109results about How to "Improved clutter suppression performance" patented technology

The invention discloses a space-time adaptive processing method under a non-homogeneous clutter environment, belonging to the technical field of airborne radar clutter suppression. The method comprises the following steps: extracting a snapshot training sample x1 along a distance direction, asking for a clutter space-time two-dimensional spectrum, and inducing a sparse solution in a clutter covariance matrix to be estimated; weighting the clutter covariance matrix to be estimated; calculating the corresponding space-time adaptive filtering device according to the estimated covariance matrix, and judging whether a moving-target exists at an output end. The invention aims to the shortage of IID training samples under the non-homogeneous clutter environment, and uses the method represented by complete sparse way to super-resolvably estimate the clutter space-time two-dimensional spectrum, thereby releasing the clutter covariance matrix estimated by a single-frame training sample. The invention can effectively avoid the rapid variation of landform caused by dispersing clutter sources, and is robust for the space-time spectrum dispersion caused by factors of the external movement of the clutter simultaneously, different channels and the like. Mountaintop real data demonstrates that the method can maintain good performance of the clutter suppression, and suitably for the strong non-homogeneous clutter environment.

The invention relates to a ground penetrating radar underground target positioning method. The method comprises the steps that 1) two-dimensional empirical mode decomposition is carried out on detection echo data of a ground penetrating radar to acquire K two-dimensional empirical mode function components IMF with orderly descending frequency and a residual; 2) the mean of the first M (M</=K) two-dimensional empirical mode function components is used as the characteristic value of the detection echo data; 3) the extreme point of the characteristic value of the detection echo data is acquired and is used as the estimation value of the vertex position of an underground target; 4) the underground propagation velocity of an electromagnetic wave is estimated; and 5) according to the estimation value of the vertex position of the underground target and the underground propagation velocity of the electromagnetic wave, a ground penetrating radar hyperbolic mathematical model is used to carry out hyperbolic fitting to position the underground target. According to the method provided by the invention, the target information is completely kept; a clutter suppression effect is improved; and the accuracy of target positioning is improved.

The invention discloses an efficient three-dimensional space-time adaptive clutter suppression method for airborne digital array radar, and belongs to the field of suppression of clutters of airborne radar. In the method, a cascading mode is adopted for the airborne non-front lateral planar array radar working in a medium and high pulse repetition frequency (PRF) system, and the method includes designing a robust adaptive digital beam former (ADBF) in a pitching dimension of airspace to suppress short-range clusters at first; and designing a two-dimensional dimension-reduction space-time adaptive processor (STAP) in a direction-pulse field to further suppress long-range clutters. By the aid of the efficient three-dimensional space-time adaptive clutter suppression method, the clutters at various fuzzy distances of the airborne non-front lateral planar array radar can be effectively filtered, the convergence speed is fast, computational complexity is low, and the method is suitable forengineering application.

The invention discloses a clutter suppression method suitable for a high pulse repetition frequency (HPRF) waveform airborne radar. The clutter suppression method comprises the steps of utilizing remote echo data above an nth array element altitude line to evaluate a long-distance main-lobe clutter Q, and utilizing Q to design a matrix filter P so as to extract short range clutter; utilizing P to extract short range clutter in first distance unit data xln of an nth array element, and estimating a short range clutter covariance matrix to adopt an opposite angle loading sampling covariance inversion method to calculate a pitching filter we; utilizing we to suppress short range clutter in xln, and obtaining data Y not containing short range clutter after all the data are processed; performing conversion from a pulse domain to a Doppler domain; taking out data from the Doppler domain and estimating a clutter suppression filter wk; utilizing the filter to suppress remote clutter, processing all Doppler channel data, and outputting to-be-detected data to be used for follow-up radar monitoring processing. According to the clutter suppression method, clutter suppression is achieved in the presence of array errors, the short range clutter can be suppressed well, industrialized achievement is easy, and target detection performance of the airborne radar can be remarkably improved.

