Journal of Xidian University ›› 2024, Vol. 51 ›› Issue (1): 1-10.doi: 10.19665/j.issn1001-2400.20230102

• Information and Communications Engineering •     Next Articles

Spectrum compression based autofocus algorithm for the TOPS BP image

ZHOU Shengwei1(), LI Ning2(), XING Mengdao1,2()   

  1. 1. National Key Laboratory of Radar Signal Processing,Xidian University,Xi’an 710071,China
    2. Academy of Advanced Interdisciplinary Research,Xidian University,Xi’an 710071,China
  • Received:2022-09-15 Online:2024-01-20 Published:2023-10-24
  • Contact: LI Ning E-mail:swzhou@stu.xidian.edu.cn;ln2walker@163.com;xmd@xidian.edu.cn

Abstract:

In the high squint TOPS mode SAR imaging of the maneuvering platform,by using the BP imaging algorithm in the rectangular coordinate system of the ground plane,the wide swath SAR image without distortion in the ground plane can be obtained in a short time.However,how to quickly complete the motion error compensation and side lobe suppression of the BP image is still difficult in practical application.This paper proposes an improved spectral compression method,which can quickly realize the follow-up operations such as autofocus of the BP image of the ground plane in the high squint TOPS mode of the mobile platform.First,by considering that the traditional BP spectral compression method is only applicable to the spotlight imaging mode,combined with the virtual rotation center theory of high-squint TOPS SAR and the wavenumber spectrum analysis,an improved exact spectral compression function is derived,which can give rise to the unambiguous ground plane TOPS mode BP image spectrum through full-aperture compression,on the basis of which the phase gradient autofocus(PGA) can be used to quickly complete the full aperture motion error estimation and compensation.In addition,based on the unambiguous aligned BP image spectrum obtained by the improved spectral compression method proposed in this paper,the image sidelobe suppression can be realized by uniformly windowing in the azimuth frequency domain.Finally,the effectiveness of the proposed algorithm is verified by simulation data processing.

Key words: TOPS mode, ground rectangular coordinate BP imaging, spectrum compression, motion error compensation, sidelobe suppression

CLC Number: 

  • TN958