volume | PIER Journals

Abstract

This paper presents an efficient imaging algorithm for Terrain Observation by Progressive Scans (TOPS) mode SAR raw data focusing. First, the use of sub-aperture is adopted to overcome the aliased Doppler spectra due to progress azimuth beam scanning. Afterwards, range compression and range cell migration correction (RCMC) are individually implemented in each azimuth block with its individual Doppler centroid. After azimuth sub-aperture signal recombination, a new Doppler centroid varying rate is introduced to avoid the reconstructed Doppler spectra wrapping. Moreover, azimuth varying beam center time is removed by azimuth frequency scaling before the final azimuth spectrum analysis (SPECAN) step. Finally, the conventional Fourier transform (FT) is replaced by the scaled Fourier transform (SCFT) step to obtain the uniform azimuth space sampling interval. Since the proposed imaging algorithm is without any interpolations and azimuth data extension, it is highly efficient. Simulation results on point targets validate the proposed algorithm.

1. Zan, F. D. and A. M. Guarnieri, "TOPSAR: Terrain observation by progressive scans," IEEE Trans. Geosci. Remote Sens., Vol. 44, No. 9, 2352-2360, Sep. 2006.
doi:10.1109/TGRS.2006.873853 Google Scholar

2. Xu, W., P. Huang, and Y.-K. Deng, "Multi-channel SPCMB-TOPS SAR for high-resolution wide-swath imaging," Progress In Electromagnetics Research, Vol. 116, 533-551, 2011. Google Scholar

3. Xu, W., P. Huang, and Y.-K. Deng, "MIMO-TOPS mode for high-resolution ultra-wide-swath full polarimetric imaging," Progress In Electromagnetics Research, Vol. 116, 533, 2011. Google Scholar

4. Meta, A., J. Mittermayer, P. Prats, R. Scheiber, and U. Steinbrecher, "TOPS imaging with TerraSAR-X: Mode design and performance analysis," IEEE Trans. Geosci. Remote Sens., Vol. 48, No. 2, 759-769, Feb. 2010.
doi:10.1109/TGRS.2009.2026743 Google Scholar

5. Prats, P., R. Scheiber, J. Mittermayer, A. Meta, and A. Moreira, "Processing of sliding spotlight and TOPS SAR data using baseband azimuth scaling," IEEE Trans. Geosci. Remote Sens., Vol. 48, No. 2, 770-780, 2010.
doi:10.1109/TGRS.2009.2027701 Google Scholar

6. Mittermayer, J., P. Prats, D. D'Aria, R. Piantanida, S. Sauer, A. M. Guarnieri, E. Attema, and P. Snoeij, "TOPS Sentinel-1 and TerraSAR-X processor comparison based on simulated data," Proc. EUSAR, 1-4, Aachen, Germany, 2010. Google Scholar

7. Prats, P., L. Marotti, S. Wollstadt, et al. "TOPS interferometry with TerraSAR-X," Proc. EUSAR, 44-47, Aachen, Germany, 2010. Google Scholar

8. Xu, W. and Y. K. Deng, "Investigation on electronic azimuth beam steering in the spaceborne SAR imaging modes," Journal of Electromagnetic Waves and Applications, Vol. 25, No. 14-15, 2076-2088, 2011.
doi:10.1163/156939311798071983 Google Scholar

9. Xu, W., P.-P. Huang, and Y.-K. Deng, "TOPSAR data focusing based on azimuth scaling preprocessing," Adv. Space Res., Vol. 48, No. 2, 270-277, 2011.
doi:10.1016/j.asr.2011.03.024 Google Scholar

10. Xu, W., P.-P. Huang, Y.-K. Deng, J.-T. Sun, and X.-Q. Shang, "An efficient imaging approach with scaling factors for TOPS mode SAR data focusing," IEEE Geosci. Remote Sens. Lett., Vol. 8, No. 5, 929-933, Sep. 2011.
doi:10.1109/LGRS.2011.2135837 Google Scholar

11. Prati, C., A. M. Guarnieri, and F. Rocca, "SPOT mode SAR focusing with the ω-k technique," Proc. IGARSS, Espoo, Finland, 1991. Google Scholar