The invention relates to an airborne meteorological radar ground clutter suppression method based on double threshold control. The airborne meteorological radar ground clutter suppression method comprises the following steps of: 1) reading inertial navigation parameters and a radio altitude value from an airborne navigation equipment; 2) compensating a clutter frequency spectrum center nearby a zero doppler frequency by utilizing prior information to obtain a clutter region and a spectrum width evaluation initial value; 3) calculating an echo power of each distance unit; 4) evaluating a clutter spectrum center and a spectrum width by utilizing a polar coordinate centroid method; 5) setting a control factor according to the echo powers; 6) calculating a spectrum width threshold and an amplitude control threshold by utilizing the control factor; 7) calculating the number of doppler channels (exceeding the thresholds) in the clutter region of each distance unit; and 8) utilizing the number of the ultralimit channels to design a self-adaptive notch filter, so that the aim that an airborne meteorological radar ground clutter can be realized. The airborne meteorological radar ground clutter suppression method is suitable for airborne meteorological radar ground clutter suppression in a wind shear mode and is simple; and with the adoption of the airborne meteorological radar ground clutter suppression method, the clutter suppression effect is good, and influences on target signal albefaction during the clutter suppression and influences of a residual clutter on a wind shear signal can be reduced.

The invention relates to a ground penetrating radar underground target position detection method. The method comprises the following steps: a ground penetrating radar B-Scan data are subjected to multi-scale amplitude, phase and direction characteristic component extraction; three characteristic components for the first scale are extracted, and a color image is combined by using an HSB channel representation method; a target area of interest is found out; graying is carried out on the color image in the target area of interest, and edge extraction is carried out on an amplitude image in the target area of interest; a target hyperbolas is positioned; and according to the target hyperbolas, target position determination is realized. the method of the invention does not need data training, and online detection is easily carried out; the target information can be kept in a complete mode, the target positioning precision is enhanced, and as for shallow layer detection, false alarms are not likely to be generated, and non metallic pipeline targets are not likely to be omitted; clutter suppression effects can be enhanced, and strong clutters and target echoes can be effectively distinguished; and the algorithm is simple, and target positioning can be ensured to be quickly carried out.

The invention relates to an adaptive clutter suppression moving-target signal processing method, which is mainly applicable to moving-target signal detection in a clutter environment in the field of radar detection. The adaptive clutter suppression moving-target signal processing method comprises processing flows as follows: firstly, dynamically matching pulse-pressed signals; carrying out primary compensation processing on the signals and sending the processed signals into narrow-band filter sets; respectively carrying out distance unit constant false-alarm processing on the signals output by each filter set, and obtaining a detecting result by selecting large output; and calculating an FIR (Finite Impulse Response) coefficient which uses a speed center as a main peak of a filter by using a given movement speed of a target which is focused on, and changing the coefficient of the filter in a adaptive manner. With the adoption of the method disclosed by the invention, the clutter is restrained obviously, the signal to noise ratio of the movement target is improved through the adaptive method, so that the signal detection performance is finally improved. Furthermore, application of VHDL (VHSIC Hardware Description Language) in FPGA (Field Programmable Gate Array) is completely realized. The method disclosed by the invention has wide application prospect in fields such as the radar detection.

The invention relates to the radar anti-interference technical field, in particular to a method for inhibiting ionospheric clutter in portable high frequency groundwave radar. In the invention, a plurality of sets of auxiliary crossed loops are arranged in the vertical direction of original crossed loop antennas of the portable high frequency groundwave radar, adaptive cancellation is carried out on the received signals of auxiliary crossed loop antennas, a main crossed loop and monopole antennas; the received signals of the main crossed loop and the monopole antenna are used as a basic input signal, the difference of the received signals between each auxiliary crossed loop antenna and the main crossed loop antenna are used as a reference signal to input three mutually independent self-adapting filters; an error signal is output from the self-adapting filters to be echoed signals of the main crossed loop and the monopole for inhibiting ionospheric clutter. The invention has the following advantages: an ideal ionospheric clutter reference signal can be obtained and the working efficiency and detection performance of radars can be greatly increased.

