51 results about "Keystone transform" patented technology

The invention discloses a moving-target instantaneous distance Doppler imaging method based on detuning and keystone processing; and problems that larger range migration exists in the traditional moving-target moving technology under a circumstance that moving-target motion parameters are unknown and complete azimuth spectra are not included in a baseband are mainly solved. The realizing process comprises the following steps of: (1) receiving an original synthetic aperture radar echo signal and carrying out Fourier transform on the echo signal at range; (2) constructing an azimuth detuning function so as to detune the echo signal; (3) removing linear walking momentum of the echo signal by using Keystone transform; (4) estimating an azimuth fuzzy number of the echo signal after the linear walking momentum is removed and filtering the echo signal at azimuth; and (5) carrying out inverse Fourier transform and Fourier transform on the echo signal, which is filtered at azimuth, at both the azimuth and the range, so as to obtain an imaging result of the echo signal; and according to the invention, an imaging effect of a moving target can be effectively improved; and the moving-target instantaneous distance Doppler imaging method based on detuning and keystone processing, disclosed by the invention, can be used for the field of moving target detection, identification and imaging.

The invention discloses an improved fractional Fourier transform maneuver weak target detection method. The present invention first establishes the uniform acceleration motion signal model of the high-speed maneuvering weak target; then performs Fourier transform on the original echo data in the fast time domain, and after the transformed data undergoes Keystone transformation, the problem of distance unit walking caused by the primary phase is corrected, Then IFFT is performed in the fast time domain, and the FRFT of all orders in p[0,2] is calculated for each range unit in the final echo data obtained to form the signal energy in the fractional order p and fractional order transformation domain u constitutes the two-dimensional distribution of the two-dimensional parameter plane (p, u), and the two-dimensional search of the peak point on this plane can realize the detection of accelerated targets. The invention can realize the detection of the weak maneuvering target in the background environment of low signal-to-noise ratio, and has good reliability, feasibility and real-time performance at the same time.

The invention discloses a method for detecting ground moving targets with bistatic forward-looking synthetic aperture radar. Aiming at the problems of ground moving targets under BFSAR configuration, the solution provided by the invention is: S1. Pre-filtering the original echo signals of each channel Processing; S2, carry out first-order Keystone transformation to the filtering result of each channel of step S1; S3, adopt time-division self-adaptive suppression ground still life clutter; S4, adopt improved Wigner-Ville distribution method to coherently accumulate target energy; The present invention utilizes to remove Oblique pre-filter and Keystone transform to suppress Doppler ambiguity and correct cross-range unit migration, eliminate the influence of cross-Doppler unit migration through time-division adaptive cancellation processing, effectively suppress ground static clutter; and use the improved The Wigner-Ville distribution method coherently accumulates the target energy and improves the signal-to-noise ratio.

The invention discloses a broadband DS / FH (Direct Spreading) / FH (Frequency Hopping) signal parameter estimation method and system based on Keystone transform, and aims to provide a high-precision andlow-complexity broadband DS / FH signal parameter fast estimation method. The technical scheme is as follows: using a differential correlation-based DS / FH signal estimation method to obtain a delay time estimation value of a received signal, dispreading the received signal to obtain a dispreading signal by referring to the delay time estimation value; judging the frequency hopping and a symbol turnover position of the received signal according to the delay time estimation value, performing segmented processing on the dispreading signal, and forming a segmented signal matrix by segmented signals; respectively performing Keystone transform on each row of the segmented signal matrix, and respectively carrying out Fourier transform on each row of the signal matrix after the Keystone transform to obtain a frequency domain matrix, taking module square for the frequency domain, and performing non-coherent accumulation according to columns to obtain accumulated vectors; and finding the frequency fm corresponding to a maximum value from the accumulated vectors, and carrying out speed estimation and completing parameter estimation.

The invention discloses a bistatic forward-looking SAR non-stationary clutter suppression method based on cascade cancellation, which is applied to the field of clutter suppression in synthetic aperture radar moving target detection. The bistatic clutter has strong non-stationary characteristics, and the traditional space-time adaptive method cannot accurately estimate the covariance matrix of the clutter, which leads to the problem that the performance of clutter suppression is seriously degraded. The present invention first adopts the deskewing pre-filter and Keystone transform They are respectively used to remove Doppler ambiguity and correct range unit migration; then use time-division STAP echo domain processing to initially suppress bistatic forward-looking SAR non-stationary clutter and improve signal-to-noise ratio; finally use DPCA image domain based on BP imaging processing, reducing the clutter unit, fully suppressing the residual non-stationary clutter, and further improving the signal-to-clutter ratio, thereby realizing the detection of moving targets.

The invention provides a coherent accumulation detection method applied to a third-order maneuvering target, which belongs to the technical field of radar signals. The invention firstly performs pulse compression in the fast time frequency domain on the echo signal, and then uses the third-order Keystone transform to correct the third-order distance migration of the target. The frequency-shifted cross-correlation and scaled Fourier transform are then used to derive a value that defines the velocity. The first-order distance walking is eliminated by using the fast-time frequency-domain matched filter equation constructed by the defined velocity, and the acceleration and jerk of the target are jointly searched by using the two-dimensional matching filter equation in the fast-time-frequency domain, and the second-order distance walking and multi-dimensional walking of the target are compensated and eliminated. Puller diffusion effect. Finally, the coherent accumulation detection of target energy is carried out by slow-time fast Fourier transform. The invention simultaneously utilizes the amplitude and phase information of the target echo to achieve coherent accumulation, eliminates the range migration and Doppler migration effects of the third-order maneuvering target, can significantly improve the detection performance of the radar, and has strong practicability.