8results about How to "Reduce sidelobe" patented technology

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 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 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.

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.

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.