The invention belongs to the technical field of airborne MIMO (Multiple-Input-Multiple-Output) radar non-adaptive filtering, and discloses a non-adaptive clutter pre-filtering space-time two-dimensional cancellation method for airborne MIMO radar. The non-adaptive clutter pre-filtering space-time two-dimensional cancellation method comprises the following steps: firstly constructing the clutter model of the airborne MIMO radar, obtaining the parameters, such as radar wavelength, pulse repletion rate, radar transmitted waveform and airborne speed in an angle-Doppler domain distribution trajectory, of clutter, and taking these parameters as prior information for the design of an airborne MIMO space-time two-dimensional pulse phase canceller; then using the designed space-time two-dimensional pulse phase canceller for pre-filtering the clutter. Due to the adoption of the method, the target detection performance by using traditional MTI (Moving Target Indication) of cascading is obviously improved compared with traditional MTI without pre-filtering. Through the application of cascading space-time self-adaptive algorithm after pre-filtering, a majority of clutter power is effectively inhibited, and the algorithm performance is improved. The method is suitable for side-looking radar, and similarly suitable for squint radar.

The invention discloses a non-adaptive clutter cancellation method for a vehicle-mounted MIMO radar and mainly solves the problems of low clutter cancellation performance and large computing amount of the prior art. In the invention, the clutter spectrum broadening caused by clutter fluctuation is taken into consideration and more degree of freedom are used, so as to improve the clutter cancellation performance of the prior art considerably. The method comprises: firstly, establishing a matrix vector model of a ground clutter signal, computing a residual clutter signal, minimizing the energy of the residual clutter signal, obtaining a coefficient matrix and consequently obtaining the result of filter design; and secondly, writing echo data of a plurality of continuous pulses as a long vector, and processing clutters by using a filter to cancel a major part of the clutters. The method is used for space-time two-dimensional cancellation of ground clutters before the conventional space-time cascade processing method and the traditional adaptive processing method. The method is suitable for both sidelooking radars and non-sidelooking radars, and has high clutter cancellation performance.

The invention discloses a unite-domain positioning space-time two-dimensional self-adaptive processing method based on data fitting, and relates to radar technology. The method comprises the steps that 1, JDL dimensionality reduction echo data and space-time guide vectors are obtained; 2, a data basis matrix of a distance unit to be detected is constructed; 3, a data basis matrix with targets blocked is obtained; 4, the fitting coefficient of auxiliary echo data is obtained; 5, the minimum fitting error of data of the distance unit to be detected is obtained; 6, unit average constant false alarm rate detection is carried out on the minimum fitting error of the data of the distance unit to be detected. The unite-domain positioning space-time two-dimensional self-adaptive processing method mainly solves the problem that a traditional STAP method is huge in computation burden and strict in sample requirement, reduces the false alarm rate, improves movable target detection probability, and has the good application prospect in measured data processing and STAP performance improvement.

The invention proposes a double-leveled block sparsity-based space-time adaptive processing radar clutter suppression method, and belongs to the technical field of radar. According to the method, pulse compression and vectorization processing are performed on data acquired by onboard radar within a coherent processing interval, and data of a plurality of distance units around a distance unit to bedetected is taken as a training sample. With the method, the clustering characteristic of clutters in a space-time plane and the combined sparsity characteristic of an adjacent distance unit are combined, the cluster spectrum estimation accuracy is improved by double-leveled block sparsity, so that more accurate cluster covariance matrix estimation is obtained, and weight of a space-time adaptiveprocessing filter is obtained by calculation, and cluster suppression of radar data of the distance unit is achieved through processing the data of the distance unit to be detected by the space-timeadaptive processing filter. By the method, better cluster suppression performance and low-speed target detection performance can be obtained under the condition of a few training samples, and high application value is achieved.

