Phase Preserving Imaging Method Based on Time Domain Perturbation for High and Low Orbit Bistatic SAR

Abstract

The invention discloses a phase-preserving imaging method for high- and low-orbit dual-base SAR based on time-domain disturbance. The main idea is to determine the high-orbit SAR satellite and the low-orbit SAR satellite, and there are several targets within the detection range of the high-orbit SAR satellite. And determine the target at the center of the ground scene as the target P o , respectively calculate the target P o The three-dimensional coordinate position of , the slant range vector of the high-orbit SAR satellite and the slant-range vector of the low-orbit SAR satellite; then calculate the target P o Based on the single-base equivalent velocity, the consistent distance migration signal is obtained, and then the two-dimensional discrete sampling SAR echo range correction signal is obtained; the consistent azimuth modulation frequency two-dimensional signal is obtained through calculation; and the focused SAR two-dimensional signal is obtained; Finally, the focused phase-preserving SAR image of the high and low orbits is obtained, and the focused phase-preserving SAR image of the high and low orbits is the result of phase-preserving imaging of the high and low orbits based on time domain perturbation.

Description

Technical field [0001] The present invention belongs to the field of signal processing, and in particular, the present invention relates to a time domain perturbation, a high and low rail dual-based SAR correction imaging method, suitable for cooperation signals transmitted by high-track SAR satellite as an active illumination source, low-orbit SAR satellite passive passive passive passive A dual base SAR system enactment imaging process for receiving ground scattering signals. Background technique [0002] The star-loaded synthetic aperture radar is one of the fastest and most effective sensors in microwave remote sensing equipment, and as active sensors can limit all day when the active sensor can limit the light and climatic conditions, all day-to-earth observation. [0003] The star-loaded SAR platform is mainly divided into earth synchronous tracks (high rails) SAR satellite and low orbit (low rail) SAR satellite, low-orbit SAR satellite track height is typically 500km ~ 100...

AI Technical Summary

Problems solved by technology

Therefore, compared with the current spaceborne SAR system, the dual-base SAR system in high and low orbits can significantly improve the earth observation capability and has broad application prospects; technical problems

[0005] Many applications of spaceborne SAR systems are based on SAR images, so it is imperative to study the imaging processing technology suitable for high and low orbit bistatic SAR systems; however, under the complex bistatic imaging geometry of the spaceborne SAR system, For targets at different locations in the scene, due to the strong spatial variability of the bistatic slant range histories in both the range and azimuth directions, the range migration of the echo signal and the azimuth modulation frequency are severely spatially varied, resulting in the traditional single-base SAR imaging In addition, the high- and low-orbit dual-base SAR system has high imaging resolution and wide observation range, and many applications of spaceborne SAR systems are based on phase-preserving SAR images. Therefore, how to achieve high- and low-orbit dual-base SAR high-resolution Phase preserving imaging of wide swaths is also a challenge

[0006] Chen Shichao et al. proposed a co-orbital dual-static SAR imaging method under large squint in the article "Journal of Xidian University, 2014, 41(3): 1-7". However, the dual-base SAR in the same orbit does not have the problem of azimuth modulation frequency space variation, so this method is not suitable for the dual-base SAR system in high and low orbits; Meng Ziqiang wrote in his doctoral thesis "SAR system characteristics and imaging Algorithm Research" (Ph.D. dissertation of Xidian University, 2016) proposed a bistatic SAR imaging method based on series inversion, but the imaging range is small, and the problems of azimuth modulation frequency space variation and phase preservation are not considered

Images