12. Lanari, R., M. Tesauro, E. Sansosti, and G. Fornaro, "Spotlight SAR data focusing based on a two-step processing approach," IEEE Trans. Geosci. Remote Sens., Vol. 39, No. 9, 1993-2004, Sep. 2001.
doi:10.1109/36.951090 Google Scholar

13. Lanari, R., S. Zoffoli, E. Sansosti, G. Fornaro, and F. Serafino, "New approach for hybrid strip-map/spotlight SAR data focusing," IEE Proc. --- Radar Sonar and Navig., Vol. 148, No. 6, 363-372, Dec. 2001.
doi:10.1049/ip-rsn:20010662 Google Scholar

14. Lanari, R., "A new method for the compensation of the SAR range cell migration based on the chirp z-transform," IEEE Trans. Geosci. Remote Sens., Vol. 33, No. 5, 1296-1299, May 1995.
doi:10.1109/36.469496 Google Scholar

15. Bai, X., J. P. Sun, and W. Hong, "On the TOPS mode spaceborne SAR," Science China --- Information Sciences, Vol. 53, No. 2, 367-378, Feb. 2010.
doi:10.1007/s11432-010-0030-z Google Scholar

16. Bamler, R., "A comparison of range-Doppler and wavenumber domain SAR focusing algorithm," IEEE Trans. Geosci. Remote Sens., Vol. 30, No. 4, 706-713, Apr. 1992.
doi:10.1109/36.158864 Google Scholar

17. Moreira, A., J. Mittermayer, and R. Scheiber, "Extended chirp scaling algorithm for air- and spaceborne SAR data processing in stripmap and ScanSAR imaging modes," IEEE Trans. Geosci. Remote Sens., Vol. 34, No. 5, 1123-1136, May 1996.
doi:10.1109/36.536528 Google Scholar

18. Guarnieri, A. M. and C. Prati, "ScanSAR focusing and interferometry," IEEE Trans. Geosci. Remote Sens., Vol. 34, No. 4, 1029-1038, Apr. 1996.
doi:10.1109/36.508420 Google Scholar

19. Mittermayer, J., R. Lord, and E. Boerner, "Sliding spotlight SAR processing for TerraSAR-X using a new formulation of the extended chirp scaling algorithm," Proc. IGARSS, Toulouse, France, 2003.

20. Lanari, R., S. Hensley, and P. A. Rosen, "Chirp z-transform based on SPECAN approach for phase-preserving ScanSAR image generation," IEE Proc. --- Radar Sonar and Navig., Vol. 145, No. 5, Oct. 1998. Google Scholar

21. Wong, F. H. and T. S. Yeo, "An improved technique for the processing of short-dwell spotlight SAR data," IEEE Trans. Geosci. Remote Sens., Vol. 41, No. 5, 953-963, May 2003.
doi:10.1109/TGRS.2003.811078 Google Scholar

22. Dai, C. and X. Zhang, "Omega-k algorithm for bistatic SAR with arbitrary geometry configuration," Journal of Electromagnetic Waves and Applications, Vol. 25, No. 11-12, 1564-1576, 2011.
doi:10.1163/156939311797164972 Google Scholar

23. Guo, D., H. Xu, and J. Li, "Extended wavenumber domain algorithm for highly squinted sliding spotlight SAR data processing," Progress In Electromagnetics Research, Vol. 114, 17-32, 2011. Google Scholar

24. An, D. X., Z.-M. Zhou, X.-T. Huang, and T. Jin, "A novel imaging approach for high resolution squinted spotlight SAR based on the deramping-based technique and azimuth NLCS principle," Progress In Electromagnetics Research, Vol. 123, 485-508, 2012.
doi:10.2528/PIER11112110 Google Scholar

25. Wu, J., Z. Li, Y. Huang, Q. H. Liu, and J. Yang, "Processing one-stationary bistatic SAR data using inverse scaled fourier transform," Progress In Electromagnetics Research, Vol. 129, 143-159, 2012. Google Scholar

Dr. Pingping Huang

Dr. Wei Xu