Bistatic SAR motion compensation method based on phase gradient autofocus improvement

Abstract

The invention discloses a bistatic SAR motion compensation method based on phase gradient autofocus improvement. The method mainly solves the problem that in the prior art, motion compensation cannot be carried out under the condition of large motion errors. The method comprises the complementation steps that 1) range migration correction, range compression and deramp processing are carried out on sub-aperture data; 2) non-empty variable phase error estimation is carried out on signals through a PGA method, rough compensation is carried out on the data through the error estimation result, and residual phase errors are obtained; 3) the residual phase errors are unfolded to be a second-order polynomial of the range, and a constant term coefficient and linear and quadratic term coefficients are obtained; 4) the minimum mean square gradient estimation of the three coefficients is obtained through a phase weighting PGA, and the sub-aperture phase errors are obtained through the gradient estimation result; 5) the phase errors of the sub-aperture data are spliced to obtain full-aperture phase errors; 6) motion compensation and bistatic SAR imaging are carried out through the full-aperture phase errors. The method can be used for processing the bistatic SAR data under the condition of the large motion errors.

Description

Technical field: [0001] The invention belongs to the technical field of radar, relates to a bibase SAR motion compensation method, and can be used for bibase SAR imaging processing in the case of large motion errors. Background technique: [0002] The transceiver system of bi-base SAR is installed on different platforms. Due to the characteristics of separate transceivers, it has more advantages than single-base SAR. For example, more abundant target scattering information can be obtained, and the concealment of the receiving station is stronger. , and has a higher anti-stealth ability, etc. However, its configuration is also more complex, so compared with single-base SAR, it puts forward higher requirements for the design of imaging algorithms and the research of motion compensation algorithms. [0003] For high-resolution SAR imaging without high-precision inertial navigation system, it is of great application value to study the motion compensation algorithm based on echo...

AI Technical Summary

Problems solved by technology

However, the above algorithms do not consider the problem of strong spatial variability of the phase error when the strip mode works, and are powerless to deal with the situation where the envelope offset is caused by large motion errors and the phase error has strong spatial variability.

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