The invention belongs to the technical field of airborne radar space time adaptation processing, and particularly relates to an airborne radar space time adaptation processing method based on environment dynamic perception. The airborne radar space time adaptation processing method based on the environment dynamic perception includes concrete steps: setting a work mode of an airborne radar to be an MIMO (multiple input multiple output) mode, using a receiving array to receive a time domain return signal Y, and representing a clutter scattering coefficient vector in an airborne radar observation area as gamma; marking the position of a jth clutter block of an ith distance unit in the airborne radar observation area as Aij; building a sparse model, and representing a basis matrix corresponding to observation data Y after discretization as H; obtaining vector estimation of the clutter scattering coefficient vector gamma of the airborne radar observation area by solving the sparse model, setting the work mode of the airborne radar to be a phased array mode so as to obtain the distance r'i between the clutter block on the position Aij and the airborne radar and an corresponding return signal arrival angle; obtaining a clutter covariance matrix of units with distance to be detected, and performing space time adaptation processing on a return signal which is received when the airborne radar works under the phased array mode.

The invention discloses a harmonic phase locking frequency source which comprises a crystal oscillator, a microwave sampling phase discriminator, a loop filter and automatic capture circuit, a voltage-controlled oscillator, a coupler and a locking detection circuit. The invention also provides a phase locking method of the harmonic phase locking frequency source. The frequency source provided by the invention has the characteristics of low phase noise, better clutter suppression characteristic and the like.

The invention discloses a design method for a recess width variable MTD filter based on prior information. The method comprises the steps of 1) searching parameters; 2) obtaining a covariance matrix of ground clutters; 3) obtaining initialized interference signal power; 4) designing an FIR filter of a digit integrated method; 5) searching a power spectrum variance of the ground clutters; 6) obtaining an FIR filter of an optimal clutter improvement factor; and 7) designing the recess width variable MTD filter. According to the invention, the prior information of a radar surrounding scene is obtained, so that the clutter improvement factor of the output end of the filter is kept optimal. The problem that the recess width in the zero frequency position of the MTD filter is fixed in the prior art is solved. The MTD filter designed in the method has different expected recess widths for different central frequencies, and detection for low-speed movement objects is enhanced.

The invention relates to the field of radar reception, in particular to a radar receiving digital coherent processing system. The radar receiving digital coherent processing system comprises a first amplification and electrical level conversion module, a second amplification and electrical level conversion module, a two-channel analog-to-digital converter used for analog-to-digital conversion, a field programmable gate array (PFGA) coherent processing model used for coherent processing, a system clock, an interface electrical level conversion module, a two-channel analog-to-digital converter used for analog-to-digital conversion, a first amplifier, a second amplifier and a power supply transformation module used for supplying power to the system, wherein the first amplification and electrical level conversion module and the second amplification and electrical level conversion module are used for receiving and amplifying a conversion, and the first amplifier and the second amplifier are used for amplifying an output signal. A digital signal processing technology and intermediate frequency direct digitalization are used in the PFGA coherent processing model, a convolution operation is conducted through the transmission of a dominant wave signal and an intermediate frequency echo wave digital signal, the influences of an initial phase, frequency instability and amplitude instability of a transmitted signal are eliminated, digital frequency stabilization phase stabilization, self-adaptation frequency compensation and receiving coherent processing can be achieved, the stability and the reliability of the system can be improved, and the clutter wave suppression ability of the complete machine system can be enhanced.

The invention discloses a clutter inhibition method based on sparse representation. The objective of the invention is to solve the problem of high calculation complexity in the prior art. The method comprises steps of 1), generating a linear frequency modulation signal; 2), generating clutter data with logarithm distribution; 3), constructing an echo signal through the generated linear frequency modulation signal and the clutter data; 4), filtering the constructed echo signal; 5), carrying out matching filtering on the filtered output data; 6), carrying out sparse constraint on the data subjected to the matching filtering and establishing a sparse condition constraint model; and 7), solving the established sparse condition constraint model by use of an alternative iteration method, and outputting an optimal weighting factor of the filter and the echo data after the clutter inhibition. According to the invention, by adding the sparse constraint, estimation of a central spectrum of the clutter is not required; the method is advantaged by simple calculation and low operation complexity; and the method can be used for target detection of radar echo signals.

