an FPGA chip; inputting two paths of data, channelized by an auxiliary antenna, into a step length calculation module through the FIFO memory, and calculating the step length through the step length calculation module; simultaneously inputting the output of the step length calculation module and two paths of output of the FIR filter module into a weight updating module; inputting an updated weight into the FIR filter module; and performing synchronous parallel output on clutter suppression results through in-phase/quadrature (I/Q) channels. The self-adaptive clutter suppression is controlled by five global clocks with the same rate and different phases. The self-adaptive clutter suppression of the external radiation source radar can be better realized. The problem of difficulty in meeting of a requirement on real-time performance caused by large conventional clutter suppression equipment amount is solved. The equipment and the method are high in processing efficiency, high in calculation speed and low in equipment complexity, and are used for implementing the self-adaptive clutter suppression of the external radiation source radar.

The invention discloses an aircraft radar clutter inhibiting method based on a knowledge assisting sparse gradient minimum variance. According to the main thought, the method comprises the steps of determining an aircraft radar and obtaining Nmax pieces of range gate radar echo data and Nmax pieces of to-be-detected unit data respectively; then determining a clutter ridge; making l belong to {1,2,...,Nmax} and calculating a final clutter power matrix of the l to-be-detected unit data xl on the clutter ridge; utilizing the final clutter power matrix of the l to-be-detected unit data xl on the clutter ridge to calculate a rebuilt space-time two-dimensional covariance matrix of the l to-be-detected unit data xl; making the value of l added with 1 until a rebuilt space-time two-dimensional covariance matrix of the Nmax to-be-detected unit data xl is obtained; utilizing the rebuilt space-time two-dimensional covariance matrix of the Nmax to-be-detected unit data tocalculate the weight used for processing the Nmax to-be-detected unit data and then obtain a space-time self-adaptive processing result, wherein the space-time self-adaptive processing result isthe aircraft radar clutter inhibiting result based on the knowledge assisting sparse gradient minimum variance.