Polar coordinate format imaging method for bistatic forward SAR of mobile platform

Abstract

The invention discloses a polar coordinate format imaging method for the bistatic forward SAR of the mobile platform, comprising the following steps: transforming the parallelogram wave spectrum support domain of MP-BFSAR into a horizontal quasi-rectangular shape using a wave spectrum support domain affine transformation method; then realizing the re-sampling from a wave spectrum distance vector polar coordinate to a cartesian coordinate by a direction vector chirp-z transformation; performing a distance compression and a scene center motion compensation; realizing the re-sampling from a wavespectrum direction vector polar coordinate to a cartesian coordinate by using a method of accumulating a upsampling map in the direction vector; performing a two-dimensional inverse Fourier transformto obtain a coarse imaging result; and obtaining a final imaging result by defocus correction. The utilization of the wave spectrum collected by the present invention is significantly improved compared to the prior art methods.

Description

technical field [0001] The invention belongs to the field of Bistatic Forward-looking Synthetic Aperture Radar (BFSAR) imaging, and in particular relates to a polar coordinate format algorithm of a bistatic forward-looking synthetic aperture radar of a mobile platform. Background technique [0002] Due to the spatial separation of the transmitting station and the receiving station, bistatic SAR breaks through the forward-looking constraints of SAR, enabling the receiving platform to image the forward-looking terrain in the direction of flight. This unique feature makes BFSAR a promising sensing technology. BFSAR can provide all-day, all-weather forward-looking high-resolution images. [0003] Due to its bistatic forward-looking configuration, the echoes of MP-BFSAR exhibit serious two-dimensional space errors, and its wavenumber spectrum support area is usually a parallelogram instead of a rectangle, so it is difficult to effectively use the collected wavenumber spectrum; d...

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Problems solved by technology

Therefore, it is not suitable for MP-BFSAR whose support area is a parallelogram; the literature "Polar format algorithm wavefront curvature compensation under arbitrary radar flight path, IEEE Geosci.RemoteSens.Lett., vol.9, no.3, pp.526–530, In May 2012", in order to compensate the phase error caused by wavefront bending, a space-varying wavefront bending compensation filter is proposed, which utilizes the internal homogeneity of the resampling operation from polar coordinates to rectangular coordinates. However, the space-varying wave The front curvature compensation filter is implicit and its computation involves two-dimensional interpolation, which means that it is inconvenient and inefficient in practice; the paper "Space-variant filtering for wavefront curvature correction in polar formatted bistatic SAR image, IEEETrans.Aerosp. In Electron.Syst.,vol.48,no.2,pp.940–950,Apr.2012", an analytical space-varying wavefront bending compensation filter is proposed. The motion trajectory is obtained by moving, so it is not suitable for MP-BFSAR, because the motion trajectory of MP-BFSAR is highly nonlinear

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