18results about How to "Reduce sidelobe" patented technology

The invention provides a communication perception integrated beamforming method and system for suppressing distance-angle side lobes, and the method comprises the steps: enabling a base station to communicate with a plurality of users under a digital beamforming ISAC architecture, and carrying out the detection of an air target in a self-transmitting and self-receiving mode at the same time; determining a sensing channel model and a communication channel model to obtain a communication receiving signal at each user position and a sensing receiving signal scattered back to the base station from the target; calculating to obtain the SINR of each user; a distance-angle-Doppler three-dimensional perception fuzzy function based on a digital beam forming ISAC architecture is obtained; extracting an expression of an integral sidelobe of a distance-angle dimension; according to the communication index, the sensing index and the integral sidelobe value in the preset distance-angle sidelobe area, a beam forming matrix of the ISAC system is designed in a joint optimization mode; auxiliary variables are introduced to convert the problem of optimizing the beam forming matrix into the problem of optimizing a covariance matrix of the beam forming matrix, and a feasible solution of the joint design problem is obtained.

A high-crosstalk array waveguide grating structure capable of changing waveforms and improving demodulation resolution comprises an input optical waveguide, the output end of the input optical waveguide is connected with the input end of a coupling module, and the output end of the coupling module is sequentially connected with a first slab waveguide, an array waveguide and a second slab waveguide. The output end of the second slab waveguide is respectively connected with the input ends of the first output waveguide, the second output waveguide, the third output waveguide and the fourth output waveguide; according to the invention, the array waveguide grating structure connected with the coupling module at the input end is adopted, so that the output spectrum of the adjacent output channels has large bandwidth, the large dynamic range of the adjacent channels during FBG wavelength demodulation is ensured, an optical waveguide width value different from a design value is adopted, the top end waveform of the output spectrum is regulated and controlled, and the demodulation precision is improved. On the premise of ensuring that the dynamic range of adjacent output channels is not changed, the resolution of the demodulation wavelength is improved; the device has the advantages of simple structure, large bandwidth, high crosstalk and high wavelength demodulation resolution.

The application discloses a kind of OFDM signal sidelobe reduction method and system suitable for polar encoding, method includes: sending end is encoded into length M bit by polar code encoder to length N information bit sequence;The element in by reordering device is rearranged to obtain by being arranged by split channel from good to bad order;Adjacent element in is modulated, and obtain;The first K elements of are mapped to the subcarrier in the middle of sending signal, and the last L-K elements are sequentially mapped to the subcarrier on both sides, and the power of L-K signals on both sides of subcarrier is reduced;IDFT conversion is carried out, and it is sent to carrier frequency modulation.The application can effectively reduce the sidelobe of sending signal, and does not affect receiving performance, and can further improve performance at high signal-to-noise ratio.

The application discloses a radar complementary sparse frequency waveform sequence set design method based on a complex circle flow surface algorithm, and specifically comprises the following steps: according to a monitored spectrum environment, delimiting a usable spectrum range and an unusable spectrum range; converting a weighted integral sidelobe level of a waveform sequence set into a quadratic function form with a waveform sequence set vector as a variable, constructing an objective function to describe the weighted integral sidelobe level of the waveform set; calculating a power spectrum of the waveform set, controlling a weighting coefficient according to an expected spectrum, performing weighted summation on the power spectrum, and converting a weighted summation expression of the power spectrum into a quadratic function form with the waveform sequence set vector as the variable; and performing weighted summation on a WISL objective function and an EFS objective function to construct a joint objective function. The CCM optimization algorithm is applied to the complementary sparse frequency waveform sequence set design problem for the first time, effectively solving the constant modulus constraint problem of the waveform sequence, and compared with the existing cyclic iteration algorithm and the interior point method.