The invention discloses a method for detecting a ground moving target of a high-orbit platform. An along-track interferometric (ATI) method is applied to the high-orbit platform. The ground moving target is detected by using a polynomial distance model-based RD algorithm in combination with a function of estimating the Doppler frequency and the modulation frequency using fractional Fourier transform (FrFT). Compared with a low-orbit satellite-borne SAR system, the high-orbit platform of the present invention has a wide illumination range, a short revisit period, and a good continuous observation capability. A double threshold detection method is used to achieve a good clutter suppression effect in a weak clutter region. Furthermore, the method can detect a plurality of moving targets in aground observation scenario.

The invention belongs to the technical field of radar self-adaptive wave beam forming, and particularly relates to an MIMO (multiple-input multiple-output) radar dimension reduction self-adaptive wave beam forming method. The method comprises the concrete steps that the received K times of echo is sampled, in addition, all vectors obtained through the sampling on the same time of echo signals are ranged according to the lines for forming a data array, and K data matrixes can be obtained; the emitting signal data in the same moment is recorded and is ranged into K data matrixes; the sampling data matrixes of each time of echo signals are used for multiplying the pseudo-inverse of the corresponding emitting signal data matrix, and in addition, the result obtained by the multiplying in each time is recorded; the multi-stage dimension reduction processing is carried out on the singular vector on weight vectors, and further, a bi-iterative algorithm is used for solving each pair of singular vector to approaching to the high-dimension optimum weight vector; the calculated optimum weight is used for carrying out wave beam formation.

The invention belongs to the technical field of radar signal processing and discloses an inhomogeneous clutter suppression method based on Mahalanobis distance reweighting. The method comprises steps of: determining eliminating coefficients corresponding to respective pieces of sampled data according to the Mahalanobis distances between the sampled data and reference data; eliminating interference samples from sampling samples by using the eliminating coefficient to obtain data samples; then selecting corresponding training samples according to the Mahalanobis distances between the data samples and the reference samples, and then constructing a reweighting coefficient for reweighting by further using the Mahalanobis distances between the training samples and the reference samples to obtain a corresponding covariance matrix; finally, constructing an adaptive weight vector by using the covariance matrix, and performing clutter suppression by using the adaptive weight vector to obtain corresponding output power. The method can obtain good clutter suppression performance in the case of different sampling number, and has universality and robustness to the clutter inhomogeneous suppression in complex clutter background.

The invention relates to a ground penetrating radar underground target positioning method and system based on a box spline wavelet framework. Echo image data of a ground penetrating radar is obtained firstly, a direct wave image in the image is removed, and then a ground penetrating radar signal after preprocessing is obtained; the ground penetrating radar signal after the preprocessing is decomposed through adoption of a box spline wavelet then, and edge positioning is performed on a decomposition result; an edge curve of the image is fitted, and a point at which the derivate of the curve is zero is selected and taken as the vertex of the radar image; and an underground target curve equation is established finally, two points on edges are asymmetrically selected on two branches of the vertex of the radar image, an underground target curve is fitted by utilizing a three-point fitting method, and then positioning of an underground target is achieved. Target positioning precision is improved through the positioning method. For possible shallow layer exploration of a metal pipeline and a nonmetallic pipeline, a false alarm is not easy to generate. An algorithm is simple, operation time is short, and target positioning efficiency is improved.

The invention discloses an airborne early warning radar moving target detecting method based on a clutter ridge guiding vector and relates to the radar technique. The method comprises the steps of (1) receiving the space-time two-dimensional echo data of an airborne early warning radar device by means of an airborne early warning radar antenna, (2) determining a normalization space-time two-dimensional frequency point corresponding to a clutter ridge curve position relevant to the space-time two-dimensional echo data, (3) constructing a clutter ridge guiding vector basis matrix according to the normalization space-time two-dimensional frequency point corresponding to the clutter ridge curve position, (4) acquiring data left after fitting, and (5) conducting cell averaging constant false alarm rate detection on the data left. The method mainly solves the problem that in practical application of traditional space-time adaptive processing, the amount of calculation is huge, and the requirement for the number of independent identically distributed samples is high. The method has good application prospects in the improvement of the airborne early warning radar moving target detecting performance.