The invention discloses a scanning leaky-wave antenna, which comprises a bent waveguide, a waveguide slot and a horn structure which are stacked to form a plurality of array units, one end of the bent waveguide is provided with a feed port, the bent waveguide is composed of a linear waveguide and a slow wave line structure, and matching structures are arranged on two sides of the linear waveguide in a staggered manner; the scanning leaky-wave antenna is composed of a plurality of array units, and reflection of the array units can be superposed at the center frequency, so that a matching structure is added to each array unit, reflection of each array unit is reduced, reflected waves of each array unit are not subjected to phase adding any more, the transmission phase is kept unchanged, and the scanning leaky-wave antenna has the advantages of being simple in structure and convenient to use. Impedance matching at the center frequency can be realized under the condition that the sweep frequency radiation characteristic is not influenced. The antenna has the characteristics of center frequency impedance matching, high gain, symmetrical large scanning range of + / -45 degrees, universality, low cost, simple design structure, low device complexity and suitability for large-range manufacturing.

The invention discloses a noise elimination method and system based on matrix reconstruction, a terminal and a storage medium, and relates to the technical field of underwater acoustic array signal processing. The noise elimination method comprises the following steps: receiving a sound source signal; establishing a noise-containing data model of the sound source signal; obtaining a data snapshot sample of the sound source signal based on the noise-containing data model, and calculating a sample covariance matrix; performing characteristic decomposition on the sample covariance matrix to obtain a signal subspace and a noise subspace; obtaining a distance relationship between two projection matrixes formed by each column vector in the signal subspace and the noise subspace based on a translation invariant subspace theory, and establishing a diagonal matrix based on the distance relationship between the two projection matrixes; and reconstructing a sample covariance matrix by using the diagonal matrix to realize noise elimination. The method has lower sidelobe, better robustness and overall performance, can adaptively process data, does not need to adjust the diagonal load shedding coefficient, and can improve the angular resolution of a target signal to a greater extent.

The application belongs to the technical field of ground penetrating radar, and provides a ground penetrating radar control method, device, equipment and storage medium, wherein the method comprises: generating a frequency sequence group matrix meeting preset requirements of a ground penetrating radar by using a chaotic mapping, optimizing the frequency sequence group matrix according to a preset genetic algorithm, obtaining an orthogonal discrete frequency coding transmission waveform set, based on the orthogonal discrete frequency coding transmission waveform set, calling a double-channel narrowband, wideband transceiver and a heterogeneous system-level chip of the ground penetrating radar to transmit a waveform to the ground and receive a reflected waveform, analyzing and processing the reflected waveform, obtaining a ground penetrating result, so as to improve work efficiency, meet high-speed operation detection requirements, improve detection accuracy of the radar, have a unique advantage for spectrum analysis and interference suppression, realize a balance between detection depth and resolution, and do not need complex signal processing technology.

The present invention discloses a near-zone anti-interference waveform design method and system for unmanned aerial vehicle-borne radar, and relates to the technical field of radar waveform design. The technical points of the present invention include: for unmanned aerial vehicle-borne radar systems, construct a set of pre-coded waveforms based on orthogonal frequency division multiplexing technology; construct waveform optimization constraints; construct waveform optimization objective functions and reference radar waveforms; use the MM algorithm to transform the waveform optimization objective function, and transform the non-convex constraints in the waveform optimization constraints into convex constraints; use standard numerical tools to iteratively solve the transformed waveform optimization objective function to obtain the optimal waveform sequence. The present invention avoids the problem that the common low peak-to-average ratio constraint fails to fully control the uniformity of the transmitting antenna power, and prevents the situation of high-power dynamic range fluctuations and low transmitting power efficiency. The present invention has significant improvements in symbol error rate and average achievable rate, and improves anti-interception performance, with a lower level of correlated side lobes.

The present invention belongs to the technical field of underwater acoustic array signal processing, and discloses a multi-constraint underwater sound source positioning method and system based on improved relative entropy distance, including: obtaining the sound source signal spectrum, extracting the expected signal frequency included in the spectrum, and calculating the covariance matrix after the expected signal frequency is normalized; reconstructing the matrix; dividing the grid points within a preset range; obtaining environmental parameters, performing K random perturbations on the environmental parameters, and obtaining the perturbation matrix at each grid point; calculating and obtaining a multi-constraint copy matrix, and performing normalization processing on the multi-constraint copy matrix to obtain the normalized multi-constraint copy matrix; calculating the improved relative entropy distance between the reconstructed covariance matrix and the normalized multi-constraint copy matrix; obtaining the normalized output power at each grid point based on the improved relative entropy distance; performing spectrum peak search on the normalized output power, and the grid point position corresponding to the maximum peak value is the position of the sound source signal. The present invention has the advantages of small positioning error and high positioning resolution.

The application discloses a MIMO radar waveform design method based on multi-dimensional joint coding, and mainly aims at solving the problems of low waveform design freedom, poor resolution performance and simple waveform form which is easily intercepted. The implementation steps are as follows: constructing a multi-dimensional joint coding MIMO radar waveform initial model; calculating the pulse synthesis result of each sampling point of each target sampling angle by using the echo signal of each target sampling angle of the generated radar array; constructing a cost function of a waveform optimization algorithm according to the sidelobe value of the pulse synthesis result; setting the constraint condition of the waveform optimization algorithm; and optimizing the MIMO radar waveform by using the cost function and the constraint condition. The MIMO radar waveform designed by the application increases the design freedom of the waveform, improves the resolution performance of the radar system on the target, and makes the waveform form complex, thereby improving the anti-interception performance of the waveform.

The invention discloses a single-vector hydrophone orientation estimation method based on a multi-joint understanding convolution projection CBF spatial spectrum, and belongs to the technical field of underwater target detection. The method solves the problem that the existing method does not consider the sound energy information of the self-correlation part of each component in the sound field, so that the performance improvement of the existing method on weak target detection is limited. The method comprises the following steps of: firstly, carrying out multiple combined processing on sound pressure and vibration velocity channel receiving signals of the single-vector hydrophone; obtaining the maximum sound energy of the sound pressure and the combined vibration velocity, the sound energy of a sound pressure channel receiving signal and a vibration velocity x channel receiving signal, the sound energy of the sound pressure channel receiving signal and a vibration velocity y channel receiving signal, the sound energy of the vibration velocity x channel and the vibration velocity y channel, and the difference between the sound energy of the vibration velocity x channel and the sound energy of the sound pressure channel; and calculating a projection CBF spatial spectrum according to the calculated sound energy and the sound energy difference, and carrying out deconvolution on the projection CBF spatial spectrum based on a point spread function to obtain an underwater target orientation estimation result. The method can be applied to underwater target orientation estimation.

The present invention relates to the field of meteorological radar technology, and specifically to an X-band dual-polarization phased array rain radar system and detection method. The system includes hardware equipment, a processing module, and auxiliary accessories; the hardware equipment includes an antenna array subsystem and a radar base subsystem; the processing module includes a polarization channel consistency calibration submodule, a particle phase identification submodule, and a rainfall estimation submodule; the auxiliary accessories include power supply equipment, a generator, lightning protection facilities, an optical fiber network, and a data storage device. A planar microstrip patch array antenna is used, which is designed with a spacing arrangement and has the characteristics of small area and high phase center consistency, ensuring high consistency, low side lobes, and high cross-polarization isolation of dual-polarization beams; at the same time, the detection accuracy is improved by setting a processing module.

The invention discloses a millimeter wave radar array antenna which mainly solves the problems that a traditional millimeter wave radar antenna is large in size, high in cost, low in precision and poor in stability. The antenna array comprises a transmitting antenna array, a receiving antenna array and a mounting platform. The transmitting antenna array comprises a transmitting antenna sub-array and a transmitting control unit, the receiving antenna array comprises five receiving antenna sub-arrays and five receiving control units, and the mounting platform comprises three antenna mounting surfaces which form different included angles with the horizontal plane. The transmitting antenna sub-array and the transmitting control unit are connected through a transmitting circuit, the five receiving antenna sub-arrays and the five receiving control units are connected through a receiving connection circuit, and the transmitting antenna sub-array and the receiving antenna arrays are respectively placed on each mounting surface of the mounting platform after connection. According to the invention, the signal coverage range can be increased, the echo signal receiving efficiency of the receiving antenna is improved, the size of the antenna is reduced, the antenna sidelobe is reduced, and the antenna can be used for unmanned aerial vehicle and automobile collision prevention, adaptive cruise control and blind area detection systems.

This invention provides a method for designing stochastic frequency-modulated waveforms to suppress range sidelobes and range ambiguity. The method includes: Step 1: Initialization, inputting the center frequency f of the waveform. c The first step is to determine the bandwidth B and pulse width T; the second step is to determine the instantaneous frequency f of the RFM waveform based on the random Fourier coefficients. t The variance Var(f) t The third step: design N and D; after determining N, use Var(f) to define the range of N and D. t The range of D can be calculated from the range of ), and the largest possible D is selected within this range to obtain a narrower main lobe width; the fourth step: generate random Fourier coefficients; the fifth step: obtain the output RFM waveform. This invention can generate a large-capacity waveform set with low sidelobes, good quasi-orthogonality, high spectral compactness, and constant amplitude. At the same time, by increasing the number of waveforms, sidelobes can be effectively reduced and the maximum unambiguous distance can be extended.

This invention discloses a dual-polarization angle-selective surface structure for reducing radar sidelobes, comprising an upper structure and a lower structure, with an air gap between them. Both the upper and lower structures include a plurality of frequency-selective surface units arranged in an array. Each frequency-selective surface unit includes a dielectric substrate. A first metal resonant unit structure is disposed on the upper surface of the dielectric substrate, and a second metal resonant unit structure is disposed on the lower surface of the dielectric substrate. The first and second metal resonant unit structures are connected through metal vias on the dielectric substrate. This structure can solve the problem that radar sidelobe blanking technology cannot simultaneously reduce radar sidelobes and avoid introducing redundant additional interference sources.

A piston-type piezoelectric composite plate, an underwater acoustic transducer and a preparation method. The piston-type piezoelectric composite plate is configured as a cylinder, and the piston-type piezoelectric composite plate is spliced ​​by an inner composite plate and an outer composite plate; the inner composite plate is configured as a cylinder that is concentric and equal in height to the piston-type piezoelectric composite plate, and the outer composite plate is configured as a circular cylinder that is concentric and equal in height to the inner composite plate, and the outer composite plate is sleeved on the outer side of the inner composite plate; the inner composite plate and the outer composite plate are both made of 1‑3 type piezoelectric composite materials, and the piezoelectric array density of the inner composite plate is higher than that of the outer composite plate. The underwater acoustic transducer formed by the present invention achieves a larger bandwidth and lower side lobes compared to existing similar products.

The invention discloses a harmonic radar nonlinear phase compensation method and system based on sparse recovery, and belongs to the technical field of harmonic synthetic aperture radar imaging. The method comprises the following steps: extracting a second harmonic component from a received harmonic echo signal; performing pulse compression by adopting an ideal reference function; randomly extracting a part of pulses from all the pulses, and constructing an observation matrix; parameterized phase fitting is carried out on the extracted pulse, and a nonlinear phase coefficient is estimated; reconstructing a full-aperture time-varying nonlinear phase trajectory through sparse recovery by using the sparsity of a phase coefficient in a transform domain; and finally, constructing a time-varying nonlinear compensation function based on the reconstructed phase, performing frequency domain compensation on the signal, and performing SAR imaging processing to obtain a harmonic synthetic aperture radar image with good focusing. Full-aperture phase reconstruction can be realized only by extracting part of pulses, and the method has the advantages of strong anti-noise capability, capability of processing spectrum distortion, avoidance of segmentation error accumulation, high compensation precision and the like.

The invention belongs to an underground cable fault positioning method, and provides a traveling wave time delay estimation method and a related device in order to solve the problem that a traveling wave signal processing algorithm cannot completely meet high-precision and high-adaptability traveling wave time delay detection requirements in a complex electric power scene. Carrying out adaptive frequency band wavelet deconstruction and detail extraction on the first sensing signal and the second sensing signal respectively, and then carrying out dynamic parameter modal splitting based on variational problem solution on each reconstructed signal in the obtained multi-layer first reconstructed signal group and the second reconstructed signal group corresponding to the scale; the method comprises the following steps: obtaining a plurality of intrinsic frequency band modal components with specific sparsity, taking the first intrinsic frequency band modal component as a main mode, comprehensively considering the energy ratio and cross-correlation sharpness of two main modes in each layer, and determining a final traveling wave time delay estimation result according to the cross correlation coefficient of the two main modes under the optimal common decomposition layer. According to the method, the calculation redundancy is reduced while the precision is ensured, and the real-time performance is improved.